Improving the bioremoval of sulfamethoxazole and alleviating cytotoxicity of its biotransformation by laccase producing system under coculture of Pycnoporus sanguineus and Alcaligenes faecalis

Deciphering key traits and dissemination of antibiotic resistance genes and degradation genes in pharmaceutical wastewater receiving environments

Discharge of pharmaceutical wastewater significantly affects the receiving environments. However, the development of antibiotic resistance and microbial enzymatic degradation in wastewater-receiving soils and rivers remains unclear. This study investigated a sulfonamide-producing factory to explore the distribution of antibiotic resistance genes (ARGs) in the receiving river and soil environments (0-100 cm depth), and the potential hosts of sadABC genes (sulfonamide-degrading genes) as well as their phylogenetic characterization. We identified plentiful ARGs (28 types and 1065 subtypes) and their hosts (30 phyla and 340 MAGs) in three media (surface water, sediment, and soil). Results indicated that the abundances of total resistome in water and sediment of receiving river (0-1.5 km) were higher than the global river resistome median levels. Wastewater significantly affected the soil resistome, leading to an average 5-fold increase in ARG abundance, and a 22-fold enrichment of sulfonamide ARGs. The abundance and diversity of soil resistome decreased significantly with depth, and the abundance was below the global soil resistome median level at the depth greater than 20 cm. The detection of 17 risk rank I ARGs and the enrichment of multidrug-resistant pathogenic bacteria in soil and river highlighted the resistance risks in the environments. Notably, 73 sadABC-carrying contigs were detected, which were mainly hosted by Microbacteriaceae and some other previously unreported bacteria, such as Mycobacteriaceae spp. The findings offer valuable insights into antimicrobial resistance (AMR) risk assessment and the bioremediation of sulfonamides pollution in the environment affected by pharmaceutical wastewater.

Environmental bioremediation of pharmaceutical residues: microbial processes and technological innovations: a review

The ubiquitous presence of pharmaceuticals and personal care products (PPCPs) in the environment has become a significant concern due to their persistence, bioaccumulation potential in biota, and diverse implications for human health and wildlife. This review provides an overview of the current state-of-the-art in environmental bioremediation techniques for reducing pharmaceutical residues, with a special emphasis on microbial physiological aspects. Numerous microorganisms, including algae, bacteria or fungi, can biodegrade various pharmaceutical compounds such as antibiotics, analgesics and beta-blockers. Some microorganisms are capable of transferring electrons within the cell, and this feature can be harnessed using Bio Electrochemical Systems (BES) to potentiate the degradation of pharmaceuticals present in wastewater. Moreover, researchers are evaluating the genetic modification of microbial strains to improve their degradation capacity and expand list of target compounds. This includes also discuss how environment changes, such as fluctuations in temperature or pH, may affect bioremediation efficiency. Furthermore, the presence of pharmaceuticals in the environment is emphasised as a major public health issue because it increases the chance for antibiotic-resistant bacteria emerging. This review combines existing information and outlines needed research areas for improving bioremediation technologies in the future.

Performance enhancement, bacterial communities optimization and emerging pollutants elimination by microalgal-bacterial consortium for treating aquaculture pond sediments

Aquaculture pond sediments have a notable influence on the ecosystem balance and farmed animal health. In this study, microalgal-bacterial immobilization (MBI) was designed to improve aquaculture pond sediments via synergistic interactions. The physicochemical characteristics, bacterial communities, and the removal efficiencies of emerging pollutants were systematically investigated. The consortium containing diatom Navicula seminulum and Alcaligenes faecalis was cultivated and established in the free and immobilized forms for evaluating the treatment performance. The results indicated that the immobilized group exhibited superior performance in controlling nutrient pollutants, shaping and optimizing the bacterial community compositions with the enrichment of functional bacteria. Additionally, it showed a stronger positive correlation between the bacterial community shifts and nutrient pollutants removal compared to free cells. Furthermore, the immobilized system maintained the higher removal performance of emerging pollutants (heavy metals, antibiotics, and pathogenic Vibrios) than free group. These findings confirmed that the employment of immobilized N. seminulum and A. faecalis produced more synergistic benefits and exerted more improvements than free cells in ameliorating aquaculture pond sediments, suggesting the potential for engineering application of functional microalgal-bacterial consortium in aquaculture.

Construction of a myoglobin scaffold-based biocatalyst for the biodegradation of sulfadiazine and sulfathiazole

Sulfonamide antibiotics, a family of broad-spectrum antibiotic drugs, are increasingly used in aquaculture and are frequently detected in aquatic environments. This poses a potential threat to organisms and may cause the evolution of antimicrobial resistance. Therefore, it is important to develop an environmentally friendly and efficient biocatalyst to degrade sulfonamides (SAs) such as sulfadiazine (SD) and sulfathiazole (ST). Here, we realized the direct and efficient degradation of SD and ST using a hydrogen peroxide-dependent artificial catalytic system based on myoglobin (Mb). The arrangements of amino acids at positions 29, 43, 64, and 68 were found to influence catalytic activity. An L29H/H64D/V68I myoglobin mutant showed the best catalytic efficiency (i.e., kcat/Km = 720.42 M-1 s-1) against SD. Next, mutant H64D/V68I showed the best degradation rate against SD (i.e., 91.45 ± 0.16%). Moreover, L29H/H64D/V68I Mb was found to efficiently catalyze ST oxidation (kcat/Km = 670.08 M-1 s-1), while H64D/V68I had the best degradation rate against ST (i.e., 99.45 ± 0.23%). Our results demonstrate that SAs can be efficiently degraded by artificial peroxygenases constructed using a myoglobin scaffold. This therefore provides a simple and economical method for the biodegradation of SD and ST.

