Colchicine after-effects on the absorption and utilisation of sucrose by Cunninghamella sp.

Summary Colchicine had no significant effects on the rate of growth of Cunninghamella when administered in 5 p.p.m. concentration; at 10 p.p.m., it induced a slight increase, while at higher concentrations it lowered the dry weight. Pretreatment with colchicine, during the fungal growth induced a persistant activation of hexose phosphorylases, particularly fructose phosphorylase; more promenantly by the continuous supply of the drug than during the recovery on Richard's medium; a phenomenon that might be partially or wholly alleviated by transfer of the treated mats to Richard's solution alone. In all cases the CO₂ output of the treated samples was unaffected by the drug except at higher levels (20 p.p.m.).Colchicine treatment favoured the accumulation of polysaccharides; the rate of accumulation depended entirely on both the dose and duration of administration. Furthermore, lower concentrations of the drug favoured nucleoprotein formation but had no effect on nucleotides while the higher concentrations reduced both fractions: a phenomenon that persisted whether the tissues were continuously fed with the drug or recovering on nutrient solution alone.The changes in the metabolic pathways of the absorbed sugars have been thoroughly discussed.     

On the mechanism of sucrose utilisation by mycelial felts of Rhizoctonia solani

Summary The utilisation of sucrose and its constituent monosaccharides, as well as of maltose and raffinose by mycelial felts of Rhizoctonia solani was studied with a view to throwing some light on the mechanism of utilisation of sucrose by the fungal mats being tested. The results obtained suggest that sucrose is, most probably, utilised through a process of hydrolysis by a -heterofructosidase enzyme.     

On the mechanism of sucrose utilisation by mycelial felts of Rhizoctonia solani

Summary The results of the present investigation proved that sucrose is utilised by mycelial mats of Rhizoctonia solani through a process of hydrolytic cleavage into glucose and fructose affected by an enzyme of the fructofuranosidase type attached to the cytoplasmic surfaces and not through the mediation of a specific sucrose phosphorylase enzyme.     

Effect of ascorbic acid on respiration and carbohydrate metabolism of mycelial felts ofCunninghamella sp.

Ascorbic acid induced rapid sucrose absorption accompanied by increased keto acid content and respiration rate. Lower concentrations of the vitamin activated glucosan and galactosan accumulation while an increase of concentration of the drug above 20 p.p.m. attenuated the former and furthered the latter with a simultaneous increase in the disaccharide content. In all cases, the acid had no effect on either the free or conjugated monosaccharides, recorded in this investigation, but increased the nucleoprotein content to a constant value regardless of the variation of concentration of the vitamin. The gain in dry weight of ascorbic acid-treated mats did not account for the high sugar uptake, suggesting an alteration in the pathways of carbohydrate metabolism.     

Effect of colchicine on the nitrogen metabolism and fate of phosphates absorbed during the formation of fungal felts of cunninghamella sp.

Summary During formation of fungal mats of Cunninghamella sp., colchicine seemed to have no effect on the mycelial dry weight but increased the phosphorus and nitrate uptake only when present in 20 p.p.m. All treatments increased the organic phosphorus content and peptide fraction of the tissue medium systems. These phenomena were furthered by raising the concentration of the drug. Colchicine showed its inhibitory effects on protein synthesis only when administered in the high concentration. The mechanism of nitrate utilisation in presence of colchicine was also discussed.     

Effect of colchicine on the carbohydrate metabolism of mycelial felts of cunninghamella Sp.

Summary An experiment is reported in which 5 days old Cunninghamella spec. mats were incubated at 25°C over Richard's medium alone or together with colchicine. The results show that, up to 20 p.p.m., colchicine had no effect on dry weight and soluble sugar content of the fungal mats but caused an acceleration in the rate of sugar absorption and utilisation and polysaccharide accumulation especially the glucosans. 10 p.p.m. concentration further induced an increase in CO₂ production and synthesis of mononucleotides and nucleoproteins as indicated by excessive accumulation of conjugated pentoses and the pentosan fraction of polysaccharides.     

Studies on the mechanism of action of sulfanilamide on mycelial felts of Rhizoctonia solani

Summary Sulfanilamide induced strong inhibitory effects on the growth, respiration and carbohydrate synthesis by mycelial felts of Rhizoctonia solani. The possible reasons for such inhibitory effects are discussed.The inhibitory effects of sulfanilamide were almost completely alleviated by the inclusion of p-aminobenzoic (PABA) acid in the culture medium of the fungal mats. R. solani normally produces certain amounts of PABA and its growth and metabolism is inhibited in presence of excess of it.     

