Xylanase production with xylan rich lignocellulosic wastes by a local soil isolate of Trichoderma viride / Produção de xilanase com resíduos lignocelulósicos ricos em xilana por uma cepa local de Trichoderma viride isolada de solo

In the present study, cultural and nutritional conditions for enhanced production of xylanase by a local soil isolate of Trichoderma viride, using various lignocellulosic substrates in submerged culture fermentation have been optimized. Of the lignocellulosics used, maize straw was the best inducer followed by jowar straw for xylanase production. The highest activity achieved was between 14 to 17 days of fermentation. A continuous increase in xylanase production was observed with increasing level of lignocellulosics in the medium and highest activity was observed with maize straw at 5 percent level. Xylanase production with higher levels of lignocellulosics (3 to 5 percent) of maize, jowar and barseem was found to be higher as compared to that with commercial xylan as carbon source. Sodium nitrate was the best nitrogen source among the six sources used. Maximum xylanase production was achieved with initial medium pH of 3.5-4.0 and incubation temperature of 25ºC.The enzyme preparation was effective in bringing about saccharification of different lignocellulosics. The xylanase production could be further improved by using alkali treated straw as carbon source.

Neste estudo, otimizou-se as condições culturais e nutricionais para produção aumentada de xilanase por uma cepa local de Trichoderma viride isolada de solo, empregando-se vários substratos lignocelulósicos, em fermentação submersa. Entre os substratos utilizados, o melhor indutor de produção de xilanase foi palha de milho, seguido de palha de sorgo. A atividade mais alta foi obtida entre 14 e 17 dias de fermentação. Com palha de milho observou-se um aumento contínuo na produção de xilanase com o aumento da concentração dos substratos lignocelulósicos no meio, sendo que a melhor atividade foi obtida com 5 por cento de palha de milho. A produção de xilanase com níveis mais altos de (3 a 5 por cento) de milho, sorgo e forragem verde (barseem) foi mais levada do que com xilana comercial como fonte de carbono. Entre as fontes de nitrogênio testadas, a melhor foi nitrato de sódio. Produção máxima de xilanase foi obtida quando o pH inicial do meio foi 3,5 4,0 e a temperatura de incubação 25ºC. A enzima foi eficiente na sacarificação de diferentes substratos lignocelulósicos. A produção de xilanase poderia ser aumentada empregando-se álcali ao invés de palha tratada como fonte de carbono.

Xylanase production with xylan rich lignocellulosic wastes by a local soil isolate of Trichoderma viride.

In the present study, cultural and nutritional conditions for enhanced production of xylanase by a local soil isolate of Trichoderma viride, using various lignocellulosic substrates in submerged culture fermentation have been optimized. Of the lignocellulosics used, maize straw was the best inducer followed by jowar straw for xylanase production. The highest activity achieved was between 14 to 17 days of fermentation. A continuous increase in xylanase production was observed with increasing level of lignocellulosics in the medium and highest activity was observed with maize straw at 5% level. Xylanase production with higher levels of lignocellulosics (3 to 5%) of maize, jowar and barseem was found to be higher as compared to that with commercial xylan as carbon source. Sodium nitrate was the best nitrogen source among the six sources used. Maximum xylanase production was achieved with initial medium pH of 3.5-4.0 and incubation temperature of 25ºC.The enzyme preparation was effective in bringing about saccharification of different lignocellulosics. The xylanase production could be further improved by using alkali treated straw as carbon source.

Effect of hydrothermal treatment of rice straw on its composition and in sacco digestibility and in vitro fermentation by rumen microorganisms.

Chemical composition, in sacco rumen disappearance of various cell wall constituents (CWC) and in vitro fermentation pattern of hydrothermally treated (1 to 14 kp/cm2 pressure for 5 min) rice straw was examined. At 10 kp/cm2 pressure treatment (maximum effect) the contents of dry matter (DM), organic matter (OM), neutral detergent fibre (NDF), acid detergent fibre (ADF), hemicellulose (HC) and cellulose (CE) were decreased by 32.5, 35.3, 27.8, 10.2, 61.2 and 25.1%, respectively (P < 0.05), over the untreated control. The in sacco rumen disappearance of DM, OM, HC and CE from rice straw treated at 8 kp/cm2 pressure (maximum effect) and incubated for 48 h was increased from 53.2 to 77.7, 52.4 to 80.3, 49.5 to 82.0 and 49.2 to 79.3%, respectively (P < 0.01). In vitro production of total volatile fatty acids and the content of TCA-insoluble protein was also significantly higher (P < 0.05) on treated compared with untreated straw.

Effect of dietary amino acids on in vitro rumen bacterial protein synthesis in buffaloes.

The effect of different ratios of urea to amino acid N at a fixed concentration of soluble sugars as energy source and varying levels of soluble sugars at optimum urea cell suspension was obtained from the rumen fluid of buffalo (Bubalus bubalis) calves fed on a growth ration. Under glucose fermentation, the bacterial protein content of the incubation mixture (I. M.) was increased to 3.91, 6.31 and 5.08 times the control value (urea alone) when 25, 50 and 75% of urea-N was replaced with amino acid N, respectively. With cellobiose, the corresponding increase was 4.06, 5.29 and 5.63 times. At 50% urea-N replacement with amino acid N (a ratio for maximum protein synthesis), the bacterial content was maximum when 1 g glucose or cellobiose per 100 ml of I. M. was added. Per cent incorporation of radioactivity from amino acids into bacterial protein was maximum at 25% amino acid N level with both the soluble sugar sources. The total amino acids incorporated into bacterial protein were, however, more at 50% than at 25% amino acid N level.

Effect of some electrolytes on in vitro rumen microbial protein synthesis in buffaloes.

In vitro studies were carried out to examine the effect of MnCl2, MgCl2, CoCl2 and CaCl2 on protein synthesis by rumen microorganisms obtained from fistulated buffalo calves (Bubalus bubalis). The concentration of the electrolytes in stained rumen fluid (SRF) ranged from 1 to 20, 1 to 20, 0.25 to 5 and 1 to 20 mM, respectively. MnCl2 (15 mM), MgCl2 (10 mM), CoCl2 (2.5 mM) and CaCl2 (20 mM) increased the protein content in the incubation mixture (IM) by 501, 230.8, 537.6 and 84% and the per cent incorporation of 35S from (NH4)2 35SO4 into microbial protein by 125.6, 108.5, 113.4 and 40.3, respectively, over the control values, when the incubation lasted 8 h. The NH3-N content in IM decreased by 8, 14, 43 and 16% when 10 mM MnCl2, 20 mM MgCl2, 1 mM CoCl2 and 1 mM CaCl2, respectively, was added and the incubation lasted 6 h. The reasons for increased protein biosynthesis by rumen microorganisms in the presence of the above electrolytes are discussed.