Influence of nutrient, pH and dissolved oxygen on the production of Metarhizium flavoviride Mf189 blastospores in submerged batch culture

The influence of different parameters on the sporulation of Metarhizium flavoviride was studied during submerged cultures in shake flasks and in 5 l bioreactors. The screening in shake flasks of several carbon and nitrogen sources allowed the definition of an optimal medium, based on sucrose and brewer's yeast with a C/N ratio of 1.6. With this medium, a production of 5.4 × 108 blastospores per ml (Bspores ml−1) was obtained after 169 h of cultivation. The influence of pH and pO2 was independently studied in 5 l working volume bioreactors using the optimal medium. The best production was obtained with pH and pO2 regulated respectively to 7 and 100%. Finally, when the culture was grown under optimized conditions, the blastospores concentration increased 16-fold, with 1.1 × 109 Bspores ml−1 obtained after 144 h cultivation. This represents a gain of productivity of about 4.8 times.