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Sulfate-reducing bacteria (SRB) of the genus Desulfovibrio are one of the groups occurring in elevated numbers in the gut of children with autistic spectrum disorders (ASD). Until now, high abundance of Desulfovibrio in individuals with RAS has been shown only by molecular methods. No cultured forms have been isolated from the gastrointestinal tract of autists. A conceivable mechanisms of SRB effect is conversion of iron into biologically unavailable forms of sulfides, causing its deficiency in the organism. In this study we isolated two Desulfovibrio strains from feces of the children with diagnosed ASD. In experiments Desulfovibrio desulfuricans AY5 formed crystalline iron sulfides, greigite and pyrite, containing iron in a biologically unavailable form.

De.sul.fo.vi.bri.o.na.ce' ae. M.L. masc. n. Desulfovibrio type genus of the family; suffix -ceae denotes family; M.L. fem. pl. n. Desulfovibrionaceae the family that comprises the genus Desulfovibrio. Proteobacteria / Deltaproteobacteria / Desulfovibrionales / Desulfovibrionaceae Keywords: Desulfovibrionaceae fam. nov.; Desulfovibrio; Deltaproteobacteria class nov.; Desulfovibrionales ord. nov

High-fat diets have been associated with overweight/obesity and increased mortality in middle-aged populations. However, it is still unclear how gut microbiota in middle-aged populations responds to dietary fats at a normal dose. In this study, we explored gut microbiota structure in middle-aged rats (aged 12 months) after feeding 4% (w/w) soybean oil, lard or fish oil for 3 months, respectively. The results showed that the gut microbiota structure in the fish oil group was substantially different from those of the soybean oil and lard groups in both in vitro and in vivo studies. The relative abundances of phylum Proteobacteria and genus Desulfovibrio in the caecal and colonic contents were the highest in the fish oil group (p

A sulphate-reducing culture of the genus Desulfovibrio was directly inhibited by the hydrogen sulphide (H2S) produced. Batch experiments carried out at pH 6.2 and 6.6 show that complete inhibition is achieved for almost the same H2S concentration of approximately 550 mg/l.

Sulphate-reducing bacteria (SRB) were found in all of 200 bovine faeces examined. The number of SRB in bovine faeces ranged from 5 times 102 to 6 times 108 bacteria g-1. Of 50 isolates identified, all were assigned to the genus Desulfovibrio.

The three types of hydrogenase hitherto characterized in genus Desulfovibrio exhibit distinctive inhibition patterns of their proton-deuterium exchange activity by CO, NO and NO2-. The (Fe) and (NiFeSe) hydrogenases are the most sensitive to all three inhibitors while the (NiFe) enzymes, relatively little inhibited by CO, are still very sensitive to NO but unaffected by NO2-. These differences together with some specific catalytic properties, in particular the pH profile and the H2 to HD ratio in the exchange reaction, constitute a simple means of characterizing multiple hydrogenases present in one or different species.

To define some aspects of the biological corrosion sulphate-reducing bacteria were studied in paper machine waters and in plugged perforations of a suction roll. The desulphuricants were most active on passive fiber recipients. Most bacteria found in fiber plugs taken from the perforations of suction rolls belonged to the genus Desulfovibrio. Desulphuricants were found mainly at the outer ends of plugged perforations, where corrosion of the roll metal is most evident.

SUMMARY: Fourteen previously unstudied strains of the genus Desulfovibrio and eight thermophilic strains of the genus Desulfotomaculum were allotted to species on the results of physiological and biochemical tests. On DNA base composition the Desulfovibrio strains fell clearly into three groups, corresponding to Dv. salexigens, Dv. desulfuricans and Dv. vulgaris. NaCl-dependence appeared to be a constant and unique feature of Dv. salexigens strains, and ‘sulphate-free’ growth on pyruvate a constant characteristic of Dv. desulfuricans, although one strain of Dv. vulgaris also dismuted pyruvate. Fumarate dismutation showed no species correlation. ‘Sulphate-free’ growth on choline was often minimal and the test appeared to be of little value. A high degree of resistance to Hibitane was not a constant characteristic of Dv. salexigens. The thermophilic strains showed great uniformity in DNA base composition, Hibitane resistance and ‘sulphate-free’ growth, and were all classified as Desulfotomaculum nigrificans.

