A plate method for rapid screening of Ketogulonicigenium vulgare mutants for enhanced 2-keto-l-gulonic acid production

  • Braz J Microbiol. 2017 Jul-Sep;48(3):397-402. doi: 10.1016/j.bjm.2017.02.002.
Weichao Yang  1 ,  Litao Han  2 ,  Mandlaa Mandlaa  1 ,  Haihong Zhang  2 ,  Zhongze Zhang  1 ,  Hui Xu  3
Affiliations
  • 1. Chinese Academy of Sciences, Institute of Applied Ecology, Shenyang, China.
  • 2. Northeast Pharmaceutical Group Co., Ltd., Fermentation & Biotechnology Laboratory, Shenyang, China.
  • 3. Chinese Academy of Sciences, Institute of Applied Ecology, Shenyang, China. Electronic address: [email protected].
PMID: 28292630 DOI: 10.1016/j.bjm.2017.02.002
Abstract

A new plate method was developed for rapid screening of Ketogulonicigenium vulgare mutants overproducing 2-keto-l-gulonic acid (2-KLG). The screening methodology took the advantage of the acidity caused by 2-KLG, which changes the color of bromothymol blue (pH indicator) from blue to yellow. Using the proposed method, a mutant, K. vulgare 65, was selected from 20,000 colonies produced by a strain subjected to spaceflight mutagenesis. When co-cultured with Bacillus megaterium 2980 in 20-L fermenters, K. vulgare 65 showed a high conversion rate (94.45%) of l-sorbose to 2-KLG. In contrast to the traditional screening method, this one significantly improved the frequency of obtaining positive mutants. The proposed plate screening method is cost-effective and easy to run and is thus useful for the isolation and screening of K. vulgare mutants overproducing 2-KLG.

Keywords
2-Keto-l-gulonic acid; Ketogulonicigenium vulgare; Rapid screening; Spaceflight mutation; pH indicator.
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