PCR-single-strand conformation polymorphism (SSCP) and Southern blotting tech-niques were adopted to investigate microbial community dynamics in a sulfate-reducing bioreactor caused by decreasing influent alkalinity. Experimental results indicated that the sulfate-removal rate approached 87% in 25 d under the conditions of influent alkalinity of 4000 mg/L (as CaCO3) and sul-fate-loading rate of 4.8 g/(L·d), which indicated that the bioreactor started up successfully. The analy-sis of microbial community structure in this stage showed that Lactococcus sp., Anaerofilum sp. and Kluyvera sp. were dominant populations. It was found that when influent alkalinity reduced to 1000 mg/L, sulfate-removal rate decreased rapidly to 35% in 3 d. Then influent alkalinity was increased to 3000 mg/L, the sulfate-removal rate rose to 55%. Under these conditions, the populations of Dysgo-nomonas sp., Sporobacte sp., Obesumbacterium sp. and Clostridium sp. got to rich, which predomi-nated in the community together with Lactococcus sp., Anaerofilum sp. and Kluyvera sp. However, when the alkalinity was decreased to 1500 mg/L, the sulfate-removal rate rose to and kept stable at 70% and populations of Dysgonomonas sp., Sporobacter sp. and Obesumbacterium sp. died out, while some strains of Desulfovibrio sp. and Clostridium sp. increased in concentration. In order to determine the minimum alkalinity value that the system could tolerate, the influent alkalinity was de-creased from 1500 to 400 mg/L secondly. This resulted in the sulfate-removal rate, pH value and ef-fluent alkalinity dropping quickly. The amount of Petrotoga sp., Prevotella sp., Kluyvera sp. and Neisseria sp. reduced obviously. The result data from Southern blotting indicated that the amount of sulfate-reducing bacteria (SRBs) decreased with influent alkalinity dropping. Analysis of the microbial community structure and diversity showed that the SRBs populations were very abundant in the in-oculated activated sludge and the alkalinity decrease caused the reduction of the p
REN Nanqi1, ZHAO Yangguo1, WANG Aijie1, GAO Chongyang2, SHANG Huaixiang1, LIU Yiwei1 & WAN Chunli1 1. School of Environmental and Municipal Engineering, Harbin Institute of Technology, Harbin 150090, China
