Comparative Proteomic Analysis of Experimental Evolution of the <i>Bacillus cereus-Ketogulonicigenium vulgare</i> Co-Culture

<div><p>The microbial co-culture system composing of <i>Ketogulonicigenium vulgare</i> and <i>Bacillus cereus</i> was widely adopted in industry for the production of 2-keto-gulonic acid (2-KGA), the precursor of vitamin C. We found serial subcultivation of the co-culture could enhance the yield of 2-KGA by 16% in comparison to that of the ancestral co-culture. To elucidate the evolutionary dynamics and interaction mechanisms of the two microbes, we performed iTRAQ-based quantitative proteomic analyses of the pure cultures of <i>K. vulgare</i>, <i>B. cereus</i> and their co-culture during serial subcultivation. Hierarchy cluster analyses of the proteomic data showed that the expression level of a number of crucial proteins associated with sorbose conversion and oligopeptide transport was significantly enhanced by the experimental evolution. In particular, the expression level of sorbose/sorbosone dehydrogenase was enhanced in the evolved <i>K. vulgare</i>, while the expression level of InhA and the transport efficiency of oligopeptides were increased in the evolved <i>B. cereus.</i> The decreased sporulating protein expression and increased peptide transporter expression observed in evolved <i>B. cereus</i>, together with the increased amino acids synthesis in evolved <i>K. vulgare</i> suggested that serial subcultivation result in enhanced synergistic cooperation between <i>K. vulgare</i> and <i>B. cereus,</i> enabling an increased production of 2-KGA.</p>