Effect of acetic acid and furfural on cellulase production of Trichoderma reesei RUT C30

Because of the high temperature applied in the steam pretreatment of lignocellulosic materials, different types of inhibiting degradation products of saccharides and lignin, such as acetic acid and furfural, are formed. The main objective of the present study was to examine the effect of acetic acid and furfural on the cellulase production of a filamentous fungus Trichoderma reesei RUT C30, which is known to be one of the best cellulase-producing strains. Mandels's mineral medium, supplemented with steam-pretreated willow as the carbon source at a concentration corresponding to 10 g/L of carbohydrate, was used. Four different concentration levels of acetic acid (0-3.0 g/L) and furfural (0-1.2 g/L) were applied alone as well as in certain combinations. Two enzyme activities, cellulase and beta -glucosidase, were measured. The highest cellulase activity obtained after a 7-d incubation was 1.55 FPU/mL with 1.0 g/L of acetic acid and 0.8 g/L of furfural added to the medium. This was 17% higher than that obtained without acetic acid and furfural. Furthermore, the results showed that acetic acid alone did not influence the cellulase activity even at the highest concentration. However, beta -glucosidase activity was increased with increasing acetic acid concentration. Furfural proved to be an inhibiting agent causing a significant decrease in both cellulase and beta -glucosidase production

Cellulase production of Trichoderma reesei Rut C 30 using steam-pretreated spruce - Hydrolytic potential of cellulases on different substrates

Various techniques are available for the conversion of lignocellulosics to fuel ethanol. During the last decade processes based on enzymatic hydrolysis of cellulose have been investigated more extensively, showing good yield on both hardwood and softwood. The cellulase production of a filamentous fungi, Trichoderma reesei Rut C 30, was examined on carbon sources obtained after steam pretreatment of spruce. These materials were washed fibrous steam-pretreated spruce (SPS), and hemicellulose hydrolysate. The hemicellulose hydrolysate contained, besides water-soluble carbohydrates, lignin and sugar degradation products, which were formed during the pretreatment and proved to be inhibitory to microorganisms. Experiments were performed in a 4-L laboratory fermentor. The hydrolytic capacity of the produced enzyme solutions was compared with two commercially available enzyme preparations, Celluclast and Iogen Cellulase, on SPS, washed SPS, and Solka Flee cellulose powder. There was no significant difference among the different enzymes produced by T, reesei Rut C 30. However, the conversion of cellulose using these enzymes was higher than that obtained with Iogen or Celluclast cellulases using steam-pretreated spruce as substrate

Cellulase production by T-reesei

Steam-pretreated willow has been found to be a suitable substrate for ethanol production in Sweden. The production of Trichoderma reesei cellulases on steam-pretreated willow (SPW) of varying cellulose content has been studied. Batch fermentations were performed in shake flasks, and in 4- and 22-l fermenters. SPW was found to be a suitable carbon source for cellulase production. At an initial solids concentration corresponding to 10 g/l cellulose, the yield was 108 filter paper units (FPU)/g cellulose after 3 days in the 22-l fermenter However, the yield was below 100 FPU/g cellulose in the shake flasks and 4-l fermenter The solid residue of enzymatically hydrolysed SPW was found to be nearly as good a substrate as SPW, although the cellulose content was as low as 20% in this hydrolysis residue. Using delignified SPW, the yield of cellulases was low, indicating that lignin does not inhibit cellulase production. By applying a pressure of 1.7 bar in the fermenter, the initial fermentation rate was increased. The productivity was increased from 12.2 FPU/l/h to 16.7 FPU/l/h, due to the higher level of dissolved oxygen at the higher pressure. Copyright (C) 1996 Elsevier Science Ltd

Dynamics of cellulase production by glucose grown cultures of Trichoderma reesei rut-C30 as a response to addition of cellulose

