Abundance and Diversity of Microorganisms in Soils and Associated Substrates (Leaf Litter and 'Suspended Soil') in Some Nature Reserves of Vietnam

摘要

-A comprehensive study of prokaryotic communities of zonal Ferralsols and intrazonal Fluvisols, as well as associated leaf litter and "suspended" soil from epiphytic fern baskets was carried out. The maximum number of bacteria determined by the direct luminescence method (5.59 billion cells) was found in the samples of Fluvisols, while the lengths of fungal (2038 m/g) and actinomycete (1086 m/g) mycelia were the largest in the mountainous Ferralsols. Bacteria of the genus Streptomyces included in the saprotrophic bacterial complex of the studied substrates made a significant contribution to the destruction of plant material. The bacteria of the phyla Firmicutes (80) and Proteobacteria (15) predominated in the prokaryotic community of the zonal Ferralsols, while the phyla Proteobacteria (51) and Actinobacteria (38) dominated in the sample of the "suspended" soil. The phyla Chloroflexi, Acidobacteria, Bacteroidetes, and Cyanobacteria were significantly less represented. Against the background of significant differences between the studied prokaryotic communities at the level of genera, they were characterized by similar functional groups of microorganisms: xenobiotic decomposers, nitrogen cycle bacteria, extremophiles, as well as bacteria that inhibit the growth of micromycetes. The metabolically active part of the prokaryotic community represented by the phyla Proteobacteria, Actinobacteria, and Acidobacteria, was the highest in the "suspended" soil and the least active in the leaf litter and A horizon of Ferralsols, which correlated with the high abundance of these phyla and the significant taxonomic diversity of bacteria in this locus. Functional genes nifH and alkB encoding nitrogenase and alkane-hydroxylase, respectively, were detected in all studied substrates. The number of copies of functional genes was the highest in the "suspended" soil sample, which makes this locus promising for isolating strains with a high biotechnological potential.