Three ranges of increasing temperatures (35-43, 37-45, 39-47 degrees C) were sequentially applied to a five-stage system continuously operated with cell recycling so that differences of 2 degrees C (between one reactor to the next) and 8 degrees C (between the first reactor at the highest temperature and the fifth at the lowest temperature) were kept among the reactors for each temperature range. The entire system was fed through the first reactor. The lowest values of biomass and viability were obtained for reactor R(3) located in the middle of the system. The highest yield of biomass was obtained in the effluent when the system was operated at 35-43 degrees C. This nonconventional system was set up to simulate the local fluctuations in temperature and nutrient concentrations that occur in different regions of the medium in an industrial bioreactor for fuel ethanol production mainly in tropical climates. Minimized cell death and continuous sugar utilization were observed at temperatures normally considered too high for Saccharomyces cerevisiae fermentations.
The selected yeast strains were examined for their ability to grow, to retain cell viability and to ferment diluted sugar cane juice (15% total sugar, w/v) to ethanol at 40°C. The degree of agitation (aeration) affects the thermotolerance while the method usedfor isolation of the strains appears to have no significant effect. 7he yeast isolated are aerobically fermentafive with increased levels of fermentation and growth resulting from agitation (aeration), the exact level of these increases being dependent on the strain used.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.