Characterization of cytochrome mutants for pellicle formation in Shewanella onedensis MR-1

Biofilm systems are effective for biosorption of metal ions. Shewanella oneidensis MR-1, a Gram-negative facultative anaerobe, is a natural pellicle-like biofilm former. The mechanisms of pellicle formation by S. oneidensis MR-1 have not yet been understood. 17 S. oneidensis MR-1 deletion mutants, including 12 c-type cytochromes were generated and tested if they were involved in pellicle formation. The results show that ΔSO4666, ΔSO1777, ΔSO1782, ΔSO2361 and ΔSO2363 have varying deficiency in pellicle formation. The deletion mutant ΔSO4666 cannot form a pellicle under non-shake conditions, suggesting that it may play an important role in pellicle formation by S. oneidensis MR-1. Overall, these data suggest a very complex picture of aerobic respiration by S. oneidensis MR-1.