Addition of spherical‐style packing improves the production of conidia by <i>Metarhizium robertsii</i> in packed column bioreactors

Abstract

Abstract BACKGROUND Conidia from Metarhizium are part of the commercial formulations used worldwide for insect pest control. Among the alternatives proposed to improve conidia production, the use of packed column bioreactors allows controlled processes with higher levels of production and productivity than those obtained with the traditional process in plastic bags. However, problems associated with overheating, low CO 2 removal, and inadequate oxygen supply in packed columns limit the scale‐up and operation at an industrial scale. RESULTS Packed densities, up to 1.5 times higher than those obtained in lab‐scale column bioreactors, negatively affected growth and conidia production by Metarhizium robertsii (ENCB‐MG‐81). Therefore, a spherical‐style packing was added to decrease packed density and improve the culture conditions in packed column bioreactors. The addition of spherical‐style packing reduced the axial temperature gradient (up to 50%), increased the maximum CO 2 production rate and the total CO 2 production (up to 2.5 times), and enhanced the volumetric conidia productivity in packed column bioreactors from 5.28 ± 1.36 to 6.77 ± 0.89 × 10 8 conidia cm −3 . CONCLUSION The use of spherical‐style packing within the culture bed in column bioreactors improves the production of conidia by Metarhizium robertsii , as well as the gas exchange and heat removal from the bed. © 2021 Society of Chemical Industry (SCI).