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PubMedDate not supplied

[Spectrophotometric micromethod to determine L-lysine-alpha-oxidase activity].

A spectrophotometric micromethod is developed for estimation of L-lysine-alpha-oxidase. The method is based on measurement of hydrogen peroxide formed in enzymatic oxidation of L-lysine. Optimal conditions were developed for estimation of the enzymatic activity in the extracts of Trichoderma sp. The saturating concentration of L-lysine was 10 mM. Km values for L- and DL-lysines constituted 3.0 . 10(-3) M and 6.4 . 10(-4) M, respectively. The reaction proceeded without a latent phase and H2O2 formation versus time plot had a linear shape within 20 min. The enzyme optimal activity was found at pH 5.8-6.0. The best buffer, required for lysine oxidation in the reaction, proved to be phosphate, but not succinate, borate or glycine buffers. The method described was highly sensitive and reproducible.

Amino Acid Oxidoreductases↗

PubMed1981

[Comparative role of exo-1,4-beta-glucosidase and cellobiase in the enzymatic hydrolysis of cellulose].

An inhibitory action of glucono-delta-lactone on individual components of cellulase complexes from Trichoderma reesei, T. longibrachiatum, T. lignorum and Aspergillus foetidus has been studied. It was shown that gluconolactone exerts an inhibiting effect on cellobiases only (the inhibition constants varied within the range of 0.03-0.1 mM) and does not influence the activities of endoglucanases, cellobiohydrolases and exoglucosidases of the complexes. This formed a basis for a new method for determination of the exoglucosidase activity in a mixture with other components of the cellulase complexes. The complete and selective inhibition of cellobiases by gluconolactone with exoglucosidases activity being intact allowed to evaluate the relative contribution of these enzymes in glucose formation in the course of enzymatic hydrolysis of cellulose (CM-cellulose, filter paper and Avicel). It was found that for most of the cellulase complexes studied the crucial role in glucose formation both from soluble and insoluble cellulose at early steps of hydrolysis belongs to exoglucosidase. On the other hand, the role of exoglucosidase (comparatively with cellobiase) progressively decreases in the course of cellulose hydrolysis. The latter effect does not presumably reflect the changes in the mechanism of cellulose conversion in the course of hydrolysis, but is due to a specific kinetic behaviour of the multienzyme cellulase system.

Aspergillus↗

PubMed1982

[Enzymatic hydrolysis of cellulose. Inactivation and stabilization of the enzymes of the cellulose complex].

The thermal inactivation of the individual cellulolytic components (endoglucanase, EC 3.2.1.4; exoglucosidase, EC 3.2.1.74; cellobiase, EC 3.2.1.21) from the fungi Trichoderma reesei, T. viride, T. lignorum an Aspergillus foetidus has been studied without resolution of the cellulase complexes. The kinetics of the thermal inactivation follow the first order for cellobiase of Asp. foetidus alone and show a more complex picture which is typical for a number of isoenzymes of different thermal stabilities for other cellulolytic components of all the cellulases under study. It was shown that selective elimination of acid proteinase from the cellulase preparations by affinity chromatography did not affect the time course of the thermal inactivation. Covalent attachment of the cellulases to porous glass and to some soluble high polymer supports only resulted in slight stabilizing effects (200-250%). Some polymer effectors (e. g. polyethylene glycols with Mr of 4000 and 40,000 and maltodextrins), as well as the end products of enzymatic hydrolysis of cellulose (i. e. glucose) did not affect the thermal stability of the cellulases under study. In some cases cellulose itself (cotton, CM-cellulose) produced a thermostabilizing effect (3-4-fold) on cellulolytic enzymes.

Aspergillus↗

PubMed1983

[Search for new antibiotics of the cyclosporin group].

A total of 160 fungal cultures belonging to Trichoderma were isolated from soil samples collected in various regions of the USSR. The cultures were tested for production of antibiotics of the cyclosporin group, having a narrow antifungal spectrum. It was found that 7 cultures produced substances having a selective inhibitory effect on Asp. niger and no activity against gram-positive and gram-negative organisms. An antibiotic substance close by its physicochemical properties to cyclosporins was isolated from T. viride 122.

Anti-Bacterial Agents↗

PubMedDate not supplied

[Hydrolysis of cellulose by fungi. 1. Screening of cellulolytic strains].

