Microbial colonization and degradation of marine microplastics in the plastisphere: A review

Rapid Colonisation of Plastic Surfaces by Marine Alcanivorax Bacteria Is Flagellum-Dependent and Influenced by Polymer Type and Photo-Weathering State

Marine plastic debris provides stable surfaces for microbial colonisation, forming a unique ecosystem known as the plastisphere. Among the early colonisers are Alcanivorax bacteria, hydrocarbon degraders commonly found in oil-polluted seawater and on marine plastic surfaces. This study examined factors influencing the adhesion and colonisation dynamics of six Alcanivorax species. Flagellated species-A. balearicus, A. dieselolei and A. xenomutans-rapidly colonised plastics, particularly polyethylene and polypropylene, while non-flagellated species did not. Notably, plastic photo-weathering treatments led to the elongation of A. dieselolei cells, secretion of extracellular polymeric substance in some cases, and increased colonisation on UVB-treated polyethylene terephthalate. These changes may be linked to the reduced plastic surface hydrophobicity recorded following photo-weathering. To confirm the role of flagella in Alcanivorax adhesion, we disrupted flagellar activity using sub-concentrations of polymyxin B sulfate, resulting in inhibition of swarming motility and complete disruption of colonisation. These results contribute to our understanding of the interactions between hydrocarbon-degrading Alcanivorax bacteria and their plastic substrate, which in turn contributes to the understanding of the ecological impact of plastic pollution in marine environments.

Guidelines toward ecologically-informed bioprospecting for microbial plastic degradation

Biological degradation of plastics by microbial enzymes offers a sustainable alternative to traditional waste management methods that often pollute the environment. This review explores ecologically-informed bioprospecting for microorganisms possessing enzymes suitable for biological plastic waste treatment. Natural habitats enriched in plastic-like polymers, such as insect-derived polyesters, epicuticular microbial biofilms in the phyllosphere of plants in extreme environments, or aquatic ecosystems, are highlighted as promising reservoirs for bioprospecting. Anthropogenic habitats, including plastic-polluted soils and the plastisphere, have yielded potent enzymes such as PETases and cutinases, which are being exploited in biotechnology. However, bioprospecting in plastispheres and artificial environments frequently leads to the isolation of environmental opportunistic microorganisms, such as Pseudomonas aeruginosa, Aspergillus fumigatus, Parengyodontium album, or species of Fusarium, which are capable of becoming human and/or plant pathogens. These cases necessitate stringent biosecurity measures, including accurate molecular identification, ecological assessment, and containment protocols. Beyond advancing bioprospecting approaches toward a broader scope of relevant habitats, this review underscores the educational value of such screenings, specifically, in understudied natural habitats, emphasizing its potential to uncover novel enzymes and microorganisms and engage the next generation of researchers in interdisciplinary study integrating environmental microbiology, molecular biology, enzymology, polymer chemistry, and bioinformatics. Finally, we offer guidelines for microbial bioprospecting in various laboratory settings, ranging from standard environmental microbiology facilities to high-biosecurity facilities, thereby maximizing the diversity of scientists who may contribute to addressing urgent environmental challenges associated with plastic waste.

Microplastic biofilms as potential hotspots for plastic biodegradation and nitrogen cycling: a metagenomic perspective

Microplastics are an emerging contaminant worldwide, with the potential to impact organisms and facilitate the sorption and release of chemicals. Additionally, they create a novel habitat for microbial communities, forming biofilms known as the plastisphere. While the plastisphere has been studied in select aquatic environments, those in estuarine ecosystems merit additional attention due to their proximity to plastic debris sources. Additionally, the role plastisphere communities play in nutrient cycling has rarely been examined. This study used metagenomic analysis to investigate the taxonomic composition and functional genes of developing plastisphere communities living on petroleum-based (polyethylene and polyvinyl chloride) and biopolymer-based (polylactic acid) substrates. Isolated metagenome-assembled genomes (MAGs) showed plastisphere communities have the genes necessary to perform nitrification and denitrification and degrade petroleum and biopolymer-based plastics. The functions of these plastispheres have implications for estuarine nitrogen cycling and provide a possible explanation for the plastisphere microbes' competitiveness in biofilm environments. Overall, microplastics in the estuarine system provide a novel habitat for microbial communities and associated nitrogen cycling, facilitating the growth of microbes with plastic-degrading capabilities.

Biofilm development as a factor driving the degradation of plasticised marine microplastics

Biodegradation of microplastics facilitated by natural marine biofouling is a promising approach for ocean bioremediation. However, implementation requires a comprehensive understanding of how interactions between the marine microbiome and dominant microplastic debris types (e.g., polymer and additive combinations) can influence biofilm development and drive biodegradation. To investigate this, polystyrene (PS) and polyvinyl chloride (PVC) microplastics (< 200 µm in diameter) were prepared either without any additives (i.e., virgin) or containing 15 wt% of the plasticisers diethylhexyl phthalate (DEHP) or bisphenol A (BPA). Each polymer-plasticiser microplastic combination was exposed to environmentally relevant conditions in a simulated seawater mesocosm representative of tropical reef waters over a 21-day period to allow for natural biofilm development. Following this, microplastic degradation and the colonising bacterial biofilm was assessed as a function of time, polymer and plasticiser type using infrared, thermal, gel permeation and surface characterisation techniques, as well as 16S ribosomal RNA bacterial gene sequencing, respectively. Together, these analyses revealed time-, polymer- and plasticiser-dependent degradation, particularly of the PS-BPA microplastics. Degradation of the PS-BPA microplastics also coincided with changes in bacterial community composition and an increased total relative abundance of putative biodegradative bacteria. These findings indicate that the metabolic potential and biodegradative capability of the colonising marine biofilm can be significantly impacted by the chemical properties of the microplastic substrate, even within short timeframes.

Non-degradable microplastic promote microbial colonization: A meta-analysis comparing the effects of microplastic properties and environmental factors

Microplastics serve as favorable substrates for microbial colonization, promoting biofilm formation, which consequently facilitates the accumulation of pollutants and aids in the degradation of microplastics. Hence, obtaining a thorough comprehension of the factors that influence the development of microplastic biofilms is imperative. Nevertheless, there have been conflicting responses concerning biofilm formation in conjunction with microplastic characteristics and environmental conditions. As a result, a meta-analysis was conducted to quantitatively evaluate the impact of microplastic properties and environmental factors on biofilm formation. The findings indicated that the type and size of microplastics significantly influence biofilm growth on their surfaces. Non-degradable microplastics, particularly polyvinyl chloride (PVC) and polystyrene (PS), exhibited higher surface biomass and biodiversity in microplastic-attached biofilms compared to degradable microplastics. Furthermore, it was observed that smaller microplastics were more conducive to microbial colonization. Model selection and correlation analysis further indicated that the environment acts as a substantial predictor of biofilm formation, with prolonged exposure significantly enhancing microbial diversity within biofilms as opposed to short-term exposure. Moreover, meta-regression analysis illustrated a positive correlation between biofilm biomass and alpha-diversity with temperature, while salinity exhibited a negative correlation in diverse aquatic settings. Notably, the ease of biofilm formation on microplastics was observed to be greater in oceans compared to lakes, yet biofilms exhibited a higher diversity increment in lakes than their oceanic counterparts. In the long-term growth of biofilms, initial biomass and diversity are influenced by microplastic characteristics and the surrounding environment, although environmental influences may assume more significance as time progresses.

Challenges of exopolysaccharides production from polystyrene degradation by bacterium CHB 1.5 strain

Polystyrene (PS), a substance that constitutes a significant portion of plastic waste, has resulted in environmental pollution and adverse health effects. Biodegradation and chemical transformation of PS are limited. However, biodegradation is one alternative way to reduce plastic pollution. This research aims to select plastic-degrading bacteria and produce exopolysaccharides (EPS) from plastic waste. Among the marine plastic waste at Chala tat Beach (Songkhla, Thailand), 35 rod-shaped and Gram-positive bacteria were found. The selected strains that exhibited the highest optical density (OD) at 600 nm were CHB1.5, CHD2.2, and CHC3.2. The efficiency of EPS production was tested and showed that CHB 1.5 could produce the maximum amount of EPS (13.47 ± 0.10 g/L) with a significant difference. After four weeks of plastic breakdown, CHB 1.5 had the highest total count (4.03 ± 0.02 Log CFU/mL), followed by CHD2.2 and CHC3.2 (3.99 ± 0.12 and 3.96 ± 0.02 Log CFU/mL, respectively). CHB 1.5 was also examined to use PS foam as a carbon source in modified Mineral Salt Medium for EPS production, with an EPS yield of 1.36 ± 0.08 g/L in week 4. The presence of amides I, polysaccharides, benzene rings, and hydroxyl groups (O-H) was detected by Fourier transform infrared spectroscopy. The Scanning Electron Microscope images confirmed the adherence of the CHB1.5 strain and EPS formation on the plastic sheet. In conclusion, the strain CHB1.5 showed promising potential for degrading PS plastic and producing EPS. Its qualities could be utilized in the future, as well as contribute to the reduction of plastic pollution in the environment in an eco-friendly way.