Using Fungi in Artificial Microbial Consortia to Solve Bioremediation Problems

There is currently growing interest in the creation of artificial microbial consortia, especially in the field of developing and applying various bioremediation processes. Heavy metals, dyes, synthetic polymers (microplastics), pesticides, polycyclic aromatic hydrocarbons and pharmaceutical agents are among the pollutants that have been mainly targeted by bioremediation based on various consortia containing fungi (mycelial types and yeasts). Such consortia can be designed both for the treatment of soil and water. This review is aimed at analyzing the recent achievements in the research of the artificial microbial consortia that are useful for environmental and bioremediation technologies, where various fungal cells are applied. The main tendencies in the formation of certain microbial combinations, and preferences in their forms for usage (suspended or immobilized), are evaluated using current publications, and the place of genetically modified cells in artificial consortia with fungi is assessed. The effect of multicomponence of the artificial consortia containing various fungal cells is estimated, as well as the influence of this factor on the functioning efficiency of the consortia and the pollutant removal efficacy. The conclusions of the review can be useful for the development of new mixed microbial biocatalysts and eco-compatible remediation processes that implement fungal cells.

Simultaneous removal of tetracycline and sulfamethoxazole by laccase-mediated oxidation and ferrate(VI) oxidation: the impact of mediators and metal ions

This study explores the impact of mediators and metal ions of laccase-mediated oxidation and ferrate(VI) oxidation for the simultaneous removal of tetracycline antibiotics (TCs) and sulfonamide antibiotics (SAs) and to effectively remove their antimicrobial activity. The results showed that the antimicrobial activity of tetracycline against Bacillus altitudinis and Escherichia coli was significantly reduced, and the antimicrobial activity of sulfamethoxazole against B. altitudinis disappeared completely after treatment with the laccase-ABTS system. The combination of 6.0 U/mL of laccase and 0.2 mmol/L of ABTS removed 100% of 20.0 mg/L of tetracycline after 1.0 min at pH 6.0 and 25.0 °C, whereas the removal ratio of 20.0 mg/L of sulfamethoxazole was only 6.7%. The Al3+ and Cu2+ ions promoted the oxidation, and the Mn2+ ion decelerated the oxidation of tetracycline and sulfamethoxazole by the laccase-mediator systems. In contrast, the antimicrobial activity of tetracycline against B. altitudinis and E. coli was shown to be significantly reduced, and the sulfamethoxazole still retained high antimicrobial activity against B. altitudinis after treatment with Fe(VI) oxidation. The removal ratio of 20.0 mg/L of tetracycline was 100% after 1.0 min of treatment with 982.0 mg/L of K2FeO4 at pH 6.0 and 25.0 °C, whereas the removal ratio of 20.0 mg/L of sulfamethoxazole was only 49.5%. The Al3+, Cu2+, and Mn2+ ions both decelerated the oxidation of tetracycline and sulfamethoxazole by Fe(VI) oxidation. In general, the combination of the laccase-ABTS system and Fe(VI) was proposed for the simultaneous treatment of TCs and SAs in wastewater and to effectively remove their antimicrobial activity.

Phenotypic and genomic characterization provide new insights into adaptation to environmental stressors and biotechnological relevance of mangrove Alcaligenes faecalis D334

Alcaligenes faecalis D334 was determined in this study as a salt-tolerant bacterium isolated from mangrove sediment. In response to 6% (w/v) NaCl, strain D334 produced the highest ectoines of 14.14 wt%. To understand adaptive features to mangrove environment, strain D334 was sequenced using Pacific BioScience platform, resulting in a circular chromosome of 4.23 Mb. Of note, D334 genome harbored 81 salt-responsive genes, among which two membrane-associated genes ompc and eric were absent in 3 selected A. faecalis genomes. Apart from that, a complete pathway for ectoine and 5-hydroxyectoine synthesis was predicted. To resist 40 mM H₂O₂, 46 genetic determinants contributing to oxidative stress response were employed. Moreover, two operons involved in polyhydroxyalkanoate (PHA) production were identified in the D334 genome, resulting in maximum PHA content of 5.03 ± 0.04 wt% and PHA concentration of 0.13 ± 0.001 g/L. A large flagellar biosynthesis operon contributing to swimming motility was found to be conserved in D334 and 8 other A. faecalis genomes. These findings shed light for the first time on the high versatility of A. faecalis D334 genome to adapt to mangrove lifestyle and the possibility to develop D334 as an industrial platform for PHA and 5-hydroxyectoine production.

Artificial microbial consortium producing oxidases enhanced the biotransformation efficiencies of multi-antibiotics

Antibiotic mixtures in the environment result in the development of bacterial strains with resistance against multiple antibiotics. Oxidases are versatile that can bio-remove antibiotics. Various laccases (LACs), manganese peroxidases (MNPs), and versatile peroxidase (VP) were reconstructed in Pichia pastoris. For the single antibiotics, over 95.0% sulfamethoxazole within 48 h, tetracycline, oxytetracycline, and norfloxacin within 96 h were bio-removed by recombinant VP with α-signal peptide, respectively. In a mixture of the four antibiotics, 80.2% tetracycline and 95.6% oxytetracycline were bio-removed by recombinant MNP2 with native signal peptide (NSP) within 8 h, whereas < 80.0% sulfamethoxazole was bio-removed within 72 h, indicating that signal peptides significantly impacted removal efficiencies of antibiotic mixtures. Regarding mediators for LACs, 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) resulted in better removal efficiencies of multi-antibiotic mixtures than 1-hydroxybenzotriazole or syringaldehyde. Furthermore, artificial microbial consortia (AMC) producing LAC2 and MNP2 with NSP significantly improved bio-removal efficiency of sulfamethoxazole (95.5%) in four-antibiotic mixtures within 48 h. Tetracycline and oxytetracycline were completely bio-removed by AMC within 48 and 72 h, respectively, indicating that AMC accelerated sulfamethoxazole, tetracycline, and oxytetracycline bio-removals. Additionally, transformation pathways of each antibiotic by recombinant oxidases were proposed. Taken together, this work provides a new strategy to simultaneously remove antibiotic mixtures by AMC.

