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Microorganisms associated with the fermentation of cotton seed and rice were studied using a combination of culture-dependent and -independent methods. Samples of the cotton seed and rice beverage were collected every 8 h during the fermentation process for analysis of the microbiota present over 48 h. The lactic acid bacteria (LAB) population reached values of approximately 8.0 log cfu/mL. A total of 162 bacteria and 81 yeast isolates were identified using polyphasic methods. LAB (Lactobacillus plantarum, Lactobacillus vermiforme, Lactobacillus paracasei) were the most frequently isolated bacteria. Bacillus subtilis was present from 16 h until the end of the fermentation process. A decrease in pH value from 6.92 (0 h) to 4.76 (48 h) was observed, and the concentration of lactic acid reached 24 g/L at the end of the fermentation process. DGGE (denaturing gradient gel electrophoresis) was performed to determine the dynamics of the communities of bacteria and yeast, and the analysis revealed a predominance of LAB throughout the fermentation process. No changes were observed in the yeast community. The yeast species detected were Candida parapsilosis, Candida orthopsilosis, Clavispora lusitaniae and Rhodotorula mucilaginosa. Our studies indicate that the DGGE technique combined with a culture-dependent method is required to discern the dynamics in the fermentation of cotton seed and rice.

Traditional Brazilian indigenous fermented foods and beverages are potential sources of new food products that promote health, but they are still produced by natural fermentation. In the present work, Lactobacillus fermentum CCMA 0215 isolated from the indigenous fermented cassava beverage yakupa was used as single or mixed starter culture with five different yeast strains (Torulaspora delbrueckii CCMA 0234 and CCMA 0235, Pichia caribbica CCMA 0198, and Saccharomyces cerevisiae CCMA 0232 and CCMA 0233) to ferment cassava. Fermentations using each yeast as single starter culture were also performed. The microbial population and metabolites produced during cassava fermentation were investigated. In all assays, the inoculated microorganisms fermented cassava, judged by lowering the pH from 6.0 to 4.0-5.0 within 24h. Lactic acid bacteria (LAB) and yeast population increased during fermentation. Lactic acid was the main organic acid produced, reaching a maximum value of 4.5g/L at 24h in the co-culture with L. fermentum CCMA 0215 and T. delbrueckii CCMA 0234. Other organic acids, such as malic, tartaric, and succinic acids, were detected in low concentrations (less than 0.5g/L). Ethanol and glycerol were produced in all assays inoculated with yeasts (single and co-cultured with LAB), reaching the maximum concentration of approximately 2.3g/L and 0.6g/L, respectively. Twenty-two volatile compounds were detected after 48h of fermentation, varying widely between single and co-cultures. The compounds 2-phenylethyl alcohol, 1-butanol, 3-methyl (isoamyl alcohol), and acetoin were detected in single and co-cultures. This study demonstrated co-cultures of yeasts and LAB had the ability to improve the aroma profile of the final product and the safety of the product by lowering the pH.

Yakupa is a traditional non-alcoholic cassava beverage produced by Brazilian Amerindians. In this work the microbial dynamics and metabolites involved in yakupa fermentation were investigated by PCR-denaturing gradient gel electrophoresis and chromatography analysis, respectively. The lactic acid bacteria (LAB) population was higher than yeast in the beginning of fermentation (5 log CFU mL(-1) and 3 log CFU mL(-1), respectively) and after 36 h both population increased reaching 7 log CFU mL(-1), remaining constant until 60 h. Culture dependent and independent methods in combination identified the bacteria Lactobacillus fermentum, L. plantarum, Weissela cibaria and W. confusa, and yeasts Saccharomyces cerevisiae and Pichia kudriavzevii. Maltose (41.2 g L(-1)), ethanol (6.5 g L(-1)) and lactic acid (7.8 g L(-1)) were the most abundant compounds identified by high performance liquid chromatography. Aldehydes, acids, alcohols and esters were identified by gas chromatography flame ionization detection. By the metabolites and PCA analysis we may assign the beverage's flavor to the microbial metabolism. Heterolactic LAB and S. cerevisiae dominated the yakupa fermentation, being responsible for the organoleptic characteristics of the final product. This is the first time that the microbial dynamics and physicochemical parameters were investigated in the yakupa beverage and it may contribute to the future selection of starter cultures to perform yakupa fermentations.

Sixty six indigenous Saccharomyces cerevisiae strains were evaluated in stressful conditions (temperature, osmolarity, sulphite and ethanol tolerance) and also ability to flocculate. Eighteen strains showed tolerant characteristics to these stressful conditions, growing at 42 °C, in 0.04% sulphite, 1 mol L−1 NaCl and 12% ethanol. No flocculent characteristics were observed. These strains were evaluated according to their fermentative performance in sugar cane juice. The conversion factors of substrates into ethanol (Yp/s), glycerol (Yg/s) and acetic acid (Yac/s), were calculated. The highest values of Yp/s in sugar cane juice fermentation were obtained by four strains, one isolated from fruit (0.46) and the others from sugar cane (0.45, 0.44 and 0.43). These values were higher than the value obtained using traditional yeast (0.38) currently employed in the Brazilian bioethanol industry. The parameters Yg/s and Yac/s were low for all strains. The UFLA FW221 presented the higher values for parameter related to bioethanol production. Thus, it was tested in co-culture with Lactobacillus fermentum. Besides this, a 20-L vessel for five consecutive batches of fermentation was performed. This strain was genetically stable and remained viable during all batches, producing high amounts of ethanol. The UFLA FW221 isolated from fruit was suitable to produce bioethanol in sugar cane juice. Therefore, the study of the biodiversity of yeasts from different environmental can reveal strains with desired characteristics to industrial applications.