Article

Biotechnology Letters

, Volume 6, Issue 9, pp 593-596

First online:

Lactase production in continuous culture by Trichoderma reesei Rut-C30

  • Francisco J. CastilloAffiliated withLab. Fermentacion, Centro De Microbiologia y Biologia Cellular, I.V.I.C.
  • , Harvey W. Blanch
  • , Charles R. WilkeAffiliated withDepartment of Chemical Engineering, University of California

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Summary

Trichoderma reesei Rut-C30 was found to produce extracellular lactase when grown on lactose medium. Maximum enzyme levels in continuous culture were observed at dilution rates (D) between 0.02 and 0.027 hr-1. The enzyme productivity reached 27.3 U/L hr at D = 0.027 hr-1. Lactase synthesis appears to be inducible and subject to catabolite repression. Optimal growth temperature and pH for enzyme production were 28°C and pH 5. Maximum enzyme activity was observed at 63°C and pH 4.6. The apparent Km, based on the nitrophenyl-galactopyranoside assay was estimated as 0.4 mM. The enzyme is suitable for lactose hydrolysis in acid whey.