Fungus Humicola Research Articles

Purification and General Properties of the Lipase of Thermophilic Fungus Humicola lanuginosa S-38

The crude lipase powder has been purified 216-fold in specific activity by means of pH adjustment, DEAE-Cellu1ose, DEAE-Sephadex A-50, CM-Sephadex C-50 and Sephadex G-200 column chromatography and the recovery of the activity was 30%. The purified lipase was confirmed to be homogeneous with disc electrophoresis and ultracentrifugal analyses. The purified lipase was stable in the pH range from 7.0 to 10.0. Optimal pH for the lipolysis of polyvinyl alcohol-emulsified olive oil at 45°C was 8.0 and optimal temperature was 60°C. The purified lipase was stable up to 60°C and retained 55% of full activity after heating at 70°C for 20 min.

Proteins of the Thermophilic Fungus Humicola lanuginosa: I. ISOLATION AND AMINO ACID SEQUENCE OF A CYTOCHROME c

Abstract Two eukaryotic cytochrome c components, ca and cb, were purified from the thermophilic fungus Humicola lanuginosa. These proteins appear to differ only in the degree of methylation of lysyl amino groups. The ca component is the first cytochrome c of fungal origin found to contain 2 residues of methylated lysine. The complete amino acid sequence of H. lanuginosa cytochrome ca, the major component, was established. The protein consists of a single polypeptide chain of 111 residues. On alignment with vertebrate cytochromes c, the peptide chain extends for 8 residues at the amino-terminal end. As with other fungal cytochromes c of known sequence, residue 104 is deleted. Considering the region of residues 1 through 103, H. lanuginosa cytochrome ca most closely resembles the primary structure of Neurospora crassa cytochrome c. The two proteins show 18 differences. H. lanuginosa cytochrome ca contains a phenylalanyl residue at position 74. Other cytochromes c of known sequence contain a constant segment from residues 70 to 80, with a tyrosyl residue situated at position 74.

Cultural Conditions and Some Properties of the Lipase of Humicola lanuginosa S-38

The cultural conditions for the production of thermostable lipase by a thermophilic fungus Humicola lanuginosa S-38 were investigated. The optimal cultural conditions to obtain the maximum yield of thermostable lipase with a 600-liter stainless steel fermentor were as follows: optimal medium- 2.0% soluble starch, 5.0% corn steep liquor, 0.2% K2HPO4, 0.1% MgSO4·7H2O, 0.5% CaCO3, 0.5% soybean oil, 0.005% deforming agent (Adecanol LG-109); optimal fermentation conditions- temperature 45°C; rate of agitation 300 rpm; initial pH 7.0; rate of aeration 1/1 volume per volume of medium per minute. The optimal pH of the crude lipase preparation for the hydrolysis of the polyvinyl alcohol-emulsified olive oil was 8.0 and the optimal temperature was 60°C. It retained 100% of activity with the heat treatment at 60°C for 2 hr, but at 70°C for 20 min only 35% activity retained.

Saprophytic Activity of Rhizoctonia as Affected by the Carbon‐Nitrogen Balance of Certain Organic Soil Amendments

AbstractCarbon (C) from cellulose added to soil slightly suppressed the competitive saprophytic activity of Rhizoctonia, whereas nitrogen (N) from NH4NO3 increased it. Cellulose and NH4NO3, combined to produce a wide range of C/N ratios and incorporated in soil, suppressed Rhizoctonia activity at most C/N ratios. With certain exceptions, soil bacteria and fungi increased in numbers with decreasing C/N ratios. Soil streptomycetes were not greatly affected. Oat straw and soybean hay enriched with NH4NO3suppressed Rhizoctonia activity at all C/N ratios tested. The cellulolytic fungus Humicola greatly increased in numbers in the presence of decomposing oat straw whereas Trichoderma was not affected.