Insights into the Applications of Extracellular Laccase-Aided Humification in Livestock Manure Composting

Traditional composting is a well-suited biotechnology for on-farm management of livestock manure (LM) but still leads to the release of toxic micropollutants and imbalance of nutrients. One in situ exoenzyme-assisted composting has shown promise to ameliorate the agronomical quality of end products by improving humification and polymerization. The naturally occurring extracellular laccase from microorganisms belongs to a multicopper phenoloxidase, which is verified for its versatility to tackle micropollutants and conserve organics through the reactive radical-enabled decomposition and polymerization channels. Laccase possesses an indispensable relationship with humus formation during LM composting, but its potential applications for the harmless disposal and resource utilization of LM have until now been overlooked. Herein, we review the extracellular laccase-aided humification mechanism and its optimizing strategy to maintain enzyme activity and in situ production, highlighting the critical roles of laccase in treating micropollutants and preserving organics during LM composting. Particularly, the functional effects of the formed humification products by laccase-amended composting on plant growth are also discussed. Finally, the future perspectives and outstanding questions are summarized. This critical review provides fundamental insights into laccase-boosted humification that ameliorates the quality of end products in LM composting, which is beneficial to guide and advance the practical applications of exoenzyme in humification remediation, the carbon cycle, and agriculture protection.

Genomic and resistome analysis of Alcaligenes faecalis strain PGB1 by Nanopore MinION and Illumina Technologies

Background

Drug-resistant bacteria are important carriers of antibiotic-resistant genes (ARGs). This fact is crucial for the development of precise clinical drug treatment strategies. Long-read sequencing platforms such as the Oxford Nanopore sequencer can improve genome assembly efficiency particularly when they are combined with short-read sequencing data.

Results

Alcaligenes faecalis PGB1 was isolated and identified with resistance to penicillin and three other antibiotics. After being sequenced by Nanopore MinION and Illumina sequencer, its entire genome was hybrid-assembled. One chromosome and one plasmid was assembled and annotated with 4,433 genes (including 91 RNA genes). Function annotation and comparison between strains were performed. A phylogenetic analysis revealed that it was closest to A. faecalis ZD02. Resistome related sequences was explored, including ARGs, Insert sequence, phage. Two plasmid aminoglycoside genes were determined to be acquired ARGs. The main ARG category was antibiotic efflux resistance and β-lactamase (EC 3.5.2.6) of PGB1 was assigned to Class A, Subclass A1b, and Cluster LSBL3.

Conclusions

The present study identified the newly isolated bacterium A. faecalis PGB1 and systematically annotated its genome sequence and ARGs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08507-7.

Exploring kinetics, removal mechanism and possible transformation products of tigecycline by Chlorella pyrenoidosa

The accumulation of antibiotics in wastewater leads to broad antibiotic resistance, threating human health. Microalgae have been receiving attention due to their ability to remove antibiotics from wastewater. Tigecycline (TGC) is a broad-spectrum glycylcycline antibiotic. It has not been investigated for removal by microalgae. The removal kinetics of TGC by Chlorella pyrenoidosa were evaluated under different initial dry cell densities, TGC concentrations, temperatures and light intensity conditions. Approximately 90% of TGC could be removed when the TGC concentration was 10 mg∙L^-1 and the initial dry cell density was more than 0.2 g∙L^-1. A low value of TGC per g dry cell weight ratio led to a high removal efficiency of TGC. The initial dry cell density of microalgae was also critical for the removal of TGC. A high initial dry cell density is better than a low initial dry cell density to remove TGC when the ratio of the TGC concentration to dry cell weight are the same at the beginning of the cultivation. The removal mechanisms were investigated. Photolysis was a slow process that did not lead to removal at the beginning. Adsorption, hydrolysis, photolysis and biodegradation by microalgae were the main contributors to the removal of TGC. TGC was easily hydrolyzed under high -temperature conditions. Three transformation products of TGC by microalgae were identified. The stability of TGC was evaluated in water and salt solutions of citric acid, K₂HPO₄·3H₂O and ferric ammonium citrate. TGC was stable in ultrapure water and citric acid solution. TGC was hydrolyzed in K₂HPO₄·3H₂O and ferric ammonium citrate solutions.

Effective degradation of Chlortetracycline using dual bio catalyst

Chlortetracycline (CTC) degradation using potential microbial consortia or individual bacterial strains was useful method for improving bioremediation potential. The co-culture (Klebsiella pneumoniae CH3 and Bacillus amyloliquefaciens CS1) of bacterial strains have the ability to degrade chlortetracycline (91.8 ± 1.7%), followed by sulfamethoxazole (62.1 ± 1.2%) and amoxicillin (73.9 ± 3.3%). It was observed that the degradation potential was maximum after 10 days incubation, 8-10% inoculum, pH 7.5, and antibiotic concentration ranged from 150 to 200 mg/L. The initial concentrations of CTC significantly affected CTC degradation. In strain CH3, maximum biodegradation of CTC (99.4 ± 2.3%) was observed at 200 mg/L initial CTC concentrations. In CS1, maximum biodegradation of CTC was obtained at 150 mg/L concentration (80.5 ± 3.2%) after 10 days of culture. Alkaline pH was found to be suitable for the degradation of antibiotic than acidic range. After initial optimization by one factor at a time approach in free cells, the bacterial strains (CH3 and CS1) were co-immobilized. The co-immobilized bacterial cells showed improved degradation potential than free cells. To determine the biodegradation potential of immobilized cells, the selected strains were immobilized in polymer beads and treated with CTC with 175 mg/L initial concentration. The experimental results revealed that after 3 days of treatment the residual CTC concentration was 150.1 ± 3.2 mg/L and it decreased as 1.28 ± 0.01 mg/L after 10 days of treatment. The present study confirmed the effectiveness and feasibility of biodegradation ability of K. pneumoniae CH3 and B. amyloliquefaciens CS1 immobilized for CTC degradation in wastewater.

