Medium Optimization for Spore Production of a Straw-Cellulose Degrading Actinomyces Strain under Solid-State Fermentation Using Response Surface Method

The strains capable of degrading cellulose have attracted much interest because of their applications in straw resource utilization in solid-state fermentation (SSF). However, achieving high spore production in SSF is rarely reported. The production of spores from Streptomyces griseorubens JSD-1 was investigated in shaker-flask cultivation in this study. The optimal carbon, organic nitrogen and inorganic nitrogen sources were sucrose, yeast extract and urea, respectively. Plackett-Burman design (PBD) was adopted to determine the key medium components, and the concentration levels of three components (urea, NaCl, MgSO4 center dot 7H(2)O) were optimized with the steepest ascent path and central composite design (CCD), achieving 1.72 x 10(9) CFU/g of spore production. Under the optimal conditions (urea 2.718% w/v, NaCl 0.0697% w/v, MgSO4 center dot 7H(2)O 0.06956% w/v), the practical value of spore production was 1.69 x 10(9) CFU/g. The determination coefficient (R-2) was 0.9498, which ensures an adequate credibility of the model.