Commercial Enzyme Products Research Articles

Isolation and characterization of gram-positive biosurfactant-producing halothermophilic bacilli from Iranian petroleum reservoirs.

Background:Petroleum reservoirs have long been known as the hosts of extremophilic microorganisms. Some of these microorganisms are known for their potential biotechnological applications, particularly production of extra and intracellular polymers and enzymes.Objectives:Here, 14 petroleum liquid samples from southern Iranian oil reservoirs were screened for presence of biosurfactant‐producing halothermophiles.Materials and Methods:Mixture of the reservoir fluid samples with a minimal growth medium was incubated under an N2 atmosphere in 40°C; 0.5 mL samples were transferred from the aqueous phase to agar plates after 72 hours of incubation; 100 mL cell cultures were prepared using the MSS-1 (mineral salt solution 1) liquid medium with 5% (w/v) NaCl. The time-course samples were analyzed by recording the absorbance at 600 nm using a spectrophotometer. Incubation was carried out in 40°C with mild shaking in aerobic conditions. Thermotolerance was evaluated by growing the isolates at 40, 50, 60 and 70°C with varying NaCl concentrations of 5% and 10% (w/v). Halotolerance was evaluated using NaCl concentrations of 5%, 10%, 12.5% and 15% (w/v) and incubating them at 40°C under aerobic and anaerobic conditions. Different phenotypic characteristics were evaluated, as outlined in Bergey's manual of determinative bacteriology. Comparing 16S rDNA sequences is one of the most powerful tools for classification of microorganisms.Results:Among 34 isolates, 10 demonstrated biosurfactant production and growth at temperatures between 40°C and 70°C in saline media containing 5%‐15% w/v NaCl. Using partial 16S rDNA sequencing (and amplified ribosomal DNA restriction analysis [ARDRA]) and biochemical tests (API tests 20E and 50 CHB), all the 10 isolates proved to be facultative anaerobic, Gram-positive moderate thermohalophiles of the genus Bacillus (B. thermoglucosidasius, B. thermodenitrificans, B. thermoleovorans, B. stearothermophilus and B. licheniformis), exhibiting surface-active behaviors.Conclusions:General patterns include decreasing the thermotolerance with increasing the salt concentrations and also more halotolerance in the aerobic environment compared with anaerobic conditions. The results demonstrated that Iranian petroleum reservoirs enjoy a source of indigenous extremophilic microorganisms with potential applications in microbial enhanced oil recovery and commercial enzyme production.

Influence of enzyme loading on enzymatic hydrolysis of cardboard waste and size distribution of the resulting fiber residue

Enzymatic hydrolysis of lignocellulosic biomass to sugars alters the properties of the cellulosic fibers. Several process variables, including enzyme loading, play an important role in these changes. Many physical properties of fibers are affected: their length and width, porosity, specific surface area, and degree of fibrillation, for instance, may undergo dramatic changes when subjected to enzymatic degradation. In this study, the influence of enzyme loading on the fiber size was investigated using milled cardboard waste as the raw material. The effect of cellulases and hemicellulases on the monosaccharide production and the resulting fiber size was studied using commercial enzyme products. It was shown that the cellulase loading largely determined the amount of sugars produced. The fiber length was reduced during the course of hydrolysis, although the size reduction was not especially dramatic. Based on the SEM images, no significant damage to the fiber surfaces occurred during the process.

Granular starch hydrolysis of babassu agroindustrial residue: A bioprocess within the context of biorefinery

The conversion of renewable feedstocks into a range of commercial products and energy is the principle underlying the concept of biorefinery. In this work, two agroindustrial by-products from babassu were used as unconventional biomasses to develop a sustainable process. Babassu cake was used to produce a multienzyme complex, which was able to hydrolyse starch granules and to release free amino nitrogen from babassu flour, yielding a hydrolysate rich in carbon and nitrogen nutrients. To exemplify its possible applications, different strategies for ethanol production by simultaneous saccharification and fermentation (SSF) were investigated and that comprising a 4-h hydrolysis step at 50°C followed by 44h of SSF at 32°C showed the most promising results (53.6g/L ethanol, 83% efficiency of starch into ethanol and productivity of 1.12g/(Lh)). On-site enzymes promoted better results than a commercial enzyme product (110.9±6.6g/L versus 74.5±1.8g/L glucose releases, respectively), and showed high efficiency and productivity also on corn flour, either similar or superior to those reported for the industrial-scale dry-grind process.

