Cellulase activity of higher fungi

The method of liquefaction of gel from cross-linked cellulose was used for monitoring the cellulolytic activity of 114 cultures of higher fungi, 47 of which belonged toPleurotus ostreatus. All cultures ofP. ostreatus had a low activity. The highest cellulase activity, manifested byPiptoporus betulinus, was comparable with that ofTrichoderma viride QM6a.     

Cellulose degradation and cellulase activity of five cellulolytic fungi

Biodegradation of pure cellulose powder, bagasse and wheatstraw by five cellulolytic fungi,Aspergillus niger, Chaetomium globosum, Scopulariopsis brevicaulis, Trichoderma koningii andTrichothecium roseum, was studied in solid culture conditions. Minimum degradation was with pure cellulose. Bagasse and wheatstraw were the most suitable for growth and activity of cellulolytic fungi. All fungi contained cellulase activity.

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Résumé On a étudié la biodégradation de la poudre de cellulose pure, de la bagasse et de la paille de froment chez cinq moisissures cellulolytiques,Aspergillus niger, Chaetomium globosum, Scopulariopsis brevicaulis, Trichoderma koningii etTrichothecium roseum, en condition de culture sur milieu solide. La dégradation minimum a lieu avec la cellulose pure. La bagasse et la paille de froment offrent la meilleure croissance et la meilleure activité cellulolytique fungale. Toutes les moisissures exhibent l'activité de la cellulase.

     

Effect of the cultivation conditions of Candida species yeast-like fungi on their sensitivity to levorin]

The effect of levorin on yeast-like fungi under (different) cultivation conditions was studied. It was shown that the medium composition and incubation temperature affected the results of determination of the test-culture sensitivity to levorin. There was correlation between the time of the population lag-phase and the critical time of the zone formation and these values depended on the temperature of the test-microbe vegetation. Strain 037 of C. utilis was more sensitive to levorin and had a longer lag-phase as compared to the other species of the yeast-like fungi, which provided favourable conditions for formation of the growth inhibition zones.     

Wood decay activity and cellulase production by freshwater lignicolous fungi

Wood decay activity and coupled cellulase production were examined for freshwater lignicolous Ascomycetes, Deuteromycetes and an Oomycete. Wood decay ability was assessed by weight changes in wood and bark blocks of ash and cottonwood colonized by test fungi. Changes in wood components were also measured. Production of coupled cellulases was determined by measurement of activity of culture filtrates. Except for early successional species, most fungi caused weight loss in sapwood blocks; all species caused weight loss in bark blocks. Bark blocks were decayed more rapidly than sapwood blocks and cottonwood blocks were decayed more rapidly than those of ash. For four species examined, cellulose and lignin disappeared simultaneously, with cellulose disappearing more rapidly than lignin. All species produced extracellular exoglucanase, endoglucanase and glucosidase when grown in liquid media containing crystalline cellulose. Enzyme production by most of the species was increased by the addition of glucose.     

Effect of cultivation conditions on the activity of respiration of Saccharomyces bayanus]

The effect of sugar and ammonium nitrogen content in the initial nutrient medium as well as the cultivation temperature on the respiration activity and respiratory quotient of yeast used in the champagne manufacture was studied. An addition of ammonium nitrogen stimulated respiratory processes in the yeast cell. The respiration activity increased with an increase of pH to 4.0. With an elevation of the sugar content of the substrate the respiratory quotient increased resulting in an uneconomic utilization of sugar. The maximum respiration activity and minimum respiratory quotient occurred at a temperature of 20 degrees.     

Effect of cultivation conditions on the adhesive activity of Rhodococcus cells towards n-Hexadecane

The effect of cultivation conditions (the composition, acidity, and salinity of the cultivation medium; temperature; and the hydrodynamic conditions of cultivation) on the adhesion of actinobacteria of the genus Rhodococcus to n-hexadecane has been investigated. A study performed showed that the adhesive activity of rhodococci depends on the composition of the cultivation medium and on the cultivation temperature. The possible mechanisms underlying the effect of growth conditions on the adhesion of rhodococci to liquid hydrocarbons and involving changes in the cell lipid content or the zeta potential of cells are addressed. Rhodococcal strains displaying high adhesive activity (80–90%) at a low temperature (18°C), high salinity (5.0% NaCl), and acidity (pH 6.0) of the cultivation medium have been selected as a result of the present work; these strains have a considerable potential for use in bioremediation of soil and water contaminated by hydrocarbons.     

