OBJECTIVETo explore the possibility of Bacteroides spp. as fecal contamination indicator bacteria with real-time quantitative PCR (RT-PCR) assay through analyzing the correlation between Bacteroides spp. and coliform group in external environment.

METHODSQuantity of coliform group and Bacteroides in water samples were detected by most-probable-number method (MPN) and RT-PCR, respectively, and their detection correlation was evaluated with linear correlation analysis. Both methods were also applied to detect the contaminated time limits and river water samples collected at four sampling sites in three different times.

RESULTSSeventy two hours were needed for the numeration of coliform group with MPN method, while RT-PCR could detect Bacteroides within 3 hours. The contaminated time limit of indoor and outdoor water samples of coliform group was more than 40 days and 9 days, and Bacteroides 13 days and 5 days, respectively. Also, the positive correlation between the quantity of Bacteroides and coliform group in outdoor water samples was obtained, the quantity of Bacteroides was from 8.3 × 10(6) copies/ml to less than 10(4) copies/ml during the first day to the fifth day, while coliform group was 4.3 × 10(6) MPN/100 ml to 2.4 × 10(3) MPN/100 ml. A 100% coincidence rate of the detection results with both methods was also observed. These results indicated that the detection results of both methods had perfect consistency.

CONCLUSIONBacteroides spp. can be potentially used as fecal contamination indicator bacteria with RT-PCR rapid detection.