pH-dependent genotypic and phenotypic variability in Oleidesulfovibrio alaskensis G20
- Saxena, Priya
- Samanta, Dipayan
- Thakur, Payal
- Mau Goh, Kian
- Subramaniam, Mahadevan
- Peyton, Brent M. [ Montana State University: Chemical & Biological Engineering ]
- Fields, Matthew [ Montana State University: Microbiology & Cell Biology ]
- Sani, Rajesh K.
Sulfate-reducing bacteria (SRB) exhibit versatile metabolic adaptability with significant flexibility influenced by pH fluctuations, which play a critical role in biogeochemical cycles. In this study, we used a model SRB, Oleidesulfovibrio alaskensis G20, to determine the temporal effects of pH variations (pH 6, 7, and 8) on both growth dynamics and metabolic gene expressions. The specific growth rate at pH 6 (0.014 h−1) closely matched that at pH 7 (0.016 h−1), while pH 8 exhibited a lower growth rate (0.010 h−1). Lactate consumption peaked at pH 7 (0.35 mM lactate.h−1) and declined at pH 8 (0.09 mM lactate.h−1). Significant hydrogen production was evident under both acidic and alkaline conditions. Gene expression studies revealed that ATPases function as proton pumps, while hydrogenases mediate reversible proton-to-hydrogen conversion. Sulfate and energy metabolism act as electron acceptors and donors, while amino acid synthesis regulates basic and acidic amino acids to mitigate pH stress. Downregulation of FtsZ at pH 6 suggests impaired division, correlating with slightly longer lengths (~2 µm), while upregulation of divisome proteins at pH 8 suggests efficient division processes, aligning with shorter lengths (~1.8 µm). This study will facilitate the employment of O. alaskensis G20 in extreme pH environments, enhancing its effectiveness in optimizing bioremediation and anaerobic digestion processes.