Use of charcoal to minimize end product inhibition in enzymatic hydrolysis of cellulose

Summary Tests made to improve saccharification of cellulose byTrichoderma cellulases showed that charcoal used as an adsorbent minimized the end product inhibition. Charcoal adsorbed both cellobiose and glucose and did not affect the enzymatic hydrolysis of cellulose. Results showed that charcoal is as effective as -glucosidase in improving the enzymatic saccharification of cellulose.     

Alternative pathway for glucose production from cellulose using Trichoderma reesei QM9414 cellulase

Summary Evidence is presented which supports the view that two routes exist for the formation of glucose when cellulosic material is saccharified using T. reesei enzyme preparations. The first is via cellobiose and for the second, glucose appears to be formed by a route not involving cellobiose. The second route becomes more apparent when dealing with less crystalline cellulose. This should be considered when constructing strains to produce enzyme preparations for saccharification of less crystalline cellulose.     

A one step process for the conversion of cellulose to ethanol using anaerobic microorganisms in mono- and co-culture

Summary The reducing sugars, glucose, and ethanol produced during growth of the anaerobes Clostridium thermocellum and Acetivibrio cellulolyticus on cellulose were assayed. Zymomonas mobilis was grown under similar conditions and could ferment glucose to ethanol. The ethanol production by the cellulolytic bacteria alone and in co-culture with Zymomonas is described. Approximately 27% of a 1% cellulose substrate could be converted to ethanol by this co-culture.     

Effects of agitation on enzymatic saccharification of cellulose

Summary Crystalline cellulose Avicel has been hydrolyzed byTrichoderma viride cellulase (Meicelase CEPB) under vaned agitation conditions and the effect of agitation on the adsorption of cellulase on cellulose has been studied. Agitation was found to enhance the hydrolysis pf crystalline cellulose; possibly the agitation enhances the adsorption of exoglucanase to shift the adsorption balance of exoglucanase and endoglucanase to a direction favorable for their synergistic action on the surface of cellulose.     

Cellulase and protein production by Chaetomium cellulolyticum strains grown on cellulosic substrates

Summary Fermentation with Chaetomium cellulolyticum was carried out on media containing either Avicel cellulose or newspaper. Production of free cellulolytic enzymes, cellulose degradation and the formation of cell protein were studied with the original strain and a mutant strain.     

Influence of oxygen and carbon dioxide on lignin degradation in solid state fermentation of wheat straw withStropharia rugosoannulata

Summary In solid state fermentation,Stropharia rugosoannulata degrades lignin of wheat straw slightly better in the presence of oxygen than that in air. The sub-atmospheric partial pressure of oxygen (0.05 atm.) inhibits lignin and organic matter degradation. the increasing partial pressure of carbon dioxide (0.1–0.3 atm.) along with 0.2 atm. of oxygen does not have any effect on lignin degradation, but slightly decreases organic matter loss and increases thein vitro digestibility of fermented wheat straw, thereby making the process more efficient.     

A continuous thermophilic cellulose fermentation in an upflow reactor by aClostridium thermocellum-containing mixed culture

Summary A continuous thermophilic cellulose fermentation by aCl. thermocellum-containing mixed culture was carried out in an upflow reactor for a period of 100 days. The cellulose conversion rate was finally 0.35 g.1^–1.h^–1. Evidence that the fermentation process was influenced by both pH and dilution rate was given by the changes of concentration of the main fermentation products, acetic acid and ethanol. The role of cellodextrins and glucose as reactive intermediates in the process of cellulose breakdown was established.     

Cellulase and xylanase production by Trichoderma reesei Rut C-30

Summary When grown on cellulose or xylan, Trichoderma reesei (strain Rut C-30) produced extra-cellular enzymes which could hydrolyze both cellulose and xylan to their respective monosaccharides. At low O₂ saturation, -glucosidase activity is greatly reduced for cellulose-grown but not xylan-grown cells.     

Enhancement of ethanol production in the presence of metabolic inhibitors inClostridium thermocellum strain SS8

Summary Clostridium thermocellum strain SS8 produced 0.25g of ethanol and 0.24g of acetic acid per g cellulose consumed. Enhancement in ethanol production upto 0.39g/g substrate was observed in the presence of 0.15mM concentration of sodium azide and 7% polyethyleneglycol along with significant repression in acetic acid formation.     

Cellulase production byTalaromyces emersonii CBS 814.70 co-immobilized with cellulose in calcium alginate

Summary The thermophilic fungusTalaromyces emersonii CBS 814.70 was co-immobilized with cellulose in calcium alginate beads. Cellulose production by this system was compared with a conventional process. The immobilized system continued to produce enzyme in a batch-fed reactor system while the non-immobilized had ceased production; levels of enzyme produced by the immobilized system were almost twice the maximum produced by the non-immobilized system.     

Effect of intermittent feeding of cellulose hydrolyzate to hemicellulose hydrolyzate on ethanol yield byPachysolen tannophilus

Summary Intermittent-feeding of cellulose hydrolyzate to hemicellulose hydrolyzate of hardwood resulted in greater yields of ethanol usingPachysolen tannophilus than batch fermentations of either hydrolyzate alone or as a mix. Conversion efficiencies as great as 0.40 g ethanol/g sugar fed were achieved.     

