摘要

The culture media for mycelial growth and sporulation of the entomopathogenic fungus Aschersonia placenta were optimized using the response surface method (RSM). Interactions of medium components and the optimization of a biphasic production system were studied using Box-Behnken design (BBD) with three levels of three variables. Experimentation confirmed that the model developed based on RSM and BBD successfully predicted mycelia production (R-2 = 0.9336) and conidia production (R-2 = 0.9532). In the first phase, mycelial dry weight was highest (2.14 +/- 0.17 g per 100 ml of culture, mean +/- SE) when the concentrations (g/l) of glucose, vitamin B-6, and MgSO4 center dot 7H(2)O were 31.4, 11.5, and 0.64, respectively. In the second phase, conidia production was highest (9.31 +/- 0.48 x 10(7) spores per cm(2)) after 18 d of cultivation in the medium containing 33.8 g/l of millet, 1.11 g/l of KH2PO4, and 0.37 g/l of MgSO4. Mycelial and conidial yields were 3.6- and 10-fold greater, respectively, with the optimized media than with the non-optimized basal media. The results indicate that RSM and BBD methods are effective for increasing the production of A. placenta mycelia and conidia.