Determination of yeast diversity in ogi, mawe, gowe and tchoukoutou by using culture-dependent and -independent methods

The maize based ogi and mawe and the sorghum based gowe and tchoukoutou are traditional, spontaneously fermented products widely consumed by the population of Benin (West Africa). Yeast occurrence in the products, as sold on local markets at different locations, was studied using a combination of culture-dependent and independent methods. Number of yeasts is varied from 3.75 log(10) colony forming units (cfu)/g for ogi to 5.60 log(10) cfu/g for tchoukoutou. Isolated yeasts (236) were identified based on different migration profiles on denaturing gradient gel electrophoresis (DGGE) and 26S rRNA gene sequencing. Candida krusei was the yeast most frequently isolated with strongest predominance in the maize based products. Other predominant yeast present at equal or lower incidence were Clavispora lusitaniae and Saccharomyces cerevisiae in ogi and mawe, Cl. lusitaniae, Candida tropicalis and Kluyveromyces marxianus in gowe and Cl. lusitaniae, S. cerevisiae and Candida rugosa in tchoukoutou. Grouping of C. krusei isolates (164) by rep-PCR analysis indicated that several biotypes were involved in fermentation of the four products. The DGGE analysis on the DNA directly extracted from the food matrices demonstrated the presence of Dekkera bruxellensis and Debaryomyces hansenii, not detected by the culture-based approach. This is the first study combining culture-dependent and independent methods to reveal predominant yeast species and biotypes in traditional foods from Benin. (c) 2013 Elsevier B.V. All rights reserved.