Some Chemical Changes in the Mycelium of Aspergillus flavus during Autolysis

Loginova, Nadezhda V.; Shishkina, Valentina N.; Trotsenko, I U

doi:10.1099/00221287-45-1-41

Cited by 25 publications

(3 citation statements)

References 18 publications

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“…Earlier work has shown decreases in the contents oflipid, carbohydrate and protein in fungal mycelium during autolysis (Lahoz et al, 1966(Lahoz et al, , 1967Lahoz & Ibeas, 1968;Lahoz et al, 1969). Among the enzymes known to be involved in autolysis are proteases (Matile, 1966) and those involved in cell-wall lysis (Mitchell & Sabar, 1966;Iten & Matile, 1970).…”

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Partial purification and properties of a β-N-acetylglucosaminidase from the fungus Sclerotinia fructigena

Reyes

Byrde

1973

Biochemical Journal

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1. As cultures of the fungus Sclerotinia fructigena autolysed, the filtrates contained increasing quantities of a beta-N-acetylglucosaminidase. 2. The enzyme was purified up to 42-fold by a combination of isoelectric focusing and gel filtration. 3. It ran as a single band in cellulose acetate strip electrophoresis and in isoelectric focusing (pI3.76). 4. The enzyme did not readily hydrolyse chitin or a glycopeptide with terminal N-acetylglucosamine residues, but rapidly degraded the N-acetylglucosamine dimer NN'-diacetylchitobiose; the monomer was readily utilized by the fungus as a nitrogen source. The K(m) value for hydrolysis of p-nitrophenyl beta-2-acetamido-2-deoxy-d-glucopyranoside at 37 degrees C was 2.0mm. The Sclerotinia enzyme was generally less susceptible to inhibition by 2-acetamido-2-deoxygluconolactone and other related sugars than the corresponding enzyme from other sources. Inhibition by excess of substrate was observed. 5. The culture filtrate also contained N-acetylgalactosaminidase activity; conflicting evidence was obtained as to whether the same enzyme was responsible for both hexosaminidase activities.

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Partial purification and properties of a β-N-acetylglucosaminidase from the fungus Sclerotinia fructigena

Reyes

Byrde

1973

Biochemical Journal

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“…Aspergillus niger grows in a dispersed filamentous mycelium. The criterium of autolysis we have adopted throughout this work has been the decrease in mycelial dry weight with incubation time, as it is usual in these studies (BEHR 1930, RITTER 1955, LAHOZ et al 1966, TRINCI and RIGHELATO 1970, REYES et al 1980. The beginning of autolysis is taken as the time a t which the mycelium weight in the culture is maximal.…”

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Lytic enzyme activity in autolysing mycelium of Aspergillus niger

Lahoz

Reyes

Gómez

et al. 1983

J of Basic Microbiology

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We have studied changes in the activity of some lytic enzymes contained in mycelium of Aspergillus niger in cultures relative to the autolytic phase of growth. Acid phosphatase, polygalacturonidase and α‐amylase activity reached its highest level (40.7, and 8 U/sample, respectively) at the initiation of the autolytic phase of growth. 1,3‐ß‐Glucanase and ß‐N‐acetylglucosaminidase reached its highest level (3.5 and 2 U/sample, respectively) during the first days of autolysis. Alkaline phosphatase, cellulase, invertase, esterase, chitinase and proteolytic activity is also present in autolysing mycelium of A. niger, though comparatively low. Their maximum activity coincided with the beginning of the autolytic phase of growth. In all enzymes studied here, as autolysis proceeded, enzyme activity decreased by about 90%. Only esterase activity remained nearly constant throughout the whole period of autolysis described here.

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“…Nitrogen availability is another possible growth limiting factor. Some estimates of the nitrogen content of fungal mycelia range from 0.2 to 9% of dry weight (Lahoz et al, 1966;Dawson et al, 1989;Watkinson et al, 2006). Assuming a typical value of 5% nitrogen content, the 0.66 g/L of (NH 4 ) 2 SO 4 (i.e., 0.14 g/L N) provided in AMS medium would correspond to the production of approximately 2.8 g/L of dry biomass.…”

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confidence: 99%

Metabolomic Analysis Reveals Contributions of Citric and Citramalic Acids to Rare Earth Bioleaching by a Paecilomyces Fungus

2020

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Conventional methods for extracting rare earth elements from monazite ore require high energy inputs and produce environmentally damaging waste streams. Bioleaching offers a potentially more environmentally friendly alternative extraction process. In order to better understand bioleaching mechanisms, we conducted an exo-metabolomic analysis of a previously isolated rare earth bioleaching fungus from the genus Paecilomyces (GenBank accession numbers KM874779 and KM 874781) to identify contributions of compounds exuded by this fungus to bioleaching activity. Exuded compounds were compared under two growth conditions: growth with monazite ore as the only phosphate source, and growth with a soluble phosphate source (K 2 HPO 4 ) added. Overall metabolite profiling, in combination with glucose consumption and biomass accumulation data, reflected a lag in growth when this organism was grown with only monazite. We analyzed the relationships between metabolite concentrations, rare earth solubilization, and growth conditions, and identified several metabolites potentially associated with bioleaching. Further investigation using laboratory prepared solutions of 17 of these metabolites indicated statistically significant leaching contributions from both citric and citramalic acids. These contributions (16.4 and 15.0 mg/L total rare earths solubilized) accounted for a portion, but not all, of the leaching achieved with direct bioleaching (42 ± 15 mg/L final rare earth concentration). Additionally, citramalic acid released significantly less of the radioactive element thorium than did citric acid (0.25 ± 0.01 mg/L compared to 1.18 ± 0.01 mg/L), suggesting that citramalic acid may have preferable leaching properties for a monazite bioleaching process.

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Some Chemical Changes in the Mycelium of Aspergillus flavus during Autolysis

Cited by 25 publications

References 18 publications

Partial purification and properties of a β-N-acetylglucosaminidase from the fungus Sclerotinia fructigena

Partial purification and properties of a β-N-acetylglucosaminidase from the fungus Sclerotinia fructigena

Lytic enzyme activity in autolysing mycelium of Aspergillus niger

Metabolomic Analysis Reveals Contributions of Citric and Citramalic Acids to Rare Earth Bioleaching by a Paecilomyces Fungus

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