Biofilms of Pseudomonas and Lysinibacillus Marine Strains on High-Density Polyethylene

Exploring marine-derived bacterial compounds targeting the μ-opioid receptor agonists through metabolic profiling to molecular modeling

Given the severe side effects of prolonged morphine use, the search for safer alternatives is a global priority. This study investigates marine bacteria from sediments along the Bejaia coast, Algeria, to identify opioid-like bioactive compounds with potential analgesic properties. A total of 45 bacterial strains were isolated using six different culture media, with 18 strains exhibiting antimicrobial activity. Molecular identification based on 16S rRNA gene sequencing classified these strains into six genera: Streptomyces, Nocardiopsis, Alloalcanivorax, Pseudonocardia, Sinomicrobium, and Lysinibacillus. One strain, S5T2H1, was identified as a new Streptomyces species through a polyphasic approach. LC-HRESIMS analysis of secondary metabolites revealed that strain S56T3J31 produced A58365A, antimycin A, and three potentially novel compounds. However, strain S5T2H1 synthesized cyclo(phenylalanyl-prolyl) and niphimycin Ia, along with three unidentified metabolites, while strain S7T2H1 secreted a single compound identified as berberifuranol. Molecular docking and molecular dynamics simulations demonstrated that A58365A exhibited strong interactions with the μ-opioid receptor (5C1M), showing a stable binding affinity comparable to morphine. These findings highlight marine-derived bacterial compounds as promising candidates for opioid drug development.

Microplastics, microfibers and associated microbiota biofilm analysis in seawater, a case study from the Vesuvian Coast, southern Italy

The growing concerns regarding pollution from microplastics (MPs) and microfibers (MFs) have driven the scientific community to develop new solutions for monitoring ecosystems. However, many of the proposed technologies still include protocols for treating environmental samples that may alter plastic materials, leading to inaccurate results both in observation and in counting. For this reason, we are refining a protocol, based on optical microscopy without the use of pretreatments, applicable to different environmental matrices, which allows not only counting but also a complete morphological characterization of MPs and MFs. Previously, the protocol has successfully been tested on marine sediments from the Vesuvian area of the Gulf of Naples (Italy) with good results. In the present study, we tested the protocol on MPs and MFs in seawater samples collected from the same geographical area to provide a comprehensive overview of their distribution in the marine environments. The protocol enabled not only the morphological characterization of MPs and MFs but also the collection of information on the colonies of microorganisms present on the microparticles. Next Generation Sequencing (NGS) metagenomic technologies enabled us to characterize the microbiota composition of the sampled MPs, the so-called Plastisphere. The analytical approach allowed the characterization of several potentially pathogenic bacteria, which represent a potential threat to the environment and human health. In fact, they may exploit their ability to form biofilms on plastics to proliferate in marine ecosystems.

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.

Identification and biodegradation characterization of high-density polyethylene using marine bacteria isolated from the coastal region of the Arabian Sea, at Gujarat, India

High-Density Polyethylene (HDPE) PE is one of the primary contributors of long-lasting and prolonged pollution in the environment. In this study, more than three hundred marine isolates collected off the Gujarat Sea coast were tested for HDPE plastic utilizing ability. Among fifty-one positive noted isolates, RS124 as a potential strain was identified as Micrococcus flavus (accession is PP858228) based on 16 S rRNA gene sequencing and total cellular fatty acid profiling. Initial bacterial adherence on the film surface was shown in a scanning electron microscopy (SEM) image as a key step to biodegradation. Moreover, atomic force microscopy (AFM) shows that the film surface became more fragile, damaged, and rougher than untreated films. Shifts and alterations in peak transmittance with emergence of two new shouldered peak in degraded HDPE observed by fourier transform infrared spectroscopy (FTIR) was associated to chemical and mechanical alteration. Thermogravimetric analysis (TGA) analysis designated larger difference in percent weight loss provisions thermal instability. In the enzymatic study, the highest activity of peroxidase and dehydrogenase was recorded on the 3rd and 4th weeks of treatment with strain, respectively, during co-incubation. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis disclosed the presence of a distinct 19 kDa size protein, uncovering its role in the colonization of bacteria on the hydrophilic HDPE surfaces. About 1.8% weight reduction in HDPE was recorded as a result after 30 days of bio-treatment with M. flavus. Hence, the entire observed results reveal that the M. flavus RS124 could be effectively applied for the degradation of HDPE. This is the first report on M. flavus that it exhibits plastic degrading characteristic ever, which may allow for green scavenging of plastic waste.

