Ugly ducklings-the dark side of plastic materials in contact with potable water

Assessing microplastics-antibiotics coexistence induced ciprofloxacin-resistant Pseudomonas aeruginosa at a water region scale

Microplastics (MPs) waste is widespread globally in water systems. The opportunistic human pathogen Pseudomonas aeruginosa can cause serious acute and chronic infections that are notoriously difficult to treat. Ciprofloxacin (CIP) is broadly applied as an anti-P. aeruginosa drug. A growing evidence reveals that antibiotic-resistance genes-carrying Pseudomonas aeruginosa were detected on MPs forming plastisphere due to their adsorbability along with high occurrence of CIP in water environments. The MPs-niched CIP-resistant P. aeruginosa has been likely to emerge as an unignorable public health issue. Here, we offered a novel approach to assess the development of CIP-resistant P. aeruginosa under MPs-antibiotic coexistence at a water region scale. By combing the adsorption isotherm models used to estimate CIP condensation around MPs and a pharmacokinetic/pharmacodynamic-based microbial population dynamic model, we predicted the P. aeruginosa development on CIP-adsorbed MPs in waters. Our assessment revealed a high antibiotic resistance in the P. aeruginosa populations (∼50 %) with a wider range of waterborne total cell counts (∼10-2-104 cfu mL-1) among water regions in that the resistance proportion was primarily determined by CIP pollution level and relative abundance of various polymer type of MPs. We implicate that water region-specific MPs were highly likely to provide media for P. aeruginosa propagation. Our results highlight the importance of antibiotic-resistant pathogen colonization-emerging environmental medium interactions when addressing global threat from MPs pollution, in the context of MPs-antibiotics co-contamination assessment and for the continued provision of water system management.

Enhancing the DNA yield intended for microbial sequencing from a low-biomass chlorinated drinking water

DNA extraction yield from drinking water distribution systems and premise plumbing is a key metric for any downstream analysis such as 16S amplicon or metagenomics sequencing. This research aimed to optimize DNA yield from low-biomass (chlorinated) reverse osmosis-produced tap water by evaluating the impact of different factors during the DNA extraction procedure. The factors examined are (1) the impact of membrane materials and their pore sizes; (2) the impact of different cell densities; and (3) an alternative method for enhancing DNA yield via incubation (no nutrient spiking). DNA from a one-liter sampling volume of RO tap water with varying bacterial cell densities was extracted with five different filter membranes (mixed ester cellulose 0.2 μm, polycarbonate 0.2 μm, polyethersulfone 0.2 and 0.1 μm, polyvinylidene fluoride 0.1 μm) for biomass filtration. Our results show that (i) smaller membrane pore size solely did not increase the DNA yield of low-biomass RO tap water; (ii) the DNA yield was proportional to the cell density and substantially dependent on the filter membrane properties (i.e., the membrane materials and their pore sizes); (iii) by using our optimized DNA extraction protocol, we found that polycarbonate filter membrane with 0.2 μm pore size markedly outperformed in terms of quantity (DNA yield) and quality (background level of 16S gene copy number) of recovered microbial DNA; and finally, (iv) for one-liter sampling volume, incubation strategy enhanced the DNA yield and enabled accurate identification of the core members (i.e., Porphyrobacter and Blastomonas as the most abundant indicator taxa) of the bacterial community in low-biomass RO tap water. Importantly, incorporating multiple controls is crucial to distinguish between contaminant/artefactual and true taxa in amplicon sequencing studies of low-biomass RO tap water.

Microplastics promote the accumulation of negative fungal groups and cause multigenerational effects in springtails

The environmental persistence of microplastics (MPs) is ubiquitous and problematic. Despite an increase in research on the soil ecotoxicity of MPs, the response of springtails to MP pollution remains unexplored. We hypothesized that MPs promote the accumulation of negative soil fungal groups and cause multigenerational effects in springtails. We performed a multigenerational study of high-density polyethylene MPs using springtail Folsomia candida and analyzed the soil fungal community. We found that soil entomopathogenic fungi and negative soil fungal groups accumulated in springtail F. candida due to soil MP pollution; subsequently, MPs negatively affected F. candida in the F2 generation. To the best of our knowledge, this is the first study to investigate the correlations between MP pollution, soil fungi, and fungi-feeding springtails. The study provides evidence of the accumulation of soil entomopathogenic fungi and negative soil fungal groups in F. candida caused by soil MP pollution.

