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

Citation
J. Espinosa-de-los-monteros et al., Metabolic profiles and aprE expression in anaerobic cultures of Bacillus subtilis using nitrate as terminal electron acceptor, APPL MICR B, 57(3), 2001, pp. 379-384
Citations number
17
Categorie Soggetti
Biotecnology & Applied Microbiology",Microbiology
Journal title
APPLIED MICROBIOLOGY AND BIOTECHNOLOGY
ISSN journal
01757598 → ACNP
Volume
57
Issue
3
Year of publication
2001
Pages
379 - 384
Database
ISI
SICI code
0175-7598(200110)57:3<379:MPAAEI>2.0.ZU;2-6
Abstract
Cultures using nitrate as the terminal electron acceptor were conducted in Schaeffer's medium to evaluate the growth performance and metabolic profile s of Bacillus subtilis, and its potential to express the aprE (subtilisin) gene under anoxic conditions. Nitrate was converted to ammonia through nitr ite reduction; and different product profiles were observed during the grow th phase when nitrate was added at various concentrations (4-24 mM) to Scha effer'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 but anediol were accumulated, suggesting an excess of reduced cofactors. Due to a strong lysis at the onset of the end of the growth phase, sporulation fr equency and aprE expression were negligible in anaerobic batch cultures. Fe d-batch fermentation allowed the development of a stationary phase through a continuous supply of glucose and nitrate. In this case, sporulation frequ ency was almost null, but interestingly aprE expression was similar to that found in aerobic cultures.