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#acidic environments

2 public questions tagged with this topic.

Microbial Physiology

Bacteria use urease for survival in acidic environments by:

Survival in strongly acidic niches such as stomach lumen colonized by Helicobacter pylori causing gastritis and ulcer disease requires exceptionally efficient neutralization of extreme acidity. Urease is extraordinarily active nickel-dependent metalloenzyme encoded by ureABIEFGH operon containing structural subunits UreA and UreB plus accessory proteins UreE, UreF, UreG, UreD for nickel insertion, hydrolyzing urea abundant in gastric juice and urine into two molecules of ammonia and one carbon dioxide. Ammonia immediately protonates to ammonium NH4+ consuming protons and raising local pH from

Ref: Madigan et al., Brock Biology of Microorganisms, 16th ed., Chapter 6: Urease and Acid Survival via Ammonia Production.

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Microbial Physiology

Which bacterial stress response is activated in acidic environments?

Acid tolerance is vital survival strategy for enteric bacteria such as Escherichia coli, Salmonella Typhimurium and Shigella flexneri that must traverse gastric compartment where pH can fall to 1-3 and organic acid stress in intestine. Enterobacteriaceae deploy multiple amino acid decarboxylase antiporter systems for pH homeostasis. Under acidic conditions, inducible decarboxylases such as CadA lysine decarboxylase, AdiA arginine decarboxylase and GadA/B glutamate decarboxylases consume an intracellular proton during decarboxylation of substrate to produce cadaverine, agmatine and gamma-aminob

Ref: Prescott's Microbiology, 11th ed., Chapter 7: Acid Stress Response and CadB Decarboxylase System.

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