Fifty-six Australian soils were examined for their ability to produce sulphate from sulphur and sulphide from added sulphur, sulphate and cystine. Selective liquid media were used to obtain initial counts and progressive activities of some of the principal organisms involved. Attempts were made to correlate soil properties, initial microbial counts, classes of micro-organisms detected and metabolic activities. Almost half of the soils oxidized sulphur very slowly or not at all, most probably due to absence of thiobacilli, particularly Th. thiooxidans . Even soils which oxidized sulphur rapidly never gave initial counts greater than 10 4 cells/g. The majority of soils produced sulphide from sulphur, between one-half and two-thirds of them formed sulphide from cystine but sulphate reduction was very rare. Sulphide escaped more readily from aerobic than from waterlogged soils. Numerous genera were isolated including Desulfovibrio and Desulfatomaculum capable of reducing sulphur, both aerobically and anaerobically, particularly sporing and non-sporing mesophiles which were sometimes present at 10 6 cells/g of soil. Sulphate reduction by the genus Desulfovibrio was uncommon, and by the genus Desulfatomaculum extremely rare. Many genera of sporing and non-sporing mesophiles seemed capable of producing sulphide from cystine when first isolated, but they quickly lost this ability on subculturing. Initial counts of 10 6 cells/g of soil were occasionally found but usually much lower. No significant correlations, only trends, were found suggesting that any soil properties measured affected the occurrence or activities of organisms capable of producing sulphate or sulphide.

Determinative studies were carried out on an obligatory anaerobic, sulfate- reducing bacterium (strain No. 61) isolated from a pond water in Skarvs Nes district in the East Antarctica. This sulfate-reducing bacterium was nonsporulating, sigmoid or straight rods with a single polar flagellum, gram negative, and possessed cytochrome c3 and desulfoviridin, characteristic of the genus Desulfovibrio. It could grow with lactate, malate, pyruvate, or choline when sulfate was present in the culture medium and had a stable sodium chloride requirement. These observations dinicated that strain No. 61 closely resembled Desulfovibrio desulfuricans var. aestuarii.

A reevaluation of the original buoyant density conversion formula used to calculate the molar percentage guanosine + cytosine (% G + C) contents of the accepted species of genus Desulfovibrio has been undertaken. It would appear that the formula used gives values 4–5% lower than those obtained using formulae more generally cited in modern literature. Recalculations of % G + C content values for Desulfovibrio DNA are presented using the formulae of three different workers, and are compared with those values originally used in the classification of genus Desulfovibrio.

Anaerobic nitrogen fixation has been studied in sediments from two Scottish sea-lochs, Loch Eil and Loch Etive. The problem was approached in three ways: 1. Estimation of nitrogen fixation (acetylene reduction) rates. 2. A characterisation of the bacteria involved. 3. An assessment of some chemical and physical factors likely to influence nitrogen fixation. Aerobic nitrogen fixation was not detected. Anaerobic nitrogen fixation rates in the range 0.06-4.10 n-moles ethylene produced. g dry weight-1 hr-1 were measured. In these sea-lochs nitrogen fixation in the sediments appears to be due principally to sulphate-reducing bacteria of the genus Desulfovibrio , which are associated with sulphide deposits and negative Eh. Clostridium spp. are also present in the sediments but do not appear to be active.

A comparison of amino-terminal amino acid sequences from the large and small subunits of hydrogenases from Desulfovibrio reveals significant differences. These results, in conjunction with antibody analyses, clearly indicate that the iron, iron + nickel, and iron + nickel + selenium containing hydrogenases represent three distinct classes of hydrogenase in Desulfovibrio.