Enzyme production by solid-state fermentation: Application to animal nutrition

Influence of exogenous enzymes on nutrient digestibility, extent of ruminal fermentation as well as milk production and composition in dairy cows

Recent studies have shown that adding exogenous fibrolytic enzymes to ruminant diets can increase milk production of dairy cows and weight gain of growing beef cattle as a result of enhanced feed d...

Mode of action of exogenous cell wall degrading enzymes for ruminants

Effects of exogenous fibrolytic enzymes on in vitro ruminal fermentation of substrates with different forage:concentrate ratios

F3 and F4 strains of Aspergillus niger were screened from five strains of fungi to produce multienzyme preparations (containing cellulase, hemicellulase, glucoamylase, pectinase, and acidic proteinase) as dietary supplementation. Enzyme activities indicated that 1:4 (F3 to F4) was the optimum mixture proportion, and 0.3% (W/W) was the preferable pitching rate. In bran mash containing 54.5% (W/W) water, F3 and F4 could produce the supplementation better when cultured 30 to 36 h at 30 °C. Monofactorial and orthogonal experiments were performed to optimize media. Results of the variance and range analysis showed that the optimum medium contained 80 g of bran, 20 g of cottonseed powder, 1 g of (NH4)2SO4, and 0.1 g of KH2PO4. When F3 and F4 strains were cultured in the optimum medium containing 54.5% (W/W) water, the activity of cellulase, hemicellulase, glucoamylase, pectinase, and acidic proteinase reached 996; 15,863; 13,378; 7,621; and 5,583 U/g, respectively.

Optimization of multienzyme production by two mixed strains in solid-state fermentation.

A series of in vitro studies was conducted to determine the effects of adding a commercial enzyme product on the hydrolysis and fermentation of cellulose, xylan, and a mixture (1:1 wt/wt) of both. The enzyme product (Liquicell 2500, Specialty Enzymes and Biochemicals, Fresno, CA) was derived from Trichoderma reesei and contained mainly xylanase and cellulase activities. Addition of enzyme (0.5, 2.55 and 5.1 microL/g of DM) in the absence of ruminal fluid increased (P < 0.001) the release of reducing sugars from xylan and the mixture after 20 h of incubation at 20 degrees C. Incubations with ruminal fluid showed that enzyme (0.5 and 2.55 microL/g of DM) increased (P < 0.05) the initial (up to 6 h) xylanase, endoglucanase, and beta-D-glucosidase activities in the liquid fraction by an average of 85%. Xylanase and endoglucanase activities in the solid fraction also were increased (P < 0.05) by enzyme addition, indicating an increase in fibrolytic activity due to ruminal microbes. Gas production over 96 h of incubation was determined using a gas pressure measurement technique. Incremental levels of enzyme increased (P < 0.05) the rate of gas production of all substrates, suggesting that fermentation of cellulose and xylan was enzyme-limited. However, adding the enzyme at levels higher than 2.55 microL/g of DM failed to further increase the rate of gas production, indicating that the maximal level of stimulation was already achieved at lower enzyme concentrations. It was concluded that enzymes enhanced the fermentation of cellulose and xylan by a combination of pre- and postincubation effects (i.e., an increase in the release of reducing sugars during the pretreatment phase and an increase in the hydrolytic activity of the liquid and solid fractions of the ruminal fluid), which was reflected in a higher rate of fermentation.

D. Colombatto

Papers

Influence of fibrolytic enzymes on the hydrolysis and fermentation of pure cellulose and xylan by mixed ruminal microorganisms in vitro.

Feed enzymes for ruminants. The need for a rational screening system