Propidium Monoazide Real-Time Quantitative Polymerase Chain Reaction for Sulfate Reducing Bacteria Viability Assay

Sulfate-reducing bacteria are harmful organisms to the oil industry. They produce hydrogen sulfide that acidifies the reservoirs (souring), corrodes structures, increases the concentration of sulfur, and consequently reduces the quality of the extracted oil. Traditional cultivation methods to detect and quantify these organisms are laborious and time-consuming. A Real Time Quantitative PCR methodology associated with propidium monoazide (PMA) was developed to assess the viability of Desulfovibrio vulgaris, which was subjected to a lethal heat treatment. After optimizing the PMA-qPCR methodology for this species, it was possible to detect reductions of 3 Log10 in samples containing 4.8 Log10 target copies/µL submitted to heat treatment and PMA at 50 µM, which corresponds to a 99.9% reduction in bacteria present in the samples. The obtained results suggests that PMA-qPCR methodology is a fast method for quantifying microbial viability in low-concentrated samples of Desulfovibrio vulgaris.