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Vitamin B sub(12) production by Citrobacter freundii or Klebsiella pneumoniae during tempeh fermentation and proof of enterotoxin absence by PCR
The influence of some fermentation parameters on vitamin B sub(12) formation by strains of Citrobacter freundii and Klebsiella pneumoniae isolated from Indonesian tempeh samples during tempeh fermentation was investigated. A decrease in fermentation temperature from 32 to 24 degree C led to a decrea...
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Published in: | Applied and environmental microbiology 1994-01, Vol.60 (5), p.1495-1499 |
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Main Authors: | , |
Format: | Article |
Language: | English |
Subjects: | |
Online Access: | Get full text |
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Summary: | The influence of some fermentation parameters on vitamin B sub(12) formation by strains of Citrobacter freundii and Klebsiella pneumoniae isolated from Indonesian tempeh samples during tempeh fermentation was investigated. A decrease in fermentation temperature from 32 to 24 degree C led to a decrease in vitamin B sub(12) formation. Inoculation of soybeans with different numbers of cells of C. freundii at the beginning of solid-substrate fermentation showed that only the velocity of vitamin formation and not the final amount of vitamin formed depended on the number of cells. The addition of cobalt and 5,6-dimethylbenzimidazole increased the vitamin B sub(12) content of tempeh. Nevertheless, levels of incorporation of the two precursors into the vitamin B sub(12) molecule were very low. Neither C. freundii nor K. pneumoniae possessed the genes encoding the enterotoxins Shiga-like toxin SLT IIA, heat-labile enterotoxin LT Ih, and heat-stable enterotoxin ST Ih, as indicated by PCR. This result supports the suggested use of these two strains to form vitamin B sub(12) during tempeh fermentation in Indonesia. |
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ISSN: | 0099-2240 |