A review focusing on mechanisms and ecological risks of enrichment and propagation of antibiotic resistance genes and mobile genetic elements by microplastic biofilms

Microplastics (MPs) are emerging ubiquitous pollutants in aquatic environment and have received extensive global attention. In addition to the traditional studies related to the toxicity of MPs and their carrier effects, their unique surface-induced biofilm formation also increases the ecotoxicity potential of MPs from multiple perspectives. In this review, the ecological risks of MPs biofilms were summarized and assessed in detail from several aspects, including the formation and factors affecting the development of MPs biofilms, the selective enrichment and propagation mechanisms of current pollution status of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) in MPs biofilms, the dominant bacterial communities in MPs biofilms, as well as the potential risks of ARGs and MGEs transferring from MPs biofilms to aquatic organisms. On this basis, this paper also put forward the inadequacy and prospects of the current research and revealed that the MGEs-mediated ARG propagation on MPs under actual environmental conditions and the ecological risk of the transmission of ARGs and MGEs to aquatic organisms and human beings are hot spots for future research. Relevant research from the perspective of MPs biofilm should be carried out as soon as possible to provide support for the ecological pollution prevention and control of MPs.

Mining strategies for isolating plastic-degrading microorganisms

Plastic waste is a growing global pollutant. Plastic degradation by microorganisms has captured attention as an earth-friendly tactic. Although the mechanisms of plastic degradation by bacteria, fungi, and algae have been explored over the past decade, a large knowledge gap still exists regarding the identification, sorting, and cultivation of efficient plastic degraders, primarily because of their uncultivability. Advances in sequencing techniques and bioinformatics have enabled the identification of microbial degraders and related enzymes and genes involved in plastic biodegradation. In this review, we provide an outline of the situation of plastic degradation and summarize the methods for effective microbial identification using multidisciplinary techniques such as multiomics, meta-analysis, and spectroscopy. This review introduces new strategies for controlling plastic pollution in an environmentally friendly manner. Using this information, highly efficient and colonizing plastic degraders can be mined via targeted sorting and cultivation. In addition, based on the recognized rules and plastic degraders, we can perform an in-depth analysis of the associated degradation mechanism, metabolic features, and interactions.

Unraveling the threat: Microplastics and nano-plastics' impact on reproductive viability across ecosystems

Plastic pollution pervades both marine and terrestrial ecosystems, fragmenting over time into microplastics (MPs) and nano-plastics (NPs). These particles infiltrate organisms via ingestion, inhalation, and dermal absorption, predominantly through the trophic interactions. This review elucidated the impacts of MPs/NPs on the reproductive viability of various species. MPs/NPs lead to reduced reproduction rates, abnormal larval development and increased mortality in aquatic invertebrates. Microplastics cause hormone secretion disorders and gonadal tissue damage in fish. In addition, the fertilization rate of eggs is reduced, and the larval deformity rate and mortality rate are increased. Male mammals exposed to MPs/NPs exhibit testicular anomalies, compromised sperm health, endocrine disturbances, oxidative stress, inflammation, and granulocyte apoptosis. In female mammals, including humans, exposure culminates in ovarian and uterine deformities, endocrine imbalances, oxidative stress, inflammation, granulosa cell apoptosis, and tissue fibrogenesis. Rodent offspring exposed to MPs experience increased mortality rates, while survivors display metabolic perturbations, reproductive anomalies, and weakened immunity. These challenges are intrinsically linked to the transgenerational conveyance of MPs. The ubiquity of MPs/NPs threatens biodiversity and, crucially, jeopardizes human reproductive health. The current findings underscore the exigency for comprehensive research and proactive interventions to ameliorate the implications of these pollutants.

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.

