Analysis On Salt Tolerance Mechanism Of Salvia Miltiorrhiza And Vibrio Cholerae In High Salt Environment

Time Course Transcriptome Changes in Shewanella algae in Response to Salt StressShewanella algae, which produces tetrodotoxin and exists in various seafoods, can cause human diseases, such as spondylodiscitis and bloody diarrhea. In the present study, we focused on the temporal, dynamic process in salt-stressed S. algae by monitoring the gene transcript levels at different time points after high salt exposure. Transcript changes in amino acid metabolism, carbohydrate metabolism, energy metabolism, membrane transport, regulatory functions, and cellular signaling were found to be important for the high salt response in S. algat. The most common strategies used by bacteria to survive and grow in high salt environments, such as Na+ efflux, K+uptake, glutamate transport and biosynthesis, and the accumulation of compatible solutes, were also observed in S. algae. In particular, genes involved in peptidoglycan biosynthesis and DNA repair were highly and steadily up-regulated, accompanied by rapid and instantaneous enhancement of the transcription of large-and small-ribosome subunits, which suggested that the structural changes in the cell wall and some stressful adaptions occurred in S. algae. Furthermore, the transcription of genes involved in the tricarboxylic acid (TCA) cycle and the glycolytic pathway was decreased, whereas the transcription of genes involved in anaerobic respiration was increased. These results, demonstrating the multi-pathway reactions of S. algae in response to salt stress, increase our understanding of the microbial stress response mechanisms.Outer Membrane Protein OmpW Confers Salt Tolerance onto Vibrio cholerae by Transporting CarnitineVibrio cholerae, which is a serious human intestinal pathogen, often resides and thrives in estuaries but requiresmajor self-regulation to overcome intestinal hyperosmotic stress or high salt stress in water and food. In the presentstudy, we selected multiple 01 and 0139 group V. cholerae strains that were isolated from different regions andduring different years to study their salt tolerance. Based on the mechanisms that other bacteria use to respond tohigh salt stress, we selected salt stress-response related genes to study the mechanisms which V, cholerae respondsto high salt stress.V. cholerae strains showed salt-resistance characteristics that varied in salt concentrations from 4%to 6%. However,group 01 and group 0139 showed no significant difference in the degree of salt tolerance. The primary responses ofbacteria to salt stress, including Na+exclusion, K+uptake and glutamate biosynthesis, were observed in V. cholera strains. In addition, some sigma factors were up-regulated in V. cholerae strains, suggesting that V. cholerae may recruitcommon sigma factors to achieve an active salt stress response. However, some changes in gene transcript levels inresponse to salt stress in V. cholerae were strain-specific. In particular, hierarchical clustering of differentially expressed genes indicated that transcript levels of these genes were correlated with the degree of salt tolerance. Therefore, elevated transcript levels of some genes, including sigma factors and genes involved in peptidoglycan biosynthesis, may be due to the salt tolerance of strains. In addition, high salt-tolerant strains may recruit common as well asadditional sigma factors to activate the salt stress response.OmpW is an outer membrane protein that elevate the ability in salinity-tolerance in many bacteria. In Salmonellaenterica serovar Typhimurium the ompW gene transports methyl viologen that is a charged quaternary cation compound (QCC). QCCs, such as betaine, carnitine, taurine, trehalose, arginine, lysine, proline, play an important role as osmoprotectants during response to salt stress. From 1998-2001, PT6 strains of V. Cholerae emerged in Sichuan province with ompW 11-bp deletion. In this study, we constructed ompW deletion strains and complemented the PT6 strains with plasmid pBR322-ompW.. These strains grown in either rich or minimal media containing different osmoprotectants under high salt conditions to identify changes in growth. The results showed that the ompW mutant decreased the salt tolerance of V. Cholerae. QCC osmoprotectants betaine, carnitine and lysine rescued growth phenotypes under hypersaline conditions. The study identified that OmpW transported osmoprotectants carnitine.