© 2018, Springer-Verlag GmbH Germany, part of Springer Nature and the University of Milan. The purpose of this study was to evaluate the inductive effect of starch and maltose, and the repressive/inhibitory effect of glucose, on amy-1 gene expression and α-amylase production by Wickerhamia sp., using continuous culture under transient-state conditions at a dilution rate (D) of 0.083 h−1. Induction and repression kinetics of α-amylase were studied by changing the medium feed from glucose to maltose or starch in the induction experiments and vice versa in the repression experiments. Expression levels of amy-1 gene were measured by RT-qPCR. Results showed that starch was a more efficient inducer of α-amylase synthesis compared to maltose, with maximum accumulation rate constants of 0.424 and 0.191 h−1, respectively. In contrast, α-amylase synthesis in starch and maltose cultures was partially repressed by glucose as indicated by a specific activity close to basal levels and a decay constant rate (− 0.065 and − 0.069 h−1, respectively) higher than − D. A linear dependence of the specific rate of α-amylase production on mRNA relative abundance of amy-1 gene was observed. An inhibitory effect of glucose was not observed even at a concentration of 30 g L−1. In conclusion, the transient continuous culture is a useful tool to determine the qualitative and quantitative effects of maltose and starch on α-amylase induction and of glucose on enzyme repression, as well as to obtain a detailed understanding of the dynamic behavior of the yeast culture. Furthermore, results showed that amylaceous substrates can be very effective carbon sources for the production of α-amylase without being inhibited by glucose.
Chávez-Camarillo, G. M., Santiago-Flores, U. M., Mena-Vivanco, A., Morales-Barrera, L., Cortés-Acosta, E., & Cristiani-Urbina, E. (2018). Transient responses of Wickerhamia sp. yeast continuous cultures to qualitative changes in carbon source supply: induction and catabolite repression of α-amylase synthesis. Annals of Microbiology, 625-635. https://doi.org/10.1007/s13213-018-1369-4