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.

The effect of inclusion of live yeast culture (YC, Saccharomyces cerevisiae plus growth medium) in a high concentrate diet given to buffalo (Bubalus bubalis) calves on the rumen microbial population and fermentation pattern and in sacco dry matter disappearance of dietary constituents was examined. Six rumen-fistulated buffalo calves of about 120 kg live iveight were divided into two equal groups. The control group was given a diet consisting of, on a dry-matter basis, 0·90 kg ivheat straw, 1 kg berseem (Trifolium alexandrinum) and ISO kg concentrate per day per calf and the yeast group the above diet plus 5 g YC which was put directly into the rumen via the fistula. After feeding this diet for 6 weeks (supplementation period), inclusion of YC was stopped and both groups were given the control diet for a period of 3 weeks to examine the performance of the YC group after withdrawal of YC. At week 4 of YC supplementation the pH was significantly increased (P < 0·01) and lactate concentration was decreased (P < 0·01) in the rumen fluid for up to 6 h post feeding. The number of total bacteria, total viable bacteria, cellulolytic bacteria, amylolytic bacteria and protozoa were increased proportionately by 0·554 (P < 002), 0·482 (P<0·01), 0·670 (P <0·01), 0·077 (P > 0·05) and 0·079 (P>0·05), respectively. The concentrations of total volatile fatty acids, particularly at 4 h post feeding (P < 0·01), acetate fP < 0·01) and propionate and the acetate to propionate ratio were higher in the YC compared with the control group. On YC inclusion, the concentration of ammonia-nitrogen was decreased while that of trichloracetic acid insoluble protein was marginally increased. All these differences in rumen variables started to disappear on YC withdrawal and values returned to control levels by the 3rd week after YC withdrawal. YC supplementation increased the in sacco dry-matter disappearance of various dietary components particularly after 3, 6 and 22 h incubation.

:The e †ect of daily supplementation of 5 g Saccharomyces cerevisiae yeast culture (YC, YEA-SACC 1026), 30 g supernatant from 5 g YC NaHCO 3 , (YCS), 5 g autoclaved YC (YCH) or 5 g c-irradiated YC (YCR) to the diet of bu †alo calves on rumen microbial populations and fermentation pattern was examined. Addition of 30 g increased the rumen pH to the level NaHCO 3 observed with YC group. The pH and the concentrations of total, total viable and cellulolytic bacteria and total volatile fatty acids (VFA) were signiÐcantly higher while that of lactic acid, hexose-unit oligosaccharides and were NH 3 -N signiÐcantly lower in the rumen Ñuid of YC compared with the control group. The e †ect of was 39É5 and 59É5% in decreasing the concentrations of NaHCO 3 lactic acid and hexose-unit oligosaccharides, 48É1, 47É2 and 45É5% in increasing the numbers of total, total viable and cellulolytic bacteria, 50É0 and 58É1% in increasing the concentrations of total VFA and protein and 51É3% in decreasing the concentration of of YC. The corresponding values for YCR addition NH 3 -N in the diet were 38É6, 45É7, 48É5, 44É4, 51É5, 39É1, 48É1 and 46É5%. The e †ect of YCS and YCH was only marginal, but conspicuous up to 2 h after feeding, in changing the above rumen variables when compared with the YC group. The results indicated that contribution of increase in pH in changing the rumen variables was approximately 50% of YC and almost all the stimulatory activity was associated with live yeast cells. Autoclaving of YC destroyed almost all and cirradiation of YC retained about 50% of stimulatory activity of YC. The e †ect of YC on rumen fermentation, which was maximum up to 2 to 4 h after feeding, decreased with time.1998 SCI. ( J Sci Food Agric 77, 407È413 (1998)

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