Trichoderma harzianum was selected from 30 strains of cellulolytic fungi with the aim of producing cellulases by solid state fermentation of lignocellulosic substrates. Special attention was paid to cellulase production (i.e. carboxymethylcellulase and filter paper activity), apical growth and conidia production. Under the conditions of our experiments, T. harzianum exhibited the highest cellulasic activities with 1,315 IU/l of carboxymethyl cellulose and 80 IU/l of filter paper activity. Apical growth (1 mm/h) and yield of conidial production (3.25 x 10(10) conidia/g of substrate dry weight) were also valuable characteristics of this strain in the use of solid state fermentation.

Cellulase↗

PubMed1982

[Protein enrichment of sugar beet bagasse for fermentation].

Leached beet pulp is a plentiful waste in the sugar beet industry in Chile, reaching 100.000 metric tons per year on a dry basis. It represents an interesting substrate for protein upgrading through fermentation by cellulolytic organisms, because of the high content of cellulose and hemicellulose, with small amounts of protein and lignin (Table 1). The fermentation of leached beet pulp by the cellulolytic fungus Trichoderma reesei QM 9414 was studied under carbon limitation, with the celluloses as the only carbon and energy source. Nitrogen was supplied as ammonium sulphate and the medium was supplemented with other mineral salts as required for growth. Results on the kinetics of cellulose and hemicellulose degradation, level of reducing sugars in the medium, mycelial growth and production of cellulolytic enzymes are presented. Mycelial growth and related parameters were evaluated by an indirect method, based on nitrogen balances during fermentation. A yield of 0.26 g. of dry cell/g. of cellulosic substrate consumed and productivity of 0.095 g. of dry cell per liter per hour were obtained and compared with reported results on similar systems. After 40 to 45 hours of fermentation, approximately 80% of the cellulose and 45% of the hemicellulose were degraded (Fig. 2). Both, exoglucanase and endoglucanase, were induced; endoglucanase was growth associated, while exoglucanase appeared later in the growth phase, reaching its maximum activity in the stationary phase (Fig. 3). The product obtained was 30% protein and only 40 to 45% residual fiber, mostly hemicellulose. Mild acid hydrolysis has been successful in degrading hemicellulose but not cellulose, in the leached beet pulp.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗

PubMed1980

The preparation of protoplasts from Aspergillus fumigatus mycelium.

Protoplasts have been prepared from the mycelium of Aspergillus funigatus, using a lytic enzyme mixture from Trichoderma harzianum. A variety of experimental conditions were investigated in order to achieve optimal conditions for protoplast production. Electron micrographs showed the preparations to be free of cell-wall. Material obtained by this procedure can be used as a source of cytoplasmic antigens for further analysis.

Aspergillus fumigatus↗

PubMed1982

[Non-steady state kinetics for action of a multienzyme cellulase system toward insoluble cellulose].

A kinetic theory for multienzyme cellulase systems in non-steady state conditions (in relation to intermediate metabolites) of hydrolysis of insoluble cellulose has been developed. To verify the kinetic regularities obtained the action of 12 different cellulases from the fungi Trichoderma, Geotrichum and Aspergillus as well as from bacterial cells Thermomonospora sp. and Rapidase preparation has been studied with respect to ball milled cotton linters and microcrystalline cellulose. The experimental data were discussed in the framework of mechanism of enzymatic hydrolysis of cellulose suggest by us recently and the main routes for glucose and cellobiose formation from insoluble cellulose have been elucidated. The effects of concentrations of cellulase preparations and the initial substrate on (i) time lags for glucose formation, (ii) stationary rate of glucose formation, and (iii) kinetics of cellulose conversion to glucose at low and high conversion degrees, were studied. A theoretical analysis of maxima and inflection points on the kinetic curves for intermediates (oligosaccharides and cellobiose) was performed. The effects and intensity of stirring on the time lag values for glucose formation were studied and the relative role of kinetic and diffusional factors in this process was evaluated. The data obtained are unequivocally indicative of the common mechanism of conversion of cellulose to glucose by cellulase complexes irrespective of their source and composition.

Actinomycetales↗

PubMed1980

[Relationship between the kinetics of hydrolysis of soluble and native celluloses under the action of cellulase multi-enzyme complexes].

