He-Ne laser irradiation of folate-producing Candida utilis and optimization of culture conditions under submerged fermentation

Yan Liu, Zheng Lian Xue, Zhi Ming Zheng, Guo Hong Gong, Peng Wang, Guang Jun Nie

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

In an attempt to obtain a microbial strain with higher yield of folate for industrial applications, we mutated the wild strain Candida utilis Y1.0 using a novel mutagenic process, i.e., irradiation by a helium-neon (He-Ne) laser with an output power of 20 mW and an exposure time of 20 min. The yield of folate in the mutated cells reached 1,102 ng/mL, which was 20.4-fold that of the wild strain. The mutant strain Y3.636 was relatively stable in terms of folate production through eight successive transfers of cultures and batch fermentation in a 3.7-L stirred-tank fermenter. Optimization further increased the yield of the mutant by 110 %, i.e., to 2,314 ± 13 ng/mL. The optimal culture conditions for folate production were: cultivation in fermentation culture medium composed of 62.5 g/L glucose, 15 g/L corn liquor, 3 g/L (NH 4)2SO4, 3 g/L MgSO4, and 1 g/L glutamic acid; inoculum size of 9 %; incubation at 28 C and 196 rpm for 36 h. A time-course study of cell growth and folate production by mutant strain Y3.636 strongly suggested that folate production in C. utilis is growth-associated.

Original languageEnglish (US)
Pages (from-to)641-647
Number of pages7
JournalAnnals of Microbiology
Volume63
Issue number2
DOIs
StatePublished - Jun 1 2013

Keywords

  • Candida utilis
  • Folate
  • He-Ne laser
  • Mutant
  • Optimization

ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology

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