Classification for Dimethylarsenate-decomposing Bacteria Using a Restrict Fragment Length Polymorphism Analysis of 16S rRNA Genes

Abstract

A new monitoring system for bacterial communities involving dimethylarsinic acid (DMAA) decomposition was provided by combining the MPN (Most Probable Number) method and RFLP (restriction-fragment-length polymorphism analysis). The abundance of DMAA decomposing bacteria was estimated by the MPN method using a bacterial culture medium, which included DMAA as the sole carbon source, indicating bacterial cell densities of 1700 cells/ml in Lake Kahokugata and 330 cells/ml in Lake Kibagata. After isolating the dominant bacteria using agar plates, the isolates were classified into some genotype groups by RFLP analysis using 16S rDNA sequences. Classification of the RFLP analysis indicated that 14 isolates of Lake Kahokugata were classified into 6 types, which included 2 dominant types related to genus Pseudomonas, while 8 isolates of Lake Kibagata displayed 6 types including one or two isolates. Moreover, the RFLP types were unique for each lake, suggesting that DMAA decomposing bacteria were specific for the aquatic environment related to the arsenic cycle. The activities of DMAA decomposition mostly matched with the RFLP type category of the isolates. Accordingly, combining the MPN method with the RFLP analysis will play an important role in elucidating the distributions and dynamics of the DMAA-decomposing bacterial community.

Phylogenetic diversity and vertical distribution of a halobacterial community in the atmosphere of an Asian dust (KOSA) source region, Dunhuang City

“…One milliliter of the filter wash solution of bioaerosol samples collected at 10 and 800 m and 5 ml of the microbial cultures with NaCl amendment were used for the extraction of genomic DNAs using sodium dodecyl sulfate (SDS), proteinase K, and lysozyme as described previously (Maki et al 2004). The genomic DNAs were purified by phenol-chloroform extraction, chloroform extraction, and ethanol precipitation.…”

Crystallization and preliminary X-ray crystallographic studies of the ArsI C–As lyase fromThermomonospora curvata

“…In the reverse direction, microbes demethylate the noncarcinogenic organoarsenical herbicide MSMA to the more carcinogenic inorganic As(III), which increases environmental exposure to this human carcinogen. Demethylating microbes have been isolated from soil and lake water (Von Endt et al, 1968;Maki et al, 2004;Maki, Takeda et al, 2006;Maki, Watarai et al, 2006). In a few cases, specific microorganisms such as Mycobacterium neoaurum (Lehr et al, 2003), Montrachet wine yeast (Crecelius, 1977) and Candida humicola (Cullen et al, 1979) have been associated with demethylation.…”

Demethylation of methylarsonic acid by a microbial community

“…Demethylation of methylarsenicals has been studied extensively in soil (Von Endt et al ., 1968; Woolson et al ., 1982; Akkari et al ., 1986; Gao and Buran, 1997; Feng et al ., 2005; Maki et al ., 2006a; Huang et al ., 2007), sludge (Sierra-Alvarez et al ., 2006), sediment (Hanaoka et al ., 1990), seawater (Sanders, 1979) and fresh water (Maki et al ., 2006b; 2009). Demethylating microbes have been found in soil (Von Endt et al ., 1968; Maki et al ., 2006a,b) and lake water (Maki et al ., 2004; 2006a). Only in a few cases have specific microorganisms been associated with demethylation such as Mycobacterium neoaurum (Lehr et al ., 2003), Montrachet wine yeast (Crecelius, 1977) and Candida humicola (Cullen et al ., 1979), and no molecular description of the demethylation pathway has been reported.…”