ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Enhancing the production of gamma-linolenic acid in Hansenula polymorpha by fed-batch fermentation using response surface methodology

Bhimabol Khongto, Kobkul Laoteng, and Anan Tongta

Division of Biotechnology, School of Bioresources and Technology, King Mongkut’s University of Technology Thonburi, Bangkhuntien, Bangkok, 10150 Thailand

E-mail: kobkul@biotec.or.th

Abstract: Gamma-linolenic acid (GLA, C18:3Δ^6,9,12) is an n-6 polyunsaturated fatty acid (PUFA) that has been used for the alleviation and treatment of a number of symptoms and diseases. Increasing GLA demand has led to a search for alternative producers and potential strategies for GLA production. Based on the successful performance of Hansenula polymorpha, a methylotrophic yeast, as a “cell factory” for the production of valuable bioproducts, a bioprocess development approach was implemented for GLA production in the recombinant yeast carrying the mutated Δ⁶-desaturase gene of Mucor rouxii. Using a substrate-feeding strategy under glycerol-limited conditions, the physical-chemical variables during the fed-batch fermentation of the recombinant H. polymorpha were optimised for GLA production through response surface methodology using a Box-Behnken design. The medium composition, including yeast extract and trace elements, and dissolved oxygen tension (DOT) were targeted. We found that DOT was the most effective variable for enhancing GLA yield. These results also suggest that the optimum conditions for GLA production are 28 % saturation of DOT, 1 g L⁻¹ of yeast extract and 3.6 mL L⁻¹ of the Pichia trace metals 1 (PTM1).

Keywords: gamma-linolenic acid – Hansenula polymorpha – medium composition – dissolved oxygen tension – response surface methodology

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-010-0099-2

Chemical Papers 65 (2) 124–131 (2011)