Oxidation of Thiosulfate by a New Bacterium, Bosea thiooxidans. (strain BI-42) gen. nov., sp. nov.: Analysis of Phylogeny Based on Chemotaxonomy and 16S Ribosomal DNA Sequencing

Abstract

A gram-negative bacterium which was capable of oxidizing reduced inorganic sulfur compounds was isolated from agricultural soil and designated BI-42. This new isolate grew on a wide range of organic substrates but was not able to grow autotrophically and lacked ribulose 1,s-bisphosphate carboxylase, a key enzyme of carbon dioxide fixation. These results suggested that strain BI-42 was a chemolithoheterotroph. Ammonia and nitrate were not used as sole nitrogen sources for growth, and strain BI-42 lacked glutamate synthase activity, which resulted in glutamate auxotrophy. The glutamate dehydrogenase activity of this organism was apparently insufficient for ammonia assimilation. On the basis of the results of additional biochemical tests, the G+C content of the DNA, the results of a respiratory ubiquinone analysis, the results of a 16s ribosomal DNA sequence analysis, the fatty acid composition, and the results of a membrane lipid analysis, strain BI-42 was identified as a phylogenetically and physiologically distinct taxon belonging to the alpha subclass of the Proteobucteria. Boseu thiooxiduns gen. nov., sp. nov. is the name proposed for this taxon.Sulfate is the end product of oxidations of reduced sulfur compounds by chemosynthetic, photosynthetic, and various heterotrophic microorganisms. Nature balances these oxidations through the biological reduction of sulfate to sulfide. Microorganisms utilize sulfur compounds for the biosynthesis of cellular material or transform these compounds as part of a respiratory energy-generating process. Most of the known sulfur-oxidizing bacteria belong to the genera Thiobacillus, Thiothrix, Beggiatoa, Thiomicrospira, Achromatium, DesuEfovibrio, Desulfomonas, Desulfococcus, and Desulfuromonas (18,55). Members of the genus Thiobacillus have been studied extensively to increase our understanding of the coupling of oxidation of reduced inorganic sulfur compounds to energy biosynthesis and assimilation of carbon dioxide (45). In addition, some phototrophic bacteria, such as members of the genus Chromatium, oxidize reduced inorganic sulfur compounds to provide reducing power for carbon dioxide assimilation during anaerobic photosynthesis (38).However, oxidation of sulfur compounds is not restricted to the true sulfur bacteria; this process also occurs in heterotrophic bacteria isolated from soil (54) and the marine environment (50, 51). Most of the heterotrophic bacteria that have such activities belong to the genera Pseudomonas (35), Mycobacterium, Arthrobacter, Flavobacterium (54), and Xanthobacter or are Escherichia coli strains (42). However, few of these heterotrophs have the ability to generate biologically useful energy from the oxidation of reduced sulfur compounds (31). An exception is Paracoccus denitrificans (6), which also grows autotrophically in the presence of thiosulfate. Only a few heterotrophic bacteria, such as Thiobacillus sp. strain Q (8) and Catenococcus thiocyclus (39), have been shown to obtain energy from the oxidation of sulfur compounds. This type of nutr...

Thiomonas bhubaneswarensis sp. nov., an obligately mixotrophic, moderately thermophilic, thiosulfate-oxidizing bacterium

“…The 16S rRNA gene of strain S10 T was amplified as described previously (Das et al, 1996;Patra et al, 2007). The 16S rRNA gene sequence (1440 nt) thus obtained was compared with those in GenBank and the Ribosomal Database Project (Maidak et al, 1997) after BLAST searches (Altschul et al, 1997).…”

Bioleaching of Arsenic-Bearing Copper Ores

“…Phylogenetic characterization found that this bacterium is grouped with the class alpha-Proteobacteria, specifically with Bosea thiooxidans, within 99% of shared identity. Bosea thiooxidans is a reported heterotrophic, strict aerobe, and inorganic sulfur oxidizer [118]. After isolating, mineral studies with arsenopyrite and pyrite-bound As confirmed that Bosea WAO oxidizes sulfide and arsenite [119].…”

Microvirga guangxiensis sp. nov., a novel alphaproteobacterium from soil, and emended description of the genus Microvirga

“…The genus currently encompasses a single species with a validly published name, Microvirga subterranea, and is assigned to the class Alphaproteobacteria, phylum Proteobacteria (Garrity & Holt, 2001;Garrity et al, 2005a), almost equidistant from Methylobacterium species (Patt et al, 1976;Urakami et al, 1993) Egli et al, 1988) and Bosea thiooxidans (Das et al, 1996), its nearest phylogenetic relatives, with a mean similarity value of 93 %.…”

“…Phase-contrast and electron microscopy of cells were performed as described by Andrews & Patel (1996). The presence of flagella and spores was assessed by the method of Das et al (1996) and Kanso & Patel (2003). The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain 25B T is EU727176.…”

“…Phase-contrast and electron microscopy of cells were performed as described by Andrews & Patel (1996). The presence of flagella and spores was assessed by the method of Das et al (1996) and Kanso & Patel (2003). The presence of poly-b-hydroxybutyrate (PHB) was demonstrated by staining lightly heat-fixed cells with Sudan Black B [0.3 % (w/v) in 70 % (v/v) ethanol] for 10 min followed by decolourizing with xylene for 10 s, drying and counterstaining with safranin [0.5 % (w/v) in water] for 1-2 min.…”