Phenotypical and molecular characterization of yeast content in the starter of “Tchoukoutou,” a Beninese African sorghum beer

Abstract

Tchoukoutou is a Beninese African sorghum beer obtained by mixed fermentation including different yeast and lactic acid bacteria (LAB). Until now, the make-up of the starter’s whole microbial communities and the main reason for the diversity of this special beer’s organoleptic quality (taste and flavor) have remained unknown. A total of 240 yeasts isolated from a Tchoukoutou starter have been characterized following the polyphasic approach and using yeast phenotype (morphology and physiology), proteins (MALDI-TOF MS), ITS1-5.8S-ITS4 and D1/D2 of the large subunit (LSU) rRNA gene as biomarkers. The microbial ecology of the starter used to produce Tchoukoutou is diverse and belongs to different strains of four species including Saccharomyces cerevisiae (75.17 %) as the dominant yeast, followed by Pichia kudriavzevii (17.24 %), Candida ethanolica (4.14 %) and Debaryomyces hansenii complex (3.45 %). D. hansenii complex and C. ethanolica are two yeast species which have never yet been isolated from Tchoukoutou. Some S. cerevisiae with an interesting fermentative profile are able to metabolize lactic acid (lactic acid bacteria metabolite) and therefore may increase the beer pH, thereby allowing the growth of LAB for further beer maturation and flavor enhancement during Yeast-LAB mixed fermentation. The co-presence of the non-Saccharomyces with S. cerevisiae in sorghum beer starter depends for the agroecology zones.