Antibiotic residues in environment: antimicrobial resistance development, ecological risks, and bioremediation

The overuse of antibiotics and their disposal without processing are leading the environment and its inhabitants towards a serious health emergency. There is abundance of diverse antibiotic resistance genes and bacteria in environment, which demands immediate attention for the effective removal of antibiotics. There are physical and chemical methods for removal, but the generation of toxic byproducts has directed the efforts towards bioremediation for eco-friendly and sustainable elimination of antibiotics from the environment. Various effective and reliable bioremediation approaches have been used, but still antibiotic residues pose a major global threat. Recent developments in molecular and synthetic biology might offer better solution for engineering of microbe-metabolite biodevices and development of novel strains endowed with desirable properties. This review summarizes the impact of antibiotics on environment, mechanisms of resistance development, and different bioremediation approaches.

Recent Progress and Prospects in Catalytic Water Treatment

Presently, conventional technologies in water treatment are not efficient enough to completely mineralize refractory water contaminants. In this context, the implementation of catalytic processes could be an alternative. Despite the advantages provided in terms of kinetics of transformation, selectivity, and energy saving, numerous attempts have not yet led to implementation at an industrial scale. This review examines investigations at different scales for which controversies and limitations must be solved to bridge the gap between fundamentals and practical developments. Particular attention has been paid to the development of solar-driven catalytic technologies and some other emerging processes, such as microwave assisted catalysis, plasma-catalytic processes, or biocatalytic remediation, taking into account their specific advantages and the drawbacks. Challenges for which a better understanding related to the complexity of the systems and the coexistence of various solid-liquid-gas interfaces have been identified.

Recent Developments in the Immobilization of Laccase on Carbonaceous Supports for Environmental Applications - A Critical Review

Τhe ligninolytic enzyme laccase has proved its potential for environmental applications. However, there is no documented industrial application of free laccase due to low stability, poor reusability, and high costs. Immobilization has been considered as a powerful technique to enhance laccase's industrial potential. In this technology, appropriate support selection for laccase immobilization is a crucial step since the support could broadly affect the properties of the resulting catalyst system. Through the last decades, a large variety of inorganic, organic, and composite materials have been used in laccase immobilization. Among them, carbon-based materials have been explored as a support candidate for immobilization, due to their properties such as high porosity, high surface area, the existence of functional groups, and their highly aromatic structure. Carbon-based materials have also been used in culture media as supports, sources of nutrients, and inducers, for laccase production. This study aims to review the recent trends in laccase production, immobilization techniques, and essential support properties for enzyme immobilization. More specifically, this review analyzes and presents the significant benefits of carbon-based materials for their key role in laccase production and immobilization.

Potential biotransformation pathways and efficiencies of ciprofloxacin and norfloxacin by an activated sludge consortium

Fluoroquinolones (FQs), such as ciprofloxacin (CIP) and norfloxacin (NOR), are types of emerging trace pollutants that have attracted great attention. In this study, an activated sludge (AS) consortium with high bio-removal capability to CIP and NOR was obtained by acclimating with CIP and NOR for 10 d. Meanwhile, a CIP- and NOR- transforming bacterial strain (S5), which is highly homologous to the 16S rRNA gene sequence of Enterobacter sp., was isolated from the acclimated AS. The bio-removal efficiency of CIP under the acclimated AS consortium was better than that under the pure culture of Enterobacter sp. S5 (93.1% vs. 89.3%), while the bio-removal efficiency of NOR under the acclimated AS consortium was lower than that under the pure culture of Enterobacter sp. S5 (83.9% vs. 89.8%). The biotransformation and bio-adsorption were two main ways to bio-remove CIP and NOR. However, the CIP and NOR biotransformation efficiencies of the acclimated AS were higher than under the pure culture of Enterobacter sp. S5, while the CIP and NOR adsorption of acclimated AS were lower than that under the pure culture of Enterobacter sp. S5. The N-acetylciprofloxacin and N-acetylnorfloxacin were the main biotransformation products of CIP and NOR. It is possible that acetyltransferase may be involved in the biotransformation process. Whether under the pure culture or AS consortium, the cytotoxicity of CIP and NOR transformation products to gram-negative bacteria was alleviated. Therefore, the acclimated AS and Enterobacter sp. S5 might provide a new strategy for removing contaminants and alleviating of FQs resistance.