Plastic pollution and fungal, protozoan, and helminth pathogens - A neglected environmental and public health issue?

Plastic waste is ubiquitous in the environment and can become colonised by distinct microbial biofilm communities, known collectively as the 'plastisphere.' The plastisphere can facilitate the increased survival and dissemination of human pathogenic prokaryotes (e.g., bacteria); however, our understanding of the potential for plastics to harbour and disseminate eukaryotic pathogens is lacking. Eukaryotic microorganisms are abundant in natural environments and represent some of the most important disease-causing agents, collectively responsible for tens of millions of infections, and millions of deaths worldwide. While prokaryotic plastisphere communities in terrestrial, freshwater, and marine environments are relatively well characterised, such biofilms will also contain eukaryotic species. Here, we critically review the potential for fungal, protozoan, and helminth pathogens to associate with the plastisphere, and consider the regulation and mechanisms of this interaction. As the volume of plastics in the environment continues to rise there is an urgent need to understand the role of the plastisphere for the survival, virulence, dissemination, and transfer of eukaryotic pathogens, and the effect this can have on environmental and human health.

Ultrasound-assisted synthesis of MIL-88(Fe) conjugated starch-Fe3O4 nanocomposite: A safe antibacterial carrier for controlled release of tetracycline

A constructing antibiotic carrier with a sustained release profile is a promising method to stop long-term bacterial infection, which is of ideal interest in different biomedical fields. To end this, the present study aims to design a novel carrier based on the modification of biopolymeric starch for the rising possible interaction between carrier and antibiotic agent. We established an in-situ ultrasound-assisted method was applied to grow and create MIL-88(Fe) framework in the structure of magnetic polysaccharide (i.e., St/Fe₃O₄) synthesized by precipitation method resulting in St/Fe₃O₄/MIL-88(Fe) nanocomposite. It was loaded with a high amount of Tetracycline (TC) through its immersion into the TC aqueous solution. The release profile of TC-loaded St/Fe₃O₄/MIL-88(Fe) displays a lower initial burst release (about 26 % after 12 h) and followed by a controlled and sustained release (about 73 % up to 168 h) in the simulated physiological environment at pH 7.4. The in vitro cytotoxicity showed good cytocompatibility against Human skin fibroblast (HFF-1) cells. TC-loaded St/Fe₃O₄/MIL-88(Fe) showed higher antibacterial activity against both S. aureus and E. coli with the MIC value of 64 and 128 μg·mL^-1, respectively.

Emissions of Fungal Volatile Organic Compounds in Residential Environments and Temporal Emission Patterns: Implications for Sampling Methods

Currently, little is known about the occurrences of fungi-derived microbial volatile organic compounds (mVOCs) in various indoor materials and their detection in residential environments, despite mVOCs being linked to several acute health effects. We identified various mVOCs emitted from fungi grown on PVC wallpaper, silicone rubber, and malt extract agar. We also investigated mVOCs temporal emission and whether fungi-derived VOCs concentration can be used to estimate fungal concentration in the air using active and passive air sampling methods. Among the three fungal growth media included in this study, silicone rubber produced the most variety of mVOCs: 106 compounds (from Aspergillus niger), 35 compounds (from Alternaria alternata), and 85 compounds (from Penicillium chrysogenum). We also found the emission patterns of eight chemical classes (i.e., aromatics, ethers, aliphatics, alcohols, ketones, aldehydes, chlorides, and nitrides) from the three different fungi. From the results of our field experiments in 11 residential environments, passive air samplers led to higher correlations coefficients (0.08 to 0.86) between mVOCs' air concentrations and airborne fungal concentrations, compared with active air samplers, which showed negative correlation coefficients (-0.99 to -0.02) for most compounds. This study elucidated the occurrence and temporal emission patterns of fungal VOCs in residential environments.