Alternative substrates for the amylase and cellulase production with rhizobial isolates

In the present study sixty root nodule bacteria were isolated from Vigna radiate and Cicer arietinum. As we know that nutrients and growth conditions promote the yield of microbial enzymes. However, carbon sources such as dextrin, fructose, glucose, lactose, maltose and starch are very expensive for commercial production of enzymes. These expensive products could be replaced in the medium with economically available agricultural by-products like corn flour, wheat flour, rice flour, sorghum and baggase as carbon substrate. The aim of this study was the production of amylases and cellulases from rhizobia using cheap carbon sources to reduce the production cost of enzymes .All isolates were screened for the amylase and cellulase production using starch and carboxy methyl cellulase (CMC) hydrolysis respectively .Isolates showing better screening results were further subjected for different starchy carbon substrates for CFU/ml at different time intervals and enzyme (amylase and cellulase) production. The results obtained in the study revealed that wheat flour yields the highest levels of amylase, and baggase promotes the highest amount of cellulase. Statistical analyses between cellulase and amylase data showed that there is a significant difference between their productions. Amount of cellulase (0.1513 u/ml) is significantly greater than that of amylase (0.0091u/ml).

Growth Performance, Blood Parameters, Immune response and Carcass Traits of Broiler Chicks Fed on Graded Levels of Wheat Instead of Corn without or With Enzyme Supplementation

Four hundred and fifty one-day Cobb broiler chicken were used to investigate the effect of partial replacement with wheat grain without or with different commercial enzyme products supplementation on growth performance, immune response, blood serum parameters and some carcass characteristics. Broiler chicken were allotted into 9 equal groups (50 chicks of mixed sex per group). Three experimental diet were formulated but the 25% or 50% corn of the basal diet was replaced by wheat grain (w/w) and the diet adjust to be iso-nitrogenous and iso-caloric diets, each diet supplemented by Kemzyme plus dry or by Combozyme (enzyme blend commercial products) to be 9 experimental groups. The experimental period continued for six continuous weeks. It was observed that wheat inclusion at 25% instead of corn non significantly reduced body weight and gain of broiler chicken, while 50% replacement improved both parameters when compared with chick group fed on corn-soybean based diet. However, it was observed that wheat inclusion at 25 or 50% instead of corn grain in broiler chicken ration increased feed intake by about 1.3% and 9.8% respectively and consequently deteriorate FCR, PER, EEU and PI by about (4.6% and 4.6%), (8.2% and 6.5%), (4.9% and 4.0%) and (13.7% and (4.2%) respectively when compared with broiler chicken group fed on corn – soybean based diet. Moreover, enzyme supplementation in 25% wheat containing diet increased feed intake but, with 50% wheat inclusion decreased feed intake also, enzyme supplementation in wheat included ration improved FCR, PER, EEU and PI when compared with broiler chick group fed on the same diet without enzyme supplementation. On the other hand, wheat inclusion had no significant effect on blood serum total protein, albumin, globulin and glucose concentrations, while reduced blood serum triglycerides and cholesterol concentrations, also wheat inclusion in the broiler chicken diet had determinately effect on liver function through elevation of some blood serum enzymes when compared with chick group fed on corn-soybean based diet. Regarding immune response, it was observed that wheat inclusion instead of corn reduced phagocytic activity and index, and reduce antibody production against NDV while enzyme supplementation improve the health status of broiler chicken when compared with broiler chicken group fed on the same diet without enzyme supplementation. It was observed that both wheat grain inclusion without or with enzyme supplementation had no significant effect on carcass traits of broiler traits and the most prominent effect was leading to reduction of abdominal fat weight and relative weight and improve thymus gland weight of broiler chicks.

Sweet Sorghum Biorefinery for Production of Fuel Ethanol and Value-Added Co-products

<abstract> <bold><sc>Abstract.</sc></bold> An integrated process has been proposed for a sweet sorghum biorefinery in which all carbohydrate components of the feedstock were used for production of fuel ethanol and industrial chemicals. In the first step, the juice was extracted from the stalks. The resultant bagasse was then pretreated using the soaking in aqueous ammonia (SAA) process, which did not result in significant loss of cellulose and hemicellulose, to enhance subsequent enzyme hydrolysis for production of fermentable sugars. Following pretreatment, the bagasse was hydrolyzed with a commercial enzyme product containing high hemicellulase activity (Accellerase XY). The xylose-rich solution obtained after solid/liquid separation was used for production of value-added co-products using suitable microorganisms. The value-added co-products produced to demonstrate the feasibility were astaxanthin and D-ribose. The residual solids were then hydrolyzed with a commercial enzyme product containing high cellulase activity (Accellerase 1500), with the juice extracted in the first step used as make-up water. By combining the sugar in the juice with the glucose released from the residual solids by enzyme hydrolysis, high ethanol concentrations could be achieved, which resulted in lower distillation cost than if pure water were used for enzyme hydrolysis and subsequent fermentation, as normally performed in cellulosic ethanol production.

