Links between carbon source selection and anaerobiosis in Shewanella oneidensis

Amoolya Singh, University of California, Berkeley

We studied the regulation of genetic networks participating in anaerobic respiration in Shewanella oneidensis, a remarkable bacterium whose metal-reducing capabilities have received attention for potential in bioremediation of nuclear waste sites. Unlike many bacteria studied to date, the ability of S. oneidensis to grow anaerobically with several electron acceptors is regulated by the cAMP-receptor protein (CRP). CRP-deficient mutants of S. oneidensis are impaired in anaerobic reduction and growth with Fe(III), Mn(IV), fumarate, nitrate, and DMSO. Loss of anaerobic respiration in crp mutants is due to loss of terminal anaerobic reductases and not due to deficiency in carbon metabolism. To further elucidate the regulatory networks and links in anaerobic respiration and catabolite repression, we ran microarray analyses to compare mRNA expression profiles of wild-type and crp mutant cells grown anaerobically with different electron acceptors. Preliminary results indicate that CRP positively regulates the expression of genes involved in energy generation and transcriptional regulation. Further work to identify the cAMP signaling pathways in S. oneidensis is underway.

Abstract Author(s): Amoolya H. Singh (joint work with Alex S. Beliaev, Grigoriy E. Pinchuk, and Jim K. Fredrickson, PNNL)