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

Marine microplastic pollution is a growing problem for ecotoxicology that needs to be resolved. In particular, microplastics may be carriers of "dangerous hitchhikers," pathogenic microorganisms, i.e., Vibrio. Microplastics are colonized by bacteria, fungi, viruses, archaea, algae and protozoans, resulting in the biofilm referred to as the "plastisphere." The microbial community composition of the plastisphere differs significantly from those of surrounding environments. Early dominant pioneer communities of the plastisphere belong to primary producers, including diatoms, cyanobacteria, green algae and bacterial members of the Gammaproteobacteria and Alphaproteobacteria. With time, the plastisphere mature, and the diversity of microbial communities increases quickly to include more abundant Bacteroidetes and Alphaproteobacteria than natural biofilms. Factors driving the plastisphere composition include environmental conditions and polymers, with the former having a much larger influence on the microbial community composition than polymers. Microorganisms of the plastisphere may play key roles in degradation of plastic in the oceans. Up to now, many bacterial species, especially Bacillus and Pseudomonas as well as some polyethylene degrading biocatalysts, have been shown to be capable of degrading microplastics. However, more relevant enzymes and metabolisms need to be identified. Here, we elucidate the potential roles of quorum sensing on the plastic research for the first time. Quorum sensing may well become a new research area to understand the plastisphere and promote microplastics degradation in the ocean.

Lysinibacilli: A Biological Factories Intended for Bio-Insecticidal, Bio-Control, and Bioremediation Activities

Microbes are ubiquitous in the biosphere, and their therapeutic and ecological potential is not much more explored and still needs to be explored more. The bacilli are a heterogeneous group of Gram-negative and Gram-positive bacteria. Lysinibacillus are dominantly found as motile, spore-forming, Gram-positive bacilli belonging to phylum Firmicutes and the family Bacillaceae. Lysinibacillus species initially came into light due to their insecticidal and larvicidal properties. Bacillus thuringiensis, a well-known insecticidal Lysinibacillus, can control many insect vectors, including a malarial vector and another, a Plasmodium vector that transmits infectious microbes in humans. Now its potential in the environment as a piece of green machinery for remediation of heavy metal is used. Moreover, some species of Lysinibacillus have antimicrobial potential due to the bacteriocin, peptide antibiotics, and other therapeutic molecules. Thus, this review will explore the biological disease control abilities, food preservative, therapeutic, plant growth-promoting, bioremediation, and entomopathogenic potentials of the genus Lysinibacillus.

Lysinibacillus sp. GG242 from Cattle Slurries Degrades 17β-Estradiol and Possible 2 Transformation Routes

Environmental estrogen pollution has long been a concern due to adverse effects on organisms and ecosystems. Biodegradation is a vital way to remove estrogen, a strain of Lysinibacillus sp. was isolated, numbered strain GG242. The degradation rate of 100 mg·L−1 17β-estradiol (E2)) > 95% in one week, and compared with extracellular enzymes, intracellular enzymes have stronger degradation ability. Strain GG242 can maintain a stable E2 degradation ability under different conditions (20−35 °C, pH 5−11, salinity 0−40 g·L−1). Under appropriate conditions (30 °C, pH 8, 1 g·L−1 NaCl), the degradation rate increased by 32.32% in one week. Based on the analysis of transformation products, inferred E2 was converted via two distinct routes. Together, this research indicates the degradation potential of strain GG242 and provides new insights into the biotransformation of E2.

Nanoplastics in Aquatic Environments: Impacts on Aquatic Species and Interactions with Environmental Factors and Pollutants

Plastic production began in the early 1900s and it has transformed our way of life. Despite the many advantages of plastics, a massive amount of plastic waste is generated each year, threatening the environment and human health. Because of their pervasiveness and potential for health consequences, small plastic residues produced by the breakdown of larger particles have recently received considerable attention. Plastic particles at the nanometer scale (nanoplastics) are more easily absorbed, ingested, or inhaled and translocated to other tissues and organs than larger particles. Nanoplastics can also be transferred through the food web and between generations, have an influence on cellular function and physiology, and increase infections and disease susceptibility. This review will focus on current research on the toxicity of nanoplastics to aquatic species, taking into account their interactive effects with complex environmental mixtures and multiple stressors. It intends to summarize the cellular and molecular effects of nanoplastics on aquatic species; discuss the carrier effect of nanoplastics in the presence of single or complex environmental pollutants, pathogens, and weathering/aging processes; and include environmental stressors, such as temperature, salinity, pH, organic matter, and food availability, as factors influencing nanoplastic toxicity. Microplastics studies were also included in the discussion when the data with NPs were limited. Finally, this review will address knowledge gaps and critical questions in plastics’ ecotoxicity to contribute to future research in the field.

