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Applied Microbiology and Biotechnology

, Volume 57, Issue 3, pp 379–384 | Cite as

Metabolic profiles and aprE expression in anaerobic cultures of Bacillus subtilis using nitrate as terminal electron acceptor

  •  J. Espinosa-de-los-Monteros
  •  A. Martinez
  •  F. Valle
Original Paper

Abstract.

Cultures using nitrate as the terminal electron acceptor were conducted in Schaeffer's medium to evaluate the growth performance and metabolic profiles of Bacillus subtilis, and its potential to express the aprE (subtilisin) gene under anoxic conditions. Nitrate was converted to ammonia through nitrite reduction; and different product profiles were observed during the growth phase when nitrate was added at various concentrations (4–24 mM) to Schaeffer's medium containing glucose (4 g l–1). If nitrate was not limiting, then acetic acid and acetoin were accumulated, suggesting a limitation of reduced cofactors but, if nitrate became limiting, then lactic acid and butanediol were accumulated, suggesting an excess of reduced cofactors. Due to a strong lysis at the onset of the end of the growth phase, sporulation frequency and aprE expression were negligible in anaerobic batch cultures. Fed-batch fermentation allowed the development of a stationary phase through a continuous supply of glucose and nitrate. In this case, sporulation frequency was almost null, but interestingly aprE expression was similar to that found in aerobic cultures.

Keywords

Nitrate Fermentation Nitrite Lactic Acid Bacillus Subtilis 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag 2001

Authors and Affiliations

  •  J. Espinosa-de-los-Monteros
    • 1
  •  A. Martinez
    • 1
  •  F. Valle
    • 2
  1. 1.Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, A.P. 510-3, Cuernavaca, Mor. 62271, México
  2. 2.Genencor International Inc., 925 Page Mill Road, Palo Alto, CA 94304-1013, USA

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