Bacterial communities of “suspended soils” of Vietnam national reserves

A comprehensive characteristic of prokaryotic communities of “suspended soils (soil-like bodies/solids)” formed in the roots of epiphytic ferns (Drynaria sp. and Asplenium sp.) in the territory of the Vietnamese nature reserves (Pu Hoat, Con Chu Rang, Song Thanh, Tay Giang and Xuan Lien) was obtained. The total number of bacteria (direct microscopic method) varied from 1.5 to 5 billion cells/g of substrate, the length of actinomycete mycelium varied from 494 to 690 m/g of substrate. Among the cultivated saprotrophic bacteria, representatives of actinomycetes dominated. According to the results of metabarcoding, the community was dominated by the phyla Pseudomonadota, Actinomycetota and Acidobacteriota. A number of bacterial genera identified by the 16S rRNA gene barcoding method belonged to typical soil bacteria capable of degrading complex organic compounds. The maximum generic diversity was found among representatives of the phylum Pseudomonadota, while less diversity was observed among the genera of the phylum Actinomycetota. Among the phylum Pseudomonadota, bacterial genera capable of actively fixing atmospheric nitrogen and synthesizing biologically active compounds are widely represented. The obtained pool of information on the diversity of the prokaryotic microbiome of “suspended soils” will allow us to form an idea of the functioning of this substrate and indicates a high biotechnological potential of the bacteria living in this biotope.