期刊
ANTONIE VAN LEEUWENHOEK INTERNATIONAL JOURNAL OF GENERAL AND MOLECULAR MICROBIOLOGY
卷 100, 期 1, 页码 99-107出版社
SPRINGER
DOI: 10.1007/s10482-011-9568-z
关键词
Dekkera bruxellensis; Ethanol fermentation; Nitrate assimilation; Sugarcane; Industrial adaptation
类别
资金
- Brazilian funding agency Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)
- Brazilian funding agency Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)
- Brazilian funding agency Fundacao de Amparo a Ciencia e Tecnologia do Estado de Pernambuco (FACEPE)
The yeast Dekkera bruxellensis has been regarded as a contamination problem in industrial ethanol production because it can replace the originally inoculated Saccharomyces cerevisiae strains. The present study deals with the influence of nitrate on the relative competitiveness of D. bruxellensis and S. cerevisiae in sugar cane ethanol fermentations. The industrial strain D. bruxellensis GDB 248 showed higher growth rates than S. cerevisiae JP1 strain in mixed ammonia/nitrate media, and nitrate assimilation genes were only slightly repressed by ammonia. These characteristics rendered D. bruxellensis cells with an ability to overcome S. cerevisiae populations in both synthetic medium and in sugar cane juice. The results were corroborated by data from industrial fermentations that showed a correlation between high nitrate concentrations and high D. bruxellensis cell counts. Moreover, the presence of nitrate increased fermentation efficiency of D. bruxellensis cells in anaerobic conditions, which may explain the maintenance of ethanol production in the presence of D. bruxellensis in industrial processes. The presence of high levels of nitrate in sugar cane juice may be due to its inefficient conversion by plant metabolism in certain soil types and could explain the periodical episodes of D. bruxellensis colonization of Brazilian ethanol plants.
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