Assessing the impact of micro and nanoplastics on the productivity of vegetable crops in terrestrial horticulture: a comprehensive review

Micro and nano plastics (MNPs) pollution has emerged as a significant environmental issue in recent years. Plastic contamination in the environment poses risks to both human health and other organisms within the ecosystem. This review discusses the overall impact of MNPs on the performance of vegetable crops, including a global perspective on the topic. Bibliometric analysis reveals that most research on this subject has been concentrated in a few countries, although the number of studies has notably increased in recent years. MNPs accumulate in arable lands due to human activities, often altering the soil's physical, chemical, and biological properties in the rhizosphere. Vegetable crops absorb these MNPs mainly through their roots, leading to accumulation in the edible parts of the plants. Consequently, this results in phytotoxic symptoms and poor growth and development. The phytotoxic effects of MNPs are attributed to genetic and metabolic changes within the plant's cellular structure. Current research on MNPs has been limited to a few vegetable cultivars. Future studies should encompass a broader range of vegetable crops under both laboratory and field conditions to advance this burgeoning field of research. Additionally, examining various types of plastics is essential to comprehensively understanding their impact.

Enhanced biodegradation of high-density polyethylene microplastics: Study of bacterial efficiency and process parameters

As global microplastic (MP) pollution intensifies, sustainable and effective remediation methods are gaining interest due to the growing environmental and health implications. Microorganisms are demonstrating remarkable capabilities to degrade these polymers, offering a promising solution for reducing MP contamination. The aim of this study was to utilize bacteria for the degradation of high-density polyethylene (HDPE) MPs, specifically Comamonas testosteroni NCIMB 8955, Bacillus firmus NCTC 10335 and Paenibacillus macquariensis NCTC 10419. During the incubation, bacterial growth, pH and carbohydrate concentration were monitored, and samples were taken to track MP weight loss and changes in surface morphology and functional groups. Gravimetric analysis revealed degradation efficiencies of 15.30 %, 13.00 %, and 12.29 % for B. firmus NCTC 10335, P. macquariensis NCTC 10419, and C. testosteroni NCIMB 8955, respectively, over 30 days or less. Scanning electron microscopy (SEM) further confirmed degradation, revealing surface deterioration and biofilm formation. Energy dispersive X-ray spectroscopy (EDS) showed changes in the functional groups on the polymer surface, indicating an increase in the O/C molar ratio. Fourier-transform infrared spectroscopy (FTIR) revealed an increase in the carbonyl and vinyl indexes. The influence of temperature, MP size, and concentration on biodegradation was systematically studied using C. testosteroni NCIMB 8955, which demonstrated the highest degradation rate. The best result, i.e., a degradation efficiency of 21.81 %, was achieved at 35 ºC, with MP sizes between 20 and 100 µm, and a concentration of 200 mg/L. These findings highlight the importance of process parameters during biodegradation and the potential of C. testosteroni NCIMB 8955 in developing sustainable bioremediation approaches to mitigate microplastic pollution.

Uncovering layer by layer the risk of nanoplastics to the environment and human health

Nanoplastics (NPs), defined as plastic particles with dimensions less than 100 nm, have emerged as a persistent environmental contaminant with potential risk to both environment and human health. Nanoplastics might translocate across biological barriers and accumulate in vital organs, leading to inflammatory responses, oxidative stress, and genotoxicity, already reported in several organisms. Disruptions to cellular functions, hormonal balance, and immune responses were also linked to NPs exposure in in vitro assays. Further, NPs have been found to adsorb other pollutants, such as persistent organic pollutants (POPs), and leach additives potentially amplifying their advere impacts, increasing the threat to organisms greater than NPs alone. However, NPs toxic effects remain largely unexplored, requiring further research to elucidate potential risks to human health, especially their accumulation, degradation, migration, interactions with the biological systems and long-term consequences of chronic exposure to these compounds. This review provides an overview of the current state-of-art regarding NPs interactions with environmental pollutants and with biological mechanisms and toxicity within cells.

Metagenomic insights into the functional potential of non-sanitary landfill microbiomes in the Indian Himalayan region, highlighting key plastic degrading genes

Solid waste management in the Indian Himalayan Region (IHR) is a growing challenge, intensified by increasing population and tourism, which strain non-sanitary landfills. This study investigates microbial diversity and functional capabilities within these landfills using a high-throughput shotgun metagenomic approach. Physicochemical analysis revealed that the Manali and Mandi landfill sites were under heavy metal contamination and thermal stress. Taxonomic annotation identified a dominance of bacterial phyla, including Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes, with genera like Pseudomonas and Bacillus prevalent. Squeezemeta analysis generated 9,216,983 open reading frames (ORFs) across the sampling sites, highlighting diverse metabolic potentials for heavy metal resistance and degrading organic, xenobiotics and plastic wastes. Hierarchical clustering and principal component analysis (PCA) identified distinct gene clusters in Manali and Mandi landfill sites, reflecting differences in pollution profiles. Functional redundancy of landfill microbiome was observed with notable xenobiotic and plastic degradation pathways. This is the first comprehensive metagenomic assessment of non-sanitary landfills in the IHR, providing valuable insights into the microbial roles in degrading persistent pollutants, plastic waste, and other contaminants in these stressed environments.

Impact of plastic pollution on ecosystems: a review of adverse effects and sustainable solutions

The primary source of the growing concern regarding marine, aquatic, and land pollution is plastic products, the majority of which are made of synthetic or semi-synthetic organic compounds. These combinations include materials like coal and natural gas that are obtained through petrochemical processes. As these two types of plastic-derived products are produced and disposed of, they have a major impact on the ecosystems. According to recent figures, around 400 million tons of plastic and related products derived from plastic are produced annually, and it became double in the last two decades. Plastic pollutants are introduced into ecosystems by a variety of stakeholders at different points in their daily lives, whether intentionally or accidentally. They have become a major source of adverse effects, toxicity development in natural entities, and problems. The aquatic, marine, and land ecosystems are vital to human existence, which emphasizes how difficult it is to stop pollution from it. This review highlights the adverse impacts of plastics, plastic-based products, and micro-nanoplastics on aquatic, terrestrial, and marine ecosystems while addressing advances in biodegradable plastics, recycling innovations, plastic-degrading enzymes, and sustainable solutions to reduce environmental risks.

Exploring the ecotoxicological impacts of microplastics on freshwater fish: A critical review

Microplastics (MPs) have become ubiquitous in the environment, prompting significant concern among ecotoxicologists due to their potential toxic effects. These particles originate from various sources, including the fragmentation of larger plastic debris (secondary microplastics) and consumer products such as liquid soaps, exfoliants, and cleaning agents. The widespread use of plastics, coupled with inadequate waste management, poses a growing threat to ecosystem health worldwide. MPs are plastic particles composed of high-molecular-weight polymers that exhibit biochemical stability. Plastics break down into MPs and even smaller nanoplastics through various degradation mechanisms, such as exposure to UV radiation from sunlight and other environmental factors. Due to their resemblance to certain types of zooplankton and food particles, MPs are often ingested by fish, entering their digestive systems. Once inside, they do not remain solely in the gut; rather, they infiltrate the fish's circulatory and lymphatic systems, eventually distributing throughout various tissues and organs. Microplastics have been found in fish gills, muscles, liver, heart, swim bladders, ovaries, spinal cords, and even brains. The presence of MPs in these organs has been linked to significant adverse effects, including reproductive, neurological, hormonal, and immune system disruptions. This toxicity extends beyond fish, as bioaccumulation and biomagnification of MPs affect other organisms as well, marking MPs as a major anthropogenic stressor that impacts ecosystems at multiple levels. Research indicates that nearly all aquatic environments globally are at risk of MP contamination. Laboratory and field studies highlight fish as particularly susceptible to MP ingestion, though freshwater species have been less extensively studied than marine counterparts. After exposure, fish may suffer various health issues, either directly from MPs or from their interaction with other contaminants. The broader environmental implications of these laboratory findings and the specific role of MPs in increasing fish exposure to harmful chemicals remain topics of ongoing debate. This review aims to contribute to ecotoxicological insights on fish contamination by MPs and outline areas for future investigation.