Anthropogenic impacts on the biodiversity and anti-interference ability of microbial communities in lakes

Lakes are critical for biogeochemical and ecological processes and are sensitive and vulnerable to anthropogenic disturbances, but how and to what extent human activities disturb the biodiversity in lakes remain unknown. Here, we showed the microbial diversity in 46 lakes and assessed the influence of 27 anthropogenic factors. We found that the economic level (e.g., per capita gross domestic product) was strongly negatively correlated (r = -0.97) with bacterial diversity but positively correlated (r = 0.17) with fungal diversity in lakes. The composition of the microbial community significantly changed with increasing economic level. Bacteria are more sensitive than fungi to anthropogenic impacts. Expanding the population size and increasing the economic level may promote the development of fungal diversity but inhibit bacterial diversity. Air quality, urbanization and ozone were negatively correlated with bacterial diversity, and fisheries had a negative correlation with fungal diversity. The anti-interference ability of lake microorganisms in the middle economic level zones (45,000-90,000 yuan/person) was stronger than that in high-level (> 90,000 yuan/person) and low-level (> 45,000 yuan/person) economic zones. Overall, our investigation provides national-scale evidence that changes in the microbial diversity in lakes were related to economic levels.

Biofilms in Water Hoses of a Meat Processing Environment Harbor Complex Microbial Communities

Safe and hygienic water distribution is essential for maintaining product quality and safety. It is known that biofilms alter the appearance and microbial quality of water along the distribution chain. Yet, biofilms in water hoses throughout the food processing environment have not been investigated in detail. Here, microbial communities from water hoses and other environmental sites in contact with water, in addition to the source water itself, were studied in the meat processing environment. Biofilms were present in all water hoses as determined by the presence of bacterial DNA and biofilm matrix components (carbohydrates, extracellular DNA, and proteins). The microbial community of the biofilms was dominated by Proteobacteria, represented mainly by Comamonadaceae and Pseudoxanthomonas. Moreover, genera that are associated with an intracellular lifestyle (e.g., Neochlamydia and Legionella) were present. Overall, the microbial community of biofilms was less diverse than the water microbial community, while those from the different sample sites were distinct from each other. Indeed, only a few phyla were shared between the water hose biofilm and the source water or associated environmental samples. This study provides first insights towards understanding the microbiota of water hose biofilms in the food processing environment.

Microbial Contamination of Rubber Ducks Floating in Bathtubs of Bathing Facilities, and an Evaluation of Their Washing Methods

Microbiological contamination inside rubber ducks floating in the bathtub at a "duck bath" of a bathing facility was analyzed by examining bacterial and amoebic counts. The results of microbial tests, such as standard plate count, heterotrophic plate count and Legionella-LAMP (Loopmediated isothermal amplification) , showed that microbial contamination increased in the rubber ducks over time. When the ducks were washed with sodium hypochlorite, those microbial contaminations were not detected; but when the ducks were washed with an electrolyzed water, the standard plate counts and the heterotrophic plate counts were detected in the amount of 10³ per duck in the wipe samples. Without proper washing of rubber ducks, bacteria and free-living amoeba can grow and colonize biofilms, and can thereby cause infection in humans. Also, microbial contamination inside ducks may reduce chlorination of the entire bathtub and cause bacterial infection such as Legionellosis from the bathtub water.

The role of antibiotics and heavy metals on the development, promotion, and dissemination of antimicrobial resistance in drinking water biofilms

