Ethanol production using hemicellulosic hydrolyzate and sugarcane juice with yeasts that converts pentoses and hexoses

The use of vegetable biomass as substrate for ethanol production could reduce the existing usage of fossil fuels, thereby minimizing negative environmental impacts. Due to mechanical harvesting of sugarcane, the amount of pointer and straw has increased in sugarcane fields, becoming inputs of great energy potential. This study aimed to analyze the use of hemicellulosic hydrolyzate produced by sugarcane pointers and leaves compared with that of sugarcane juice fermented by yeasts that unfold hexoses and pentoses in the production of second generation biofuel, ethanol. The substrates used for ethanol production composed of either sugarcane juice (hexoses) or hemicellulosic hydrolyzate from sugarcane leaves and pointers (pentoses and hexoses), and the mixture of these two musts. Fermentation was performed in a laboratory scale using the J10 and FT858 yeast strains using 500 ml Erlenmeyer flasks with 180 ml of must prepared by adjusting the Brix to 16 ± 0.3°; pH 4.5 ± 0.5; 30°C; 107 CFU/ml with constant stirring for 72 h, with four replications. Cell viability, budding, buds viability, and ethanol production were evaluated. Among the yeasts, the cell viability was greater for J10. The use of FT858 + J10 was effective in producing ethanol. The hemicellulosic hydrolyzate had low efficiency in ethanol production compared with sugarcane juice. Key words: Hydrolysis of sugarcane straw and pointers, sugarcane juice, xylose, cell viability, ethano

Production of α-amylase by solid state fermentation by Rhizopus oryzae

A thermotolerant strain of Rhizopus oryzae was grown in three agro-industrial by-products: brewers’ rice, corn grits and wheat bran. Different substrates, cultivation time, moisture content, additional nitrogen sources, pH and temperature of incubation were evaluated aiming to optimize growing conditions. The highest enzymatic activity was observed after 24 h of cultivation using wheat bran as substrate with the following salt solutions: NH4NO3, MgSO4.7H2O and (NH4)2SO4 0.1% at temperature of 35°C. It was observed that changes in the pH range 4.0-6.0 did not significantly affect α-amylase activity. The optimum operation conditions were 75°C and pH 4.5. The enzymes remained stable at 75°C in the absence of substrate for 25 min.Key words: Starch hydrolysis, fermentation parameters, amylolytic enzyme

Moringa extracts used in sugarcane juice treatment and effects on ethanolic fermentation

The objective of this study was to evaluate the effects of sugarcane juice treatment using Moringa oleifera leaf and seeds extracts on ethanolic fermentation. The experiment was arranged in a split plot statistical design, with four replications. Main treatments were three sedimentation agents (synthetic polyelectrolyte, moringa leaf and seed extracts) and control while the secondary treatments were two sugarcane varieties (RB867515 and CTC4). Extracted sugarcane juice was clarified by simple defecation with pH adjusted to 6.0. The flocculating agents were added in a decanter before the limed juice. After then, the juice was standardized to 16° Brix at pH 4.5, and musts were inoculated with yeast Saccharomyces cerevisiae strain, FT858. At the end of the fermentation process, wines were recovered by centrifugation. In all experimental stages, extracted juice, clarified juice and wine were chemically and technologically characterized. The use of moringa leaf and seed extracts as sedimentation adjuvants did not increase the sedimentation speed of impurities. However, there was a high sludge compaction, which was essential for maintenance of yeast and bud population at the beginning of fermentation, and yeast budding rate in the end. The use of different sedimentation agents as adjuvants in juice treatment did not affect wine quality and ethanol yield.Keywords: Juice clarification, Moringa oleifera Lamarck, simple defecation, polyelectrolyte, flocculating agents, saccharomyces cerevisiaeAfrican Journal of Biotechnology, Vol 13(42) 4124-413

Infestation of froghopper nymphs changes the amounts of total phenolics in sugarcane

The increased rate of sugarcane harvest without previous burn has provided a very favorable environment to the froghopper Mahanarva fimbriolota (Stal, 1854), with high Moisture and low temperature variation. Few works have Studied the response of sugarcane to this pest, so little is known about resistant cultivars. Plant phenolics are widely studied compounds because of their known antifierbivore effect. This research aims to determine if the attack of M.fimbriolata nymphs stimulates the acccumulation of total phenolics in sugarcane. The experiment was carried Out in greenhouse and arranged in completely randomized design, in a 3 x 2 x 4 factorial with three replications. Second instar nymphs of M. fimbriolota were infested at the following rates: control, 2-4 and 4-8 nymphs per pot (first-second infestations, respectively). Pots were covered with nylon net and monitored daily to isolate the effect of leaf Sucking adults. Leaf and root samples were collected and kept frozen in liquid nitrogen until analyses. Infested plants showed higher levels of phenolics in both root and leaf tissues. In roots, the cultivar SP80-1816 accumulated more phenolic compounds in response to the infestation of M. fimbriolata. on the other hand, higher levels were found in leaves and roots of control plants of SP86-42, which might be an indication of a non-preference mechanism. The increase of total phenolics in sugarcane infested with root-sucking froghopper nymphs does not seem to be useful to detect the resistance to this pest