Cultivation of entomopathogenic fungi in orbitally shaken bioreactors: Investigation of respiratory activity in scale-up experiments

Abstract: Scale-up considerations are an everlasting challenge in industrial scale production processes of all biotechnological applications. Bioengineering parameters are consulted and process control strategies utilizing on-line, at-line or off-line measurements are necessary. Analysis of cellular respiration allows improved understanding of cell metabolism and direct determination of cultivation conditions. In this study, batch cultivations with Metarhizium brunneum using complex medium supplemented with ground barley in Erlenmeyer flasks and the single-use OrbShake system SB10-X (Kuhner Shaker) were performed. Data concerning the respiratory activity and sugar consumption of Metarhizium brunneum using off-line sugar and on-line exhaust gas measurements were obtained. High reproducibility in shake flasks and a comparable respiratory and sugar consumption profile in the OrbShake system was observed. The sum of carbon dioxide production resulted in 563.0 mmol/l and 532.9 mmol/l for the shake flasks and OrbShake system respectively, after 240 h of cultivation. Sugar depletion occurred after 163.5 h and 189.5 h of cultivation for the shake flasks and OrbShake system respectively, with changing respiratory quotients due to a metabolic change in starch hydrolysis. We therefore present a reliable process monitoring strategy, which is easily applicable across lab- and pilot-scale cultivation processes, with simplified process monitoring and contamination detection.