Antimicrobial resistance (AMR), as well as the development of biofilms in drinking water distribution systems (DWDSs), have become an increasing concern for public health and management. As bulk water travels from source to tap, it may accumulate contaminants of emerging concern (CECs) such as antibiotics and heavy metals. When these CECs and other selective pressures, such as disinfection, pipe material, temperature, pH, and nutrient availability interact with planktonic cells and, consequently, DWDS biofilms, AMR is promoted. The purpose of this review is to highlight the mechanisms by which AMR develops and is disseminated within DWDS biofilms. First, this review will lay a foundation by describing how DWDS biofilms form, as well as their basic intrinsic and acquired resistance mechanisms. Next, the selective pressures that further induce AMR in DWDS biofilms will be elaborated. Then, the pressures by which antibiotic and heavy metal CECs accumulate in DWDS biofilms, their individual resistance mechanisms, and co-selection are described and discussed. Finally, the known human health risks and current management strategies to mitigate AMR in DWDSs will be presented. Overall, this review provides critical connections between several biotic and abiotic factors that influence and induce AMR in DWDS biofilms. Implications are made regarding the importance of monitoring and managing the development, promotion, and dissemination of AMR in DWDS biofilms.

Microplastics accumulate fungal pathogens in terrestrial ecosystems

Microplastic (MP) is a pervasive pollutant in nature that is colonised by diverse groups of microbes, including potentially pathogenic species. Fungi have been largely neglected in this context, despite their affinity for plastics and their impact as pathogens. To unravel the role of MP as a carrier of fungal pathogens in terrestrial ecosystems and the immediate human environment, epiplastic mycobiomes from municipal plastic waste from Kenya were deciphered using ITS metabarcoding as well as a comprehensive meta-analysis, and visualised via scanning electron as well as confocal laser scanning microscopy. Metagenomic and microscopic findings provided complementary evidence that the terrestrial plastisphere is a suitable ecological niche for a variety of fungal organisms, including important animal and plant pathogens, which formed the plastisphere core mycobiome. We show that MPs serve as selective artificial microhabitats that not only attract distinct fungal communities, but also accumulate certain opportunistic human pathogens, such as cryptococcal and Phoma-like species. Therefore, MP must be regarded a persistent reservoir and potential vector for fungal pathogens in soil environments. Given the increasing amount of plastic waste in terrestrial ecosystems worldwide, this interrelation may have severe consequences for the trans-kingdom and multi-organismal epidemiology of fungal infections on a global scale.

Fingerprinting Plastic-Associated Inorganic and Organic Matter on Plastic Aged in the Marine Environment for a Decade

The long-term aging of plastic leads to weathering and biofouling that can influence the behavior and fate of plastic in the marine environment. This is the first study to fingerprint the contaminant profiles and bacterial communities present in plastic-associated inorganic and organic matter (PIOM) isolated from 10 year-aged plastic. Plastic sleeves were sampled from an oyster aquaculture farm and the PIOM was isolated from the intertidal, subtidal, and sediment-buried segments to investigate the levels of metal(loid)s, polyaromatic hydrocarbons (PAHs), per-fluoroalkyl substances (PFAS) and explore the microbial community composition. Results indicated that the PIOM present on long-term aged high-density polyethylene plastic harbored high concentrations of metal(loid)s, PAHs, and PFAS. Metagenomic analysis revealed that the bacterial composition in the PIOM differed by habitat type, which consisted of potentially pathogenic taxa including Vibrio, Shewanella, and Psychrobacter. This study provides new insights into PIOM as a potential sink for hazardous environmental contaminants and its role in enhancing the vector potential of plastic. Therefore, we recommend the inclusion of PIOM analysis in current biomonitoring regimes and that plastics be used with caution in aquaculture settings to safeguard valuable food resources, particularly in areas of point-source contamination.

Exploring the Composition and Functions of Plastic Microbiome Using Whole-Genome Sequencing

Besides the ecotoxicological consequences of microplastics and associated chemicals, the association of microbes on plastics has greater environmental implications as microplastics may select for unique microbiome participating in environmentally significant functions. Despite this, the functional potential of the microbiome associated with different types of plastics is understudied. Here, we investigate the interaction between plastic and marine biofilm-forming microorganisms through a whole-genome sequencing approach on four types of microplastics incubated in the marine environment. Taxonomic analysis suggested that the microplastic surfaces exhibit unique microbial profiles and niche partitioning among the substrates. In particular, the abundance of Vibrio alginolyticus and Vibrio campbellii suggested that microplastic pollution may pose a potential risk to the marine food chain and negatively impact aquaculture industries. Microbial genera involved in xenobiotic compound degradation, carbon cycling, and genes associated with the type IV secretion system, conjugal transfer protein TraG, plant-pathogen interaction, CusA/CzcA family heavy metal efflux transfer proteins, and TolC family proteins were significantly enriched on all the substrates, indicating the variety of processes operated by the plastic-microbiome. The present study gives a detailed characterization of the rapidly altering microbial composition and gene pools on plastics and adds new knowledge surrounding the environmental ramifications of marine plastic pollution.

