Differential proteomic analysis of an engineered Streptomyces coelicolor strain reveals metabolic pathways supporting growth on n-hexadecane

The alkB gene, encoding an alkane monooxygenase in the actinomycete Gordonia sp. SoCg, was expressed in the non-alkane-degrading actinomycete Streptomyces coelicolor M145. The resulting engineered strain, M145-AH, can grow on n-hexadecane as sole carbon source. To unravel proteins associated with growth on n-alkanes, proteome of M145-AH after 6, 24, and 48 h of incubation in the Bushnell-Haas (BH) mineral medium containing n-hexadecane as sole carbon source (H condition) and in BH without any carbon source (0 condition) were compared using 2D-differential gel electrophoresis. Proteome analysis revealed significant changes only at 48 h, showing 48 differentially abundant proteins identified by mass spectrometry procedures. To asses if these proteins were specifically related to n-hexadecane metabolism, their expression was investigated, comparing H proteome with that of M145-AH incubated in BH with glucose as sole carbon source (G condition). Thus, protein expression profiles at 6, 24, and 48 h under H, 0, and G conditions were combined, revealing that M145-AH regulates in a temporally- and carbon source-dependent manner the expression of proteins involved in regulatory events, central carbon metabolism, respiration, β-oxidation, membrane transport, and amino acid and protein metabolism. Interestingly, 21 % of them, mostly involved in membrane transport and protein metabolism, showed a n-hexadecane-dependent regulation with regulatory proteins such as CRP likely to have a key role in M145-AH n-hexadecane growth. These results, expanding the knowledge on n-alkane utilization in Gram-positive bacteria, reveal genes to be targeted to develop an efficient S. coelicolor M145-AH-based bioremediation system.