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Brackish Groundwaters Contain Plastic- and Cellulose-Degrading Bacteria

Microbial Ecology 2023 8 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Vladimir Šaraba, Jelena Milovanović, Jasmina Nikodinović‐Runić, Clémence Budin, Tjalf E. de Boer, Milica Ciric

Summary

Researchers discovered that brackish groundwater springs in Serbia harbor bacteria capable of degrading plastics and cellulose, with over 85% of isolated strains showing growth on at least one plastic or lignocellulosic substrate. Key plastic-degrading genera included Stenotrophomonas, Flavobacterium, Pseudomonas, and Serratia. As microplastic contamination of groundwater grows, these naturally occurring microbial communities could potentially be harnessed for bioremediation of plastic-polluted subsurface water resources.

The selected brackish groundwater occurrences in the geotectonic regions of Inner Dinarides of western Serbia (Obrenovačka Banja) and Serbian crystalline core (Lomnički Kiseljak and Velika Vrbnica) were sampled for isolation and identification of plastic- and lignocellulose-degrading bacteria, as well as for the assessment of their enzymatic potential. The examined occurrences belong to the cold and warm (subthermal), weakly alkaline, neutral, and weakly acidic groundwater, and their genetic types are HCO-Na + K and HCO-Ca, Mg. The most abundant genera identified by next-generation 16S sequencing of cultivated groundwater samples belong to Aeromonas and Exiguobacterium. Of isolates screened on plastic and lignocellulosic substrates, 85.3% demonstrated growth and/or degrading activity on at least one tested substrate, with 27.8% isolates degrading plastic substrate Impranil® DLN-SD (SD), 1.9% plastic substrate bis(2-hydroxyethyl)terephthalate, and 5.6% carboxymethyl cellulose (CMC). Isolates degrading SD that were identified by 16S rDNA sequencing belonged to genera Stenotrophomonas, Flavobacterium, Pantoea, Enterobacter, Pseudomonas, Serratia, Acinetobacter, and Proteus, while isolates degrading CMC belonged to genera Rhizobium and Shewanella. All investigated brackish groundwaters harbor bacteria with potential in degradation of plastics or cellulose. Taking into account that microplastics contamination of groundwater resources is becoming a significant problem, the finding of plastic-degrading bacteria may have potential in bioremediation treatments of polluted groundwater. Subterranean ecosystems, which are largely untapped resources of biotechnologically relevant enzymes, are not traditionally considered the environment of choice for screening for plastic- and cellulose-degrading bacteria and therefore deserve a special attention from this aspect.

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