Potencial da produção de etanol por leveduras

Abstract

the main Brazilian biomes and accounts for 5% of the earth's surface, occupying about 1/3 of the world's tropical rainforest reserves. Its biodiversity comprises the largest existing genetic bank, thus presenting a source of great potential for biotechnological exploitation. The microbiota of the Amazon region is a favorable means for the identification of new microorganisms and, being part of this universe, yeasts have been recognized with a high development potential. Considering the lack of studies on the diversity of Amazonian yeasts, the objective of this work was to verify and evaluate the potential of ethanol production from yeasts isolated from 3 fruits present in the Amazon region. Nine strains were used, six isolated from Araçá-boi (Eugenia stipitata), four of them from Saccharomyces cerevisiae and two Lachancea fermentati, from Cocoa (Theobroma cacao) Torulaspora delbrueckii and Cupuaçu (Theobroma grandiflorum) to Pichia kudriavzevii. The microorganisms were submitted to microbiological flocculation, cell viability, sugar assimilation and alcohol resistance tests and the fermentation to analytical tests such as pH, Brix grade and reducing sugars in order to verify the fermentative activity and analyze their alcohol generation. The pH of the fermentations remained in the range of 5.21 to 3.01, in all it was also noted that the greatest pH reduction is in the first 24 hours of fermentation. For the Brix grade, an initial average of 15.4 ° was obtained and throughout the fermentation period the largest reduction, indicating higher consumption of dissolved sugars, was S. cerevisiae isolated from Araçá-boi. By the DNS method the largest sugar consuming yeast was also S. cerevisiae isolated from Araçá, with approximately 98% reduction and final concentration of 5 g / L sugar and the lowest decay rate was Torulaspora delbrueckii, about 7%. % reduction, indicating possible microbiological contamination. As expected, all yeasts were able to assimilate glucose and sucrose, but none showed activity with xylose. For the ethanol tolerance test, no CO2 bubbles were observed in all samples containing 15% and 20% ethanol concentrations, only Lachancea fermentati showed no activity in medium with 10% alcohol content and all yeasts. CO2 at 5% alcohol concentration. The flocculation test only found that T. delbrueckii was able to flocculate, but during fermentation it was possible to observe floc formation in the samples of 100% of non - Saccharomyces yeasts. At the end, the cell viability of the yeast was measured and the lowest reduction rate presented was by Saccharomyces cerevisiae isolated from Araçá. In general most yeasts obtained positive results when compared to commercial Cat2 yeast, also tested on all the above parameters. Finding a national yeast capable of producing alcohol at significant levels represents a major objective: to intensify research in order to make better use of Amazonian biodiversity, combining its conservation and sustainable use to result in incalculable social and economic benefits for the region.