Evaluation of Basic Fermentation Parameters and Effective Combinations of Predominant Yeasts from Traditional Starter Materials of Indigenous Communities from Northeast India

Abstract

In this study, yeasts inherent in traditional starter materials of four indigenous communities from northeast India were characterized. These included Saccharomyces and non-Saccharomyces types representing several genera and species such as Saccharomyces cerevisiae, Wickerhamomyces anomalus, Candida glabrata and Candida tropicalis. The yeasts were cultured in synthetic minimal media (2% glucose and 2% starch), both individually and in combinations. The propensity of growth of individual isolates in glucose appeared as W. anomalus > C. tropicalis > C. glabrata > S. cerevisiae. In starch, the propensity appeared as C. tropicalis > W. anomalus > C. glabrata > S. cerevisiae. The findings were incongruent when isolates were co-cultured in dual combinations in glucose and starch. In glucose, W. anomalus could not prosper with C. tropicalis, which otherwise was reversed in starch. C. tropicalis dominated all the co-cultures in starch followed by W. anomalus, S. cerevisiae and C. glabrata. In glucose, the order appeared as W. anomalus > C. tropicalis > S. cerevisiae > C. glabrata. S. cerevisiae could not thrive in competition with C. tropicalis and appeared dominant over C. glabrata in both glucose and starch. W. anomalus was dominant over S. cerevisiae and C. glabrata, while C. tropicalis outnumbered C. glabrata in both carbon sources. The fermentation efficiency was highest when S. cerevisiae and C. glabrata were co-cultured together, in both starch and glucose. This study suggests an advantage in co-culturing selective indigenous yeasts as consortia to yield a productive fermentation output that could have commercial benefit but additional strains of each species still needed to be investigated.