Optimisation of MTGase production in Pichia pastoris under controlled growth rates and oxygen conditions

Ersöz, F. and Tefon-Öztürk, B.E. and İnan, M. and Türkanoğlu-Özçelik, A. (2025) Optimisation of MTGase production in Pichia pastoris under controlled growth rates and oxygen conditions. ACTA ALIMENTARIA: AN INTERNATIONAL JOURNAL OF FOOD SCIENCE, 54 (4). pp. 708-722. ISSN 0139-3006

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Abstract

In this study, microbial transglutaminase (MTGase) enzyme was produced recombinantly in Pichia pastoris with the constitutive GAP promoter under different growth rate-dependent normoxic and ethanol-dependent hypoxic conditions. The fermentations were performed at 20 °C temperature and the pH of 7. It was observed that the maximum enzyme production was 6236.3 U L −1 at the lowest specific growth rate 0.015 μ, in the normoxia fed-batch culture. While there was no statistically significant difference in wet cell weight at different growth rates under normoxic conditions, the highest total protein (307.7 mg L −1 ) was obtained at 0.015 µ. Furthermore, MTGase production was tested under hypoxic conditions with low oxygen demand by maintaining the ethanol concentration at 1% (v/v); however, unexpectedly, hypoxic conditions were not achieved at high pH and low temperature. It was concluded that hypoxia strategy is not suitable for producing MTGase in P. pastoris. This is the first study on optimisation of different growth rates and hypoxic conditions for MTGase production under the control of GAP promoter. In this study, the fermentation parameters were systematically optimised to increase the yield of MTGase enzyme.

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