Effect of different dietary levels of low-glucosinolate rapeseed (canola) meal and non-starch polysaccharide-degrading enzymes on growth performance and gut physiology of growing turkeys

Zdunczyk, Z., Jankowski, J., Juskiewicz, J., Mikulski, D. and Slominski, B. A. 2013. Effect of different dietary levels of low-glucosinolate rapeseed (canola) meal and non-starch polysaccharide-degrading enzymes on growth performance and gut physiology of growing turkeys. Can. J. Anim. Sci. 93: 353-362. One-day-old male turkey poults were randomly assigned to eight dietary treatments and were fed diets containing 0, 60, 120, or 180 g kg-1 of low-glucosinolate rapeseed meal (RSM) from 1 to 56 d of age without or with a commercial non-starch polysaccharide-degrading enzyme product containing pectinase, cellulase, xylanase, glucanase, mannanase and galactanase activities. There were no significant differences (P>0.05) in body weight and feed conversion ratio between the Control soybean meal-based diet and the diets containing RSM. Overall, the inclusion of up to 180 g kg-1 of RSM did not affect the growth performance of turkeys. When compared with the Control treatment, the diet with the lowest RSM content i...

Effect of different dietary levels of low-glucosinolate rapeseed (canola) meal and non-starch polysaccharide-degrading enzymes on growth performance and gut physiology of growing turkeys

Zduńczyk, Z., Jankowski, J., Juśkiewicz, J., Mikulski, D. and Slominski, B. A. 2013. Effect of different dietary levels of low-glucosinolate rapeseed (canola) meal and non-starch polysaccharide-degrading enzymes on growth performance and gut physiology of growing turkeys. Can. J. Anim. Sci. 93: 353–362. One-day-old male turkey poults were randomly assigned to eight dietary treatments and were fed diets containing 0, 60, 120, or 180 g kg−1of low-glucosinolate rapeseed meal (RSM) from 1 to 56 d of age without or with a commercial non-starch polysaccharide-degrading enzyme product containing pectinase, cellulase, xylanase, glucanase, mannanase and galactanase activities. There were no significant differences (P&gt;0.05) in body weight and feed conversion ratio between the Control soybean meal-based diet and the diets containing RSM. Overall, the inclusion of up to 180 g kg−1of RSM did not affect the growth performance of turkeys. When compared with the Control treatment, the diet with the lowest RSM content increased the pH of the small intestinal contents and the amounts of cecal digesta. The moderate level of RSM also increased the pH of the small intestinal contents although no increase in the cecal digesta contents was noted. In comparison with other treatments, the highest RSM content increased the content of the small intestinal digesta considerably and decreased the pH of the small intestinal contents to that of the Control treatment. All three dietary levels of RSM significantly reduced the activity of bacterial β-glucuronidase in the ceca. Enzyme supplementation tended to reduce ileal viscosity (P=0.079), decreased ammonia concentration, increased the glycolytic activities of the intestinal microflora enzymes α-glucosidase, α-galactosidase, and β-galactosidase, decreased the activity of β-glucuronidase and increased the growth rate of turkeys.

Isolation of digested sludge-assimilating fungal strains and their potential applications

Digested sludge (DS) is a major waste product of anaerobic digestion of sewage sludge and is resistant to biodegradation. In this study, we isolated and characterized DS-assimilating fungi from soil. We tried to isolate DS-assimilating strains by enrichment culture using DS as the nutrient source, but microbial growth was not observed in any culture. To eliminate the inhibitory effect of metals in DS on microbial growth, acid-treated DS was subsequently used for enrichment, and eight fungal strains were isolated from the subcultures. At least 10-30% reduction in sludge was observed after 1-week cultivation, and prolonged cultivation led to further sludge reduction. All isolates produced xylanase, chitinase and keratinase. Phylogenetic analysis revealed that the isolates were Penicillium, Fusarium, Chaetomium, Cunninghamella, Neosartorya and Umbelopsis. Some isolates were suggested novel species. To the best of our knowledge, our study is the first to report the isolation of DS-assimilating strains. These isolates may be useful for commercial production of microbial enzymes using DS as the substrate. Because xylan, chitin and keratin in sludge-hyphae complexes are considered to be partially depolymerized, this material could also be utilized as a readily available fertilizer.

