Showing papers on "Aspergillus niger published in 1974"

Hydrolysis of lactose in acid whey using beta-galactosidase immobilized on porous glass particles: preparation and characterization of a reusable catalyst for the production of low-lactose dairy products

Abstract: Partially purified lactoses (β-D-galactoside galactohydrolase, EC 3.2.1.23) from Aspergillus niger, Ladobacillus helveticus, and Saccharomyces lactis were immobilized on diazotized porous glass particles (mean pore diameter, 86.5 nm: particle size diameters, 75–125 μm). In acid whey containing 4–4.5% lactose, A. niger lactase gave the highest activity (89 μmoles lactose hydrolyzed/g glass, min) at 55°C and pH 4.5. Glass-immobilized A. niger laclases (lactase-BG) retained much hydrolytic activity after storage and periodic use for 165 days at 55°C. For values of X greater than 30%, hydrolysis of 0.12M lactose in acid whey by a continuous flow column packed with 2 ml of lactase-BG particles could be correlated by X = 17.2(V/F) + 12.5 where X = lactose hydrolysis, percent of lactose originally present; V = volume of packed bed of lactase-BG, ml; F = flow rate of acid whey, ml/min.

Gel entrapment of enzymes: Kinetic studies of immobilized glucose oxidase

Abstract: Glucose oxidase (EC 1134, from Aspergillus niger) has been entrapped in a crosslinked 2-hydroxycthyl methaerylate gel containing 20% poly(vinyl pyrrolidone) The kinetic behavior and thermal stability of the entrapped enzyme were found to closely approximate that of the free enzyme The entrapped glucose oxidase shows a broadened pH profile which is attributed to a buffering effect of the gel Stability of gel entrapped glucose oxidase is extremely good at room temperature, suggesting a variety ofanalytical and control uses for this system

Malformin in Aspergillus niger-Infected Onion Bulbs (Allium cepa)

Abstract: Malformin was identified, by its biological activity and chromatography, in acetone extracts of the outer scales of onion bulbs infected with Aspergillus niger. Malformin was not detected in tissue underlying the infected areas or in the central portions of the bulbs, nor was malformein liberated from extracts or extracted tissues after reduction with zinc in acetic acid. This is the first report of naturally occurring malformin.

The function of the carbohydrate units of three fungal enzymes in their resistance to dehydration.

Abstract: Glucose oxidase (from Aspergillus niger), glucoamylase (from Rhizopus spp.), and cellulase (from Aspergillus niger) of fungal origin are all glycosylated proteins. Dehydration of the three enzymes to a range of water potentials did not affect their activity. However, when more than 10% of the carbohydrate associated with the molecules was removed by periodate oxidation, the enzymes were highly susceptible to dehydration when compared with oxidized controls. Polyvinyl pyrrolidone and Dextran T500 protected the three enzymes in their oxidized state against the effects of dehydration.The carbohydrate units of the enzymes have a function in protecting the enzymes from dehydration and this may be a contributing factor to the survival of microorganisms in environments of low water potentials. The involvement of water associated with the enzyme molecules due to the presence of carbohydrate units is considered to be the protecting mechanism.

Conversion of (-)-Carvone and (+)-Carvone by a Strain of Aspergillus niger

Abstract: The conversion of (−)-carvone and (+)-carvone by a strain of Aspergillus niger was studied as one of the series of biochemical reduction of terpenes.(−)-Carvone was found to be reduced essentially to (+)-neodihydrocarveol, although (+)-dihydrocarvone and (+)-isodihydrocarvone were also formed in small amounts, whereas (+)-carvone was converted to (−)-isodihydrocarvone, (−)-isodihydrocarveol, (−)-neoisodihydrocarveol, (−)-dihydrocarvone, (−)-neodihydrocarveol, and (+)-dihydrocarveol, of which the former three were the major products.The metabolic pathways for (−)-carvone and (+)-carvone by the strain of Aspergillus niger are discussed and the results on microbial and chemical reductions of carvone and dihydrocarvone are summarized.

Production, Purification and Properties of Ribonuclease from Aspergillus niger

Abstract: Aspergillus niger NRC–A–1–233 was cultivated by the shaking method. The optimal cultural conditions for ribonuclease (RNase) production were: composition of medium: sucrose, 15%; NH4NO3, 0.2%; KH2PO4, 0.1%; MgSO4·7 aq., 0.025%; initial pH, 2.2; shaking conditions: 50 ml of medium /500 ml flask; cultivation time, 120 hr. The RNase was purified by acid clay treatment and chromatography on DEAE-cellulose and Sephadex G–75 columns. The purified RNase was homogeneous by ultracentrifuge and disc electrophoresis.The molecular weight of the RNase was estimated to be 28,500 on SDS-polyacrylamide gel and its isoelectric point was 2.8 by Ampholine electrofocusing method. Digestion rate of RNA by the RNase was 100%. The RNase did not have an exact base specificity and produced four kinds of 3′-nucleotides from yeast RNA.

