Aerobic and anaerobic degradation of a range of alkyl sulfides by a denitrifying marine bacterium

Abstract

A pure culture of a bacterium was obtained from a marine microbial mat by using an anoxic medium containing dimethyl sulfide (DMS) and nitrate. The isolate grew aerobically or anaerobically as a denitrifier on alkyl sulfides, including DMS, dimethyl disulfide, diethyl sulfide (DES), ethyl methyl sulfide, dipropyl sulfide, dibutyl sulfide, and dibutyl disulfide. Cells grown on an alkyl sulfide or disulfide also oxidized the corresponding thiols, namely, methanethiol, ethanethiol, propanethiol, or butanethiol. Alkyl sulfides were metabolized by induced or derepressed cells with oxygen, nitrate, or nitrite as electron acceptor. Cells grown on DMS immediately metabolized DMS, but there was a lag before DES was consumed; with DES-grown cells, DES was immediately used but DMS was used only after a lag. Chloramphenicol prevented the eventual use of DES by DMS-grown cells and DMS use by DES-grown cells, respectively, indicating-separate enzymes for the metabolism of methyl and ethyl groups. Growth was rapid on formate, acetate, propionate, and butyrate but slow on methanol. The organism also grew chemolithotrophically on thiosulfate with a decrease in pH; growth required carbonate in the medium. Growth on sulfide was also carbonate dependent but slow. The isolate was identified as a 7hiobaciUlus sp. and designated strain ASN-1. It may have utility for removing alkyl sulfides, and also nitrate, nitrite, and sulfide, from wastewaters.

Organic Sulfur Metabolisms in Hydrothermal Environments

“…Various mesophilic Bacteria and Archaea that metabolize OSCs have been identified in a number of low-temperature environments (Kiene et al, 1986;Oremland et al, 1989;Visscher et al, 1991;Finster et al, 1992;Visscher & Taylor, 1993a;Tallant & Krzycki, 1997;Lomans et al, 1999bLomans et al, , 2002aBorodina et al, 2000;Lyimo et al, 2000Lyimo et al, , 2009de Bok et al, 2006;Vila-Costa et al, 2006;Kim et al, 2007;Schäfer, 2007;van Leerdam et al, 2008b;Boden et al, 2010). Microbial metabolism of OSCs has been documented in numerous aerobic environments, as well as anaerobic fresh water, estuarine, salt marsh, mangrove, and hypersaline sediments (Kiene & Visscher, 1987;Lomans et al, 1999bLomans et al, , 2002aVisscher et al, 2003;Lyimo et al, 2009).…”

“…Aerobic bacteria that can metabolize methylated sulfur compounds include species of Thiobacillus, Methylophaga, Hyphomicrobia, Arthrobacter, Rhodovulum, and Thiocapsa (Sivela & Sundman, 1975;Suylen et al, 1986;Kanagawa & Mikami, 1989;Visscher et al, 1991;Visscher & Taylor, 1993a;Lomans et al, 1999cLomans et al, , 2002bBorodina et al, 2000;Kim et al, 2007;Schäfer, 2007). Oxidation of DMS by Thiobacillus and Hyphomicrobia spp.…”

Isolation and characterization of sp. nov.: an obligately methylotrophic, aerobic, dimethylsulfide oxidizing bacterium from a microbial mat

“…Thus far, Hyphomicrobium spp. [6,36] and Thiobacillus spp. [37] have generally been found to be responsible for aerobic DMS degradation in (fresh water) waste systems and from marine systems, Thiobacillus spp.…”

“…[37] have generally been found to be responsible for aerobic DMS degradation in (fresh water) waste systems and from marine systems, Thiobacillus spp. capable of aerobic DMS degradation have been isolated [5,6]. Recently, a versatile aerobic methylotrophic bacterium, which could de-grade a wide range of substrates as well as DMS was isolated from marine samples [7].…”

“…In spite of the important role of marine bacteria as a major sink for DMS, the number of marine bacteria known to be capable of using DMS as an energy source is still small. Thiobacillus thioparus T.5 and Thiobacillus ASN-1 are able to oxidize DMS aerobically, and were both isolated from marine samples [5,6]. Recently, an aerobic, facultatively methylotrophic bacterium, strain BE-6 was isolated from marine sediment [7].…”