Diversity of culturable thermophilic actinobacteria and their producing cellulase activity in several dry-hot environments in Yunnan Province

Abstract:

[Objective] This study focus on the diversity of culturable thermophilic actinobacteria isolated from Dong Chuan dry hot river valley, Yuan Mou soil forests, and some high-temperature composts, hot springs nearby Kunming in Yunnan province, and exploring their cellulase producing activity. [Methods] Over five hundreds strains were isolated by the plate dilution method. After dereplication and removing the similar strains based on colony-characteristics, more than three hundreds strains were sequenced for further research. The cellulase producing activity of 451 strains were further detected by Congo red solution. [Results] BLAST analysis of the partial 16S rRNA gene sequences revealed that these strains have the highest similarity with 33 described genera, which were distributed in 15 families of 9 suborders. Among of them, five actinobacterial strains were selected as potential candidates for further polyphasic taxonomic research, based on the lower similarities of 16S rRNA gene sequences. Cellulase screening results showed that the positive rate was about 57% in total 451 strains. Most of them were distributed in three genera of Streptomyces, Micromonospora and Nonomuraea. [Conclusion] There are considerable diversity of culturable thermophilic actinobacteria in dry hot environments of Yunnan province. Meanwhile, these strains exhibited higher positive rate and stronger activity of cellulase, which will provide high-quality experimental materials for future research.