Sorbitol synthesis by an engineered Lactobacillus casei strain expressing a sorbitol-6-phosphate dehydrogenase gene within the lactose operon

Authors

  • Lorenzo Nissen,

    1. Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (CSIC), 46100 Burjassot, Valencia, Spain
    2. Department of Agroenvironmental Sciences and Technologies, Microbiology area, Alma Mater Studiorum, Università di Bologna, 40127 Bologna, Italy
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  • Gaspar Pérez-Martínez,

    1. Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (CSIC), 46100 Burjassot, Valencia, Spain
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  • María J. Yebra

    Corresponding author
    1. Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (CSIC), 46100 Burjassot, Valencia, Spain
      *Corresponding author. Tel.: +34 96 390 0022; fax: +34 96 363 6301., E-mail address: yebra@iata.csic.es
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  • Edited by E. Ricca

*Corresponding author. Tel.: +34 96 390 0022; fax: +34 96 363 6301., E-mail address: yebra@iata.csic.es

Abstract

Sorbitol is claimed to have important health-promoting effects and Lactobacillus casei is a lactic acid bacterium relevant as probiotic and used as a cheese starter culture. A sorbitol-producing L. casei strain might therefore be of considerable interest in the food industry. A recombinant strain of L. casei was constructed by the integration of a d-sorbitol-6-phosphate dehydrogenase-encoding gene (gutF) in the chromosomal lactose operon (strain BL232). gutF expression in this strain followed the same regulation as that of the lac genes, that is, it was repressed by glucose and induced by lactose. 13C-nuclear magnetic resonance analysis of supernatants of BL232 resting cells demonstrated that, when pre-grown on lactose, cells were able to synthesize sorbitol from glucose. Inactivation of the l-lactate dehydrogenase gene in BL232 led to an increase in sorbitol production, suggesting that the engineered route provides an alternative pathway for NAD+ regeneration.

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