ALCOHOLIC FERMENTATION OF HEMICELLULOSIC HYDROLYZATE FROM SUNFLOWER CAKE BYGalactomyces geotrichum UFVJM-R10 AND Candida akabanensis UFVJM-R131. The use of the hemicellulosic fraction of plants for the production of second generation bioethanol depends on microorganisms capable to ferment pentoses. Two yeast strains habile to xylose fermenting in synthetic medium, Candida akabanensis UFVJM-R131 and Galactomyces geotrichum UFVJM-R10, not yet registered in the literature for the production of bioethanol, were evaluated here in the alcoholic fermentation of the hemicellulosic hydrolyzate from sunflower cake. The biomass hydrolysis was performed by 38 minutes at 120 °C / 1 atm with 6% H 2 SO 4 solution and solid / liquid ratio of 1:3.2. Chromatographic characterization of the hemicellulosic hydrolyzate showed the presence of glucose (7.57 g L ). Both yeasts were able to produce ethanol from the acid hydrolyzate from sunflower cake. The fermentation carried out with G. geotrichum UFVJM-R10 and C. akabanensis UFVJM-R131 presented Y P/S values of 0.29 and 0.27 g ethanol g -1 sugars , respectively. The amounts of the inhibitors identified in the hydrolyzate did not affect the efficiency of the alcoholic fermentation. The supplementation of the hydrolyzate with nitrogen and mineral sources increased the rate of consumption of xylose and arabinose.
Superbugs are a public health problem, increasing the need of new drugs and strategies to combat them. Our group has previously identified LyeTxI, an antimicrobial peptide isolated from Lycosa erythrognatha spider venom. From LyeTxI, we synthesized and characterized a derived peptide named LyeTxI-b, which has shown significant in vitro and in vivo activity. In this work, we elucidate the interaction of LyeTxI-b with artificial membranes as well as its effects on resistant strains of bacteria in planktonic conditions or biofilms. Isothermal titration calorimetry revealed that LyeTxI-b interacts more rapidly and with higher intensity with artificial vesicles, showing higher affinity to anionic vesicles, when compared to synthetic LyeTxI. In calcein experiments, LyeTxI-b caused greater levels of vesicle cleavage. Both peptides showed antibacterial activity at concentrations of μmol L−1 against 12 different clinically isolated strains, in planktonic conditions, in a concentration-dependent manner. Furthermore, both peptides elicited a dose-dependent production of reactive oxygen species in methicillin-resistant Staphylococcus aureus. In S. aureus biofilm assay, LyeTxI-b was more potent than LyeTxI. However, none of these peptides reduced Escherichia coli biofilms. Our results show LyeTxI-b as a promising drug against clinically resistant strains, being a template for developing new antibiotics.
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