A Superstar in Biocontrol Enterprise:Trichodermaspp

The role of biocontrol agents (BCAs) is a well established fact and has become increasingly crucial in replacing the chemical pesticides for plant pathogen control. Currently, Trichoderma spp. share almost 70% of fungal BCAs market. Trichoderma is a potential biocontrol agent included in the gazette of India on 26th March 1999. Trichoderma harzianum is extensively used for its twin advantages of controlling several soil and seed borne phytopathogens in addition to its capacity to act as an effective biofertilizer. Competence of Trichoderma spp. to other fungal biocontrol agents owes to its relatively faster metabolic rates; secretion of anti-microbial secondary metabolites and physiological conformation are some of the key factors which contribute to its vigorous antagonistic effect in field conditions. On the other hand, Trichoderma spp. has also been exploited for commercial production of enzymes like cellulases, hemicellulases, proteases, and â-1, 3-glucanase. This article advertises the commercial potential of Trichoderma spp. discussing its status in various aspects viz., pest control, plant growth promotion, bioremediation and production processes.

Biochemical and Molecular Characterization of Secreted α-Xylosidase from Aspergillus niger

α-Linked xylose is a major component of xyloglucans in the cell walls of higher plants. An α-xylosidase (AxlA) was purified from a commercial enzyme preparation from Aspergillus niger, and the encoding gene was identified. The protein is a member of glycosyl hydrolase family 31. It was active on p-nitrophenyl-α-d-xyloside, isoprimeverose, xyloglucan heptasaccharide (XXXG), and tamarind xyloglucan. When expressed in Pichia pastoris, AxlA had activity comparable to the native enzyme on pNPαX and IP despite apparent hyperglycosylation. The pH optimum of AxlA was between 3.0 and 4.0. AxlA together with β-glucosidase depolymerized xyloglucan heptasaccharide. A combination of AxlA, β-glucosidase, xyloglucanase, and β-galactosidase in the optimal proportions of 51:5:19:25 or 59:5:11:25 could completely depolymerize tamarind XG to free Glc or Xyl, respectively. To the best of our knowledge, this is the first characterization of a secreted microbial α-xylosidase. Secreted α-xylosidases appear to be rare in nature, being absent from other tested commercial enzyme mixtures and from the genomes of most filamentous fungi.

Levels of endogenous β-glucanase activity in barley affect the efficacy of exogenous enzymes used to supplement barley-based diets for poultry

To improve the nutritive value of barley-based diet for broilers, 2 experiments using 2 different barley lots were performed to evaluate the capacity of a mesophilic cellulase when fused to a β-glucan specific family 11 carbohydrate-binding module. The data revealed that the recombinant β-glucanase derivatives were not appropriate for feed supplementation because of a lack of stability at acidic pH levels. However, under the same experimental conditions, a commercial enzyme mixture improved the nutritive value of 1 of the cereal lots used. Analysis of the nutritive value of the 2 barleys revealed intrinsic differences in the levels of endogenous β-glucanase activity. These differences were extensively evident when the studies were expanded to a range of 64 barley lots. Thus, to clarify the effect of endogenous cellulases on the efficacy of exogenous β-glucanases used to supplement barley-based diets for poultry, 2 barley lots presenting low and high levels of endogenous plant cell wall-degrading enzymes were selected. These lots were used to prepare 2 barley-based diets, which were supplemented with or without a commercial enzyme product and fed to broiler chicks. The data revealed that the exogenous enzymes were effective when the basal diet presented low levels of endogenous β-glucanases but were unable to improve the nutritive value of the barley lot displaying higher β-glucanase activity. Thus, these studies suggest that levels of endogenous β-glucanases may affect the efficacy of exogenous enzymes used to improve the nutritive value of barley-based diets for broilers. The development of a quick β-glucanase assay that could be applied for cereal-based feeds may help identify those barley-based diets that are more responsive to the action of feed enzymes.