Microplastic and nanoplastic pollution: Assessing translocation, impact, and mitigation strategies in marine ecosystems

The widespread presence of plastic debris in marine ecosystems was first highlighted as a serious concern in the United Nations Convention on the Law of the Sea (UNCLOS) and the 1972 London Convention. This realization identified plastic pollution as one of the major global environmental issues. Majorities of plastic debris are neither recycled nor incinerated, as a result, it eventually makes its way into lakes, rivers, and oceans. Analysis of water and sediment worldwide indicates that microplastics and nanoplastic are ubiquitous in soils, freshwater, and marine ecosystems. Microplastic and nanoplastics are distributed throughout marine environments via processes such as biofouling and chemical leaching, contaminating both pelagic and benthic species. Despite growing recognition of the hazards posed by microplastics and nanoplastics, regulatory efforts remain hampered by limited understanding of their broader ecological impacts, particularly how diverse factors translate into population declines and ecosystem disruptions. This review examines the pathways of microplastic and nanoplastic pollution, their interactions with other environmental stressors such as climate change and chemical pollution, and their effects on marine food webs. The review highlights the urgent need for further research into the behavior and fate of nanoplastics, which are the degradation product of microplastics, owing to their nano size they pose additional risks, unique properties, and potential for widespread ecological impacts. Studies have demonstrated that smaller microplastics and nanoplastics, particularly nanoplastics, are more toxic than larger microplastics. Additionally, microplastics and nanoplastics serve as vectors for contaminants such as heavy metals, exacerbating their toxicity. They also translocate through marine food chains, posing potential health risks. While evidence of their impact continues to grow, the chronic toxicity of microplastics and nanoplastics remains poorly understood, emphasizing the need for further research, particularly at the cellular level, to fully understand their effects on marine ecosystems and human health. This review also concludes with a call for standardized measurement methods, effective mitigation strategies, and enhanced international cooperation to combat this escalating threat. Future research should prioritize the complex interactions between microplastics and nanoplastics, other pollutants, and marine ecosystems, with the ultimate goal of developing holistic approaches to manage and mitigate the impact of plastic pollution. PRACTITIONER POINTS: Microplastic/nanoplastic translocate through marine food webs, affecting species and human health. Nanoplastics are more toxic than microplastics, exacerbating environmental risks. Nanoplastic aggregation influences their distribution and ecological interactions. Future research should focus on nanoplastic behavior, transport, and toxicity.

Human Activity as a Growing Threat to Marine Ecosystems: Plastic and Temperature Effects on the Sponge Sarcotragus spinosulus

Human activities increasingly threaten marine ecosystems through rising waste and temperatures. This study investigated the role of plastics as vectors for Vibrio bacteria and the effects of temperature on the marine sponge Sarcotragus spinosulus. Samples of plastics and sponges were collected during July, August (high-temperature period), and November (lower-temperature period). Bacterial growth and sponge responses were analysed using biochemical biomarkers. The results revealed a peak in colony-forming units (CFU), particularly of Vibrio alginolyticus, on plastics and sponges in August, followed by a decrease in November. In August, CFU counts of Vibrio spp. were significantly higher in sponges with poor external appearance (characterized by dull coloration and heavy epiphytic growth) but returned to levels observed in healthy sponges by November. Microplastics were detected in the tissues of both sponge groups, with higher concentrations found in affected specimens. Biomarker analyses revealed increased lysozyme, glutathione S-transferase, catalase, and superoxide dismutase activities in healthy sponges during August, while malondialdehyde levels, indicating oxidative damage, were higher in affected sponges. In conclusion, affected sponges exhibited elevated CFU counts of Vibrio spp. and reduced antioxidant and detoxification responses under elevated temperatures. These findings suggest that combined impacts of plastics and warming may pose significant risks to S. spinosulus in the context of global climate change.

Analysis of microplastic contamination and associated human health risks in Clarias gariepinus and Oreochromis niloticus from Kubanni Reservoir, Zaria Nigeria

Environmental safety has become a major concern in recent years due to the global increase in microplastic pollution. These ubiquitous, tiny, and potentially toxic plastic particles enter aquatic environments through weathering of larger plastics and the release of microbeads. Although numerous studies have focused on microplastic pollution in developed regions, information from developing countries remains limited. This study assessed the presence of MPs and associated oxidative stress responses in two commercial fish species, Clarias gariepinus (Catfish) and Oreochromis niloticus (Nile Tilapia), from Kubanni reservoir, Zaria, Nigeria, over six months spanning both the dry and rainy seasons. Fibers were identified as the most abundant MP particles, followed by fragments, films, and beads, in the order of fibers > fragments > films > beads. The highest fiber concentrations were recorded in the gills, with Clarias garipinus showing 11.5 MP items/individual and Oreochromis niloticus showing 22.5 MP items/individual. Black microplastics were predominant, and the most common ingested MP ranged from 1.0 to 2.0 mm. The primary polymers identified were polypropylene and polyethylene terephthalate. Evidence of oxidative stress and cellular damage was observed in the gills, liver, and dorsal muscles of both fish species, which correlated with MPs ingestion. According to recommendations from the European Food Safety Authority regarding fish consumption by children and adults, individuals consuming Clarias gariepinus and Oreochromis niloticus from the Kubanni reservoir may be exposed to between 70 and 700 MP items/organ. The risk associated with consuming MPs found in fish gills and guts was notably higher, posing significant concerns for human health. This study provides insights into microplastic contamination in commercially important fish from the Kubanni Reservoir and highlights the environmental and public health risks associated with consuming contaminated fish from this ecosystem.

The effects of plastisphere on the physicochemical properties of microplastics

The plastisphere is the microbial communities that grow on the surface of plastic debris, often used interchangeably with plastic biofilm or biofouled plastics. It can affect the properties of the plastic debris in multiple ways. This review aims to present the effects of the plastisphere on the physicochemical properties of microplastics systematically. It highlights that the plastisphere modifies the buoyancy and movement of microplastics by increasing their density, causing them to sink and settle out. Smaller and film microplastics are likely to settle sooner because of larger surface areas and higher rates of biofouling. Biofouled microplastics may show an oscillating movement in waterbodies when settling due to diurnal and seasonal changes in the growth of the plastisphere until they come close to the bottom of the waterbodies and are entrapped by sediments. The plastisphere enhances the adsorption of microplastics for metals and organic pollutants and shifts the adsorption mechanism from intraparticle diffusion to film diffusion. The plastisphere also increases surface roughness, reduces the pore size, and alters the overall charge of microplastics. Charge alteration is primarily attributed to changes in the functional groups on microplastic surfaces. The plastisphere introduces carbonyl, amine, amide, hydroxyl, and phosphoryl groups to microplastics, causing an increase in their surface hydrophilicity, which could alter their adsorption behaviors for heavy metals. The plastisphere may act as a reactive barrier that enhances the leaching of polar additives. It may anchor bacteria that can break down plastic additives, resulting in decreased crystallinity of microplastics. This review contributes to a better understanding of how the plastisphere alters the fate, transport, and environmental impacts of microplastics. It points to the possibility of engineering the plastisphere to improve microplastic biodegradation.

Shallow shotgun sequencing of healthcare waste reveals plastic-eating bacteria with broad-spectrum antibiotic resistance genes

The burgeoning crises of antimicrobial resistance and plastic pollution are converging in healthcare settings, presenting a complex challenge to global health. This study investigates the microbial populations in healthcare waste to understand the extent of antimicrobial resistance and the potential for plastic degradation by bacteria. Our metagenomic analysis, using both amplicon and shallow shotgun sequencing, provided a comprehensive view of the taxonomic diversity and functional capacity of the microbial consortia. The viable bacteria in healthcare waste samples were analyzed employing full-length 16S rRNA sequencing, revealing a diverse bacterial community dominated by Firmicutes and Proteobacteria phyla. Notably, Proteus mirabilis VFC3/3 and Pseudomonas sp. VFA2/3 were detected, while Stenotrophomonas maltophilia VFV3/2 surfaced as the predominant species, holding implications for the spread of hospital-acquired infections and antimicrobial resistance. Antibiotic susceptibility testing identified multidrug-resistant strains conferring antimicrobial genes, including the broad-spectrum antibiotic carbapenem, underscoring the critical need for improved waste management and infection control measures. Remarkably, we found genes linked to the breakdown of plastic that encoded for enzymes of the esterase, depolymerase, and oxidoreductase classes. This suggests that specific bacteria found in medical waste may be able to reduce the amount of plastic pollution that comes from biological and medical waste. The information is helpful in formulating strategies to counter the combined problems of environmental pollution and antibiotic resistance. This study emphasises the importance of monitoring microbial communities in hospital waste in order to influence waste management procedures and public health policy. The findings highlight the need for a multidisciplinary approach to mitigate the risks associated with antimicrobial resistance and plastic waste, especially in hospital settings where they intersect most acutely.

