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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.

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.