Taxonomic and functional diversity of bacteria isolated from technogenic alkaline reservoir
Authors:   Institute of Ecology and Genetics of Microorganisms, UB RAS, Nechaeva Yulia I. ,   Perm State University, Aleev Vladislav S. ,   Institute of Ecology and Genetics of Microorganisms, UB RAS, Shestakova Elena A. ,   Institute of Ecology and Genetics of Microorganisms, UB RAS, Pyankova Anna A. ,   Institute of Ecology and Genetics of Microorganisms, UB RAS, Plotnikova Elena G. ,   Institute of Ecology and Genetics of Microorganisms, UB RAS; Perm State University
Published: October 2024

Currently, more and more attention is paid to the study of microorganisms living in various extreme environments and those characterized by high salinity and alkalinity, in particular. The microbial communities of natural halo-alkaline ecosystems have been studied well. However, there is insufficient knowledge about the microorganisms of artificial ecosystems formed under the influence of technogenic factors. This work was aimed to study the diversity of cultivated bacteria in the microbial community of the bottom sediments of an alkaline technogenic reservoir located on the territory of the Verkhnekamsk potassium-magnesium salt deposit (Perm Krai, Russia). The studied reservoir is an extreme ecosystem characterized by a high content of watersoluble salts, heavy metals, and alkalinity of the environment. Various organic pollutants, namely, aromatic and aliphatic compounds can be found there as well. In this regard, the study was aimed to search for haloalkaliphilic destructor bacteria that are promising for bioremediation of saline/alkaline media (soils, water bodies) contaminated with toxic organic compounds. Thirty-three strains of alkalitolerant and halophilic/halotolerant bacteria were isolated from the bottom sediments of the alkaline technogenic reservoir. Based on the analysis of the nucleotide sequences of the 16S rRNA gene, the isolated strains belonged to the classes Bacilli, Gammaproteobacteria, Alphaproteobacteria, and Actinomycetes. The dominant group among the identified cultivated microorganisms were bacteria of the Bacillaceae family (13 strains), represented by the genera Evansella, Oceanobacillus, Bacillus, Alkalihalobacillus, Paralkalibacillus, Salipaludibacillus, Cytobacillus and Exiguobacterium. Most of the isolates were extremophiles capable of growing at high concentrations of NaCl (up to 250 g/l) and pH 7-11. Strains Microbacterium sp. СXP-56, Brachybacterium sp. CXP-58, Salipaludibacillus sp. CX3-6 and Alkalihalobacillus sp. CX2-3.1 were obligate alkalophiles which grow in the pH range of 9.5-10.5. Alkalihalobacillus spp. CX2-3 and CX2-3.1, Salipaludibacillus sp. CX3-6 may be described as new taxa because these new strains had low percentage of similarity in 16S rRNA genes (97.27; 97.12 and 97.75%) with closely related type strains. Most of the isolated strains had biodegradable properties and were able to use naphthalene, biphenyl, ortho-phthalic, benzoic acids, and diesel fuel as the sole source of carbon and energy. The destructor strains, which carry out effective decomposition of aromatic compounds at high alkalinity and salinity of the environment, presented interest, namely, Kocuria sp. CXP-33, Evansella sp. СX2-1, Halomonas sp. CX2-8, Micrococcus sp. CXP-15, Brevibacterium spp. CXP-21, CXP-53, and Brachybacterium spp. CXP-46, CXP-58. The results obtained in this study are of fundamental importance and of interest for possible practical application in the restoration of saline/alkaline soils and water bodies contaminated with various organic compounds. Data on the identification of the bacterial strains and on their ecological and physiological characteristics are available in supplements on the journal’s website: https://journals.tsu.ru/biology/&journal_page=archive&id=2383