Dissemination of antibiotic-resistant bacteria associated with microplastics collected from Monastir and Mahdia coasts (Tunisia)

The exponential use of plastics and their recalcitrant nature leads to their significant accumulation in the environment. The occurrence of plastic wastes is considered as a serious environmental problem. Additionally, plastic wastes can break down into smaller pieces called microplastics (MPs), leading to further interactions with the environment and living organisms. In this study, sixty-six strains were isolated from microplastic particles collected on different coastal areas of Monastir and Mahdia (Tunisia). The different bacterial isolates were identified according to some biochemical tests such as catalase, oxidase, and were subjected to molecular characterization. Amplification of the internal transcribed spacer (ITS) revealed the presence of 31 ITS haplotypes. The partial sequencing of the 16S ribosomal DNA of representative strains was analyzed. The majority of bacterial isolates (84.31 %) belonged to Gamma-proteobacteria (84.78 %), while the remaining isolates were affiliated to Firmicutes (15.21 %). The microplastic-associated bacterial isolates belonged to 10 genera, namely Acinetobacter, Pseudomonas, Bacillus, Staphylococcus, Shewanella, Aeromonas, Vibrio, Stutzerimonas, Exiguobacterium, Enterobacter. Among the well-represented Acinetobacter genus, the most common species identified was Acinetobacter johnsonii. Susceptibility patterns of these strains were studied against 21 antibiotics commonly used in Tunisia. A high level of antibiotic resistance was observed for Penicillin G (97.82 %) and Temocillin (86.95 %). S26 strain presented the highest multidrug resistance with a multiple antibiotic resistance (MAR) index of 0.71.

Rapid colonisation of environmental plastic waste by pathogenic bacteria drives adaptive phenotypic changes

Microbial biofilms on environmental plastic pollution can serve as a reservoir for both pathogenic and commensal bacteria. Associating with this 'plastisphere', provides a mechanism for the wider dissemination of pathogens within the environment and a greater potential for human exposure. For pathogens to bind to environmental plastic waste they need to be in close contact with it; therefore, understanding how rapidly pathogens can bind to plastics and the temporal colonisation dynamics of the continual cycling between the plastisphere and the environment are important factors for quantifying the persistence of human pathogens. Using simulated environmental conditions, we demonstrate that pathogenic E. coli O157 can rapidly colonise plastics (within 30 min) and persist for extended periods (at least 21 days), at concentrations sufficient to cause human infection. Importantly, repeated colonisation and dissociation cycles of E. coli O157 from the plastisphere leads to an enhanced capacity for persistence and the emergence of variants with increased virulence traits, including improved biofilm formation and antibiotic tolerance. This phenotypic adaptation to repeated colonisation of environmental plastic surfaces could be selecting for more persistent and virulent strains of pathogens, and hence increase the co-pollutant risks associated with plastic pollution.

Microplastics: The imperative influencer in blueprint of blue economy

The burgeoning issue of microplastic pollution in marine ecosystems has emerged as a significant concern, presently multifaceted difficulty to the sustainability and prosperity of the blue economy. This review examines the intricate link between microplastics (MPs) and the blue economy (BE), exploring how microplastics infiltrate marine environments, their persistence, and their impacts on economic activities reliant on healthy oceans in a global scenario. Diminished seafood quality and quantity, degraded coastal aesthetics affecting tourism revenues, and increased operational costs due to fouling and contamination are among the economic repercussions identified. Additionally, the review discusses the potential long-term consequences on human health and food security, emphasizing the urgency for proactive mitigation measures and policy interventions in the global scenario. The study highlights the interconnectedness of the blue economy and environmental health, prompting a comprehensive strategy to mitigate microplastic pollution. It calls for collaborative efforts among stakeholders, including policymakers, industries, academia, and civil society, to develop innovative strategies for combating microplastic pollution and promoting sustainable blue economic practices. In conclusion, the review stresses the pressing need for concerted action to address microplastic threats to the blue economy, recommending science-based policies, technological innovations, and public awareness campaigns to protect marine ecosystems and ensure the resilience and prosperity of ocean-dependent economic activities.

Potentially pathogenic bacteria in the plastisphere from water, sediments, and commercial fish in a tropical coastal lagoon: An assessment and management proposal

Microplastics in aquatic ecosystems harbor numerous microorganisms, including pathogenic species. The ingestion of these microplastics by commercial fish poses a threat to the ecosystem and human livelihood. Coastal lagoons are highly vulnerable to microplastic and microbiological pollution, yet limited understanding of the risks complicates management. Here, we present the main bacterial groups, including potentially pathogenic species, identified on microplastics in waters, sediments, and commercial fish from Ciénaga Grande de Santa Marta (CGSM), the largest coastal lagoon in Colombia. DNA metabarcoding allowed identifying 1760 bacterial genera on microplastics, with Aeromonas and Acinetobacter as the most frequent and present in all three matrices. The greatest bacterial richness and diversity were recorded on microplastics from sediments, followed by waters and fish. Biochemical analyses yielded 19 species of potentially pathogenic culturable bacteria on microplastics. Aeromonas caviae was the most frequent and, along with Pantoea sp., was found on microplastics in all three matrices. Enterobacter roggenkampii and Pseudomonas fluorescens were also found on microplastics from waters and fish. We propose management strategies for an Early Warning System against microbiological and microplastic pollution risks in coastal lagoons, illustrated by CGSM. This includes forming inter-institutional alliances for research and monitoring, accompanied by strengthening governance and health infrastructures.

Plastisphere in a low-pollution mountain river: Influence of microplastics on survival of pathogenic bacteria

Microplastics (MPs) are found even in remote and low-pollution freshwater ecosystems. However, the microbial communities associated with MPs in these environments remain poorly understood. We characterized the plastisphere in a low-pollution riverine ecosystem and evaluated the influence of different MPs in the persistence of pathogens in such environments. A mixture of MPs (MPs Mix) composed of polyethylene (PE), polypropylene (PP) and polyethylene terephthalate (PET), was submerged at three locations (L1, L2 and L3) in the river. For comparison purposes, water and sand communities were also analyzed. Our results revealed distinct bacterial communities on MPs compared to those in water or on the natural substrate (sand). However, the resemblance between the plastisphere and communities on natural particles was higher than what has been reported for polluted ecosystems. Although pathogens were predominantly enriched in the water, a few genera (e.g. Acinetobacter, Legionella and Mycobacterium) were enriched in the plastisphere. The abundance of antibiotic resistance genes did not differ significantly between water, sand, and MPs. The influence of different MPs (PE, PP, PET) on the persistence of antibiotic-resistant pathogens (i.e. cefotaxime-resistant Escherichia coli and meropenem-resistant Enterobacter kobei) in unpolluted water was assessed in microcosms. Significant differences were observed between the microcosms with MPs and those with natural particles (sand), after a 36-day exposure. A significantly higher persistence of the pathogens was registered in microcosms with PE and PET. Our results provide new insights into the plastisphere in non-pollution environments and demonstrate that even in these settings, MPs can facilitate the survival and dissemination of pathogens.

Impacts of microplastics on ecosystem services and their microbial degradation: a systematic review of the recent state of the art and future prospects

Microplastics are tiny plastic particles with a usual diameter ranging from ~ 1 μ to 5 µm. Recently, microplastic pollution has raised the attention of the worldwide environmental and human concerns. In human beings, digestive system illness, respiratory system disorders, sleep disturbances, obesity, diabetes, and even cancer have been reported after microplastic exposure either through food, air, or skin. Similarly, microplastics are also having negative impacts on the plant health, soil microorganisms, aquatic lives, and other animals. Policies and initiatives have already been in the pipeline to address this problem to deal with microplastic pollution. However, many obstacles are also being observed such as lack of knowledge, lack of research, and also absence of regulatory frameworks. This article has covered the distribution of microplastics in water, soil, food and air. Application of multimodel strategies including fewer plastic item consumption, developing low-cost novel technologies using microorganisms, biofilm, and genetic modified microorganisms has been used to reduce microplastics from the environment. Researchers, academician, policy-makers, and environmentalists should work jointly to cope up with microplastic contamination and their effect on the ecosystem as a whole which can be reduced in the coming years and also to make earth clean.

Plastic Polymers and Antibiotic Resistance in an Antarctic Environment (Ross Sea): Are We Revealing the Tip of an Iceberg?

Microbial colonization of plastic polymers in Antarctic environments is an under-investigated issue. While several studies are documenting the spread of plastic pollution in the Ross Sea, whether the formation of a plastisphere (namely the complex microbial assemblage colonizing plastics) may favor the spread of antibiotic-resistant bacteria (ARB) in this marine environment is unknown yet. A colonization experiment was performed in this ecosystem, aiming at exploring the potential role of plastic polymers as a reservoir of antibiotic resistance. To this end, the biofilm-producing activity and the antibiotic susceptibility profiles of bacterial strains isolated from biofilms colonizing submerged polyvinylchloride and polyethylene panels were screened. The colonization experiment was carried out at two different sites of the Ross Sea, namely Road Bay and Tethys Bay. Most of bacterial isolates were able to produce biofilm; several multidrug resistances were detected in the bacterial members of biofilms associated to PVC and PE (also named as the plastisphere), as well as in the bacterial strains isolated from the surrounding water. The lowest percentage of ARB was found in the PE-associated plastisphere from the not-impacted (control) Punta Stocchino station, whereas the highest one was detected in the PVC-associated plastisphere from the Tethys Bay station. However, no selective enrichment of ARB in relation to the study sites or to either type of plastic material was observed, suggesting that resistance to antibiotics was a generalized widespread phenomenon. Resistance against to all the three classes of antibiotics assayed in this study (i.e., cell wall antibiotics, nucleic acids, and protein synthesis inhibitors) was observed. The high percentage of bacterial isolates showing resistance in remote environments like Antarctic ones, suffering increasing anthropic pressure, points out an emerging threat with a potential pathogenic risk that needs further deepening studies.

