PRJNA553033
Zymomonas mobilis strain:ZM4 Raw sequence reads
In this study, Adaptive Laboratory Evolution (ALE) was used to adapt Z. mobilis at low pH and two mutant strains named as ZM4-3.6M and ZM4-3.5M with enhanced low pH tolerance were identified. Mutant strains exhibited 50%-130% enhancement on growth rate, 4-9 h reduction on fermentation time and 20%-63% improvement on ethanol production than wild-type ZM4 at low pH, when the growth and ethanol production of ZM4-3.6M were consistent with these of ZM4, and these of ZM4-3.5M was slightly lower than other strain at normal pH. Whole Genome Resequencing (WGR) and RNA Sequencing (RNA-Seq) technologies were used to reveal the low pH tolerant mechanism of mutant strains, and the analyzed data indicated that the native plasmids copy numbers of mutant strains and wild type were different significantly at different pH. WGR uncovered four proteins with SNPs may be related with the low pH tolerance. The RNA-Seq showed a significant upregulation of ABC transporters and ammonia transporter in two mutant strains at low pH. These proteins are related to excretion of proton and acidic end-product, and important for the maintenance of cellular pH homeostasis. The genes expression of ATP synthase-related subunits in dominant mutant strain ZM4-3.6M significantly upregulated at low pH which may further improved resistance to low pH.