Detection of biofilm and planktonic microbial communities in litter/soil mixtures

Microbial community of the soil can be subdivided into a planktonic community of motile organisms and a community of sessile organisms, including those constituting biofilms on physical surfaces of different texture. Biofilm communities on surfaces of organic particles represent a crucial factor involved in decomposition of plant litter and soil particulate organic matter in general. In spite of their great ecological importance, the composition of soil biofilm communities is only scarcely studied due to methodological problems connected with dis-tinguishing biofilm inhabitants from other soil organisms.In this study, we were able to distinguish microbial communities colonizing four compartments of the experimental system: particles of the litter/soil mixture, biofilms on adjacent smooth or fibrous glass surfaces, and plankton. Existence of different preferences of microbial operational taxonomic units (OTUs) to occupy the experimental compartments has been suggested on the basis of their relative abundance in the community. Three main OTU groups have been defined according to these preferences. They are tentatively termed generalists, OTUs corresponding to organisms preferring the litter particles and OTUs corresponding to selective organisms discriminating between different surface types. At the same time, temperature has been identified as a factor influencing the switching between preferences of organisms for experimental compartments. Our work con-tributes to the description of the spatial microscale distribution of microorganisms in soil containing decom-posing organic matter.

Automated summary

The microbial community of soil can be divided into planktonic organisms and biofilm communities. Biofilm communities are crucial for decomposition of plant litter and soil organic matter. However, the composition of soil biofilm communities is not well studied due to methodological challenges.