Enzymatic production of L-amino acids from the corresponding DL-5-substituted hydantoins by Bacillus fordii MH602

Yan Zhen Mei, Bing Fang He, Ping Kai Ouyang

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Abstract

Bacillus fordii MH602 was newly screened from soil at 45°C and exhibited high activities of hydantoinase and carbamoylase, efficiently yielding l-amino acids including phenylalanine, phenylglycine and tryptophan with the bioconversion yield of 60-100% from the corresponding dl-5-substituted hydantoins. Hydantoinase activity was found to be cell-associated and inducible. The optimal inducer was dl-5-methylhydantoin with concentration of 0.014 mol L-1 and added to the fermentation medium in the exponential phase of growth. In the production of optically pure amino acids from dl-5-benylhydantoin, the optimal temperature and pH of this reaction were 45-50°C and 7.5 respectively. The hydantoinase was non-stereoselective, while carmbamoylase was l-selective. The hydantoinase activity was not subject to substrate inhibition, or product inhibition by ammonia. In addition, The activities of both enzymes from crude extract of the strain were thermostable; the hydantoinase and carbamoylase retained about 90% and 60% activity after 6 h at 50°C, respectively. Since reaction at higher temperature is advantageous for enhancement of solubility and for racemization of dl-5-substituted hydantoins, the relative paucity of l-selective hydantoinase systems, together with the high level of hydantoinase and carbamoylase activity and unusual substrate selectivity of the strain MH602, suggest that it has significant potential applications.

Original languageEnglish
Pages (from-to)375-381
Number of pages7
JournalWorld Journal of Microbiology and Biotechnology
Volume24
Issue number3
DOIs
StatePublished - Mar 2008

Keywords

  • Bacillus fordii MH602
  • Carbamoylase
  • Hydantoinase
  • L-amino acids

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