Monday, July 27, 2009 - 10:10 AM
S21

Diversity and dynamics of bacterial populations during spontaneous sorghum fermentations used to produce ting, a South African food

Evelyn Madoroba1, Emma T. Steenkamp1, Jacques Theron1, T. Eugene Cloete1, Geert Huys2, and Ilse Sheirlinck3. (1) Microbiology and Plant Pathology, University of Pretoria, 74 Lynnwood Road, Pretoria, South Africa, (2) Laboratory for Microbiology, Faculty of Sciences,, Ghent University, , Belgium, K. L. Ledeganckstraat 35, B-9000 Gent, Gent, Belgium, (3) Laboratory for Microbiology, Faculty of Sciences, Gent University, K. L. Ledeganckstraat 35, B-9000 Gent,, Gent, Belgium

Ting is a spontaneously fermented cooked South African food that is popular for its sour taste and unique flavour. Insight of microbial diversity and population dynamics during sorghum fermentations is an initial but imperative step in the development of starter cultures for commercial production of ting. In this study, microorganisms associated with spontaneous fermentations of two sorghum types were examined using culture-independent and culture-dependent methods. Culture-independent polymerase chain reaction (PCR) of the V3 region of the 16S rRNA gene and analysis of the resulting amplicons using denaturing gradient gel electrophoresis (DGGE), followed by sequence analyses of the most intense bands, revealed that lactic acid bacteria (LAB), including close relatives of Lactococcus lactis, Lactobacillus curvatus, Weissella cibaria and some members of the Enterobacteriaceae family, were predominant at the end of fermentation in both sorghum types. L. lactis, however, showed the most intense band.  Culture-dependent methods, involving isolation of the various bacteria, followed by 16S rRNA gene sequence analyses indicated that Enterococcus mundtii was present at the start of fermentation, whilst Lb. fermentum, Lb. plantarum, Lb. rhamnosus, E. faecalis, W. cibaria and L. lactis were predominant at the end of fermentation. Lb. curvatus was not detected in culture media, but it was predominant in DGGE gels. Likewise, Lb. fermentum, Lb. plantarum, Lb. rhamnosus, E. faecalis and E. mundtii were isolated in culture media, but they were absent in DGGE gels. Therefore, the combined approach was effective in revealing the microbial diversity and dynamics during spontaneous sorghum fermentations. 

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