BACKGROUND: Efficient conversion of glucose/xylose mixtures from lignocellulose is necessary for commercially viable ethanol production. Oxygen and carbon sources are of paramount importance for ethanol yield. The aim of this work was to evaluate different glucose/xylose mixtures for ethanol production using S. cerevisiae ITV-01 (wild type yeast) and P. stipitis NRRL Y-7124 and the effect of supplying oxygen in separate and co-culture processes.

The use of synthetic dyes for laccase induction in vivo has been scarcely explored. We characterized the effect of adding different synthetic dyes to liquid cultures of Pycnoporus sanguineus on laccase production. We found that carminic acid (CA) can induce 722 % and alizarin yellow 317 % more laccase than control does, and they promoted better fungal biomass development in liquid cultures. Aniline blue and crystal violet did not show such positive effect. CA and alizarin yellow were degraded up to 95 % during P. sanguineus culturing (12 days). With this basis, CA was selected as the best inducer and used to evaluate the induction of laccase on solid-state fermentation (SSF), using sugarcane bagasse (SCB) as substrate, in an attempt to reach selective delignification. We found that laccase induction occurred in SSF, and a slight inhibition of cellulase production was observed when CA was added to the substrate; also, a transformation of SCB under SSF was followed by the C cross polarization magic angle spinning (CPMAS) solid-state nuclear magnetic resonance (NMR). Results showed that P. sanguineus can selectively delignify SCB, decreasing aromatic C compounds by 32.67 % in 16 days; O-alkyl C region (polysaccharides) was degraded less than 2 %; delignification values were not correlated with laccase activities. Cellulose-crystallinity index was increased by 27.24 % in absence of CA and 15.94 % when 0.01 mM of CA was added to SCB; this dye also inhibits the production of fungal biomass in SSF (measured as alkyl C gain). We conclude that CA is a good inducer of laccase in liquid media, and that P. sanguineus is a fungus with high potential for biomass delignification.

No abstract

No abstract

Alkalinea nd biological lignocellulosep re-treatments are commonly used to enhance enzymatic hydrolysis and improve ethanol production. In this study, 13 CC PMAS NMR spectroscopy was used to describec hanges in sugarcane bagasse( SCB) pretreated with NaOH, Ca(OH) 2 andw ith Pycnoporus sanguineus. Changes in the contentso fa lkyl C, Carboxyl C, Aromatic C (tertiary, quaternary and p-hydroxyphenyl C), O-alkyl C, amino acids, ergosterol and chitin, as well as in the crystallinity index of cellulose were observed. Through am ultivariate analysis, relations betweenc hanges in the chemical compositiono fS CB and enzymatic hydrolysis were established. P. sanguineus promotes better lignin decay,g lucoser elease and hydrolysis yields than chemical pre-treatments, and increases the amount of amino acids and ergosterol in SCB, while NaOH increases the cellulose crystallinity index. The hydrolysates weref ermented with Saccharomyces cerevisiae for 96 h, and analysed through HPLC. The initial compositionofthe hydrolysates [mg.ml À1 ]and biomass production (cells.ml À1 )w ere then relatedt ot he ethanol production and fermentation yields. We found that ethanol production and fermentation yields were negatively correlated with cell growth in Saccharomyces,b ut positively correlated with glucose consumption in the P. sanguineus pretreatment. We conclude that the biological pre-treatmentusing P. sanguineus in the conditions hereby described, has a potentialtoincreaseethanol productivity.