The role of gut microbiota in MP/NP-induced toxicity

Microplastics (MPs) and nanoplastics (NPs) are globally recognized as emerging environmental pollutants in various environmental media, posing potential threats to ecosystems and human health. MPs/NPs are unavoidably ingested by humans, mainly through contaminated food and drinks, impairing the gastrointestinal ecology and seriously impacting the human body. The specific role of gut microbiota in the gastrointestinal tract upon MP/NP exposure remains unknown. Given the importance of gut microbiota in metabolism, immunity, and homeostasis, this review aims to enhance our current understanding of the role of gut microbiota in MP/NP-induced toxicity. First, it discusses human exposure to MPs/NPs through the diet and MP/NP-induced adverse effects on the respiratory, digestive, neural, urinary, reproductive, and immune systems. Second, it elucidates the complex interactions between the gut microbiota and MPs/NPs. MPs/NPs can disrupt gut microbiota homeostasis, while the gut microbiota can degrade MPs/NPs. Third, it reveals the role of the gut microbiota in MP/NP-mediated systematic toxicity. MPs/NPs cause direct intestinal toxicity and indirect toxicity in other organs via regulating the gut-brain, gut-liver, and gut-lung axes. Finally, novel approaches such as dietary interventions, prebiotics, probiotics, polyphenols, engineered bacteria, microalgae, and micro/nanorobots are recommended to reduce MP/NP toxicity in humans. Overall, this review provides a theoretical basis for targeting the gut microbiota to study MP/NP toxicity and develop novel strategies for its mitigation.

Isolation of marine polyethylene (PE)-degrading bacteria and its potential degradation mechanisms

Microbial degradation of polyethylene (PE) offers a promising solution to plastic pollution in the marine environment, but research in this field is limited. In this study, we isolated a novel marine strain of Pseudalkalibacillus sp. MQ-1 that can degrade PE. Scanning electron microscopy and water contact angle results showed that MQ-1 could adhere to PE films and render them hydrophilic. Analyses using X-ray diffraction, fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy showed a decrease in relative crystallinity, the appearance of new functional groups and an increase in the oxygen-to‑carbon ratio of the PE films, making them more susceptible to degradation. The results of gel permeation chromatography and liquid chromatography-mass spectrometry indicated the depolymerization of the long PE chains, with the detection of an intermediate, decanediol. Furthermore, genome sequencing was employed to investigate the underlying mechanisms of PE degradation. The results of genome sequencing analysis identified the genes associated with PE degradation, including cytochrome P450, alcohol dehydrogenase, and aldehyde dehydrogenase involved in the oxidative reaction, monooxygenase related to ester bond formation, and esterase associated with ester bond cleavage. In addition, enzymes involved in fatty acid metabolism and intracellular transport have been identified, collectively providing insights into the metabolic pathway of PE degradation.

Biofilms in plastisphere from freshwater wetlands: Biofilm formation, bacterial community assembly, and biogeochemical cycles

Microorganisms can colonize to the surface of microplastics (MPs) to form biofilms, termed "plastisphere", which could significantly change their physiochemical properties and ecological roles. However, the biofilm characteristics and the deep mechanisms (interaction, assembly, and biogeochemical cycles) underlying plastisphere in wetlands currently lack a comprehensive perspective. In this study, in situ biofilm formation experiments were performed in a park with different types of wetlands to examine the plastisphere by extrinsic addition of PVC MPs in summer and winter, respectively. Results from the spectroscopic and microscopic analyses revealed that biofilms attached to the MPs in constructed forest wetlands contained the most abundant biomass and extracellular polymeric substances. Meanwhile, data from the high-throughput sequencing showed lower diversity in plastisphere compared with soil bacterial communities. Network analysis suggested a simple and unstable co-occurrence pattern in plastisphere, and the null model indicated increased deterministic process of heterogeneous selection for its community assembly. Based on the quantification of biogeochemical cycling genes by high-throughput qPCR, the relative abundances of genes involving in carbon degradation, carbon fixation, and denitrification were significantly higher in plastisphere than those of soil communities. This study greatly enhanced our understanding of biofilm formation and ecological effects of MPs in freshwater wetlands.

Microplastics in marine ecosystems: A comprehensive review of biological and ecological implications and its mitigation approach using nanotechnology for the sustainable environment

Microplastic contamination has rapidly become a serious environmental issue, threatening marine ecosystems and human health. This review aims to not only understand the distribution, impacts, and transfer mechanisms of microplastic contamination but also to explore potential solutions for mitigating its widespread impact. This review encompasses the categorisation, origins, and worldwide prevalence of microplastics and methodically navigates the complicated structure of microplastics. Understanding the sources of minute plastic particles infiltrating water bodies worldwide is critical for successful removal. The presence and accumulation of microplastics has far reaching negative impacts on various marine creatures, eventually extending its implications to human health. Microplastics are known to affect the metabolic activities and the survival of microbial communities, phytoplankton, zooplankton, and fauna present in marine environments. Moreover, these microplastics cause developmental abnormalities, endocrine disruption, and several metabolic disorders in humans. These microplastics accumulates in aquatic environments through trophic transfer mechanisms and biomagnification, thereby disrupting the delicate balance of these ecosystems. The review also addresses the tactics for minimising the widespread impact of microplastics by suggesting practical alternatives. These include increasing public awareness, fostering international cooperation, developing novel cleanup solutions, and encouraging the use of environment-friendly materials. In conclusion, this review examines the sources and prevalence of microplastic contamination in marine environment, its impacts on living organisms and ecosystems. It also proposes various sustainable strategies to mitigate the problem of microplastics pollution. Also, the current challenges associated with the mitigation of these pollutants have been discussed and addressing these challenges require immediate and collective action for restoring the balance in marine ecosystems.

Rapid effects of plastic pollution on coastal sediment metabolism in nature

While extensive research has explored the effects of plastic pollution, ecosystem responses remain poorly quantified, especially in field experiments. In this study, we investigated the impact of polyester pollution, a prevalent plastic type, on coastal sediment ecosystem function. Strips of polyester netting were buried into intertidal sediments, and effects on sediment oxygen consumption and polyester additive concentrations were monitored over 72-days. Our results revealed a rapid reduction in the magnitude and variability of sediment oxygen consumption, a crucial ecosystem process, potentially attributed to the loss of the additive di(2-ethylhexyl) phthalate (DEHP) from the polyester material. DEHP concentrations declined by 89% within the first seven days of deployment. However, effects on SOC dissipated after 22 days, indicating a short-term impact and a quick recovery by the ecosystem. Our study provides critical insights into the immediate consequences of plastic pollution on ecosystem metabolism in coastal sediments, contributing to a nuanced understanding of the temporal variation of plastic pollution's multifaceted impacts. Additionally, our research sheds light on the urgent need for comprehensive mitigation strategies to preserve marine ecosystem functionality from plastic pollution impacts.

Changes in microbial community structure of bio-fouled polyolefins over a year-long seawater incubation in Hawai'i

Plastic waste, especially positively buoyant polymers known as polyolefins, are a major component of floating debris in the marine environment. While plastic colonisation by marine microbes is well documented from environmental samples, the succession of marine microbial community structure over longer time scales (> > 1 month) and across different types and shapes of plastic debris is less certain. We analysed 16S rRNA and 18S rRNA amplicon gene sequences from biofilms on polyolefin debris floating in a flow-through seawater tank in Hawai'i to assess differences in microbial succession across the plastic types of polypropylene (PP) and both high-density polyethylene (HDPE) and low-density polyethylene (LDPE) made of different plastic shapes (rod, film and cube) under the same environmental conditions for 1 year. Regardless of type or shape, all plastic debris were dominated by the eukaryotic diatom Nitzschia, and only plastic type was significantly important for bacterial community structure over time (p = 0.005). PE plastics had higher differential abundance when compared to PP for 20 bacterial and eight eukaryotic taxa, including the known plastic degrading bacterial taxon Hyphomonas (p = 0.01). Results from our study provide empirical evidence that plastic type may be more important for bacterial than eukaryotic microbial community succession on polyolefin pollution under similar conditions.

