Tolumonas auensis gen. nov., sp. nov., a Toluene-Producing Bacterium from Anoxic Sediments of a Freshwater Lake

Abstract

A new toluene-producing bacterium, strain TA 4T (T = type strain), was isolated from anoxic sediments of a freshwater lake. The individual cells of this organism were nonmotile, gram-negative rods that were 0.9 to 1.2 by 2.5 to 3.2 pm. The optimum temperature and pH for growth were 22°C and pH 7.2, respectively. The G+C content of the DNA was 49 mol%. Toluene was produced from phenylalanine, phenylpyruvate, phenyllactate, and phenylacetate, and phenol was produced from tyrosine. Both the presence of a carbon source and the presence of a toluene precursor were essential for initiation of toluene production. Bacterial growth occurred under oxic and anoxic conditions. Acetate, ethanol, and formate were the major fermentation products of the bacterium when it was grown on glucose. The major lipoquinones were ubiquinone 8 and menaquinone 8 under both oxic and anoxic growth conditions. On the basis of the results of a 16s ribosomal DNA sequence analysis, we concluded that this organism is a member of the y subclass of the Proteobacteria, and we suggest the name Tolumonas auensis for this species.Anoxic waters are inhabited by a wide variety of bacteria, including sulfate reducers and methanogens, which have been studied extensively (31). The products of the sulfate reducers and methanogens, sulfide and methane, can be detected easily in water. Methane is produced almost exclusively by methanogens, and a major part of the sulfide found in anoxic lake water is the result of reduction of sulfate ions by sulfate reducers. However, in the anoxic parts of many freshwater lakes other compounds also accumulate, and the presence of these compounds cannot be explained by the activity of sulfate reducers and methanogens. One such compound is the aromatic hydrocarbon toluene, which has recently been detected at high concentrations (>3 pg/liter) in anoxic hypolimnia of several small lakes (9). This compound accumulated during the course of the year in the hypolimnion of a eutrophic lake, and accumulation began as soon as stratification of the water occurred and anoxic conditions were established (1 1). The time course of toluene accumulation clearly points to microbial production of this compound, and this finding makes the rather popular use of toluene as a tracer of pollution questionable. The bacteria responsible for toluene production in lakes are not known yet. In a previous study, microbial production of toluene in artificial anoxic lake water inoculated with lake sediment was observed under laboratory conditions (lo), but it was not clear which organisms were responsible for this production. Inhibitor experiments performed with 2-bromoethanesulfonate and molybdate revealed that the sulfate reducers and methanogens are not involved in production of toluene (unpublished data). In this paper we describe the isolation of a toluene-producing microorganism from anoxic lake sediments; this organism represents a new species of a new genus belonging to the y subclass of the Proteobacteria. MATERIALS AND METHODSMedia and cultivation ...

Microbial population and functional dynamics associated with surface potential and carbon metabolism

“…As for fermenters, Bacilli, Clostridia and Gammaproteobacteria presumably performed sugar fermentation because these strains were observed more frequently in both the anode and anolytes of sugar-fed reactors (Figures 7a and b, Supplementary Figure S8), and also their close relatives are known as sucrose fermenters (Fischer-Romero et al, 1996;Cho et al, 2008). Some of the fermenting Clostridium, Aeromonas and Tolumonas strains have been reported as EET-active fermenters (Park et al, 2001;Pham et al, 2003;Chung and Okabe, 2009;Luo et al, 2013), suggesting the Clostridium, Aeromonas and Tolumonas phylotypes in our sugar-fed reactors might conduct EET reactions directly.…”

Oceanisphaera litoralis gen. nov., sp. nov., a novel halophilic bacterium from marine bottom sediments

“…T (Rosselló -Mora et al, 1995), Tolumonas auensis DSM 9187 T (Fischer-Romero et al, 1996) and members of the families Vibrionaceae, Enterobacteriaceae and Aeromonadaceae were more distantly related (<92 % sequence similarity). This relationship is displayed in the 16S rRNA gene sequence dendrogram based on the additive treeing algorithm of DeSoete (1983) (Fig.…”

Anaerobic utilization of toluene by marine alpha- and gammaproteobacteria reducing nitrate

“…Petroleum hydrocarbons produced during diagenesis of organic-rich sediments and oil emitted by nearsurface hydrocarbon seepages constitute a natural source of hydrocarbons in sediments. Some other hydrocarbons of biogenic origin are produced in living organisms such as bacteria, phytoplankton, plants and metazoans (Chen et al, 1998;Fischer-Romero et al, 1996;Tissot & Welte, 1984). Furthermore, in addition to hydrocarbons of biogeochemical or biogenic origin, anthropogenic activities, such as offshore production, transportation or tanker accidents, municipal or industrial wastes and runoff, are responsible for additional inputs of petroleum hydrocarbons into the marine environment.…”