Biodegradation of sulfonamide antibiotics through the heterologous expression of laccases from bacteria and investigation of their potential degradation pathways

In this study, seven laccase genes from different bacteria were linked with the signal peptides PelB, Lpp or Ompa for heterologous expression in E. coli. The recombinant strains were applied for the removal of sulfadiazine (SDZ), sulfamethazine (SMZ), and sulfamethoxazole (SMX). The results obtained for different signal peptides did not provide insights into the removal mechanism. The removal ratios of SDZ, SMZ, and SMX obtained with the recombinant strain 6#P at 60 h were around 92.0%, 89.0%, and 88.0%, respectively. The degradation pathways of sulfonamides have been proposed, including SO₂ elimination, hydroxylation, oxidation, pyrimidine ring cleavage, and N-S bond cleavage. Different mediators participate in the degradation of antibiotics through different mechanisms, and different antibiotics have different responses to the same mediator. The addition of 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) slightly promoted the removal of sulfonamides by most recombinant strains with different signal peptides, especially for the recombinant strain 2#O. The removal of sulfonamides by 1-hydroxybenzotriazole (HBT) varied with the recombinant strains. Syringaldehyde (SA) had a slight inhibitory effect on the removal of sulfonamides, with the most significant effect on strains 7#L and 7#O.

Potential use of fungal-bacterial co-cultures for the removal of organic pollutants

Fungi and bacteria coexist in a wide variety of natural and artificial environments which can lead to their association and interaction - ranging from antagonism to cooperation - that can affect the survival, colonization, spatial distribution and stress resistance of the interacting partners. The use of polymicrobial cultivation approaches has facilitated a more thorough understanding of microbial dynamics in mixed microbial communities, such as those composed of fungi and bacteria, and their influence on ecosystem functions. Mixed (multi-domain) microbial communities exhibit unique associations and interactions that could result in more efficient systems for the degradation and removal of organic pollutants. Several previous studies have reported enhanced biodegradation of certain pollutants when using combined fungal-bacterial treatments compared to pure cultures or communities of either fungi or bacteria (single domain systems). This article reviews: (i) the mechanisms of pollutant degradation that can occur in fungal-bacterial systems (e.g.: co-degradation, production of secondary metabolites, enhancement of degradative enzyme production, and transport of bacteria by fungal mycelia); (ii) case studies using fungal-bacterial co-cultures for the removal of various organic pollutants (synthetic dyes, polycyclic aromatic hydrocarbons, pesticides, and other trace or volatile organic compounds) in different environmental matrices (e.g. water, gas/vapors, soil); (iii) the key aspects of engineering artificial fungal-bacterial co-cultures, and (iv) the current challenges and future perspectives of using fungal-bacterial co-cultures for environmental remediation.

Enhancement of laccase production by Cerrena unicolor through fungal interspecies interaction and optimum conditions determination

The present study aimed to identify a pair of fungal strains that promote laccase production in the co-cultivation of white-rot basidiomycetes and to determine the optimum conditions to enhance enzyme synthesis under co-fermentation of mandarin peels. Co-cultivation of Cerrena unicolor with Trametes versicolor, Lenzites betulina, and Panus lecomtei led to up-regulation of laccase activity. Moreover, interspecific interaction of Cerrena unicolor and Trametes versicolor induced the production of two new laccase isoenzymes. By contrast, interactions of Cerrena unicolor with Trametes coccineus and Trametes hirsuta resulted in a multiple decreased ability of Cerrena unicolor to produce laccase. Co-cultivation of Cerrena unicolor with other fungi 3- to 12-fold down-regulated manganese peroxidase (MnP) activity. The outcomes of these fungal interactions are closely related to the initial concentration and availability of the nutrients, the partners' inoculum ratio, time, and sequence of their inoculation. Co-cultivation of Cerrena unicolor and Trametes versicolor in fermenter resulted in the accumulation of 476 U/mL laccase and 1.12 U/mL MnP.

Alternative, environmentally conscious approaches for removing antibiotics from wastewater treatment systems

Prevalence of antibiotic resistance in the environment is of critical concern from a public health perspective, with many human impacted environments showing increased incidence of antibiotic resistant bacteria. Wastewater treatment environments are of particular interest due to their high levels of antibiotic residuals, which can select for antibiotic resistance genes in bacteria. However, wastewater treatment plants are generally not designed to remove antibiotics from collected waste, and many of the currently proposed methods are unsafe for environmental use. This has prompted researchers to identify alternative environmentally safe methods for removing antibiotics from wastewater to be used in parallel with conventional wastewater treatment, as it is a potential strategy towards the mitigation of environmental antibiotic resistance selection. This paper reviews several methods developed to absorb and/or degrade antibiotics from aqueous solutions and wastewater biosolids, which includes ligninolytic fungi and ligninolytic enzymes, algae-driven photobioreactors and algae-activated sludge, and organically-sourced biochars.

From Laboratory Tests to the Ecoremedial System: The Importance of Microorganisms in the Recovery of PPCPs-Disturbed Ecosystems

The presence of a wide variety of emerging pollutants in natural water resources is an important global water quality challenge. Pharmaceuticals and personal care products (PPCPs) are known as emerging contaminants, widely used by modern society. This objective ensures availability and sustainable management of water and sanitation for all, according to the 2030 Agenda. Wastewater treatment plants (WWTP) do not always mitigate the presence of these emerging contaminants in effluents discharged into the environment, although the removal efficiency of WWTP varies based on the techniques used. This main subject is framed within a broader environmental paradigm, such as the transition to a circular economy. The research and innovation within the WWTP will play a key role in improving the water resource management and its surrounding industrial and natural ecosystems. Even though bioremediation is a green technology, its integration into the bio-economy strategy, which improves the quality of the environment, is surprisingly rare if we compare to other corrective techniques (physical and chemical). This work carries out a bibliographic review, since the beginning of the 21st century, on the biological remediation of some PPCPs, focusing on organisms (or their by-products) used at the scale of laboratory or scale-up. PPCPs have been selected on the basics of their occurrence in water resources. The data reveal that, despite the advantages that are associated with bioremediation, it is not the first option in the case of the recovery of systems contaminated with PPCPs. The results also show that fungi and bacteria are the most frequently studied microorganisms, with the latter being more easily implanted in complex biotechnological systems (78% of bacterial manuscripts vs. 40% fungi). A total of 52 works has been published while using microalgae and only in 7% of them, these organisms were used on a large scale. Special emphasis is made on the advantages that are provided by biotechnological systems in series, as well as on the need for eco-toxicological control that is associated with any process of recovery of contaminated systems.

