Desulfovibrio sp genes involved in the respiration of sulfate during metabolism of hydrogen and lactate

To develop a better understanding of respiration by sulfate-reducing bacteria, we examined transcriptional control of respiratory genes during growth with lactate or hydrogen as an electron donor. RNA extracts of Desulfovibrio desulfuricans subsp. aestuarii were analyzed by using random arbitrarily primed PCR. RNA was reverse transcribed under low-stringency conditions with a set of random primers, and candidate cDNAs were cloned, sequenced, and characterized by BLAST analysis. Putative differentially expressed transcripts were confirmed by Northern blot analysis. Interestingly, dissimilatory bisulfite reductase was upregulated in the presence of hydrogen. To link these transcriptional changes to the physiology of sulfate-reducing bacteria, sulfide was measured during growth of several strains of Desulfovibrio on hydrogen or lactate, and this revealed that hydrogen-grown cells produced more sulfide per unit of cell mass than lactate-grown cells. Transcription of other redox proteins was characterized by Northern blotting to determine whether or not they were also transcribed to higher levels in hydrogen-grown cells. Growth on lactate produced greater transcription of [NiFe] hydrogenase. H-2-grown cells transcribed the adenylylsulfate reductase b subunit and HmcA to higher levels. The results we describe here provide new insight into the continuing debate over how Desulfovibrio species utilize redox components to generate membrane potential and to channel electrons to sulfate, the final electron acceptor.