Efficient ethanol production from corncob residues by repeated fermentation of an adapted yeast

Zymomonas mobilis IMMOBILIZED ON LOOFA SPONGE AND SUGARCANE BAGASSE FOR LEVAN AND ETHANOL PRODUCTION USING REPEATED BATCH FERMENTATION

“…There was a reduction after the fourth cycle to values next to zero, with no statistically significant difference between them, which could be due to the death of the microorganisms immobilized on the support (Table 4 and Figure 4). This behavior could be due to exposition of microorganisms to long periods of stress, such as, high temperatures and inhibitors like acetic acid, which are potentially inhibitors of the microbiota at concentrations above 3 g.L -1 (Fan et al, 2013;Slininger et al, 2011;Jin et al, 2012).…”

“…As from the second cycle they found a slight fall in production, with values between 36.45 and 40.27 g.L -1 . Fan et al (2013), using Pichia guilliermondii to produce ethanol from corncob, obtained a production between 51.2 -49.7 g.L -1 from the first to the third fermentation cycles. The above results indicate that Zymomonas mobilis immobilized on loofa sponge and sugarcane bagasse supports is a viable alternative for ethanol production, especially in batch fermentation process with reuse cycles from immobilization support, being the sugarcane bagasse a more promising support, since loofa sponge presented viable microbiota only up to the fourth cycle.…”

“…Bioethanol production arose as a means of solving the world energy crisis caused by the scarcity of fossil fuels (Bellido et al, 2011;Fan et al, 2013). On a worldwide scale, the ethanol production is concentrated in Brazil and the USA and uses edible raw materials, mainly sugarcane and corn, which is of concern in relation to food scarcity, due to the need to increase environmental exploration.…”

Triggering Respirofermentative Metabolism in the Crabtree-Negative Yeast Pichia guilliermondii by Disrupting the CAT8 Gene

“…The parental P. guilliermondii, which is an inhibitortolerant strain isolated and maintained in our laboratory (3), was maintained as described previously (4). YNB medium was used for the molecular biology experiments (17), and 0.05 g of uracil liter Ϫ1 and/or 1 g of 5-fluoroorotic acid (5-FOA) liter Ϫ1 was supplemented for selection purposes.…”

“…The current trend toward white biotechnology appears to favor the use of P. guilliermondii due to its extraordinary capacity to metabolize both C 5 and C 6 sugars from lignocellulosic hydrolysates and tolerate the harsh conditions of nondetoxified hydrolysate (1)(2)(3)(4). Previously, a self-screened P. guilliermondii was used to produce ethanol from lignocellulosic hydrolysate in our lab; an ethanol titer of 56 g liter Ϫ1 and productivity higher than 1 g liter Ϫ1 h Ϫ1 were obtained in this experiment (4). In contrast to Crabtreepositive yeasts, such as Saccharomyces cerevisiae, the onset of fermentation in P. guilliermondii does not depend on the sugar concentration but is regulated by a decrease in the oxygen levels.…”