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Alkaline saline soils known also as “soda solonchaks” represent a natural soda habitat which differed from soda lake sediments by higher aeration and lower humidity. The microbiology of soda soils, in contrast to the more intensively studied soda lakes, remains poorly explored. In this work we present information on the diversity of culturable aerobic haloalkalitolerant bacteria with various hydrolytic activities from soda soils at different locations in Central Asia and Africa. In total, 180 isolates were obtained by using media with various polymers at pH 10 and 0.6 M total Na+. According to the 16S rRNA gene sequences analysis, most of the isolates belonged to Firmicutes and Actinobacteria. Most isolates possessed multiple hydrolytic activities, including endoglucanase, xylanase, amylase and protease. The pH profiling of selected representatives of actinobacteria and endospore-forming bacteria showed, that the former were facultative alkaliphiles, while the latter were mostly obligate alkaliphiles. The hydrolases of both groups were active at a broad pH range from 6 to 11. Overall, this work demonstrated the presence of a rich hydrolytic bacterial community in soda soils which might be explored further for production of haloalkalistable hydrolases.
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Supplemental Tables S1-S2 & a Supplemental Figure S1
Supplementary Table S1. SILVAngs Project Summary and Project Settings.
Suppl. Table S2. Site-specific taxonomic distribution of isolates different locations.
Suppl. Figure S1. Unrooted 16S rRNA gene sequence Maximum likelihood phylogenetic trees of the haloalkaliphilic isolates, possibly representing novel taxa, and its nearest relatives. All positions with less than 95 % site coverage were eliminated. There were a total of 1338 (A), 1394 (B), 1442 (C), 1373 (D) and 1103 (E) positions in the final datasets. The tree is drawn to scale, with branch lengths measured in the number of substitutions per site with corrections, associated with the model. Bootstrap values as percentages of 1000 repetitions are shown next to the branches. Type strains of validly published species are underlined. Genbank numbers are indicated at the beginning of each sequence designation.