The kinetics of cellulase multi-enzyme complex under steady- and non-steady-state conditions have been studied. To verify the kinetic regularities obtained the action of eight different cellulases from Trichoderma, Geotrichum and Aspergillus has been studied with respect to ball milled cotton linters. On the other hand, the activities of the individual components of cellulase complexes, i.e. endoglucanase, exoglucosidase and cellobiase have been determined with respect to soluble cellulose derivatives. Theoretical and experimental evidence for the existence of a linear correlation between the rate of hydrolysis of native cellulose under certain experimental conditons, on the one hand, and that of its soluble polymeric compounds (particularly, carboxymethyl cellulose) on the other, have been obtained. The kinetics of the cellulase multi-enzyme system suggest that this correlation is a substantiation of the fact that endoglucanse is a cellulolytic component which is the first to attack native cellulose. The data obtained contradict the hypothesis being discussed in literature for the last 30 years about the presence in cellulase complexes of some "pre-hydrolytic C1-enzyme", which presumably attacks native cellulose. Evidently, a hypothetical "C1-enzyme" is the endoglucanase of random action.

Aspergillus↗

PubMed1982

[Regulation of the formation and conversion of intermediate cellooligosaccharides and cellobiose during ezymatic hydrolysis of insoluble cellulose].

A kinetic analysis of the main regularities for formation and consumption of the intermediate metabolites (i.e. cellooligosaccharides and cellobiose) in the course of enzymatic hydrolysis of cellulose has been performed. The boundary relationships between the velocities of the individual steps of hydrolysis controlling the transition of the multienzyme cellulase system to be steady-state with respect to the intermediate metabolites were revealed. Using the kinetic approaches developed here, the values of the steady-state concentrations of insoluble intermediate oligosaccharides were determined experimentally for a number of cellulases from the fungi Trichoderma and Geotrichum. It was shown experimentally that when studying the kinetics of enzymatic hydrolysis of cellulose it is necessary to take into account the structural irregularities of the insoluble substrate even when a practically negligible fraction of it (with respect to its weight) is converted to soluble products. In other cases the kinetic parameters obtained could not be corresponding to the actual reactivity of the cellulose/cellulase system, reflecting rather a difference in reactivity between the labile (amorphous) and stable (crystalline) fractions of a cellulose substrate.

Cellobiose↗

PubMed1981

[Effect of composition of multienzyme cellulase complexes on rate-limiting steps for non-soluble (native) cellulose hydrolysis].

It was shown that the kinetics of multienzyme cellulase complexes are generally characterized by the absence of any single rate-limiting step of hydrolysis, even when the rates of individual steps of the process are substantially different. This peculiarity of the kinetic behaviour of cellulases can be explained in terms of certain "shunt ways" in a series of individual steps of enzymatic degradation of cellulose into glucose. A basic kinetic scheme for the degradation of cellulose was developed and proved experimentally for hydrolysis of milled cotton linters under the action of ten various cellulase complexes from the fungi Trichoderma, Geotrichum and Aspergillus. It was found that the value of the stationary rate of glucose formation in all cases is determined by the effect of two or three cellulolytic components of the complexes. It was concluded that the mechanism of native cellulose hydrolysis is the same for all cellulase complexes under study irrespective of their composition and origin.

Aspergillus niger↗

PubMed1981

[Toxicological characteristics of mold isolated from corn silage].

Tested for toxicity were a total of 48 strains of pure cultures of the fungi: Aspergillus flavus, As. fumigatus, Penicillium, F. moniliforme, F. graminearum, Tr. lignorum. The methods of dermal tests, chick embryos, and feeding of young birds were employed. It was found that through dermal tests ten strains of the following species proved toxic: As. fumigatus, As. flavus, F. moniliforme, F. garminearum, and Trichoderma lignorum. Toxic for chick embryos were 13 strains of the same species. When young chickens were fed moulded silage toxic proved As. flavus and F. moniliforme. Chick embryos showed highest sensitivity to mycotoxins. The toxicity of the investigated strains varied depending on the methods employed, however, it was manifested to a different extent with all three methods.

Animal Feed↗

PubMed1995

Hybrid process for ethanol production from rice straw.