Solid state fermentation of oat straw by Polyporus sp A-336 and the effect of added sugars

Summary Supplementing oat straw in SSF by Polyporus sp A-336 with xylose, mannose, glucose and arabinogalactan at levels of 5 and 10% of straw weight stimulated lignin degradation and cellulose hydrolysis. Degradation of lignin, hemicellulose and cellulose was monitored for 30 days in plain straw, and straw plus xylose and showed that xylose shortened the lag in lignin breakdown and slowed hemicellulose utilization. At 24 days, similar polymer losses occurred in both systems and enzymatic cellulose hydrolysis had reached a maximum of 47% weight loss.     

Solid state fermentation and fractionation of oat straw by Basidiomycetes

Summary Seventee white-rot and brown-rot fungi were screened for their ability to fractionate the lignocellulose structure of oat straw through the preferential attack of lignin or cellulose. Fermentations were carried out under solid-state conditions with 25 g quantities of straw. The fermented straw was analyzed for weight loss, Klason lignin loss and cellulase digestion. All the fungi attacked both lignin and carbohydrate fractions causing 3–28% weight losses and 26–34 g/100 g enzymatic digestibility. Polyporus tulipiferae, Phanerochaete chrysosporium and Polyporus sp. were tested for the effects of various nitrogen, phosphate and carbon levels, incubation temperatures and incubation time. The three fungi had different responses to these factors.     

Ethanol production byClostridium thermocellum SS8, a newly isolated thermophilic bacterium

Summary Clostridium thermocellum SS8, has a broad substrate spectrum. It produced 0.25–0.29 g. of ethanol per g. of cellulose consumed. Cellulose fermentation was repressed by both glucose and cellobiose. pH had an effect on ethanol productivity at high substrate concentration. Best results were obtained at 30 g/l with an E/S and E/A ratios of 0.29 and 2.4 respectively.     

Cellulase and hemicellulase production by Cellulomonas flavigena NIAB 441

Summary Cellulomonas flavigena (strain NIAB 441) produced cellulase and hemicellulase activities when grown on Leptochloa fusca L. Kunth (Kallar grass), found to be the best inducer for enzyme production. The enzyme possessed the potential to saccharify bagasse, Kallar grass straw, wheat straw, carboxymethyl cellulose (CMC) and xylan to reducing sugars.     

Estimation of fungal growth on lignocellulosic substrates using an enzyme-linked immunosorbent assay

Summary The feasibility of using an enzyme-linked immunosorbent assay (ELISA) for quantifying the growth ofThielavia terrestris on cellulosic substrates was studied. WhenT. terrestris was grown, using glucose as the substrate, the ELISA readings correlated well with the mycelial dry weight values. When lignocellulosic substrates were used, the ELISA appeared to slightly overestimate fungal growth. The ELISA values indicated that the fungi grew more slowly on steam-treated aspenwood than on commercial sources of cellulose (Avicel).     

Some characteristics of the cellulolytic enzyme system of Chaetomium cellulolyticum

Summary The effects of pH and temperature on the activities of endoglucanase, exoglucanase and -glucosidase of C. cellulolyticum were studied. Thermal stability of these enzymes was characterized. Enzymatic hydrolyses of cellulose were performed yielding predominantly glucose and cellobiose. Glucose was shown to be a potent inhibitor of its own formation in cellulose saccharification.     

Biomass protein formation by filamentous fungi on woody substrates

Summary Growth and biomass protein formation by filamentous fungi grown on pretreated tropical woods of Mesta (Hibiscus cannabinus Linn.) and Subabul [Leucaena leucocephala (Lam.) de Witt] as well as their isolated hemicellulose and cellulose fractions have been studied. Penicillium janthinellum and Penicillium funiculosum produced a biomass having 20 to 30% crude protein when grown on either hemicellulose, while growth on pretreated (autoclaved in 1% NaOH) wood or isolated cellulose fractions was comparatively poor and crude protein content only 5 to 8% in the biomass.NCL Communication no.3550     

Cellulose acetate entrapment of Escherichia coli on cotton cloth for aspartate production

Summary Aspartase containingEscherichia coli cells were entrapped in cellulose acetate aggregated on cotton cloth. The enzyme activity of the cloth was stabilized by treatment with polyethylenimine and alkaline glutaraldehyde in the presence of 0.1 M sodium dithionite. A column packed with the cloth segments catalyzed 100% conversion of 1 M ammonium fumarate to aspartic acid at a space velocity of 7/h. When the same cloth segments were stirred at 100 rpm in the substrate solution, the productivity of the cloth increased 2.5 times.     

ATP measurement for cellulase production control

Summary Plotting intracellular ATP concentrations as a function of time during cellulase production byTrichoderma reesei, provides a good evaluation of fungal growth and specific rate of cellulose consumption. ATP content evaluation is of great help for running fed-batch and semi-continuous fermentations.