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Dynamics and Spatial Expression of Signal Proteins in the Desulfovibrio vulgaris Biofilm and its Implication to Iron Corrosion

Weiwen Zhang, Principal Investigator

Regulation of Cellular Metabolism
Domain structures of bacterial two-component signal transduction systems. (a) Typical two-component phosphotransfer system containing sensor histidine kinases and cytoplasmic response regulators. (b) A multi-component phosphorelay system containing hybrid-type histidine kinase and a histidine-containing phosphotransfer (HPt) protein. Click for a larger version.

Iron corrosion is a serious economic problem. Whereas aerobic corrosion of iron is a chemical process, anaerobic corrosion of iron is frequently linked to the activity of sulphate-reducing bacteria (SRB), which can form biofilms on the surface of steel. The underlying mechanisms of biofilm formation are complex and insufficiently understood. Pacific Northwest National Laboratory's (PNNL's) Dynamics and Spatial Expression of Signal Proteins in the Desulfovibrio vulgaris Biofilm and its Implication to Iron Corrosion project team is studying SRB biofilm formation on the iron metal surface.

SRB act upon iron primarily by producing hydrogen sulfide as a corrosive agent and by consuming “cathodic hydrogen” formed on iron in contact with water. Among SRB, Desulfovibrio species, which have the capacity to consume hydrogen effectively, are conventionally regarded as the main culprits of anaerobic corrosion.

Recent studies have shown that biofilm formation is controlled by two-component signal transduction systems (TCSTS) in many bacteria, such as Streptococcus and Pseudomonas. In our previous study, a large number of TCSTS, including 59 putative sensory histidine kinases (HK) and 55 response regulators (RR), was identified from the Desulfovibrio vulgaris (D. vulgaris) genome, indicating their important roles in regulating cellular metabolism. In this study, we are constructing reporter proteins that consist of the promoter of selected two-component signal genes fused to a gfp gene encoding a green fluorescent protein. We are studying the expressions of these fusion proteins following the formation of a D. vulgaris biofilm grown on an iron metal surface.

Our experiments will illustrate for the first time the dynamic and spatial expression of two-component signal proteins in D. vulgaris biofilms growing on a metal surface. The efforts will facilitate investigations of the complex regulatory networks controlling biofilm formation and iron corrosion in natural environments, and provide guidance to the efforts of corrosion control.

Systems Biology at PNNL

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