Ultrasound-assisted synthesis of MIL-88(Fe) coordinated to carboxymethyl cellulose fibers: A safe carrier for highly sustained release of tetracycline

For stopping long-time harmful bacterial infection, designing a drug carrier with a highly prolonged release profile is a promising approach that is of interest to different biomedical areas. The subject of this work is to synthesis a novel carrier system through coordination of MIL-88(Fe) to carboxymethyl cellulose (CMC) for enhancing interaction between drug and carrier. We established an ultrasound-assisted synthetic method for in situ synthesis of MIL-88(Fe) in the presence of CMC resulting in CMC/MIL-88(Fe) composite. The CMC/MIL-88(Fe) was loaded with a high amount of Tetracycline (TC) by immersion of carrier to the TC aqueous solution. The release profile in the simulated physiological conditions, pH 7.4, revealed a low initial burst release followed by a sustained and prolonged release over 384 h. The in vitro cytotoxicity of CMC/MIL-88(Fe) against Human skin fibroblast (HFF-1) cells was calculated by MTT assay and showed a good cytocompatibility. The antibacterial activity was found for TC-loaded CMC/MIL-88(Fe) toward both E. coli and S. aureus with MIC 64 mg·ml^-1.

Distinct fungal plastisphere across different river functional zones: A watershed scale study

Fungi not only play important roles in biogeochemical processes but also can form biofilm on plastic debris. However, knowledge of structure composition and spatiotemporal pattern of fungal plastisphere on different kinds of plastic debris in river with specific usages, known as river functional zones, is still missing. In this study, we investigated the spatial distribution of the fungal plastisphere across a complete urban river with different functional zones (drinking, farm irrigation, aquaculture, and tail lake). Our research was performed based on both field residual plastic debris collection and a 30-day field in situ incubation experiments. Our study revealed that plastic debris enriched distinct fungal communities (including pathogenic fungi) significantly different from the surrounding water. Tracking the source of the fungi colonized on plastic debris suggested that the fungal taxa colonized on the different kinds of plastic debris were not from the surrounding water. Human activities had considerable effects on the fungal community structure on plastic debris, and the plastisphere fungal community structure strikingly varied across different river functional zones. Plastisphere may be used as an indicator for fungi biogeography and pathogenic fungi pollution in river with different functional zones. These findings are essential for ecological risk assessment and management decisions for pollution control of plastic debris and maintaining ecological health.

