Establishment of cultivating strategy for highly aggregated mycelia of Morchella esculenta in a stirred-tank bioreactor

Abstract

Mycelia of Morchella esculenta were found to aggregate rapidly in a submerged culture, which caused the decrease in dispersed mycelia and the problem of diffusion limitation. The effect of different agitation schemes on the growth of mycelia was investigated in a stirred-tank bioreactor. At the constant speed of 100 or 300 rpm, rapid aggregation caused the biomass concentration to drop to zero in 30 h, which was even worse than achieved under static culture. Intermittent agitation maintained a higher mycelium fragment concentration for 48 h and enhanced the biomass concentration to 4.73 g/L at 120 h. The operation with a polytron connection disrupted effectively mycelium aggregation, thus increasing the specific growth rate, biomass concentration and maximum productivity to 0.0613 1/h, 7.73 g/L and 0.0878 g/L h at 88 h, respectively. Moreover, logistic equations and genetic algorithm (GA) were used for the simulation of biomass growth and estimation of all kinetic coefficients. The operating strategy developed in this study could be used for the production of highly aggregated mycelia, which could also achieve a high cell-density culture in a stirred tank reactor.