Diversity of bacteria, archaea and protozoa in a perchlorate treating bioreactor

V.N. Anupama, P.V.G. Prajeesh, S. Anju, P. Priya, B. Krishnakumar

Environmental Technology, CSIR-National Institute for Interdisciplinary Science & Technology (CSIR-NIIST), Industrial Estate (PO), Thiruvananthapuram-19, India.

Abstract

A microbial consortium reducing high level of perchlorate was developed and in a fed batch bioreactor using acetate as substrate perchlorate was reduced at 0.25 g/g vss. day. Under stable performance, the microbial community structure of the reactor was analyzed through molecular and phenotypic methods. The diversity of bacteria and archaea were analyzed through whole cell Fluorescence In-Situ Hybridization (FISH) and PCR-Denaturing Gradient Gel Electrophoresis (DGGE), whereas higher trophic community was analyzed phenotypically. FISH analysis revealed the presence of alpha, beta, gamma and delta proteobacteria in the sludge, dominated by beta proteobacteria (68.7%). DGGE analysis of bacteria revealed the presence of a single known perchlorate reducing bacterium-Dechloromonas, nitrate reducers like Thaeura and Azoarcus and a number of other genera so far not reported as perchlorate or nitrate reducing. The archaea community was represented by an acetoclastic methanogen, Methanosaeta harundinacea. We have also observed the presence of an acetate consuming flagellate, Polytomella sp. in significant number in the reactor. Archaea and protozoa community in perchlorate treating bioreactor is reported first time in this study and point out further the significance of non perchlorate reducing but acetate scavenging microbial groups in acetate fed perchlorate treating reactors.

Keywords: Anoxic treatment; Biodegradation; DGGE; FISH; Oxyanion.