Identification of Chromobacterium violaceum genes with potential biotechnological application in environmental detoxification

Chromobacterium violaceum is a Gram-negative bacterium found in a wide variety of tropical and subtropical ecosystems. The complete genome sequence of C. violaceum ATCC 12472 is now available, and it has considerable biotechnological potential for various applications, such as environmental detoxification, as well as medical and agricultural use. We examined the biotechnological potential of C. violaceum for environmental detoxification. Three operons, comprising the ars operon, involved in arsenic resistance, the cyn operon, involved in cyanate detoxification, and the hcn operon, encoding a cyanase, responsible for biogenic production of cyanide, as well as an open reading frame, encoding an acid dehalogenase, were analyzed in detail. Probable catalytic mechanisms for the enzymes were determined, based on amino acid sequence comparisons and on published structural information for these types of proteins

Hydrogen metabolism in Desulfovibrio desulfuricans strain New Jersey (NCIMB 8313)--comparative study with D. vulgaris and D. gigas species.

This article aims to study hydrogen production/consumption in Desulfovibrio (D.) desulfuricans strain New Jersey, a sulfate reducer isolated from a medium undergoing active biocorrosion and to compare its hydrogen metabolism with two other Desulfovibrio species, D. gigas and D. vulgaris Hildenborough. Hydrogen production was followed during the growth of these three bacterial species under different growth conditions: no limitation of sulfate and lactate, sulfate limitation, lactate limitation, pyruvate/sulfate medium and in the presence of molybdate. Hydrogen production/consumption by D. desulfuricans shows a behavior similar to that of D. gigas but a different one from that of D. vulgaris, which produces higher quantities of hydrogen on lactate/sulfate medium. The three species are able to increase the hydrogen production when the sulfate became limiting. Moreover, in a pyruvate/sulfate medium hydrogen production was lower than on lactate/sulfate medium. Hydrogen production by D. desulfuricans in presence of molybdate is extremely high. Hydrogenases are key enzymes on production/consumption of hydrogen in sulfate reducing organisms. The specific activity, number and cellular localization of hydrogenases vary within the three Desulfovibrio species used in this work, which could explain the differences observed on hydrogen utilization.

Isolation and characterisation of a novel sulphate-reducing bacterium of the Desulfovibrio genus.

A novel sulphate-reducing bacterium (Ind 1) was isolated from a biofilm removed from a severely corroded carbon steel structure in a marine environment. Light microscopy observations revealed that cells were Gram-negative, rod shaped and very motile. Partial 16S rRNA gene sequencing and analysis of the fatty acid profile demonstrated a strong similarity between the new species and members from the Desulfovibrio genus. This was confirmed by the results obtained following purification and characterisation of the key proteins involved in the sulphate-reduction pathway. Several metal-containing proteins, such as two periplasmic proteins: hydrogenase and cytochrome c3, and two cytoplasmic proteins: ferredoxin and sulphite reductase, were isolated and purified. The latter proved to be of the desulfoviridin type which is typical of the Desulfovibrio genus. The study of the remaining proteins revealed a high degree of similarity with the homologous proteins isolated from Desulfovibrio gigas. However, the position of the strain within the phylogenetic tree clearly indicates that the bacterium is closely related to Desulfovibrio gabonensis, and these three strains form a separate cluster in the delta subdivision of the Proteobacteria. On the basis of the results obtained, it is suggested that Ind 1 belongs to a new species of the genus Desulfovibrio, and the name Desulfovibrio indonensis is proposed.