Transcriptome Analysis to Understand Salt Stress Regulation Mechanism of Chromohalobacter salexigens ANJ207

Abstract

Soil salinity is one of the major global issues affecting soil quality and agricultural productivity. The plant growth-promoting halophilic bacteria that can thrive in regions of high salt (NaCl) concentration have the ability to promote the growth of plants in salty environments. In this study, attempts have been made to understand the salinity adaptation of plant growth-promoting moderately halophilic bacteria Chromohalobacter salexigens ANJ207 at the genetic level through transcriptome analysis. In order to identify the stress-responsive genes, the transcriptome sequencing of C. salexigens ANJ207 under different salt concentrations was carried out. Among the 8,936 transcripts obtained, 93 were upregulated while 1,149 were downregulated when the NaCl concentration was increased from 5 to 10%. At 10% NaCl concentration, genes coding for lactate dehydrogenase, catalase, and OsmC-like protein were upregulated. On the other hand, when salinity was increased from 10 to 25%, 1,954 genes were upregulated, while 1,287 were downregulated. At 25% NaCl, genes coding for PNPase, potassium transporter, aconitase, excinuclease subunit ABC, and transposase were found to be upregulated. The quantitative real-time PCR analysis showed an increase in the transcript of genes related to the biosynthesis of glycine betaine coline genes (gbcA, gbcB, and L-pro) and in the transcript of genes related to the uptake of glycine betaine (OpuAC, OpuAA, and OpuAB). The transcription of the genes involved in the biosynthesis of L-hydroxyproline (proD and proS) and one stress response proteolysis gene for periplasmic membrane stress sensing (serP) were also found to be increased. The presence of genes for various compatible solutes and their increase in expression at the high salt concentration indicated that a coordinated contribution by various compatible solutes might be responsible for salinity adaptation in ANJ207. The investigation provides new insights into the functional roles of various genes involved in salt stress tolerance and oxidative stress tolerance produced by high salt concentration in ANJ207 and further support the notion regarding the utilization of bacterium and their gene(s) in ameliorating salinity problem in agriculture.

Genome analysis of a halophilic Virgibacillus halodenitrificans ASH15 revealed salt adaptation, plant growth promotion, and isoprenoid biosynthetic machinery

“…These findings demonstrate that strain ASH15 is moderately halophilic and is able to withstand up to 25% NaCl concentrations. In accordance with our findings recently, Srivastava et al ( 2022 ) reported that Chromohalobacter salexigens ANJ207 was able to grow up to 30% NaCl concentration. The capacity to withstand moderate salt stress might help ASH15 survive as a free-living bacterium in saline soils.…”

“…These results showed the possible strategies that the strain ASH15 might employ on its host plant for salt stress alleviation and plant growth promotion. These findings are consistent with previous research studies, where halophilic bacteria, such as Bacillus halophilus, Marinococcus halophilus, Halobacillus litoralis, Saliiococcus hispanicus, and Halobacillus halophilus, were recognized to grow optimally between 10 and 15% NaCl concentrations (Sarwar et al, 2015;Reang et al, 2022;Srivastava et al, 2022).…”

Tandem mass tag‐based quantitative proteomics reveals osmotic adaptation mechanisms in Alkalicoccus halolimnae BZ‐SZ‐XJ29T, a halophilic bacterium with a broad salinity range for optimal growth

“…As the biosynthesis of compatible solutes is energetically costly, halophilic bacteria can import these compatible solutes or their precursors from their surroundings (Kempf & Bremer, 1998; Shah et al, 2022). In Chromohalobacter salexigens ANJ207, RT‐PCR analysis showed an increase in the transcript levels of genes related to the biosynthesis of glycine betaine coline ( gbcA and gbcB ), and genes related to the uptake of glycine betaine ( opuAC , opuAA , and opuAB ) (Srivastava et al, 2022). In A. halolimnae , the correlational expression levels of glycine betaine transport‐related proteins were strongly regulated by salinity (Table 2).…”

Integrated Genomics and Transcriptomics Provide Insights into Salt Stress Response in Bacillus subtilis ACP81 from Moso Bamboo Shoot (Phyllostachys praecox) Processing Waste

“…It has been shown that the gbsB and betB genes encode choline dehydrogenase and glycine betaine aldehyde dehydrogenase, respectively, both of which are involved in glycine betaine synthesis, linked to NADPH [ 51 , 52 ]. In addition, we detected an upregulation in the expression of the serA gene that encodes a stress response protein, 3-phosphoglycerate dehydrogenase, which catalyzes the initial phase of L-serine synthesis [ 53 ]. We suggest that the resistance of B. subtilis ACP81 to salt stress can be attributed to the biosynthetic regulation of cellular osmosis by glycine, serine, threonine, and choline–glycine betaine.…”