Harmful and beneficial aspects of Parthenium hysterophorus: an update

Parthenium hysterophorus is a noxious weed in America, Asia, Africa and Australia. This weed is considered to be a cause of allergic respiratory problems, contact dermatitis, mutagenicity in human and livestock. Crop production is drastically reduced owing to its allelopathy. Also aggressive dominance of this weed threatens biodiversity. Eradication of P. hysterophorus by burning, chemical herbicides, eucalyptus oil and biological control by leaf-feeding beetle, stem-galling moth, stem-boring weevil and fungi have been carried out with variable degrees of success. Recently many innovative uses of this hitherto notorious plant have been discovered. Parthenium hysterophorus confers many health benefits, viz remedy for skin inflammation, rheumatic pain, diarrhoea, urinary tract infections, dysentery, malaria and neuralgia. Its prospect as nano-medicine is being carried out with some preliminary success so far. Removal of heavy metals and dye from the environment, eradication of aquatic weeds, use as substrate for commercial enzyme production, additives in cattle manure for biogas production, as biopesticide, as green manure and compost are to name a few of some other potentials. The active compounds responsible for hazardous properties have been summarized. The aim of this review article is to explore the problem P. hysterophorus poses as a weed, the effective control measures that can be implemented as well as to unravel the latent beneficial prospects of this weed.

English

&nbsp; Aureobasidium pullulans, popularly known as black yeast, is one of the most widespread saprophyte fungus associated with wide range of terrestrial and aquatic habitats, in temperate and tropical environment. It is a polymorphic fungus that is able to grow in single yeast-like cells or as septate, polykaryotic hyphae showing synchronous conditions, with budding cells. This fungus has been exploited potentially for commercial production of various enzymes (amylase, xylanase, pectinase, etc). Single cell protein, alkaloids and polysaccharide, especially pullulan, an exopolysaccharide, is a linear &alpha;-d-glucan connected with &alpha;-1,4 glycosidic bond mainly of maltotriose repeating units interconnected by &alpha;-1,6 linkages. Pullulan has been considered as one of the important polysaccharide for production of biodegradable plastics. More than 300 patents for applications have been developed. It is the only fungus which produce higher amount of pullulan and has been exploited all over the world. The fungus has excellent genetic make-up to produce various important metabolites at commercial production with limited species. Some of the&nbsp;A. pullulans&nbsp;have potential antagonistic activity against a number of phytopathogenic fungi used as bio-control agents of post-harvest diseases. It has been found to be tolerant to many metal ions which are common pollutants of soil and water. Several strains of this fungus have ability to degrade xenobiotic compounds. In the light of the above facts, this review article has emphasized on the orientation, morphology, biochemical characteristics, habitats and its economic potentials with special reference to pullulan.&nbsp; &nbsp; Key words:&nbsp;Aureobasidium pullulans, single cell protein, xenobiotic compounds, pullulan.

Effects of cellulase addition to canola meal in tilapia (Oreochromis niloticus L.) diets

The effects of commercial cellulase enzyme products on the nutritive value of canola meal (CM) were determined in tilapia fry. Nine diets were prepared by adding cellulase enzyme (1–5 g kg−1) to control diet (containing no canola), low canola (41.7 g kg−1 CM) and high canola (208.3 g kg−1 CM). Tilapia fry was fed for 90 days, and growth, feed conversion ratio (FCR), body composition and nutrient digestibility were determined. Fish fed the diets containing the lowest levels of canola meal (41.7 g kg−1) had similar final weight and FCR relative to the group fed the control diet, and high canola diet showed significantly lower growth than other groups (P < 0.05), irrespective of cellulase enzyme. The addition of canola meal to tilapia diets resulted in lower protein digestibility and cellulose digestibility. There were no significant differences in body compositions in all treatments. Addition of enzymes to canola meal diets had no significant effects on growth performance, body compositions and nutrient digestibility. The results of this study indicate that use in higher level of canola meal in tilapia diet was adversely affected growth parameters and FCR. Adding dietary cellulase enzyme in different rations to diets showed no significant differences in growth parameter.

