Real Time Fluorescent Quantitative PCR Analysis Of The Acid Shock Response Of Acidithiobacillus Ferrooxidans ATCC 23270

The flexibility of the metabolism of microbes enables them to respond and adapt to environmental changes outside their range for optimal growth.Research on environmental stresses,such as nutrient starvation,temperature stress,salt stress and pH stress,has revealed several mechanisms that enable bacteria to survive under adverse conditions.The bacterial has its appropriate growth range of pH.Leaching bacillu,which is chemoautotroph,acidophilic and aerobic,environmental acidity affected the growth of bacterial significantly.It was reported that the range of optimal pH to oxidize Fe²⁺is 1.5-2.5.Acidithiobacillus ferrooxidans(abbreviation is A.f)is of the most commercial value in metallurgy industry,and is one of the most studied bacterium.Generally, its optimal pH is 2.0-3.5.In this paper,we studied the the affect to A.f ATCC 23270 cells in different initial pH medium.From this,we got to know the growth of A.f ATCC 23270 in different pH medium.The results showed that A.f ATCC 23270 had a wide range of initial pH,and cells can live in medium.That cells could live in medium of initial pH 4.0,5.0, 6.0,and 7.0 is because medium pH fell to 3.0 immediately after inoculation.Generally,optimal pH of A.f is 2.0-3.5.The growth of A.f ATCC 23270 in medium of initial pH 1.3 was depressed,and the cells were 1/2 or 1/3 of cells in other medium.The response of Acidithiobacillus ferrooxidans ATCC 23270 to variations in extracellular pH was investigated based on some gene expression profiling.Real-time PCR analysis revealed that cells elicited both general and specific transcriptional responses when challenged with environmental acid(pH 1.3)or base(pH 2.3)conditions over a 6-h period. These responses included the differential expression of genes functionally linked to cell membrane structure,transcriptional regulation and signal transduction.Response to acid stress included the elevated expression of genes encoding the two component response regulator OmpR,the global regulator Fur,and the RNA polymerase sigma-38 factor(rpoS)and so on. Collectively,these results suggest that Acidithiobacillus ferrooxidans modulates multiple cell envelope components,transcription regulators and as part of its response to changing external pH conditions.