Macrogenomes reveal microbial-mediated microplastic degradation pathways in the porcine gut: a hope for solving the environmental challenges of microplastics

It is increasingly recognized that microplastics (MPs) are being transmitted through the food chain system, but little is known about the microorganisms involved in MP degradation, functional biodegradation genes, and metabolic pathways of degradation in the intestinal tract of foodborne animals. In this study, we explored the potential flora mainly involved in MP degradation in the intestinal tracts of Taoyuan, Duroc, and Xiangcun pigs by macrogenomics, screened relevant MP degradation genes, and identified key enzymes and their mechanisms. The pig colon was enriched with abundant MP degradation-related genes, and gut microorganisms were their main hosts. The fiber diet did not significantly affect the abundance of MP degradation-related genes but significantly reduced their diversity. We identified a total of 94 functional genes for MP degradation and classified them into 27 categories by substrate type, with polystyrene (PS), polyethylene terephthalate (PET), and di(2-ethylhexyl) phthalate (DEHP) were the most predominant degradation types. The MP degradation functional genes were widely distributed in a variety of bacteria, mainly in the phylum Firmicutes and Bacteroidetes. Based on the identified functional genes for MP degradation, we proposed a hypothetical degradation mechanism for the three major MP pollutants, namely, PS, PET, and DEHP, which mainly consist of oxidoreductase, hydrolase, transferase, ligase, laccase, and isomerase. The degradation process involves the breakdown of long polymer chains, the oxidation of short-chain oligomers, the conversion of catechols, and the achievement of complete mineralization. Our findings provide insights into the function of MP degradation genes and their host microorganisms in the porcine colon.

Parity in bacterial communities and resistomes: Microplastic and natural organic particles in the Tyrrhenian Sea

Petroleum-based microplastic particles (MPs) are carriers of antimicrobial resistance genes (ARGs) in aquatic environments, influencing the selection and spread of antimicrobial resistance. This research characterized MP and natural organic particle (NOP) bacterial communities and resistomes in the Tyrrhenian Sea, a region impacted by plastic pollution and climate change. MP and NOP bacterial communities were similar but different from the free-living planktonic communities. Likewise, MP and NOP ARG abundances were similar but different (higher) from the planktonic communities. MP and NOP metagenome-assembled genomes contained ARGs associated with mobile genetic elements and exhibited co-occurrence with metal resistance genes. Overall, these findings show that MPs and NOPs harbor potential pathogenic and antimicrobial resistant bacteria, which can aid in the spread of antimicrobial resistance. Further, petroleum-based MPs do not represent novel ecological niches for allochthonous bacteria; rather, they synergize with NOPs, collectively facilitating the spread of antimicrobial resistance in marine ecosystems.

Magnetic Microrobot Swarms with Polymeric Hands Catching Bacteria and Microplastics in Water

The forefront of micro- and nanorobot research involves the development of smart swimming micromachines emulating the complexity of natural systems, such as the swarming and collective behaviors typically observed in animals and microorganisms, for efficient task execution. This study introduces magnetically controlled microrobots that possess polymeric sequestrant "hands" decorating a magnetic core. Under the influence of external magnetic fields, the functionalized magnetic beads dynamically self-assemble from individual microparticles into well-defined rotating planes of diverse dimensions, allowing modulation of their propulsion speed, and exhibiting a collective motion. These mobile microrobotic swarms can actively capture free-swimming bacteria and dispersed microplastics "on-the-fly", thereby cleaning aquatic environments. Unlike conventional methods, these microrobots can be collected from the complex media and can release the captured contaminants in a second vessel in a controllable manner, that is, using ultrasound, offering a sustainable solution for repeated use in decontamination processes. Additionally, the residual water is subjected to UV irradiation to eliminate any remaining bacteria, providing a comprehensive cleaning solution. In summary, this study shows a swarming microrobot design for water decontamination processes.

Plastic pollution and degradation pathways: A review on the treatment technologies

In recent years, the production of plastic has been estimated to reach 300 million tonnes, and nearly the same amount has been dumped into the waters. This waste material causes long-term damage to the ecosystem, economic sectors, and aquatic environments. Fragmentation of plastics to microplastics has been detected in the world's oceans, which causes a serious global impact. It is found that most of this debris ends up in water environments. Hence, this research aims to review the microbial degradation of microplastic, especially in water bodies and coastal areas. Aerobic bacteria will oxidize and decompose the microplastic from this environment to produce nutrients. Furthermore, plants such as microalgae can employ this nutrient as an energy source, which is the byproduct of microplastic. This paper highlights the reduction of plastics in the environment, typically by ultraviolet reduction, mechanical abrasion processes, and utilization by microorganisms and microalgae. Further discussion on the utilization of microplastics in the current technologies comprised of mechanical, chemical, and biological methods focusing more on the microalgae and microbial pathways via fuel cells has been elaborated. It can be denoted in the fuel cell system, the microalgae are placed in the bio-cathode section, and the anode chamber consists of the colony of microorganisms. Hence, electric current from the fuel cell can be generated to produce clean energy. Thus, the investigation on the emerging technologies via fuel cell systems and the potential use of microplastic pollutants for consumption has been discussed in the paper. The biochemical changes of microplastic and the interaction of microalgae and bacteria towards the degradation pathways of microplastic are also being observed in this review.

The comparative plastisphere microbial community profile at Kung Wiman beach unveils potential plastic-specific degrading microorganisms

Background

Plastic waste is a global environmental issue that impacts the well-being of humans, animals, plants, and microorganisms. Microplastic contamination has been previously reported at Kung Wiman Beach, located in Chanthaburi province along with the Eastern Gulf of Thailand. Our research aimed to study the microbial population of the sand and plastisphere and isolate microorganisms with potential plastic degradation activity.

Methods

Plastic and sand samples were collected from Kung Wiman Beach for microbial isolation on agar plates. The plastic samples were identified by Fourier-transform infrared spectroscopy. Plastic degradation properties were evaluated by observing the halo zone on mineral salts medium (MSM) supplemented with emulsified plastics, including polystyrene (PS), polylactic acid (PLA), polyvinyl chloride (PVC), and bis (2-hydroxyethyl) terephthalate (BHET). Bacteria and fungi were identified by analyzing nucleotide sequence analysis of the 16S rRNA and internal transcribed spacer (ITS) regions, respectively. 16S and ITS microbiomes analysis was conducted on the total DNA extracted from each sample to assess the microbial communities.

Results

Of 16 plastic samples, five were identified as polypropylene (PP), four as polystyrene (PS), four as polyethylene terephthalate (PET), two as high-density polyethylene (HDPE), and one sample remained unidentified. Only 27 bacterial and 38 fungal isolates were found to have the ability to degrade PLA or BHET on MSM agar. However, none showed degradation capabilities for PS or PVC on MSM agar. Notably, Planococcus sp. PP5 showed the highest hydrolysis capacity of 1.64 ± 0.12. The 16S rRNA analysis revealed 13 bacterial genera, with seven showing plastic degradation abilities: Salipiger, Planococcus, Psychrobacter, Shewanella, Jonesia, Bacillus, and Kocuria. This study reports, for the first time of the BHET-degrading properties of the genera Planococcus and Jonesia. Additionally, The ITS analysis identified nine fungal genera, five of which demonstrated plastic degradation abilities: Aspergillus, Penicillium, Peacilomyces, Absidia, and Cochliobolus. Microbial community composition analysis and linear discriminant analysis effect size revealed certain dominant microbial groups in the plastic and sand samples that were absent under culture-dependent conditions. Furthermore, 16S and ITS amplicon microbiome analysis revealed microbial groups were significantly different in the plastic and sand samples collected.

Conclusions

We reported on the microbial communities found on the plastisphere at Kung Wiman Beach and isolated and identified microbes with the capacity to degrade PLA and BHET.

Microorganism-mediated biodegradation for effective management and/or removal of micro-plastics from the environment: a comprehensive review

Micro- plastics (MPs) pose significant global threats, requiring an environment-friendly mode of decomposition. Microbial-mediated biodegradation and biodeterioration of micro-plastics (MPs) have been widely known for their cost-effectiveness, and environment-friendly techniques for removing MPs. MPs resistance to various biocidal microbes has also been reported by various studies. The biocidal resistance degree of biodegradability and/or microbiological susceptibility of MPs can be determined by defacement, structural deformation, erosion, degree of plasticizer degradation, metabolization, and/or solubilization of MPs. The degradation of microplastics involves microbial organisms like bacteria, mold, yeast, algae, and associated enzymes. Analytical and microbiological techniques monitor microplastic biodegradation, but no microbial organism can eliminate microplastics. MPs can pose environmental risks to aquatic and human life. Micro-plastic biodegradation involves fragmentation, assimilation, and mineralization, influenced by abiotic and biotic factors. Environmental factors and pre-treatment agents can naturally degrade large polymers or induce bio-fragmentation, which may impact their efficiency. A clear understanding of MPs pollution and the microbial degradation process is crucial for mitigating its effects. The study aimed to identify deteriogenic microorganism species that contribute to the biodegradation of micro-plastics (MPs). This knowledge is crucial for designing novel biodeterioration and biodegradation formulations, both lab-scale and industrial, that exhibit MPs-cidal actions, potentially predicting MPs-free aquatic and atmospheric environments. The study emphasizes the urgent need for global cooperation, research advancements, and public involvement to reduce micro-plastic contamination through policy proposals and improved waste management practices.

