Aims: In this study, the relationship between morphology and cephalosporin C (CPC) production in a 30-l bioreactor culture of Cephalosporium acremonium M25 using a 3:7 seed mixture was investigated. In addition, the kinetic model was established and applied.
Methods and results: CPC production was performed in a 30-l bioreactor using a 3:7 seed mixture. It was recognized that a 3:7 seed mixture was able to reduce lag phase and enhance CPC production. The maximum CPC production and cell mass were 1.96 and 81.5 g l-1 respectively. Through a morphology study by observation using image analysis, it was concluded that changes of morphological features predicted the progressive production of CPC and that a morphology study could be useful in monitoring the CPC fermentation by C. acremonium M25. In the kinetics study, a kinetic model of CPC fermentation was developed and applied. The proposed model could adequately describe the fermentation of C. acremonium M25 in a 30-l bioreactor.
Conclusions: CPC productivity was improved by using a 3:7 seed mixture in a 30-1 bioreactor. The changes in morphological features showed a very similar tendency with CPC production. A kinetic model of CPC fermentation was successfully established.
Significance and impact of the study: The results of the present study suggest that the use of a 3:7 seed mixture inocula has considerable possibilities for improving CPC productivity if applied to industrial scale fermentations. Through morphology and kinetics study, the kinetic model to describe the morphological differentiation and CPC production by C. acremonium M25 was established.