Simplified feeding strategies for the fed-batch cultivation of Kluyveromyces lactis GG799 for enhanced recombinant xylanase production

• Published in: Bioprocess and biosystems engineering 2014-09, Vol.37 (9), p.1887-1898
• Main Authors: Fuzi, Siti Fatimah Zaharah Mohamad, Razali, Firdausi, Jahim, Jamaliah Md, Rahman, Roshanida A., Illias, Rosli Md
• Format: Article
• Language: English
• Subjects: Bioengineering; Bioreactors; Biotechnology; Carbon sources; Chemistry; Chemistry and Materials Science; Dissolved oxygen; Environmental Engineering/Biotechnology; Enzymes; Fermentation; Food Science; Fungi; Hypocrea jecorina; Industrial and Production Engineering; Industrial Chemistry/Chemical Engineering; Kinetics; Kluyveromyces - enzymology; Kluyveromyces - growth & development; Kluyveromyces lactis; Models, Biological; Nitrogen sources; Original Paper; Recombinant Proteins - biosynthesis; Xylosidases - biosynthesis; Yeasts
• ISSN: 1615-7591; 1615-7605
• DOI: 10.1007/s00449-014-1163-z

A xylanase gene ( xyn2 ) from Trichoderma reesei ATCC 58350 was previously cloned and expressed in Kluyveromyces lactis GG799. The production of the recombinant xylanase was conducted in a developed medium with an optimised batch and with fed-batches that were processed with glucose. The glucose served as a carbon source for cell growth and as an inducer for xylanase production. In a 1-L batch system, a glucose concentration of 20 g L −1 and 80 % dissolved oxygen were found to provide the best conditions for the tested ranges. A xylanase activity of 75.53 U mL −1 was obtained. However, in the batch mode, glucose depletions reduced the synthesis of recombinant xylanase by K . lactis GG799. To maximise the production of xylanase, further optimisation was performed using exponential feeding. We investigated the effects of various nitrogen sources combined with the carbon to nitrogen (C/N) molar ratio on the production of xylanase. Of the various nitrogen sources, yeast extract was found to be the most useful for recombinant xylanase production. The highest xylanase production (110.13 U mL −1 ) was measured at a C/N ratio of 50.08. These conditions led to a 45.8 % increase in xylanase activity compared with the batch cultures. Interestingly, the further addition of 500 g L −1 glucose led to a 6.2-fold increase (465.07 U mL −1 ) in recombinant xylanase activity. These findings, together with those of the exponential feeding strategy, indicate that the composition of the C/N molar ratio has a substantial impact on recombinant protein production in K . lactis .