Detection of bacterial diversity in clean and contaminated surface water with DGGE

Objective To compare bacterial diversities in surface water contaminated by domestic sewage,industrial wastewater,and agricultural and animal husbandry wastewater and to explore the correlation between environmental pollution and bacteria diversity for providing a theoretical basis to the recovery of water environment.Methods Totally 70 surface water samples were collected from an unpolluted mountain spring and three rivers contaminated by different pollution sources in Hangzhou city and bacterial diversity of the water samples was detected with microbial plate culture and PCR-denaturing gradient gel electrophoresis(DGGE)technique.Results The pH of mountain spring sample was the lowest(7.25);the pH for all other contaminated water samples was above 7.4 and the pH of samples from Binwen river was the highest(8.04).The number of cultural bacteria in water samples from Puyan river(contaminated by industrial wastewater)was the highest(821.00 colony forming unitCFU/mL),followed by that of from Xiaoshan river(contaminated by livestock breeding wastewater),and that of from Hupao spring the lowest(8.00 CFU/mL).There was a close relationship between the number of cultural bacteria and pH of the water samples.E.coli and Staphylcoccus were detected in all contaminated water samples,but Salmonella was not detected in the water samples contaminated by domestic sewage and Streptococcus was not detected in the water samples contaminated by industrial wastewater.DGGE bands showed that in the contaminated water the main bacteria were Proteobacteria(23 bands,71.9%),Actinobacteria(8 bands,25%),and Firmicutes(1 band,3.9%).In addition,different samples had specific bands.For example,T5 and T7 representing β-Proteobacteria were only detected in industrial wastewater contaminated water;T3 and T4 representing Aeromona were only detected in domestic sewage contaminated water and T10,T29 and T30 representing Gordonibacter were only detected in livestock breeding wastewater contaminated water.Conclusion Different contaminations affect the pH and the profile of bacteria in water directly and the pathogens in the contaminated water are different.