Effect of bongkrekic acid on growth and metabolism of filamentous fungi.

Abstract: The antifungal activity of bongkrekic acid against 17 tested molds was determined. Bongkrekic acid prevented spore germination and mycelial proliferation of Aspergillus niger, Rhizopus oryzae and Penicillium italicum. The action of bongkrekic acid was fungicidal. Under these conditions, the incorporation of 14C-leucine and 14C-uracil into the perchloric acid insoluble material of germinating A. niger conidia was significantly reduced by bongkrekic acid. Respiratory activity of resting spores was not affected by bongkrekic acid. Respiratory activity of germinated spores was inhibited by bongkrekic acid to the extent of 30 to 60% of controls for A. niger, R. oryzae and P. italicum. It has been concluded that operation of adenine nucleotide translocation in mitochondria of tested fungi is obligatory both for normal spore germination and fungal growth.

Increase of fungitoxicity of mercuric chloride by methionine, ethionine and S-methylcysteine.

Abstract: The fungitoxicity of mercuric chloride to Aspergillus niger was increased in the presence of d-, l-, dl-methionine, dl-ethionine, dl-S-methylcysteine or sodium methylmercaptide. The same effect was observed with methionine for two other fungi investigated: Cladosporium cucumerinum and Scopulariopsis brevicaulis. It is suggested that this effect can be ascribed to the formation of CH3SHg+ or (CH3S)2Hg, or the corresponding ethyl compounds. CH3SHgCl and (CH3S)2Hg were synthetically prepared and proved indeed far more fungitoxic than HgCl2. The hypothesis was further substantiated by the observation that A. niger rapidly converts dl-methionine into CH3SH, which undoubtedly reacts with Hg2+ to give the above mentioned methylthiomercury compounds.

The oxidation of D-1-thioglucose by cell-free extract from Aspergillus niger.

Abstract: It was found that d-1-thioglucose was quantitatively converted to the corresponding disulfide with oxygen uptake by incubation with cell-free extract of Asp. niger. The molar ratio of the oxygen uptake to the d-1-thioglucose consumption was 0.22. The oxygen uptake was not affected by KCN, NH2OH and NaN3, but decreased by dialysis of the cell-free extract. The decrease of the oxygen uptake due to dialysis for 4 hr was recovered by the addition of FMN. From these results, a tentative mechanism of the oxidation of d-1-thioglucose was proposed.

Biologically active material

Abstract: Purified polyhedral virus particles capable of stimulating the production of interferon in animals are obtained from the fungal cells of the mold Aspergillus foetidus or Aspergillus niger or from the nutrient medium in which or on which said molds have been grown.

Process for preparing double stranded RNA

Abstract: Virus particles capable of stimulating the production of interferon are isolated from fungal cells of the mould Aspergillus foetidus or Aspergillus niger or from the nutrient medium in which or on which Aspergillus foetidus or Aspergillus niger mould has been grown. Double-stranded RNA material can be isolated from the virus particles extracted from Aspergillus foetidus or Aspergillus niger and said RNA material is capable of stimulating production of interferon. Pharmaceutical compositions comprising said particles or said RNA material in combination with pharmaceutically acceptable carriers and excipients are also provided.

Esterase activity of Aspergillus niger in continuous culture.

Abstract: In citrate limiting medium the esterase activity of Aspergillus niger had a maximum value at the lowest dilution rate (D=0.013 h-1) and at all higher dilution rates progressively decreased in activity. In glucose limiting medium the esterase activity values were always lower than in citrate limiting medium and did not show much variation with varying dilution rate. Electrophoresis of cell free extracts from all dilution rates revealed a multimolecular esterase profile only at D=0.013 h-1 in citrate limiting medium, which was also the only dilution rate to support good conidiation. The increase in esterase activity at D=0.013 h-1 was observed cytochemically to occur in the phialides. No cytochemical esterase staining occurred in the vegetative cultures at all other dilution rates.

Skins and pelts one-step treatment - to effect soaking, unhairing, skin disintegration and drenching, using aq. bath contg. fungus- and bacterial proteinase

Abstract: Unhaired hides ready for tanning to high quality leather are prepd. by treating the raw material, washed free from preserving salt, in a vat or mixer, using an aq. bath contng. dissolved (a) fungus proteinase having optimum activity towards casein at pH >7, (b) bacterial proteinase having optimum activity towards haemoglobin at pH >9, (c) a pri. sec. or tert. amine or cpd. dissociating to form such an amine and opt. (d) a reducing organic S cpd., and adjusting bath to pH 9-12. Pref. proportions of fungus- and bacterial proteinases used are such that proteolytic activity of fungus proteinase in bath is higher than that of bacterial proteinase. Fungus proteinase is derived esp. from aspergillus niger or -flavus cultures, and is used in mixture contng. esp. bacillus subtilis-generated proteinase.