Enzyme Optimization for Lignocellulose Hydrolysis using Mechanistic Modeling

A novel mechanistic model for the saccharification of cellulose and hemicellulose is utilized to predict the products of hydrolysis over a range of enzyme loadings and times. The mechanistic model considers the morphology of the substrate and the kinetics of enzymes to optimize enzyme concentrations for the enzymatic hydrolysis of cellulose and hemicellulose simultaneously. Substrates are modeled based on their fraction of accessible sites, glucan content, xylan content, and degree of polymerizations. This enzyme optimization model takes into account the kinetics of six core enzymes for lignocellulose hydrolysis: endoglucanase I (EG1), cellobiohydrolase I (CBH1), cellobiohydrolase II (CBH2), and endo-xylanase (EX) from Trichoderma reesei; β-glucosidase (BG), and β-xylosidase (BX) from Aspergillus niger. The model employs the synergistic action of these enzymes to predict optimum enzyme concentrations for hydrolysis of Avicel and ammonia fiber explosion (AFEX) pretreated corn stover. Glucan, glucan + xylan, glucose and glucose + xylose conversion predictions are given over a range of mass fractions of enzymes, and a range of enzyme loadings. Simulation results are compared with optimizations using statistically designed experiments. BG and BX are modeled in solution at later time points to predict the effect on glucose conversion and xylose conversion.

The Cellulolytic Activity And Volatile Fatty Acid Product Of Rumen Bacteria Of Buffalo And Cattle On Rice Straw, Elephant Grass, and Sesbania Leaves Substrates

Experiment on The Cellulolytic Activity and Volatile Fatty Acid Product of Rumen Bacteria of Buffalo and Cattle on Rice Straw, Elephant Grass, and Sesbania Leaves Substrates had been conducted at Feedstuff Laboratory of Animal Science Soedirman University. The basic design  that was used in this experiment was Completely Randomized Design (CRD) with factorial pattern of 6 x 3, three replications. The bacteria isolate as the factors were cellulolytic rumen bacteria isolate of buffalo (A1, A2, and A3) and cattle (A4, A5 and A6) while the substrates (second factor)  were NDF rice straw (S1), elephant grass (S2), and sesbania leaves (S3) Cell walls. The result of this experiment showed that the interaction between bacteria isolate and substrate  type were significant on pH, NDF digestibility, cellulase activity, pH was  6.28 until 6.43.  The NDF digestibility range was 12.27 until 55.61 percent. The lowers of cellulase activity was 5.11 IU/ml and the higher was 24.47 IU/ml. The range of acetic acid yield was 63.37 to 307.467 mg/100 ml. Range of  propionic production was 15.17 to 352.20 mg/ 100 ml. The production of butiric acid was 8.77 to 40.87 mg/ 100 ml. The cellulase activity  of cellulolytic rumen bacteria of buffalo was higher than cattle, and also their effect on NDF digestibility of rice straw, elephant grass, and sesbania leaves cell walls. The A3 of cellulolytic rumen bacteria isolate of  buffalo changed cell walls substrat to volatile fatty  acid was more effective than cattle, especially on cell elephant grass. Propionic and butiric  acid that was produced by cellulolytic rumen bacteria isolate of buffalo more higher than cattle (Animal Production 1 (1) : 1-9 (1999)Key Words: Cellulolytic, VFA, Rumen Bacteria, Buffalo, Cattle.

Increasing of Energy Quality of Waste Product with Trichoderma and Aspergillus

Biomasa of agricultural residues are potensial as ruminant feeds. However due it is low palatability, digestibility and nutritive value limited their use. In order to improve their use, treatment need to be applied. Biological treatment by using microba seems to be an alternative because of their capability with no pollution problems. The first experiment aims to select the microorganism which have a potensial to degrade the crude fiber, based the production of reduction sugar. The second experiment aims to improve the protein and amino acid on rice straw, cassava, waste, and rice husk, by inoculated the starter of Candida utilis and or Sacharomyces cerevise. The second experiment has been conducted on Animal Nutrition and Feed Laboratory, Faculty of Animal Husbandry UNSOED for eight month Fermentation trial has been done in semi solid media, by the method of Kjic (1964), in Batch System, Variables measure were: (1) reduction sugar, (2) cellulose, (3) protein, (4) amino acids, (5) cellulase activity, (6) essensial mineral and (7) energy. Based on the all variables measured that were conclused that the quality of  rice straw can be improved by mixed culture of  T, viride – S. cerevise, the rice husk by A. niger – C. utilis, T. viride – C. utilis and A. niger – S cerevise while for cassava waste by  A. niger – S. cerevise and A. niger – C. utilis  (Animal Production 1(1) : 10-16 (1999). Key Words: Waste Product, Energy, Microorganism