Bio-removal of tetracycline antibiotics under the consortium with probiotics Bacillus clausii T and Bacillus amyloliquefaciens producing biosurfactants

The contamination of the aquatic environments by tetracycline antibiotics (TCs) is an increasingly pressing issue. Here, we used the addition of exogenous surfactants and in situ biosynthesis of biosurfactants to remove tetracycline (TC), oxytetracycline (OTC), chlortetracycline (CTC), and their mixtures using the co-culture of probiotic Bacillus clausii T and Bacillus amyloliquefaciens HM618 producing surfactin. The addition of exogenous biosurfactants to remove TCs was superior to nonionic surfactants. The maximal bio-removal efficiencies for OTC and CTC among mixed antibiotics under the co-culture of B. clausii T and B. amyloliquefaciens HM618 were 76.6% and 88.9%, respectively, which were both better than the efficiency of the pure culture of B. clausii T. TCs were removed mainly through biotransformation rather than absorption and hydrolysis. The removal efficiency was in the order CTC > OTC > TC. The co-culture of B. clausii T and B. amyloliquefaciens HM618 alleviated the cytotoxicity of OTC and CTC. The toxicity of the biotransformation products was lower than that of the parent compounds. Demethylation, hydroxylation, and dehydration are likely the major mechanisms of TC biotransformation. These results illustrate the potential of using surfactants in the bioremediation of tetracycline antibiotics, and provide new avenues for further exploration of the bioremediation of antibiotics pollution.

Characterization of a robust cold-adapted and thermostable laccase from Pycnoporus sp. SYBC-L10 with a strong ability for the degradation of tetracycline and oxytetracycline by laccase-mediated oxidation

A native laccase (Lac-Q) with robust cold-adapted and thermostable characteristics from the white-rot fungus Pycnoporus sp. SYBC-L10 was purified, characterized, and used in antibiotic treatments. Degradation experiments revealed that Lac-Q at 10.0 U mL^-1 coupled with 1.0 mmol L^-1 ABTS could degrade 100% of the tetracycline or oxytetracycline (50 mg L^-1) within 5 min with a static incubation at 0 °C (pH 6.0). The presence of the Mn²⁺ ion inhibited the removal rate of tetracycline and oxytetracycline by the Lac-Q-ABTS system, and the presence of Al³⁺, Cu²⁺, and Fe³⁺ accelerated the removal rate of tetracycline and oxytetracycline by the Lac-Q-ABTS system. Furthermore, the growth inhibition of Bacillus altitudinis SYBC hb4 and E. coli by tetracycline antibiotics revealed that the antimicrobial activity was significantly reduced after treatment with the Lac-Q-ABTS system. Finally, seven transformation products of oxytetracycline (namely TP 445, TP 431, TP 413, TP 399, TP 381, TP 367, and TP 351) were identified during the Lac-Q-mediated oxidation process by using UPLC-MS/MS. A possible degradation pathway including deamination, demethylation, and dehydration was proposed. These results suggest that the Lac-Q-ABTS system shows a great potential for the treatment of antibiotic wastewater containing different metal ions at various temperatures.

The Use of Algae and Fungi for Removal of Pharmaceuticals by Bioremediation and Biosorption Processes: A Review

The occurrence and fate of pharmaceuticals in the aquatic environment is recognized as one of the emerging issues in environmental chemistry. Conventional wastewater treatment plants (WWTPs) are not designed to remove pharmaceuticals (and their metabolites) from domestic wastewaters. The treatability of pharmaceutical compounds in WWTPs varies considerably depending on the type of compound since their biodegradability can differ significantly. As a consequence, they may reach the aquatic environment, directly or by leaching of the sludge produced by these facilities. Currently, the technologies under research for the removal of pharmaceuticals, namely membrane technologies and advanced oxidation processes, have high operation costs related to energy and chemical consumption. When chemical reactions are involved, other aspects to consider include the formation of harmful reaction by-products and the management of the toxic sludge produced. Research is needed in order to develop economic and sustainable treatment processes, such as bioremediation and biosorption. The use of low-cost materials, such as biological matrices (e.g., algae and fungi), has advantages such as low capital investment, easy operation, low operation costs, and the non-formation of degradation by-products. An extensive review of existing research on this subject is presented.

The presence of in situ sulphamethoxazole degraders and their interactions with other microbes in activated sludge as revealed by DNA stable isotope probing and molecular ecological network analysis

Wastewater treatment plants (WWTPs) are the main hotspots for the release of antibiotics, including the widely used sulphonamides. Microbes play important roles in eliminating sulphonamides in WWTPs, and knowledge about these degraders and their interactions within the microbial community is crucial for operating and optimising WWTPs. In the present study, stable isotope probing (SIP) coupled with high-throughput sequencing as culture-independent approach revealed four operational taxonomic units (OTUs) involved in sulphamethoxazole (SMX) degradation in activated sludge. Except for the OTU affiliated with Gammaproteobacteria, the others have not been previously reported to possess the ability to metabolise SMX. The isolated SMX degrader by culture-dependent method did not participate in SMX biodegradation in situ according to the SIP analysis, and showed weak correlations with other members in the activated sludge. The complex interactions between in situ active SMX degraders and non-degrading microbes might explain our failure to isolate these degraders. In addition, sul1 genes associated with SMX resistance were also labelled with ¹³C, suggesting that they might benefit from SMX degradation and/or originate from the active SMX degraders. These findings broaden our understanding of the diversity of SMX-degrading microbes and their associated characteristics in WWTPs.

