The Microbial Community Analysis And New Cellulase Gene Mining In Saline Soils

Hypersaline ecosystems,such as salt lakes,solar salterns or saline springs,are globally distributed;but most studies focused on the microorganisms in saline waters or saline sediments of these ecosystems,the microbial community distribution in saline soils was still unclear.Lots of halophilic or halotolerant microorganisms thrive in hypersaline environments,these microorganisms and many halotolerant hydrolases secreted by them have great industrial prospects.The present study investigated the microbial community in saline soils collected from Qarhan Salt Lake,Qinghai,China with the high-throughput sequencing technology.Firstly,the environmental factors that drive the microbial community distribution were clarified: TOC was the primary driver of the prokaryotic community distribution in surface saline soils(0-10 cm),so was pH in subsurface saline soils(15-30 cm);salinity had more effects on the prokaryotic community in subsurface saline soils than in surface saline soils and played a less important role in saline soils than in saline waters or saline sediments.Then,the DNA extraction methods from saline soils were optimized and the biases of the 16 S rRNA gene amplicon sequencing data affected by DNA extraction methods were estimated.Though the DNA extraction methods can bias the microbial diversity and community and the relative abundances of some phyla/classes can vary by a factor more than five,the soil type was still the most important factor of the whole community.Soil washing pretreatment can efficiently improve DNA yields and the achieved microbial diversities from hypersaline soils,and we recommend soil washing pretreatment should be employed for hypersaline soils that cannot be achieved with enough DNA amounts for further sequencing without the pretreatment.Also,increasing the number of samples and pooling DNA solutions achieved with different DNA extraction methods for further sequencing can represent the real soil microbial community better.Finally,nearly 600,000 genes from the shotgun metagenomic sequencing data of a saline soil were predicted and 17 new cellulase genes with particular domains were screened for further functional verification.In addition,12 bins with completeness from 2.8% to 99.1% were achieved after the metagenomic binning analysis.The present research was very important for future microbial resource exploitation in Qarhan salt lake or many other hypersaline environments in China and provided references for further studies about the microbial communities in saline soils.