RAPID COMPARISON OF THE CYTOCHROME-C3 GENE FROM 9 STRAINS OF DESULFOVIBRIO-VULGARIS USING POLYMERASE CHAIN-REACTION AMPLIFICATION

Polymerase chain reaction amplification was used to compare different regions of the cytochrome c3 gene from nine strains of Desulfovibrio v ulgaris, to examine homology within the species. Six 30-base polymeras e chain reaction primers and three probes were synthesized on the basi s of the published nucleic acid sequence of the cytochrome C3 gene fro m D. vulgaris, NCIMB 8303. Amplifications were performed on genomic DN A isolated from NCIMB 8303 as well as eight other strains. Six strains , NCIMB 8302, 8305, 8306, 8311, 11779, and DSM 2119, showed amplificat ion products of equal size and quantity to those of strain 8303. Two o ther strains, NCIMB 8456 and DSM 1744, either showed reduced levels or no detectable amplification products. These results were confirmed by hybridization of amplified DNA to radiolabeled probes specific for ea ch product. DNA sequencing of a 145-bp polymerase chain reaction fragm ent from strains NCIMB 8302, 8303, 11779, and DSM 2119 revealed comple te sequence homology between these strains, whereas slight differences were seen with strain NCIMB 8456. Amino acid sequencing of the first 20 residues of cytochrome C3 purified from strains NCIMB 8456 and 8303 also showed differences in the two proteins. In contrast to the resul ts obtained with strain NCIMB 8456, limited homology was observed betw een the first 20 amino acid residues of cytochrome C3 from strain DSM 1744 and strain NCIMB 8303.