Effect of cellulase size reduction on activity and accessibility

Summary Reducing the size of crude cellulase from Trichoderma reesei with various proteases showed that while the -glucosidase activity on CMC generally increased, the extent of hydrolysis of hardwood and pretreated hardwood decreased. The rank in the decrease in hydrolytic activity is the same as the rank in the decrease in enzyme adsorption on the hardwood or pretreated hardwood.     

Effect of culture conditions on manganese peroxidase production and activity by some white rot fungi

The ligninolytic system of white rot fungi is primarily composed of lignin peroxidase, manganese peroxidase (MnP) and laccase. The present work was carried out to determine the best culture conditions for production of MnP and its activity in the relatively little-explored cultures of Dichomitus squalens, Irpex flavus and Polyporus sanguineus, as compared with conditions for Phanerochaete chrysosporium and Coriolus versicolor. Studies on enzyme production under different nutritional conditions revealed veratryl alcohol, guaiacol, Reax 80 and Polyfon H to be excellent MnP inducers. Electronic Publication     

Effect of cultivation conditions on proteinase production byLactobacillus murinus

Proteinase production byLactobacillus murinus was influenced by temperature, glucose concentration, initial pH and nitrogen sources. Maximum proteinase production occurred at 45°C, pH 6.6 and with 0.5 % (W/V) glucose. Tryptone, peptone and gelatin inhibited it. Member of theScientific Researcher’s Career of theConsejo Nacional de Investigaciones Cientificas y Técnicas (Conicet), Argentina.     

A simple assay with dyed substrates to quantify cellulase and hemicellulase activity of fungi

Summary A simple assay is described for the quantitative measurement of cellulase and hemicellulase activities. It is based on the enzymatic release of stained cleavage products originating from dyed substrates such as different celluloses, mannan and xylan, diffusing from an upper into a lower agar layer. The amount of cleavage products is assessed by direct absorbance measurement in the agar tubes employing an ordinary filter photometer. The method proved to be applicable to various species of basidiomycete fungi.     

Effect of cultivation conditions on the activity of the beromycin producerStreptomyces glomeratus 3980 and its spontaneous variants

Optimal conditions for the submerged cultivation ofStreptomyces glomeratus 3980, producer of the anthracycline antibiotics beromycins, and its variants were sought in media with glucose, soybean meal and salts differing in the content of ammonium sulphate. As compared with the original activity of the strain the antibiotic titre of some variants increased about 12 times on increasing the glucose concentration from 3 to 5 %, or on omitting CaCO₃ from the medium (i.e. under conditions leading to an increased production of propionic acid and suppression of production of the melanin-like pigment). In melanin-less variants accumulating propionate even under standard conditions the activity increased about 18–40 times in the medium with 3 % glucose and 0.2 % CaCO₃ under conditions of more intensive aeration (i.e. under conditions when no propionic acid accumulated). Individual strains also differed in the requirement for (NH₄)₂SO₄ in the medium, their response to changes of volume of the vegetative inoculum and sensitivity to MgSO₄.7H₂O. The biosyiithetic activity of all strains was inhibited by the addition of ZnSO₄.7H₂O or CaCl₂ and substitution of glucose with starch, lactose or sucrose.     