The biodegradation of cefuroxime, cefotaxime and cefpirome by the synthetic consortium with probiotic Bacillus clausii and investigation of their potential biodegradation pathways

Cephalosporin residues in the environment are a great concern, but bioremediation options do exist. Bacillus clausii T reached a removal rate of 100% within 8 h when challenged with a mixture of cefuroxime (CFX), cefotaxime (CTX), and cefpirome (CPR). The co-culture of B. clausii T and B. clausii O/C displayed a higher removal efficiency for the mixture of CFX, CTX and CPR than a pure culture of B. clausii O/C. B. clausii T alleviated the biotoxicity of CFX and CPR. What's more, the biotoxicity of for CFX and CPR transformation products released by the co-culture of B. clausii T and B. clausii O/C was lower than that in pure cultures. Real-time PCR was applied to detect the changes in the expression levels of the relevant antibiotic-resistance genes of B. clausii T during CFX and CPR degradation. The results indicated that CFX and CPR enhanced the expression of the β-lactamase gene bcl1. Hydrolysis, deacetylation and decarboxylation are likely the major mechanisms of CTX biodegradation by B. clausii. These results demonstrate that B. clausii T is a promising strain for the bioremediation of environmental contamination by CFX, CTX, and CPR.

Bacteria That Make a Meal of Sulfonamide Antibiotics: Blind Spots and Emerging Opportunities

The release of sulfonamide antibiotics into the environment is alarming because the existence of these antibiotics in the environment may promote resistance in clinically relevant microorganisms, which is a potential threat to the effectiveness of antibiotic therapies. Controllable biodegradation processes are of particular significance for the inexpensive yet effective restoration of sulfonamide-contaminated environments. Cultivation-based techniques have already made great strides in successfully isolating bacteria with promising sulfonamide degradation abilities, but the implementation of these isolates in bioremediation has been limited by unknown microbial diversity, vast population responsiveness, and the impact of perturbations from open and complex environments. Advances in DNA sequencing technologies and metagenomic analyses are being used to complement the information derived from cultivation-based procedures. In this Review, we provide an overview of the growing understanding of isolated sulfonamide degraders and identify shortcomings of the prevalent literature in this field. In addition, we propose a technical paradigm that integrates experimental testing with metagenomic analysis to pave the way for improved understanding and exploitation of these ecologically important isolates. Overall, this Review aims to outline how metagenomic studies of isolated sulfonamide degraders are being applied for the advancement of bioremediation strategies for sulfonamide contamination.

Fungi extracellular enzyme-containing microcapsules enhance degradation of sulfonamide antibiotics in mangrove sediments

Mangroves represent a special coastal vegetation along the coastlines of tropical and subtropical regions. Sulfonamide antibiotics (SAs) are the most commonly used antibiotics. The application of white-rot fungi extracellular enzyme-containing microcapsules (MC) for aerobic degradation of SAs in mangrove sediments was investigated in this study. Degradation of three SAs, sulfamethoxazole (SMX), sulfadimethoxine (SDM), and sulfamethazine (SMZ), was enhanced by adding MC to the sediments. The order of SA degradation in batch experiments was SMX > SDM > SMZ. Bioreactor experiments revealed that SA removal rates were higher with than without MC. The enhanced SA removal rates with MC persisted with three re-additions of SAs. Thirteen bacteria genera (Achromobacter, Acinetobacter, Alcaligenes, Aquamicrobium, Arthrobacter, Brevundimonas, Flavobacterium, Methylobacterium, Microbacterium, Oligotropha, Paracoccus, Pseudomonas, and Rhodococcus) were identified to be associated with SA degradation in mangrove sediments by combination of next-generation sequencing, bacterial strain isolation, and literature search results. Results of this study suggest that MC could be used for SA removal in mangrove sediments.

Improvement of sulfamethoxazole (SMX) elimination and inhibition of formations of hydroxylamine-SMX and N4-acetyl-SMX by membrane bioreactor systems

Sulfamethoxazole (SMX) has frequently been detected in aquatic environments. In natural environment, not only individual microorganism but also microbial consortia are involved in some biotransformation of pollutants. The competition for space under consortia causing cell-cell contact inhibition changes the cellular behaviors. Herein, the membrane bioreactor system (MBRS) was applied to improve SMX elimination thorough exchanging the cell-free broths (CFB). The removal efficiency of SMX was increased by more than 24% whether under the pure culture of A. faecalis or under the co-culture of A. faecalis and P. denitrificans with MBRS. Meanwhile, MBRS significantly inhibited the formation of HA-SMX, and Ac-SMX from parent compound. Additionally, the cellular growth under MBRS was obviously enhanced, indicating that the increases in the cellular growth under MBRS are possibly related to the decreases in the levels of HA-SMX and Ac-SMX compared to that without MBRS. The intracellular NADH/NAD⁺ ratios of A. faecalis under MBRS were increased whether thorough itself-recycle of CFB or exchanging CFB between the pure cultures of A. faecalis and P. denitrificans, suggesting that the enhancement in the bioremoval efficiencies of SMX under MBRS by A. faecalis is likely related to the increases in the NADH/NAD⁺ ratio. Taken together, the regulation of cell-to-cell communication is preferable strategy to improve the bioremoval efficiency of SMX.

