Suspension cultures of Taxus cuspidata were challenged with various concentrations and combinations of methyl jasmonate and ethylene. Taxol productivity increased 19-fold when T. cuspidata suspension cultures were exposed to 5 ppm ethylene and 10 microM methyl jasmonate. This increase was 15-fold when either 0 or 10 ppm ethylene was combined with 10 microM methyl jasmonate. The induction of taxol occurred within 51 h after elicitation and would reduce fermentation times and costs. Ethylene concentration at 50 ppm had an inhibitory effect on taxol production but not on phosphate uptake rate, suggesting independent regulation of taxol and physiological functions of the cell. A simple induction model is proposed to explain the action and effects of both ethylene and methyl jasmonate with regard to receptor binding and regulatory systems in plants.
Phytase production was studied by three Mucor and eight Rhizopus strains by solid-state fermentation (SSF) on three commonly used natural feed ingredients (canola meal, coconut oil cake, wheat bran). Mucor racemosus NRRL 1994 (ATCC 46129) gave the highest yield (14.5 IU/g dry matter phytase activity) on coconut oil cake. Optimizing the supplementation of coconut oil cake with glucose, casein and (NH(4))(2)SO(4), phytase production in solid-state fermentation was increased to 26 IU/g dry matter (DM). Optimization was carried out by Plackett-Burman and central composite experimental designs. Using the optimized medium phytase, alpha-amylase and lipase production of Mucor racemosus NRRL 1994 was compared in solid-state fermentation and in shake flask (SF) fermentation. SSF yielded higher phytase activity than did SF based on mass of initial substrate. Because this particular isolate is a food-grade fungus that has been used for sufu fermentation in China, the whole SSF material (crude enzyme, in situ enzyme) may be used directly in animal feed rations with enhanced cost efficiency.
The production of phytase by three feed-grade filamentous fungi ( Aspergillus ficuum NRRL 3135, Mucor racemosus NRRL 1994 and Rhizopus oligosporus NRRL 5905) on four commonly used natural feed ingredients (canola meal, cracked corn, soybean meal, wheat bran) was studied in solid substrate fermentation (SSF). A. ficuum NRRL 3135 had the highest yield [15 IU phytase activity/g dry matter (DM)] on wheat bran. By optimizing the supplementation of wheat bran with starch and (NH(4))(2)SO(4), phytase production increased to 25 IU/g DM. Optimization was carried out by Plackett-Burman and central composite experimental designs. Using optimized medium, phytase, phosphatase, alpha-amylase and xylanase production by A. ficuum NRRL 3135 was studied in Erlenmeyer flask and tray SSF. By scaling up SSF from flasks to stationary trays, activities of 20 IU phytase activity/g DM were reproducibly obtained.
Batch fermentations were run at varying agitation rates and were either pressurized to 1 bar (15.2 psig) or nonpressurized. Agitation and pressure both affect the level of dissolved hydrogen gas in the media, which in turn influences solvent production. In nonpressurized fermentations volumetric productivity of butanol increased as the agitation rate decreased. While agitation had no significant effect on butanol productivity under pressurized conditions, overall butanol productivity was increased over that obtained in the nonpressurized runs. Maximum butyric acid productivity, however, was found to occur earlier and increased as agitation increased. Peak hydrogen productivity occurred simultaneously with peak butyric acid productivity. The proporation of reducing equivalents used in forming the above products was determined using a redox balance based on the fermentation stoichiometry. An inverse relationship between the final concentrations of acetone and acetoin was found in all fermentations studied. The results show that agitation and pressure are important parameters for solvent productivity in acetone-butanol fermentation.
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