Abundance and diversity of sulphate-reducing bacteria within a crude oil gathering and transferring system in China

The abundance and diversity of sulphate-reducing bacteria (SRB) in crude-oil and oilfield production water samples from a oil gathering and transferring system in Changqing Oilfield of China were investigated by the most probable number technique and sequence analysis of the 16S rRNA gene, respectively. All the water samples and crude-oil samples contained SRB, and the abundance of SRB in the water samples (n = 15) is about 100 times than that in the crude-oil samples (n = 15). However, their relative abundances increased durring the period of oil gathering and thansferring process. The highest count (6.8 ± 0.8 CFU · ml^-1 crude-oil and 760.0 ± 23.1 CFU · ml^-1 water) were obtained at the site of oil comprehensive treatment station, while the lowest count (1.0 ± 0.5 CFU · ml^-1 crude-oil and 95.0 ± 8.2 CFU · ml ^-1 water) were obtained at the site of oil-well. Sequence analysis of the 16S rRNA gene indicated that SRB related to Desulfovibrionaceae sp., Desulfococcus biacutus were detected in the water and crude-oil samples, simultaneously. However, SRB related to Desulfomonile sp., Desulfotomaculum sp. and Desulfosarcina sp. were detected in the water samples but not in crude-oil samples. Changes of abundance and diversity of SRB is due to the variation of environmental condition during the period of oil gathering and transferring process.