Simultaneous removal of ciprofloxacin, norfloxacin, sulfamethoxazole by co-producing oxidative enzymes system of Phanerochaete chrysosporium and Pycnoporus sanguineus

Pycnoporus sanguineus could remove 98.5% ciprofloxacin (CIP), 96.4% norfloxacin (NOR), 100% sulfamethoxazole (SMX), and 100% their mixture through biotransformation within 2 d, while Phanerochaete chrysosporium could only remove 64.5% CIP, 73.2% NOR, and 63.3% SMX through biosorption and biotransformation within 8 d, respectively. The efficiencies of antibiotic bioremoval under co-culture were more than that under the pure culture of P. chrysosporium but less than that under the pure culture of P. sanguineus. However, only 2% CIP and 3% NOR under co-culture were detected in the mycelia. In vitro enzymatic degradation and in vivo cytochrome P450 inhibition experiments revealed that laccase and cytochrome P450 could play roles in the removal of above all antibiotics, while manganese peroxidase could only play role in SMX removal. Transformation products of CIP and NOR under the pure culture of P. chrysosporium could be assigned to three different reaction pathways: (i) defluorination or dehydration, (ii) decarboxylation, and (iii) oxidation of the piperazinyl substituent. Additionally, other pathways, (iv) monohydroxylation, and (v) demethylation or deethylation at position N₁ also occurred under the co-culture and pure culture of P. sanguineus. Antibacterial activity of antibiotics could be eliminated after treatments with pure and co-culture of P. chrysosporium and P. sanguineus. The cytotoxicity of the metabolites of SMX and NOR under co-culture was lower than that under the pure culture of P. sanguineus, indicating co-culture is a more environmentally friendly strategy to eliminate SMX and NOR.

Emergent contaminants: Endocrine disruptors and their laccase-assisted degradation - A review

Herein, an effort has been made to highlight the trends of the state-of-the-art of laccase-assisted degradation of emerging contaminants at large and endocrine disruptors in particular. Since first described in the 19th century, laccase has received particular interest for inter- and multidisciplinary investigations due to its uniqueness and remarkable biotechnological applicability. There has always been a paramount concern over the widespread occurrences of various pollutant types, around the globe. Therefore, pollution free processes are gaining ground all over the world. With ever increasing scientific knowledge, socioeconomic awareness, human health-related issues and ecological apprehensions, people are more concerned about the widespread environmental pollutants. In this context, the occurrences of newly identified pollutants so-called "emerging contaminants - ECs" in our main water bodies is of continued and burning concern worldwide. Undoubtedly, various efforts have already been made to tackle this challenging ECs concern though using different approaches including physical and chemical, however, each has considerable limitations. In this review, we present information on how laccase-assisted approach can change this limited tendency of physical and chemical based approaches. A special focus has been given to the laccase-assisted systems including pristine laccase, laccase-mediator catalyzed system and immobilized-laccase catalyzed system that promotes the endocrine disruptors removal. Towards the end, a list of outstanding questions and research gaps are given that can pave the way for future studies.

Laccase-Mediated Treatment of Pharmaceutical Wastes

Laccases are versatile multi-copper enzymes belonging to the superfamily of oxidase enzymes, which have been known since the nineteenth century. Recent discoveries have refined investigators' views of the potential of laccase as a magic tool for remarkable biotechnological purposes. A literature review of the capabilities of laccases, their assorted substrates, and their molecular mechanism of action now indicates the emergence of a new direction for laccase application as part of an arsenal in the fight against the contamination of water supplies by a number of frequently prescribed medications. This chapter provides a critical review of the literature and reveals the pivotal role of laccases in the elimination and detoxification of pharmaceutical contaminants in aquatic environments and wastewaters.

White rot fungi and advanced combined biotechnology with nanomaterials: promising tools for endocrine-disrupting compounds biotransformation

Endocrine-disrupting compounds (EDCs) can interfere with endocrine systems and bio-accumulate through the food chain and even decrease biodiversity in contaminated areas. This review discusses a critical overview of recent research progress in the biotransformation of EDCs (including polychlorinated biphenyl and nonylphenol, and suspected EDCs such as heavy metals and sulfonamide antibiotics) by white rot fungi (WRF) based on techniques with an emphasis on summarizing and analyzing fungal molecular, metabolic and genetic mechanisms. Not only intracellular metabolism which seems to perform essential roles in the ability of WRF to transform EDCs, but also advanced applications are deeply discussed. This review mainly reveals the removal pathway of heavy metal and antibiotic pollutants because the single pollution almost did not exist in a real environment while the combined pollution has become more serious and close to people's life. The trends in WRF technology and its related advanced applications which use the combined technology, including biocatalysis of WRF and adsorption of nanomaterials, to degrade EDCs have also been introduced. Furthermore, challenges and future research needs EDCs biotransformation by WRF are also discussed. This research, referring to metabolic mechanisms and the combined technology of WRF with nanomaterials, undoubtedly contributes to the applications of biotechnology. This review will be of great benefit to an understanding of the trends in biotechnology for the removal of EDCs.

Laccases: Production, Expression Regulation, and Applications in Pharmaceutical Biodegradation

Laccases are a family of copper-containing oxidases with important applications in bioremediation and other various industrial and biotechnological areas. There have been over two dozen reviews on laccases since 2010 covering various aspects of this group of versatile enzymes, from their occurrence, biochemical properties, and expression to immobilization and applications. This review is not intended to be all-encompassing; instead, we highlighted some of the latest developments in basic and applied laccase research with an emphasis on laccase-mediated bioremediation of pharmaceuticals, especially antibiotics. Pharmaceuticals are a broad class of emerging organic contaminants that are recalcitrant and prevalent. The recent surge in the relevant literature justifies a short review on the topic. Since low laccase yields in natural and genetically modified hosts constitute a bottleneck to industrial-scale applications, we also accentuated a genus of laccase-producing white-rot fungi, Cerrena, and included a discussion with regards to regulation of laccase expression.