Identification of lactic acid bacteria associated with traditional cachaça fermentations

Microbial interactions in alcoholic beverages

This review examines the different types of interactions between the microorganisms involved in the fermentation processes of alcoholic beverages produced all over the world from cereals or fruit juices. The alcoholic fermentation converting sugars into ethanol is usually carried out by yeasts, mainly Saccharomyces cerevisiae, which can grow directly using fruit sugars, such as those in grapes for wine or apples for cider, or on previously hydrolyzed starch of cereals, such as for beers. Some of these beverages, or the worts obtained from cereals, can be distilled to obtain spirits. Besides S. cerevisiae, all alcoholic beverages can contain other microorganisms and especially in spontaneous fermentation when starter cultures are not used. These other microbes are mostly lactic acid bacteria and other yeasts-the non-Saccharomyces yeasts. The interactions between all these microorganisms are very diverse and complex, as in any natural occurring ecosystem, including food fermentations. To describe them, we have followed a simplified ecological classification of the interactions. The negative ones are amensalism, by which a metabolic product of one species has a negative effect on others, and antagonism, by which one microbe competes directly with others. The positive interactions are commensalism, by which one species has benefits but no apparent effect on others, and synergism, by which there are benefits for all the microbes and also for the final product. The main interactions in alcoholic beverages are between S. cerevisiae and non-Saccharomyces and between yeasts and lactic acid bacteria. These interactions can be related to metabolites produced by fermentation such as ethanol, or to secondary metabolites such as proteinaceous toxins, or are feed-related, either by competition for nutrients or by benefit from released compounds during yeast autolysis. The positive or negative effects of these interactions on the organoleptic qualities of the final product are also revised. Focusing mainly on the alcoholic beverages produced by spontaneous fermentations, this paper reviews the interactions between the different yeasts and lactic acid bacteria in wine, cider, beer, and in spirits such as tequila, mezcal and cachaça.

Identification of the bacterial community responsible for traditional fermentation during sour cassava starch, cachaça and minas cheese production using culture-independent 16s rRNA gene sequence analysis

We used a cultivation-independent, clone library-based 16S rRNA gene sequence analysis to identify bacterial communities present during traditional fermentation in sour cassava starch, cachaça and cheese production in Brazil. Partial 16S rRNA gene clone sequences from sour cassava starch samples collected on day five of the fermentation process indicated that Leuconostoc citreum was the most prevalent species, representing 47.6% of the clones. After 27 days of fermentation, clones (GenBank accession numbers GQ999786 and GQ999788) related to unculturable bacteria were the most prevalent, representing 43.8% of the clones from the bacterial community analyzed. The clone represented by the sequence GQ999786 was the most prevalent at the end of the fermentation period. The majority of clones obtained from cachaça samples during the fermentation of sugar cane juice were from the genus Lactobacillus. Lactobacillus nagelli was the most prevalent at the beginning of the fermentation process, representing 76.9% of the clones analyzed. After 21 days, Lactobacillus harbinensis was the most prevalent species, representing 75% of the total clones. At the end of the fermentation period, Lactobacillus buchneri was the most prevalent species, representing 57.9% of the total clones. In the Minas cheese samples, Lactococcus lactis was the most prevalent species after seven days of ripening. After 60 days of ripening, Streptococcus salivarius was the most prevalent species. Our data show that these three fermentation processes are conducted by a succession of bacterial species, of which lactic acid bacteria are the most prevalent.