Prokaryotic community formation on polyethylene films incubated for six months in a tropical soil.

Polyethylene film is one of the most common types of recalcitrant plastic waste materials. Information regarding the fate of plastic films in soil is scarce compared to the fate of plastic films in aquatic environments. The aim of this study was to evaluate the effects of soil fauna and of impregnation of polyethylene films with oil on the colonization of low-density polyethylene films by prokaryotic communities. The field experiment was performed in a monsoon tropical forest (Vietnam). Polyethylene films were incubated in thermally pre-defaunated soil isolated from the surrounding soil by a stainless steel mesh. Three mesh sizes were used, allowing access to different size groups of soil fauna. The diversity, taxonomic structure and co-occurrence patterns in prokaryotic communities were studied using high-throughput sequencing of 16S rRNA gene libraries. The prokaryotic communities that formed on polyethylene films were slightly different from those inhabiting the surrounding soil. Contrary to our expectations, no difference in the diversity of prokaryotes was observed between microcosms with different mesh sizes. Oil impregnation also had only a minor influence on the prokaryotic community structure. Polyethylene films incubated in microcosms with soil appeared to be colonized by various consortia of prokaryotes as a barren and inert surface.

[Monitoring of the chitinolytic microbial complex of the phylloplane].

A comprehensive study of chitinolytic microbial complexes of the phylloplane from cultured and forest plants has been conducted. An increase of the number and biomass of metabolically active cells of the representatives of the domain Bacteria and a decrease in fungal biomass in the experimental microcosms have been shown to occur after the introduction of chitin. The characteristic features of the taxonomic structure of metabolically active chitinolytic complexes of the phylloplane of the plants studied have been elucidated. Representatives of the phyla Proteobacteria, Bacteroidetes, and Verrucomicrobia have been shown to play important roles in the chitinolytic complexes of green leaf samples, while mycelial actinobacteria of the phylum Actinobacyteria played a similar role in needles of coniferous trees. A collection of chitinolytic microorganism cultures isolated from the phylloplane of different plant species has been created.