Novel functional insights into the microbiome inhabiting marine plastic debris: critical considerations to counteract the challenges of thin biofilms using multi-omics and comparative metaproteomics

BACKGROUND

Microbial functioning on marine plastic surfaces has been poorly documented, especially within cold climates where temperature likely impacts microbial activity and the presence of hydrocarbonoclastic microorganisms. To date, only two studies have used metaproteomics to unravel microbial genotype-phenotype linkages in the marine 'plastisphere', and these have revealed the dominance of photosynthetic microorganisms within warm climates. Advancing the functional representation of the marine plastisphere is vital for the development of specific databases cataloging the functional diversity of the associated microorganisms and their peptide and protein sequences, to fuel biotechnological discoveries. Here, we provide a comprehensive assessment for plastisphere metaproteomics, using multi-omics and data mining on thin plastic biofilms to provide unique insights into plastisphere metabolism. Our robust experimental design assessed DNA/protein co-extraction and cell lysis strategies, proteomics workflows, and diverse protein search databases, to resolve the active plastisphere taxa and their expressed functions from an understudied cold environment.

RESULTS

For the first time, we demonstrate the predominance and activity of hydrocarbonoclastic genera (Psychrobacter, Flavobacterium, Pseudomonas) within a primarily heterotrophic plastisphere. Correspondingly, oxidative phosphorylation, the citrate cycle, and carbohydrate metabolism were the dominant pathways expressed. Quorum sensing and toxin-associated proteins of Streptomyces were indicative of inter-community interactions. Stress response proteins expressed by Psychrobacter, Planococcus, and Pseudoalteromonas and proteins mediating xenobiotics degradation in Psychrobacter and Pseudoalteromonas suggested phenotypic adaptations to the toxic chemical microenvironment of the plastisphere. Interestingly, a targeted search strategy identified plastic biodegradation enzymes, including polyamidase, hydrolase, and depolymerase, expressed by rare taxa. The expression of virulence factors and mechanisms of antimicrobial resistance suggested pathogenic genera were active, despite representing a minor component of the plastisphere community.

CONCLUSION

Our study addresses a critical gap in understanding the functioning of the marine plastisphere, contributing new insights into the function and ecology of an emerging and important microbial niche. Our comprehensive multi-omics and comparative metaproteomics experimental design enhances biological interpretations to provide new perspectives on microorganisms of potential biotechnological significance beyond biodegradation and to improve the assessment of the risks associated with microorganisms colonizing marine plastic pollution. Video Abstract.

Psychrobacter species enrichment as potential microplastic degrader and the putative biodegradation mechanism in Shenzhen Bay sediment, China

Microplastic (MP) pollution has emerged as a pressing environmental concern due to its ubiquity and longevity. Biodegradation of MPs has garnered significant attention in combatting global MP contamination. This study focused on MPs within sediments near the sewage outlet of Shenzhen Bay. The objective was to elucidate the microbial communities in sediments with varying MPs, particularly those with high MP loads, and to identify microorganisms associated with MP degradation. The results revealed varying MP abundance, ranging from 211 to 4140 items kg-1 dry weight (d. w.), with the highest concentration observed near the outfall. Metagenomic analysis confirmed the enrichment of Psychrobacter species in sediments with high MP content. Psychrobacter accounted for ∼16.71% of the total bacterial community and 41.71% of hydrocarbon degrading bacteria at the S3 site, exhibiting a higher abundance than at other sampling sites. Psychrobacter contributed significantly to bacterial function at S3, as evidenced by the Kyoto Encyclopedia of Genes and Genomes pathway and enzyme analysis. Notably, 28 enzymes involved in MP biodegradation were identified, predominantly comprising oxidoreductases, hydrolases, transferases, ligases, lyases, and isomerases. We propose a putative mechanism for MP biodegradation, involving the breakdown of long-chain plastic polymers and subsequent oxidation of short-chain oligomers, ultimately leading to thorough mineralization.

Responses of submerged macrophytes to different particle size microplastics and tetracycline co-pollutants at the community and population level

Microplastics (MPs) and antibiotics are ubiquitous in aquatic ecosystems, and their accumulation and combined effects are considered emerging threats that may affect biodiversity and ecosystem function. The particle size of microplastics plays an important role in their combined effects with antibiotics. Submerged macrophytes are crucial in maintaining the health and stability of freshwater ecosystems. However, little is known about the combined effects of different particle size of MPs and antibiotics on freshwater plants, particularly their effects on submerged macrophyte communities. Thus, there is an urgent need to study their effects on the macrophyte communities to provide essential information for freshwater ecosystem management. In the present study, a mesocosm experiment was conducted to explore the effects of three particle sizes (5 µm, 50 µm, and 500 µm) of polystyrene-microplastics (PSMPs) (75 mg/L), tetracycline (TC) (50 mg/L), and their co-pollutants on interactions between Hydrilla verticillata and Elodea nuttallii. Our results showed that the effects of MPs are size-dependent on macrophytes at the community level rather than at the population level, and that small and medium sized MPs can promote the growth of the two test macrophytes at the community level. In addition, macrophytes at the community level have a stronger resistance to pollutant stress than those at the population level. Combined exposure to MPs and TC co-pollutants induces species-specific responses and antagonistic toxic effects on the physio-biochemical traits of submerged macrophytes. Our study provides evidence that MPs and co-pollutants not only affect the morphology and physiology at the population level but also the interactions between macrophytes. Thus, there are promising indications on the potential consequences of MPs and co-pollutants on macrophyte community structure, which suggests that future studies should focus on the effects of microplastics and their co-pollutants on aquatic macrophytes at the community level rather than only at the population level. This will improve our understanding of the profound effects of co-pollutants in aquatic environments on the structure and behavior of aquatic communities and ecosystems.

Biodegradation of Typical Plastics: From Microbial Diversity to Metabolic Mechanisms

Plastic production has increased dramatically, leading to accumulated plastic waste in the ocean. Marine plastics can be broken down into microplastics (<5 mm) by sunlight, machinery, and pressure. The accumulation of microplastics in organisms and the release of plastic additives can adversely affect the health of marine organisms. Biodegradation is one way to address plastic pollution in an environmentally friendly manner. Marine microorganisms can be more adapted to fluctuating environmental conditions such as salinity, temperature, pH, and pressure compared with terrestrial microorganisms, providing new opportunities to address plastic pollution. Pseudomonadota (Proteobacteria), Bacteroidota (Bacteroidetes), Bacillota (Firmicutes), and Cyanobacteria were frequently found on plastic biofilms and may degrade plastics. Currently, diverse plastic-degrading bacteria are being isolated from marine environments such as offshore and deep oceanic waters, especially Pseudomonas spp. Bacillus spp. Alcanivoras spp. and Actinomycetes. Some marine fungi and algae have also been revealed as plastic degraders. In this review, we focused on the advances in plastic biodegradation by marine microorganisms and their enzymes (esterase, cutinase, laccase, etc.) involved in the process of biodegradation of polyethylene terephthalate (PET), polystyrene (PS), polyethylene (PE), polyvinyl chloride (PVC), and polypropylene (PP) and highlighted the need to study plastic biodegradation in the deep sea.

Convergence effect during spatiotemporal succession of lacustrine plastisphere: loss of priority effects and turnover of microbial species

Succession is a fundamental aspect of ecological theory, but studies on temporal succession trajectories and ecological driving mechanisms of plastisphere microbial communities across diverse colonization environments remain scarce and poorly understood. To fill this knowledge gap, we assessed the primary colonizers, succession trajectories, assembly, and turnover mechanisms of plastisphere prokaryotes and eukaryotes from four freshwater lakes. Our results show that differences in microbial composition similarity, temporal turnover rate, and assembly processes in the plastisphere do not exclusively occur at the kingdom level (prokaryotes and eukaryotes), but also depend on environmental conditions and colonization time. Thereby, the time of plastisphere colonization has a stronger impact on community composition and assembly of prokaryotes than eukaryotes, whereas for environmental conditions, the opposite pattern holds true. Across all lakes, deterministic processes shaped the assembly of the prokaryotes, but stochastic processes influenced that of the eukaryotes. Yet, they share similar assembly processes throughout the temporal succession: species turnover over time causes the loss of any priority effect, which leads to a convergent succession of plastisphere microbial communities. The increase and loss of microbial diversity in different kingdoms during succession in the plastisphere potentially impact the stability of entire microbial communities and related biogeochemical cycles. Therefore, research needs to integrate temporal dynamics along with spatial turnovers of the plastisphere microbiome. Taking the heterogeneity of global lakes and the diversity of global climate patterns into account, we highlight the urgency to investigate the spatiotemporal succession mechanism of plastisphere prokaryotes and eukaryotes in more lakes around the world.