A hybrid process for the fermentation of rice straw hydrolysates into ethanol was designed to simultaneously utilize cellulose and hemicellulose fractions of the agro-residue. The process involved dilute acid hydrolysis (for obtaining C-5 sugars) followed by enzymatic saccharification of cellulose enriched fraction with crude cellulase produced by mixed cultures of Trichoderma reesei Rut C-30 and Aspergillus ochraceus IMI 317911. The fermentation medium containing acid and enzymatic hydrolysate mixture of pentoses and hexoses monomers was fermented with yeast coculture of Saccharomyces cerevisiae and Pachysolen tannophilus resulting in 295.0 ml ethanol/kg of rice straw. The hybrid process resulted in an efficient utilization of both cellulosic and hemicellulosic components of the rice straw for ethanol production.

Aspergillus ochraceus↗

PubMed1995

Simultaneous saccharification and fermentation of rice straw into ethanol.

The physicochemical pretreatment of ball milled rice straw with different oxidizing agents, peracetic acid, alkali-peroxide, manganese-peroxide compounds under steaming pressure were studied. The pretreatment resulted in major changes in chemical composition of rice straw. The peroxide treated substrates were found to be most susceptible to enzymatic saccharification. A maximum saccharification (77.4%) of alkaline-peroxide treated rice straw (5%, w/v) was achieved using cellulase enzyme produced by mixed cultivation of Trichoderma reesei Rut C-30 and Aspergillus ochraceus containing 1.83 FPU, 1.63 cellobiase and xylanase 2.03 IU/ml. The hydrolysate was fermented using coculture of a temperature resistant strain of Saccharomyces cerevisiae and Pachysolen tannophilus resulting in 1.5% (w/v) ethanol. The SSF of 10.0% (w/v) H2O2-MnSO4 treated straw yielded maximum ethanol (2.9%, w/v) after 72 h at 40 degrees C. As a consequence of the well-balanced cellulase production by mixed fungal culture, the supplementation of cellobiase or xylanase was not necessary in the simultaneous saccharification and fermentation process.

Aspergillus ochraceus↗

PubMed1994

[Mildewproof of Chinese traditional medicinal materials].

A study on the anti-mold activity of BCM, cinnamaldehyde and clove oil, was made by means of ultramicrostructural observation. The results show that both cinnamaldehyde and clove oil have strong anti-mold activity, (the former being even stronger), while BCM works well only in cases of Aspergillus, Penicillium and Trichoderma. SME and TME have found out that cinnamaldehyde is able to destroy the wall of fungal cells, the coagulate plasma and dissolve the cell organs.

Acrolein↗

PubMed1994

Statistic method for determining the fusion-recombination of cellulase genome.

A hypothesis was proposed based on cellulase synergism and multiple variable statistics that the experimental value of N strains out of total fusants from the same cell fusion pool, Aspergillus niger x Trichoderma reesei, could be a sample for the definite fusion cross due to the independence and random of DNA recombination. It could be reduced if fusion recombination happened by analyzing the sample with the provided computer program selected 40 strains of about 2000 fusants of A. niger x T. reesei were analyzed under this procedure as an example and was showed that was effective method on guiding cellulase breeding.

Aspergillus niger↗

PubMed1995

Prohevein is poorly processed but shows enhanced resistance to a chitin-binding fungus in transgenic tomato plants.

In latex of rubber tree (Hevea brasiliensis), prohevein, homologous to potato win gene-encoded proteins, is processed to yield mature hevein. This mature hevein is composed of one chitin-binding domain and the C-terminal polypeptide homologous to pathogenesis-related proteins such as tobacco PR-4 and tomato P2 proteins. In contrast, prohevein was poorly cleaved to form the C-terminal polypeptide in transgenic tomato plants expressing hevein gene (HEV1)-driven polypeptides. However, mature hevein, the N-terminal cleavage form, was not found in this system. Immunoblot analysis of extracellular and intracellular fluid proteins showed that HEV1-encoded polypeptides accumulated intracellularly. In addition, retardation of growth of Trichoderma hamatum was observed in transgenic tomatoes constitutively expressing HEV1-encoded proteins.

Allergens↗

PubMed1977

Microbiological assay for saponin in alfalfa products.

A bioassay is described for determining medicagenin-type saponin in dried alfalfa, leaf protein concentrates, and alfalfa sprouts. Samples are extracted by refluxing 2 1/2 hr with 50% ethanol, ethanol is evaporated, and aliquots of an aqueous solution are added to potato dextrose agar (PDA) and assayed for saponin by using the fungus Trichoderma viride. The growth of the fungus on PDA is compared with a standard saponin, and saponin levels are calculated by means of a slope ratio analysis.

Biological Assay↗