Design of an efficient fermentation process for the production of Metarhizium acridum blastospores

Using a sequential approach, we described efficient blastospore production in a stirred tank bioreactor (3 L capacity). We used the response surface methodology to optimise the media ingredients and fermentation parameters to obtain the maximum production of blastospores by a locally collected isolate of Metarhizium acridum (Ascomycota: Hypocreales). The results showed that a liquid culture medium supplemented with monopotassium phosphate (15.17 g/L), corn steep liquor (69.25 g/L), and casamino acids (80.68 g/L) in a stirred tank bioreactor under operating conditions constant at 635 rpm, a temperature of 26°C, and pH 3.3 produced 1.25 × 108 blastospores (bls)/ml, with 93% viability after 120 h of fermentation. This bioreactor yield compares favourably with the yields obtained by shake flask production and confirms the suitability of the media and production parameters for the potential scale-up fermentation production of M. acridum.