Biofouling and me: My Stockholm syndrome with biofilms

Biofouling is the undesired deposition and growth of microorganisms on surfaces, forming biofilms. The definition is subjective and operational: not every biofilm causes biofouling - only if a given a subjective "threshold of interference" is exceeded, biofilms cause technical or medical problems. These range from the formation of slime layers on ship hulls or in pipelines, which increase friction resistance, to separation membranes, on which biofilms increase hydraulic resistance, to heat exchangers where they interfere with heat transport to contamination of treated water by eroded biofilm cells which may comprise hygienically relevant microorganisms, and, most dangerous, to biofilms on implants and catheters which can cause persistent infections. The largest fraction of anti-fouling research, usually in short-term experiments, is focused on prevention or limiting primary microbial adhesion. Intuitively, this appears only logical, but turns out mostly hopeless. This is because in technical systems with open access for microorganisms, all surfaces are colonized sooner or later which explains the very limited success of that research. As a result, the use of biocides remains the major tool to fight persistent biofilms. However, this is costly in terms of biocides, it stresses working materials, causes off-time and environmental damage and it usually leaves large parts of biofilms in place, ready for regrowth. In order to really solve biofouling problems, it is necessary to learn how to live with biofilms and mitigate their detrimental effects. This requires rather an integrated strategy than aiming to invent "one-shot" solutions. In this context, it helps to understand the biofilm way of life as a natural phenomenon. Biofilms are the oldest, most successful and most widely distributed form of life on earth, existing even in extreme environments and being highly resilient. Microorganisms in biofilms live in a self-produced matrix of extracellular polymeric substances (EPS) which allows them to develop emerging properties such as enhanced nutrient acquisition, synergistic microconsortia, enhanced tolerance to biocides and antibiotics, intense intercellular communication and cooperation. Transiently immobilized, biofilm organisms turn their matrix into an external digestion system by retaining complexed exoenzymes in the matrix. Biofilms grow even on traces of any biodegradable material, therefore, an effective anti-fouling strategy comprises to keep the system low in nutrients (good housekeeping), employing low-fouling, easy-to-clean surfaces, monitoring of biofilm development, allowing for early intervention, and acknowledging that cleaning can be more important than trying to kill biofilms, because cleaning does not cut the nutrient supply of survivors and dead biomass serves as an additional carbon source for "cannibalizing" survivors, supporting rapid after growth. An integrated concept is presented as the result of a long journey of the author through biofouling problems.

Resource or waste? A perspective of plastics degradation in soil with a focus on end-of-life options

'Capable-of-being-shaped' synthetic compounds are prevailing today over horn, bone, leather, wood, stone, metal, glass, or ceramic in products that were previously left to natural materials. Plastic is, in fact, economical, simple, adaptable, and waterproof. Also, it is durable and resilient to natural degradation (although microbial species capable of degrading plastics do exist). In becoming a waste, plastic accumulation adversely affects ecosystems. The majority of plastic debris pollutes waters, accumulating in oceans. And, the behaviour and the quantity of plastic, which has become waste, are rather well documented in the water, in fact. This review collects existing information on plastics in the soil, paying particular attention to both their degradation and possible re-uses. The use of plastics in agriculture is also considered. The discussion is organised according to their resin type and the identification codes used in recycling programs. In addition, options for post-consumer plastics are considered. Acknowledged indicators do not exist, and future study they will have to identify viable and shared methods to measure the presence and the degradation of individual polymers in soils.

Critical Assessment of Methods to Quantify Biofilm Growth and Evaluate Antibiofilm Activity of Host Defence Peptides

Biofilms are multicellular communities of bacteria that can adhere to virtually any surface. Bacterial biofilms are clinically relevant, as they are responsible for up to two-thirds of hospital acquired infections and contribute to chronic infections. Troublingly, the bacteria within a biofilm are adaptively resistant to antibiotic treatment and it can take up to 1000 times more antibiotic to kill cells within a biofilm when compared to planktonic bacterial cells. Identifying and optimizing compounds that specifically target bacteria growing in biofilms is required to address this growing concern and the reported antibiofilm activity of natural and synthetic host defence peptides has garnered significant interest. However, a standardized assay to assess the activity of antibiofilm agents has not been established. In the present work, we describe two simple assays that can assess the inhibitory and eradication capacities of peptides towards biofilms that are formed by both Gram-positive and negative bacteria. These assays are suitable for high-throughput workflows in 96-well microplates and they use crystal violet staining to quantify adhered biofilm biomass as well as tetrazolium chloride dye to evaluate the metabolic activity of the biofilms. The effect of media composition on the readouts of these biofilm detection methods was assessed against two strains of Pseudomonas aeruginosa (PAO1 and PA14), as well as a methicillin resistant strain of Staphylococcus aureus. Our results demonstrate that media composition dramatically alters the staining patterns that were obtained with these dye-based methods, highlighting the importance of establishing appropriate biofilm growth conditions for each bacterial species to be evaluated. Confocal microscopy imaging of P. aeruginosa biofilms grown in flow cells revealed that this is likely due to altered biofilm architecture under specific growth conditions. The antibiofilm activity of several antibiotics and synthetic peptides were then evaluated under both inhibition and eradication conditions to illustrate the type of data that can be obtained using this experimental setup.