Effects of Supplemental Enzymes in Diets Containing Distillers Dried Grains with Solubles on Finishing Pig Growth Performance

ABSTRACT Four experiments involving 4,506 pigs were conducted to determine the effects of different commercial enzymes on the growth performance of growing-finishing pigs fed distillers dried grains with solubles (DDGS). All experiments were conducted in the same commercial swine research facility. Experiments 1 and 2 used corn- and soybean meal-based diets with 15% DDGS. A β-mannanase enzyme was used in Exp. 1, and a blend of enzymes that contained β-glucanase, cellulase, and protease activities was used in Exp. 2. There were no differences (P > 0.10) in ADG, ADFI, and G:F between pigs fed diets with added enzyme and pigs fed diets without enzyme in either experiment (ADG 1.00 vs. 1.01 kg/d, and G:F 0.408 vs. 0.408; ADG 0.94 vs. 0.94 kg/d, and G:F 0.424 vs. 0.421, in Exp. 1 and 2, respectively) In Exp. 3, diets containing 45 and 60% DDGS were fed with or without 2 commercial proprietary enzyme products designed for use in diets containing DDGS. Average daily gain (0.85 vs. 0.86 kg/d) and G:F (0.370 vs. 0.373) were not different (P > 0.10) among treatments. In Exp. 4, an enzyme product with bacterial endo-1,4-β-xylanase was evaluated in diets containing 30% DDGS. Average daily gain (0.82 vs. 0.82 kg/d) and G:F (0.391 vs. 0.387) were not different (P > 0.10) among treatments. Based on the results, the different enzymes evaluated in these experiments did not enhance finishing pig growth performance when diets contained varying levels of DDGS.

Evaluation of low molecular weight fractions and crude enzyme preparation from a Trichoderma cellulase complex as a treatment for fibrous feeds

An experiment was conducted to evaluate effects of an enzyme filtrate or a crude enzyme preparation on in vitro disappearance of six common fibrous feeds being: alfalfa hay, brome grass hay, cottonseed hulls, soybean hulls, wheat bran and wheat straw. A commercial liquid feed grade enzyme product originating from a strain of Trichoderma reesei was used. To obtain filtrates, the crude enzyme preparation was filtered through membranes with molecular weight cutoffs of 5 and 10 kDa. Feeds were exposed to enzymes, filtrates, or a buffer, for 20 h. Filtrates and crude enzyme preparation were diluted in 12.5 mM sodium citrate buffer. In vitro fermentation followed treatment of the feeds for 24 and 48 h. Release of glucose and total monosaccharides was quantified following treatment of alfalfa hay and soybean hulls at 2 and 24 h, and release of phenolic monomers was measured at 24 h of incubation. For in vitro dry matter disappearance (IVDMD), treatment x time interactions occurred for alfalfa hay ( P=0.01) and cottonseed hulls ( P=0.04). Higher ( P<0.01) IVDMD occurred at 48 h of incubation vs 24 h. The IVDMD of alfalfa hay and wheat bran was not affected by treatments. The crude enzyme preparation (CE) increased IVDMD compared to Ctrl for brome grass hay, cottonseed hulls, soybean hulls and wheat straw. Likewise, CE resulted in higher IVDMD than the 5 and 10 kDa treatments for the same feeds. Release of total monosaccharides from soybean hulls and alfalfa hay was higher ( P<0.001) after 24 h than after 2 h of treatment. Although the 10 kDa treatment resulted in release of monosaccharides from soybean hulls, the greatest response was from CE after the 24 h treatment. Phenolics were released from alfalfa hay and wheat straw as a result of the treatments during a single 24 h incubation, with the biggest response from the 10 kDa and CE. When the enzyme complex from a commercial T. reesei enzyme product was partitioned by molecular weight and used as a treatment for brome grass hay, cottonseed hulls, soybean hulls and wheat straw, both the filtrates and the crude enzyme preparation increased IVDMD, with the crude enzyme preparation treatment causing the biggest IVDMD response. Release of monosaccharides and phenolics from the substrates also occurred as a result of the treatments. The addition of fungal enzymes or their subunits may prove a viable management opportunity to increase rumen digestibility of forages to enhance animal performance.

