Comparison of extracellular proteome from Rhizopus chinensis in solid-state and submerged cultures

Abstract:

[Objective] We studied the influence of solid-state and submerged cultures on the extracellular proteome of filamentous fungus Rhizopus chinensis CCTCC M201021, to understand the specificity of enzyme production by filamentous fungi in different cultures. [Methods] Using same media, we carried out solid-state agar-plate culture and submerged culture of R. chinensis. Two-dimensional electrophoresis (2-DE) and MALDI-TOF/TOF-MS were used to analyze the extracted extracellular proteins, and the differential proteins were identified. [Results] Protease activity of extracellular protein from the solid-state culture was much higher (9.2-fold) than that from submerged culture. The 2-DE gel maps indicate the differences in the extracellular proteomes between solid-state and submerged cultures, and most proteins (about 70%) were special from solid-state or submerged culture. After identification, the variety and expression level of extracellular proteins from the two different cultures were significantly different. Among these differential proteins, hydrolases were the majority, most of which were related with protein degradation. [Conclusion] Different cultures influenced the composition of extracellular proteome by R. chinensis, and some proteins were only expressed in a specific culture. Relatively more variety and higher expression level of some proteases under solid-state culture could be the reason, which resulted in the much higher protease activity of extracellular protein. These results suggested the possible inconsistencies of extracellular enzymes produced by filamentous fungi between the strain screening and submerged fermentation in industry production, when solid-state culture and submerged culture were used.