Biochemical features and early adhesion of marine Candida parapsilosis strains on high-density polyethylene

AIMS

Plastic debris are constantly released into oceans where, due to weathering processes, they suffer fragmentation into micro- and nanoplastics. Diverse microbes often colonize these persisting fragments, contributing to their degradation. However, there are scarce reports regarding the biofilm formation of eukaryotic decomposing microorganisms on plastics. Here, we evaluated five yeast isolates from deep-sea sediment for catabolic properties and early adhesion ability on high-density polyethylene (HDPE).

METHODS AND RESULTS

We assessed yeast catabolic features and adhesion ability on HDPE fragments subjected to abiotic weathering. Adhered cells were evaluated through Crystal Violet Assay, Scanning Electron Microscopy, Atomic Force Microscopy and Infrared Spectroscopy. Isolates were identified as Candida parapsilosis and exhibited wide catabolic capacity. Two isolates showed high adhesion ability on HDPE, consistently higher than the reference C. parapsilosis strain, despite an increase in fragment roughness due to weathering. Isolate Y5 displayed the most efficient colonization, with production of polysaccharides and lipids after 48 h of incubation.

CONCLUSION

This work provides insights on catabolic metabolism and initial yeast-HDPE interactions of marine C. parapsilosis strains.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our findings represent an essential contribution to the characterization of early interactions between deep-sea undescribed yeast strains and plastic pollutants found in oceans.

Structural and Functional Characteristics of Microplastic Associated Biofilms in Response to Temporal Dynamics and Polymer Types

The colonization of bacterial communities and biofilm formation on microplastics (MPs) have aroused great concern recently. However, the influence of time and polymer types on the structural and functional characteristics of biofilms remains unclear. In this study, three types of MPs (polyethylene, polypropylene, and polystyrene) were exposed for different time periods (10, 20 and 30 days) in seawater using a microcosm experiment. Microscopic spectroscopy and high-throughput gene sequencing techniques were used to reveal the temporal changes of structural and functional characteristics of MPs associated biofilms. The results indicate that the biofilm formation is affected by both the incubation time and the polymer type. In addition, bacterial diversity and community structure in the biofilms show selectivity towards seawater, and tend to shift over time and among different polymer types. Moreover, biofilms are shown to harbor plastic degrading bacteria, leading to the changes of functional groups and surface hydrophobicity, and thereby enhancing the biodegradation of MPs.

Plastic Degradation by Extremophilic Bacteria

Intensive exploitation, poor recycling, low repeatable use, and unusual resistance of plastics to environmental and microbiological action result in accumulation of huge waste amounts in terrestrial and marine environments, causing enormous hazard for human and animal life. In the last decades, much scientific interest has been focused on plastic biodegradation. Due to the comparatively short evolutionary period of their appearance in nature, sufficiently effective enzymes for their biodegradation are not available. Plastics are designed for use in conditions typical for human activity, and their physicochemical properties roughly change at extreme environmental parameters like low temperatures, salt, or low or high pH that are typical for the life of extremophilic microorganisms and the activity of their enzymes. This review represents a first attempt to summarize the extraordinarily limited information on biodegradation of conventional synthetic plastics by thermophilic, alkaliphilic, halophilic, and psychrophilic bacteria in natural environments and laboratory conditions. Most of the available data was reported in the last several years and concerns moderate extremophiles. Two main questions are highlighted in it: which extremophilic bacteria and their enzymes are reported to be involved in the degradation of different synthetic plastics, and what could be the impact of extremophiles in future technologies for resolving of pollution problems.