Assessment of fibrolytic activities of 18 commercial enzyme products and their abilities to degrade the cell wall fraction of corn stalks in in vitro enzymatic and ruminal batch cultures

Fibrolytic activity distributions of 18 enzyme products, mostly obtained in China, were examined in terms of protein concentration and fibrolytic activities on model substrates. The hydrolytic capacities were determined by an in vitro ruminal degradation assessment and the enzymatic release of reducing sugars or ferulic acid from neutral detergent fibre fractions of corn stalks (NDF cs). Most enzyme products were characterized by xylanase, carboxymethyl cellulase (CMCase) and β-glucanase (EG), which had the potential to improve in vitro dry matter disappearance of NDF cs after a 16-h enzymatic pre-treatment followed by a 24-h ruminal degradation using a batch culture method (P<0.05). Quadratic effects of xylanase, CMCase, EG and ferulic acid esterase (FAE) occurred on the release of reducing sugars or ferulic acid from NDF cs (P<0.05). The effective fibrolytic activity combinations required to reach the highest release of reducing sugars were 418–1385 U xylanase, 111–567 U CMCase, 347–376 U EG and 2.0 U FAE per g NDF cs substrate. The addition of an enzyme product with a dominant FAE activity did not alter the total volatile fatty acid production at a low dose level of 1.0 mg/g or 4140 U/g substrate of corn stalks after a 48-h in vitro batch culture. However, a lower ratio of non-glucogenic to glucogenic acids occurred in the fermentation of corn stalks with inclusion of the FAE dominated enzyme product (P<0.05). These results suggest that all enzyme products in China were characterized or blended with enzyme extracts with xylanase, CMCase and EG. The rational combination of enzyme products necessary to reach a specific FAE activity with a specific fibrous forage, together with xylanase, CMCase and EG activities, should be considered in the design of a compound enzyme product for enhancing the cell wall degradation of fibrous crop residues, based on scientific understanding of the mode of enzymatic actions in the rumen.

Deficiency of Cellulase Activity Measurements for Enzyme Evaluation

Switchgrass was used as a model feedstock to determine the influence of pretreatment conditions and biomass quality on enzymatic hydrolysis using different enzyme products. Dilute sulfuric acid and soaking in aqueous ammonia pretreatments were used to produce biomass with varied levels of hemicellulose and lignin sheathing. Pretreated switchgrass solids were tested with simple enzymatic hydrolysis and simultaneous saccharification and fermentation (SSF) with three commercial enzyme products: Accellerase 1000 (Genencor), Spezyme CP (Genencor)/Novozyme 188 (Novozymes), and Celluclast/Novozyme 188 (Novozymes). Enzymes were loaded on a common activity basis (FPU/g cellulose and CBU/g cellulose). Despite identical enzyme loadings, glucose yields were significantly different for both acid and alkaline pretreatments but differences diminished as hydrolysis progressed for acid-pretreated biomass. Cellobiose concentrations in Accellerase treatments indicated an initial beta-glucosidase limitation that became less significant over time. SSF experiments showed that differences in glucose and ethanol yields could not be attributed to enzyme product inhibition. Yield discrepancies of glucose or ethanol in acid pretreatment, alkaline pretreatment, and acid pretreatment/SSF were as much as 15%, 19%, and 5%. These results indicate that standardized protocols for measuring enzyme activity may not be adequate for assessing activity using pretreated biomass substrates.

Effect of various dietary enzymes on energy digestibility of diets high in distillers dried grains with solubles for broilers

Two trials of similar experimental design were conducted to assess the effects of various dietary enzymes on energy digestibility of diets high in distillers dried grains with solubles (DDGS) for broilers. A 2 × 4 factorial arrangement of treatments was used in which a corn- soybean meal control diet and a diet with 30% DDGS were supplemented with 2 different commercial enzyme products. In addition to the unsupplemented control, each enzyme was fed at the level suggested by the manufacturer, twice the recommended level, and 4 times the recommended level. Allzyme SSF (Alltech, Nicholasville, KY) was used in the first experiment, and Rovabio Excel (Adisseo, Alpharetta, GA) was used in the second experiment. Male commercial strain chicks that were 15 (trial 1) or 20 (trial 2) d old were randomly assigned to the experimental diets, with each treatment replicated 3 times. Celite (Celite Corp., Santa Barbara, CA) was used as an indigestible marker. After a 5-d period of acclimation to the diets, excreta samples were collected. The energy contents of the diet and excreta were determined and digestibility of dietary energy was calculated. In both trials, there was a significant (P < 0.05) difference in gross energy digestibility between the corn-soybean meal control diets and diets with 30% DDGS. However, no significant improvement in gross energy digestibility was obtained by adding any level of the 2 enzymes. Moreover, no significant interactions were found between the basal diets and various enzyme levels. Therefore, addition of the enzymes used in these studies had no apparent beneficial effect on energy digestibility of corn-soybean meal diets or diets with a high level of DDGS.