Current advances, challenges and strategies for enhancing the biodegradation of plastic waste

Due to its highly recalcitrant nature, the growing accumulation of plastic waste is becoming an urgent global problem. Biodegradation is one of the best possible approaches for the treatment of plastic waste in an environmentally friendly manner, but our current knowledge on the underlying mechanisms, as well as strategies for the development and enhancement of plastic biodegradation are still limited. This review aims to provide an updated and comprehensive overview of current research on plastic waste biodegradation, focusing on enhancement strategies with ongoing research significance, including the mining of highly efficient plastic-degrading microorganisms/enzymes, utilization of synergistic additives, novel pretreatment approaches, modification via molecular engineering, and construction of bacterial/enzyme consortia systems. Studying these strategies can (i) enrich the high-performance microbial/enzymes toolbox for plastic degradation, (ii) provide methods for recycling and upgrading plastics, as well as (iii) enable further molecular modification and functional optimization of plastic-degrading enzymes to realize economically viable biodegradation of plastics. To the best of our knowledge, this is the first review to discuss in detail strategies to enhance biodegradation of plastics. Finally, some recommendations for future research on plastic biodegradation are listed, hoping to provide the best direction for tackling the plastic waste dilemma in the future.

Microplastic pollution: Understanding microbial degradation and strategies for pollutant reduction

Microplastics are ubiquitous environmental pollutants with the potential for adverse impacts on ecosystems and human health. These particles originate from the fragmentation of larger plastic items, shedding from synthetic fibers, tire abrasions, and direct release from personal care products and industrial processes. Once released into the environment, microplastics can disrupt ecosystems, accumulate in organisms, cause physical harm, and carry chemical pollutants that pose risks to both wildlife and human health. There is an urgent need to comprehensively explore the multifaceted issue of microplastic pollution and understand microbial degradation to reduce environmental pollution caused by microplastics. This paper presents a comprehensive exploration of microplastics, including their types, composition, advantages, and disadvantages, as well as the journey and evolution of microplastic pollution. The impact of microplastics on the microbiome and microbial communities is elucidated, highlighting the intricate interactions between microplastics and microbial ecosystems. Furthermore, the microbial degradation of microplastics is discussed, including the identification, characterization, and culturing methods of microplastic-degrading microorganisms. Mechanisms of microplastic degradation and the involvement of microbial enzymes are elucidated to shed light on potential biotechnological applications. Strategies for reducing microplastic pollution are presented, encompassing policy recommendations and the importance of enhanced waste management practices. Finally, the paper addresses future challenges and prospects in the field, emphasizing the need for international collaboration, research advancements, and public engagement. Overall, this study underscores the urgent need for concerted efforts to mitigate microplastic pollution and offers valuable insights for researchers, policymakers, and stakeholders involved in environmental preservation.

When microplastics meet electroanalysis: future analytical trends for an emerging threat

Microplastics are a major modern challenge that must be addressed to protect the environment, particularly the marine environment. Microplastics, defined as particles ≤5 mm, are ubiquitous in the environment. Their small size for a relatively large surface area, high persistence and easy distribution in water, soil and air require the development of new analytical methods to monitor their presence. At present, the availability of analytical techniques that are easy to use, automated, inexpensive and based on new approaches to improve detection remains an open challenge. This review aims to outline the evolution and novelties of classical and advanced methods, in particular the recently reported electroanalytical detectors, methods and devices. Among all the studies reviewed here, we highlight the great advantages of electroanalytical tools over spectroscopic and thermal analysis, especially for the rapid and accurate detection of microplastics in the sub-micron range. Finally, the challenges faced in the development of automated analytical methods are discussed, highlighting recent trends in artificial intelligence (AI) in microplastics analysis.

Microplastics in the environment: A critical overview on its fate, toxicity, implications, management, and bioremediation strategies

Microplastics are small plastic pieces ranging in size from 1μ to <5 mm in diameter, are water-soluble, and can be either primary as they are initially created in small sizes or secondary as they develop due to plastic degradation. Approximately 360 million tons of plastic are produced globally every year, with only 7% recycled, leaving the majority of waste to accumulate in the environment and pose a serious threat in the form of microplastics. All ecosystems, particularly freshwater ecosystems, experience microplastic accumulation and are also prone to degrading processes. Degraded microplastics accumulate in many aquatic systems, contaminate them, and enter the food chain as a result of the excessive discharge of plastic trash annually from the domestic to the industrial sector. Due to their pervasiveness, these tiny plastic particles are constantly present in freshwater environments, which are essential to human life. In this sense, microplastic pollution is seen as a worldwide problem that has a detrimental impact on every component of the freshwater environment. Microplastics act as carriers for various toxic components such as additives and other hazardous substances from industrial and urbanized areas. These microplastic-contaminated effluents are ultimately transferred into water systems and directly ingested by organisms associated with a particular ecosystem. The microplastics components also pose an indirect threat to aquatic ecosystems by adsorbing surrounding water pollutants. This review mainly focuses on the sources of microplastics, the ecotoxicity of microplastics and the impact microplastics have on aquatic and marine life, management, and bioremediation of microplastics. Policies and strategies adopted by the Government to combat microplastic pollution are also discussed in this review.

Shotgun metagenomics and computational profiling of the plastisphere microbiome: unveiling the potential of enzymatic production and plastic degradation

Plastic pollution is one of the most resilient types of pollution and is considered a global environmental threat, particularly in the marine environment. This study aimed to identify plastic-degrading bacteria from the plastisphere and their pharmaceutical and therapeutic potential. We collected samples from soil and aquatic plastisphere to identify the bacterial communities using shotgun metagenomic sequencing and bioinformatic tools. Results showed that the microbiome comprised 93% bacteria, 0.29% archaea, and 3.87% unidentified microbes. Of these 93% of bacteria, 54% were Proteobacteria, 23.9% were Firmicutes, 13% were Actinobacteria, and 2.1% were other phyla. We found that the plastisphere microbiome was involved in degrading synthetic and polyhydroxy alkanoate (PHA) plastic, biosurfactant production, and can thrive under high temperatures. However, no association existed between thermophiles, synthetic plastic or PHA degraders, and biosurfactant-producing bacterial species except for Pseudomonas. Other plastisphere inhabiting plastic degrading microbes include Streptomyces, Bacillus, Achromobacter, Azospirillum, Bacillus, Brevundimonas, Clostridium, Paenibacillus, Rhodococcus, Serratia, Staphylococcus, Thermobifida, and Thermomonospora. However, the plastisphere microbiome showed potential for producing secondary metabolites that were found to act as anticancer, antitumor, anti-inflammatory, antimicrobial, and enzyme stabilizers. These results revealed that the plastisphere microbiome upholds clinical and environmental significance as it can open future portals in a multi-directional way.

Quorum sensing bacteria in microplastics epiphytic biofilms and their biological characteristics which potentially impact marine ecosystem

Microplastics (MPs) have been shown to be a new type of pollutant in the oceans, with complex biofilms attached to their surfaces. Bacteria with quorum sensing (QS) systems are important participants in biofilms. Such bacteria can secrete and detect signal molecules. When a signal molecule reaches its threshold level, bacteria with QS systems can perform several biological functions, such as biofilm formation and antibiotic metabolite production. However, the ecological effects of QS bacteria in biofilm as MPs distribute globally with ocean currents are not to be elucidate yet. In this study, polypropylene and polyvinyl chloride were selected for on-site enrichment to acquire microplastics with biofilms. Eight culturable QS bacteria in the resulting biofilm were isolated by using biosensor assays, and their biodiversity was analyzed. The profiles of the N-acyl-homoserine lactones (AHLs) produced by these bacteria were analyzed by using thin-layer chromatography (TLC)-bioautography and gas chromatography and mass spectrometry (GC-MS). Biofilm-forming properties and several biological characteristics, such as bacteriostasis, algal inhibition, and dimethylsulfoniopropionate (DMSP) degradation, were explored along with QS quenching. Results showed that QS bacteria were mainly affiliated with class Alphaproteobacteria, particularly Rhodobacteraceae, followed by class Gammaproteobacteria. TLC-bioautography and GC-MS analyses revealed that seven AHLs, namely, C6-HSL, C8-HSL, 3-oxo-C6-HSL, 3-oxo-C8-HSL, 3-oxo-C10-HSL, and two unidentified AHLs were produced. The QS system equipped bacteria with strong biofilm-forming capacity and may contribute to the keystone roles of Rhodobacteraceae. In addition, QS bacteria may exacerbate the adverse environmental effects of MPs, such as inducing the misfeeding of planktons on MPs. This study elucidated the diversity of QS bacteria in MP-associated biofilms and provided a new perspective of the effect of key membrane-forming bacteria on the marine ecological environment.