Optimization of the composition of the nutrient medium for cellulase and protein biosynthesis by thermophilic Aspergillus fumigatus NRC 272

Twelve isolates of thermophilic, acidophilic, cellulolytic bacteria were obtained from three different primary enrichment cultures from acidic hot springs at Yellowstone National Park, Wyo. The three isolates which had the highest cellulolytic activity, as shown by the diameter of clearing zones surrounding colonies on cellulose agar plates, were selected for intensive study. All were gram-variable, nonsporulating aerobic rods which formed no pigment. They grew at 37 to 65"C, with optimum growth at 55°C. The pH range for growth was 3.5 to 7, with an optimum pH of 5. The guanine-plus-cytosine content of the deoxyribonucleic acid was 60.7 k 0.6 mol%. The organisms are resistant to penicillin G at 100 pglml. They share several important features with Thermus strains, namely heterotrophic, aerobic, and thermophilic mode of growth; morphological features; sensitivity to lysozyme; and presence of catalase. They differ in other important aspects, such as the pattern of carbon sources utilized for growth, the pH and temperature profiles of growth, the pattern of sensitivity to antibiotics, the guanine-plus-cytosine content of DNA, the composition of amino acids in the cell walls, and the structure of the cell walls. Thermus species are very sensitive to penicillin G, whereas our strains are resistant. Our strains also are different, in important respects, from the genus Thermomicrobium. Therefore, we designate the organism Acidothermus ceZZuZoZyticus gen. nov., sp. nov., of which the type strain is our strain 11B, ATCC 43068.This research effort was undertaken as part of a research program on the production of fuel alcohol from cellulosic biomass materials. The driving hypothesis is that a thermophilic, acidophilic, cellulolytic bacterium can be grown in coculture with other thermotolerant microorganisms to produce ethanol at a high rate from cellulosic wastes. Alternatively, the cellulolytic organism could be used to produce cellulase, which could be added to a cellulose-containing culture of an organism which ferments glucose to ethanol.Most of the thermophilic, cellulolytic microorganisms isolated to date are sporeforming anaerobes belonging to the genus Clostridium. None of these are acidophilic, and all have an optimum pH near 7. Thus, they would not grow well under the acidic conditions (pH 3 to 5 ) prevalent in an ethanolic fermentation.Aerobic, thermophilic, cellulolytic microorganisms include several species of fungi (10) and a few species of filamentous bacteria belonging to the family Actinomycetaceae (33). Among the fungi, Myceliophthora thermophila is of considerable interest, since it grows well on cellulose in submerged culture at 50°C and pH 4.5 and synthesizes cellulolytic enzymes (10). Thus, the organism is acidophilic, as well as cellulolytic and thermophilic. Rosenberg (24) screened 21 species of thermophilic and thermotolerant fungi for the ability to degrade cellulose and found that 13 species had this ability. It was not determined whether these organisms could grow well in submerged culture under...

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“…fumigatus has been shown to grow well on cellulose in submerged culture at 45°C and pH 4.6 and to produce considerable amounts of cellulase (27).…”

mentioning

confidence: 99%

Isolation and Characterization of Acidothermus cellulolyticus gen. nov., sp. nov., a New Genus of Thermophilic, Acidophilic, Cellulolytic Bacteria

Mohagheghi¹,

Grohmann²,

Himmel³

et al. 1986

International Journal of Systematic Bacteriology

140

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“…Shaker et al 44 studied the effect of temperature on growth and cellulase production by Aspergillus fumigatus. They achieved high levels of CMCase and FPA when the temperature was controlled between 40 and 45°C.…”

Section: B Effect Of Temperaturementioning

confidence: 99%

“…In a recent study, Shaker et al 44 reported enhanced levels of cellulase production by the thermophile Aspergillus fumigatus when treated wheat straw was used as the carbon source. Furthermore, they also showed that as the concentration of the inducer (treated wheat straw) was increased, a concomitant increase in cellulase yield resulted.…”

mentioning

confidence: 98%

Thermostable Cellulases from Thermophilic Microorganisms

Margaritis

Merchant

Yaguchi

1986

Critical Reviews in Biotechnology

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“…Cellulase was assayed as described by Shoemaker and Brown (1978). The galactanase, xylanase, arabinogalactanase and polygalacturonase were assayed according to Bateman et al (1969) and the increase in reducing end groups liberated was measured photometrically as previously described.…”

Section: Enzyme Assaysmentioning

confidence: 99%

Impact of salinity stress on soil-borne fungi of sugarbeet

1992

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The sugarbeet cultivar Kaumera was found to be highly susceptible to infection by the root-rot pathogens Rhizoctonia solani and Sclerotium rolfsii in the absence of salinity stress. Under this environmental condition, R. solani was more efficient than S. rolfsii in producing cell wall-degrading enzymes in infected hypocotyls. Xylanase and galactanase were most effective. The rate of cell wall degradation by R. solani was nearly 2.5 times that of S. rolfsii when cells walls of healthy hypocotyls were used as sole carbon substrate for the in vitro produced crude enzymes.Under salinity stress the pathogenicity and the performance of cell wall-degrading enzymes of R.solani and S. rolfsii varied profoundly. Pathogenicity studies showed that R. solani appeared to be more tolerant than S. rolfsii of the salinity stresses applied, and relatively more virulent to cv Kaumera. The activities of cell wall enzymes of R. solani decreased and those of S. rolfsii increased with increased salt concentration when cell wall material was used as a sole carbon source. The metabolic products produced under salinity stress by R. solani and S. rolfsii in the cell wall amended culture media shifted the initial pH towards neutrality or slight alkalinity for R. solani and to high acidity for S. rolfsii.When model substrates were used, xylan and galactan were the most responsive substrates for degradation by the cell wall enzymes of the two fungi studied. The rate of degradation was higher for S.rolfsii than for R. solani. The excessive acidity in salt stressed S. rolfsii culture media suggested reduced activities of the enzymes involved in cell wall degradation in vivo. This may explain the decreased virulence potentialities.

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Optimization of the composition of the nutrient medium for cellulase and protein biosynthesis by thermophilic Aspergillus fumigatus NRC 272

Cited by 11 publications

References 15 publications

Isolation and Characterization of Acidothermus cellulolyticus gen. nov., sp. nov., a New Genus of Thermophilic, Acidophilic, Cellulolytic Bacteria

Isolation and Characterization of Acidothermus cellulolyticus gen. nov., sp. nov., a New Genus of Thermophilic, Acidophilic, Cellulolytic Bacteria

Thermostable Cellulases from Thermophilic Microorganisms

Impact of salinity stress on soil-borne fungi of sugarbeet

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