Plastic Debris in the Aquatic Environment: An Emerging Substratum for Antimicrobial Resistant (AMR) Biofilms.

Plastic pollution has quadrupled over the past years and has become a global concern due to its direct impact on life forms. The present study analysed whether the plastic debris in aquatic environments could act as the substratum for the antimicrobial-resistant (AMR) bacteria to form biofilm for survival. We have collected various plastic debris (n = 32) from six sites of the Periyar River, the drinking water source for the entire city and one of the most polluted rivers in Kerala (India). The chemical composition of plastics was screened via FTIR analysis and found that they comprised two types, viz., polyethylene and polypropylene. Bacteria isolated from the samples were screened for the AMR characteristics towards eight different classes of antibiotics. All isolates showed 100% resistance towards colistin and obtained the MAR index value of 0.1-0.4 range. Six representative bacterial isolates with high multiple antibiotic resistance (MAR) index were selected and identified by 16sRNA sequencing as Lysinibacillus mangiferihumi, Bacillus pumilus, Bacillus safensis, Bacillus cereus, Bacillus altitudins and Bacillus pumilus. In vitro biofilm formation was experimented on the purchased plastic samples in artificial media and river water using two selected strains, Bacillus pumilus and Bacillus cereus. Significant variations were observed in biofilm growth in different media (P < 0.05) regardless of plastic types (P > 0.05). The extracellular polymeric substances (EPS) and the characteristic holes on the surface morphology were visualized in SEM analysis, thus indicating the conditioning of the plastics by the isolates for biofilm formation.

Suresh S ，Ambily SKA ，Chandran P 《-》

Biofilm influenced metal accumulation onto plastic debris in different freshwaters.

Microbial biofilms can rapidly colonize plastic debris in aquatic environments and subsequently, accumulate chemical pollutants from the surrounding water. Here, we studied the microbial colonization of different plastics, including polyethylene terephthalate (PET), polypropylene (PP), polyvinyl chloride (PVC), and polyethylene (PE) exposed in three freshwater systems (the Qinhuai River, the Niushoushan River, and Donghu Lake) for 44 days. We also assessed the biofilm mass and associated metals attached to plastics. The plastics debris characteristics, such as contact angle and surface roughness, greatly affected the increased biofilm biomass. All types of metal accumulation onto the plastic substrate abundances significantly higher than the concentrations of heavy metal in the water column, such as Ba (267.75 μg/g vs. 42.12 μg/L, Donhu Lake), Zn (254 μg/g vs. 0.023 μg/L the Qinhuai River), and Cr (93.75 μg/g vs. 0.039 μg/L, the Niushoushan River). Compared with other metals, the heavy metal Ba, Cr and Zn accumulated easily on the plastic debris (PET, PP, PVC, and PE) at all incubation sites. Aquatic environmental factors (total nitrogen, total phosphorus, and suspended solids concentrations) largely shaped metal accumulation onto plastic debris compared with plastic debris properties.

Liu Z ，Adyel TM ，Miao L ，You G ，Liu S ，Hou J ... -  《-》

Taxonomic variation, plastic degradation, and antibiotic resistance traits of plastisphere communities in the maturation pond of a wastewater treatment plant.

Maday SDM ，Kingsbury JM ，Weaver L ，Pantos O ，Wallbank JA ，Doake F ，Masterton H ，Hopkins M ，Dunlop R ，Gaw S ，Theobald B ，Risani R ，Abbel R ，Smith D ，Handley KM ，Lear G ... -  《-》

Biodegradation of low-density polyethylene and polypropylene by microbes isolated from Vaigai River, Madurai, India.

The present study aimed to evaluate the microplastic degradation efficiency of bacterial isolates collected from Vaigai River, Madurai, India. The isolates were processed with proper methods and incorporated in to the UV-treated polyethylene (PE) and polypropylene (PP) degradation. Based on preliminary screening, four bacterial isolates such as Bacillus sp. (BS-1), Bacillus cereus (BC), Bacillus sp. (BS-2), and Bacillus paramycoides (BP) were proceed to further degradation experiment for 21 days. The microplastics were filled with bacterial isolates which is use microplastic (PE, PP) as carbon source for their growth and proceed for shake flask experiment were carried out by two approaches with control. The microplastic degradation was confirmed through their weight loss, increasing fragmentations and changes of surface area against control experiments (microplastic without isolates) also confirms degrading efficiency of isolated bacterial strains through non-changes in their weight and surface area. The highest degradation of PP and PE were observed in BP (78.99 ± 0.005%), and BC (63.08 ± 0.009%) in single approach, while in combined approach BC & BP recorded the highest degradation in both PP (78.62 ± 2.16%), and PE (72.50 ± 20.53%). The formation of new functional groups is confirming the biofilm formation in the surface area of microplastics by isolates and proving their efficiency in degrade the microplastics. The degradation of microplastic experiments should be cost effective and zero waste which is helpful to save the environment and the present findings could reveal the way to degrade the microplastics and prevent the microplastic pollution in aquatic environment.

Nanthini Devi K ，Raju P ，Santhanam P ，Dinesh Kumar S ，Krishnaveni N ，Roopavathy J ，Perumal P ... -  《-》

Bacterial isolates from the Arctic region (Pasvik River, Norway): assessment of biofilm production and antibiotic susceptibility profiles.

Laganà P ，Votano L ，Caruso G ，Azzaro M ，Lo Giudice A ，Delia S ... -  《-》