An economic process for the enzymatic hydrolysis of cellulose would allow utilization of cellulosic biomass for the production of easily fermentable low-cost sugars. New and more efficient fermentation processes are emerging to convert this biologic currency to a variety of commodity products with a special emphasis on fuel ethanol production. Since the cost of cellulase production currently accounts for a large fraction of the estimated total production costs of bioethanol, a significantly less expensive process for cellulase enzyme production is needed. It will most likely be desirable to obtain cellulase production on different carbon sources-including both polymeric carbohydrates and monosaccharides. The relation between enzyme production and growth profile of the microorganism is key for designing such processes. We conducted a careful characterization of growth and cellulase production by the soft-rot fungus Trichoderma reesei. Glucose-grown cultures of T. reesei Rut-C30 were subjected to pulse additions of Solka-floc (delignified pine pulp), and the response was monitored in terms of CO2 evolution and increased enzyme activity. There was an immediate and unexpectedly strong CO2 evolution at the point of Solka-floc addition. The time profiles of induction of cellulase activity, cellulose degradation, and CO2 evolution are analyzed and discussed herein

Use of hemicellulose hydrolysate for beta-glucosidase fermentation

Hydrolysis of cellulose by Trichoderma cellulases often results in a mixture of glucose, cellobiose, and low-mol-wt cellodextrins. Cellobiose is nonfermentable for most yeasts, and therefore it has to be hydrolyzed to glucose by beta-glucosidase prior to ethanol fermentation. In the present study, the beta-glucosidase production of one Penicillium and three Aspergillus strains, which were previously selected out of 24 strains, was investigated on steam pretreated willow. Both steam-pretreated willow and hemicellulose hydrolysate, released during steam explosion of willow, were used as carbon sources. Reference cultivation runs were performed using prehydrolyzed Solka Flee and glucose. The four strains were compared with Trichoderma reesei regarding sugar consumption and beta-glucosidase production. Aspergillus niger and Aspergillus phoenicis proved to be the best enzyme producers on hemicellulose hydrolysate. The maximum beta-glucosidase activity, 4.60 IU/mL, was obtained when A. phoenicis was cultivated on the mixture of hemicellulose hydrolysate and steam-pretreated willow. The maximum yield of enzyme activity, 502 IU/g total carbohydrate, was obtained when Aspergillus foetidus was cultivated on the hemicellulose hydrolysate

Hydrogen production from paper sludge hydrolysate

The main objective of this study was to develop a system for the production of 'renewable' hydrogen. Paper sludge is a solid industrial waste yielding mainly cellulose, which can be used, after hydrolysis, as a feedstock in anaerobic fermentation by (hyper)thermophilic organisms, such as Thermotoga elfii and Caldicellulosiruptor saccharolyticus. Tests on different medium compositions showed that both bacteria were able to produce hydrogen from paper sludge hydrolysate, but the amount of produced hydrogen and the requirement for other components differed. Hydrogen production by T. elfii strongly depended on the presence of yeast extract and salts. By contrast, C. saccharolyticus was less dependent on medium components but seemed to be inhibited by a component present in the sludge hydrolysate. Utilization of xylose was preferred over glucose by C. saccharolyticus

Simultaneous detoxification and enzyme production of hemicellulose hydrolysates obtained after steam pretreatment

In the process of making ethanol from lignocellulosic materials, compounds inhibitory to microorganisms are generated during steam pretreatment of the wood. Water-soluble inhibitors and pentoses are liberated and washed from the cellulose structure which is further enzymatically hydrolyzed. To make the process economically feasible, rite pentoses have to be fermented to ethanol. A major drawback with the pentose-fermenting organisms that have been suggested for this purpose is that they do not tolerate an inhibitory environment and there fore, the pentose stream has to be detoxified prior to fermentation. An alternative use of the hemicellulose hydrolysate obtained after steam;pretreatment of willow is to use it for. enzyme production by the cellulolytic fungus Trichoderma reesei. The sugars in the pentose function are almost completely utilized, and simultaneously the hemicellulose hydrolysate is detoxified and can be recirculated in rite process to minimize the need for freshwater. (C) 1997 by Elsevier Science Inc