Desulfovibrio vulgaris str. 'Miyazaki F'
   
   
 

Desulfovibrio vulgaris Miyazaki F strain has been the sulfate-reducing strain of choice for examination of electron transfer components in Japan since the late 1960’s (1).  The ability to respire sulfate allows occupation of environments otherwise restricted by limiting electron acceptors and low fermentable carbon sources.  However, before sulfate can be reduced, it requires activation at the expense of two high energy phosphate bonds.  The subsequent reduction of sulfate, and then sulfite, to sulfide is believed to generate about three ATP equivalents, therefore producing a net of one ATP for eight electrons transferred.  The proteins and enzymes involved in electron transfer in the sulfate reducers have proven a rich source of metalloenzymes for biochemical and biophysical analysis through the years (2).

The discovery of cytochromes in these anaerobes heralded respiration of substrates other than oxygen.  Curiously, in some strains, hydrogen was shown to be both generated and consumed during sulfate respiration. To understand the roles of the various proteins and enzymes, many researchers have explored their biochemistry and in vitro activities.   Enzymes of sulfate reduction, cytochromes and hydrogenases have been purified and characterized from D. vulgaris Miyazaki (for example, 3) and have been the basis for comparison for similar work with D. vulgaris Hildenborough (sequenced and published in 2004; 4).  These strains are similar in physiology (5) and many results are automatically considered applicable to all D. vulgaris strains.  However, little is known about the genetics and true similarity of the Miyazaki strain to D. vulgaris. 

Recent work (5) has revealed several unexpected differences between these strains that may elucidate alternative systems for electron transfer.  From the genome sequence, genes for at least six different hydrogenase enzymes can be seen in the Hildenborough strain and three bands of activity can be seen in activity stains of extracts on gels.  In contrast, the Miyazaki strain has been shown to have genes for only one NiFe hydrogenase to date and exhibited a single activity band for hydrogenase in extracts.  Whereas a deletion has been constructed for a NiFe hydrogenase of Hildenborough, the gene encoding the NiFe enzyme of Miyazaki has not been successfully interrupted.  Thus genome sequence of Miyazaki may reveal differences in the redundancy of systems for energy generation from that seen for Hildenborough and allow for more definitive experiments to establish electron flow. 

References:

(1) Yagi, T. 1969. Formate: Cytochrome Oxidoreductase of Desulfovibrio vulgaris  J. Biochem. (Tokyo) 66:473-478.
(2) Peck, H. D., Jr., and LeGall, J. 1994. Inorganic microbial sulfur metabolism.  Meth. Enzymol. Vol. 243.  
(3) Yagi, T. 1994. Monoheme cytochromes. Meth. Enzymol. 243:104-118.  
(4) Heidelberg et al.  2004.  The genome sequence of the anaerobic, sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough: consequences for its energy metabolism and reductive metal bioremediation.  Nature Biotech. 22:554 – 559.
(5) Goenka Agrawal, Aruna, 2005, Molecular biological and spectroscopic characterisation of the [NiFe]-hydrogenase from Desulfovibrio vulgaris, Ph.D. Dissertation, Heinrich-Heine-Universität Düsseldorf - July 2005.