Visualizing cellulase activity

Commercial exploitation of lignocellulose for biotechnological production of fuels and commodity chemicals requires efficient—usually enzymatic—saccharification of the highly recalcitrant insoluble substrate. A key characteristic of cellulose conversion is that the actual hydrolysis of the polysaccharide chains is intrinsically entangled with physical disruption of substrate morphology and structure. This “substrate deconstruction” by cellulase activity is a slow, yet markedly dynamic process that occurs at different length scales from and above the nanometer range. Little is currently known about the role of progressive substrate deconstruction on hydrolysis efficiency. Application of advanced visualization techniques to the characterization of enzymatic degradation of different celluloses has provided important new insights, at the requisite nano‐scale resolution and down to the level of single enzyme molecules, into cellulase activity on the cellulose surface. Using true in situ imaging, dynamic features of enzyme action and substrate deconstruction were portrayed at different morphological levels of the cellulose, thus providing new suggestions and interpretations of rate‐determining factors. Here, we review the milestones achieved through visualization, the methods which significantly promoted the field, compare suitable (model) substrates, and identify limiting factors, challenges and future tasks. Biotechnol. Bioeng. 2013; 110: 1529–1549. © 2013 Wiley Periodicals, Inc.     

Effect of dithiocarbamates on cellulase activity in culture filtrates of Trichoderma reesei

Different concentrations of tetramethylthiuram disulfide (TMTD), sodium dimethyldithiocarbamate (NaDDC), and zinc dimethyldithiocarbamate (ZnDDC) affected the amount of cellulase(s) activity in the culture of Trichoderma reesei. After eight days incubation at 28 degrees C the greatest increase in Avicelase, CMCase, and beta-glucosidase over the control were observed at 0.1 ppm (TMTD) and 0.4 ppm (NaDDC and ZnDCC). There was decrease in the growth in the ZnDDC, but beta-glucosidase activity was reduced considerably. Total protein in the culture filtrate increased with the increase in cellulase(s) activity. No change in pH was observed at eight days incubation but pH increased (not exceeding 5.9) at 12 days incubation.     

Diversity and activity of aquatic fungi under low oxygen conditions

1. The objective was to test whether a decrease in oxygen concentration in streams affects the diversity and activity of aquatic hyphomycetes and consequently leaf litter decomposition. 2. Senescent leaves of Alnus glutinosa were immersed for 7 days in a reference stream, for fungal colonization, and then incubated for 18 days in microcosms at five oxygen concentrations (4%, 26%, 54%, 76% and 94% saturation). Leaf decomposition (as loss of leaf toughness), fungal diversity, reproduction (as spore production) and biomass (ergosterol content) were determined. 3. Leaf toughness decreased by 70% in leaves exposed to the highest O₂ concentration, whereas the decrease was substantially less (from 25% to 45%) in treatments with lower O₂. Fungal biomass decreased from 99 to 12 mg fungi g⁻¹ ash‐free dry mass on exposure to 94% and 4% O₂ respectively. Sporulation was strongly inhibited by reduction of dissolved O₂ in water (3.1 × 10⁴ versus 1.3 × 10³ spores per microcosms) for 94% and 4% saturation respectively. 4. A total of 20 species of aquatic hyphomycetes were identified on leaves exposed to 94% O₂, whereas only 12 species were found in the treatment with 4% O₂ saturation. Multidimensional scaling revealed that fungal assemblages exposed to 4% O₂ were separated from all the others. Articulospora tetracladia, Cylindrocarpon sp. and Flagellospora curta were the dominant species in microcosms with 4% O₂, while Flagellospora curvula and Anguillospora filiformis were dominant at higher O₂ concentrations. 5. Overall results suggest that the functional role of aquatic hyphomycetes as decomposers of leaf litter is limited when the concentration of dissolved oxygen in streams is low.     

Antibiotics from higher fungi

Summary Peculiarities of antibiotic production by higher fungi (Hymenomycetes) are discussed, incidentally the condition for antibiotic production by Penicillium patulum is referred to.Antibacterial action of Psalliota campestris (wild variety) studied in the laboratory is fully described, it is active against Salmonella typhi, Escherichia coli and Staphylococcus aureus. In clinical trials in typhoid cases in our hospitals filtrates used orally and intramuscularly, are giving encouraging results.Laboratory study of antibacterial action of Marasmius campanella has been completed with a view to application to clinical trials in future.