Studies on the mechanism of fungicidal action of crystal violet on mycelial felts of fusarium culmorum

Summary Crystal violet, when incorporated in culture media of mycelial felts of Fusarium culmorum, reduced, or in certain cases stopped, the uptake of nitrate-nitrogen, protein and peptide synthesis, and carbon dioxide output by the mycelial mats.Addition of cysteine hydrochloride or sodium glutamate to the culture media did not alleviate the toxicity of crystal violet.The possible mode of fungicidal action of crystal violet is discussed.     

Studies on the mechanism of fungicidal action of mercuric chloride on mycelial felts of Rhizoctonia solani

Summary Mercuric chloride induced strong inhibitory effect on the growth, respiration and carbohydrate synthesis by mycelial felts of R. solani. Such inhibitory effects can be antagonised by the amino acid cysteine when mixed with the toxin in the nutritive medium. Methionine failed to do so. The possible explanations for the inhibitory actions of mercuric chloride are thoroughly discussed.     

Effect of organic acids on the growth,respiration, and nitrogen metabolism of mycelial felts of fusarium culmorum

Summary The rate of building up of proteins by Fusarium culmorum seems to be accelerated, to a marked extent, in presence of sodium salts of various organic acids, a fact which is most pronounced in case of sodium fumarate.The presence of sodium fumarate in the culture medium induced a slight increase, while the presence of sodium acetate led to a marked decrease, in the amounts of carbon dioxide given off by the mycelial mats when compared to the control samples.The presence of fumarate, succinate or citrate in the culture medium led to a significant increase in mycelial dry weights over the controls.     

氮饥饿补糖分批培养小克银汉霉产γ-亚麻酸的研究

对小克银汉霉C2(Cunninghamella sp．C2)发酵生产γ-亚麻酸工艺进行研究,发现氮饥饿补糖能有效地积累γ-亚麻酸,在第5、6、7d每天补糖15g／L,培养10d后生物量、油脂和γ-亚麻酸的产量分别达到47．4g／L、19.74g／L和1．86g／L,为分批培养的2．85、2．08和2．07倍。     

Metabolism of naphthalene by Cunninghamella elegans.

Cunninghamella elegans grown on Sabouraud dextrose broth in the presence of naphthalene produced six metabolites. Each product was isolated and identified by conventional chemical techniques. The major metabolites were 1-naphthol (67.9%) and 4-hydroxy-1-tetralone (16.7%). Minor products isolated were 1,4-naphthoquinone (2.8%), 1,2-naphthoquinone (0.2%), 2-naphthol (6.3%), and trans-1,2-dihydroxy-1,2-dihydronaphthalene (5.3%). C. elegans oxidized both 1-naphthol and 1,4-naphthoquinone to 4-hydroxy-1-tetralone. The results suggest that C. elegans oxidizes naphthalene by a sequence of reactions similar to those reported for the mammalian metabolism of this hydrocarbon.     

Antimicrobial activity and carbohydrate specificity of new mycelial lectins from Fusarium sp.

In the present study, ten Fusarium sp. were screened for the presence of lectins by hemagglutination assay using human and animal erythrocytes. Amongst them nine species, namely F. acuminatum, F. chlamydosporium, F. coeruleum, F. compactum, F. concolor, F. crookwellense, F. culmorum, F. decemcellulare and F. dimerum were found to possess lectin activity. Neuraminidase treatment to rabbit erythrocytes considerably augmented hemagglutination titre, but no such effect was observed with protease-treated erythrocytes. Lectins were tested for inhibition of hemagglutination activity against a panel of carbohydrates. Majority of the lectins were inhibited by L-fucose, D-galactose, bovine submaxillary mucin and dextran. γ-Globulin was inhibitory against lectins from F. acuminatum, F. chlamydosporium, F. compactum and F. culmorum at a concentration of >250 μg/mL, whereas bovine submaxillary mucin and porcine stomach mucin were observed to be strongest inhibitors of lectin from F. compactum with minimum inhibitory concentration of 7.18 μg/mL and 15.6 μg/mL, respectively. Most of the lectins displayed antimicrobial activity against Bacillus cereus, Escherichia coli, Staphylococcus aureus and Aspergillus niger. Lectins from F. chlamydosporium, F. culmorum and F. crookwellense have also exhibited antimicrobial activity against Candida albicans. These findings illustrate the significance of Fusarium sp. lectins in clinical applications.     

Biotransformation of fluorene by the fungus Cunninghamella elegans.

The metabolism of fluorene, a tricyclic aromatic hydrocarbon, by Cunninghamella elegans ATCC 36112 was investigated. Approximately 69% of the [9-14C]fluorene added to cultures was metabolized within 120 h. The major ethyl acetate-soluble metabolites were 9-fluorenone (62%), 9-fluorenol, and 2-hydroxy-9-fluorenone (together, 7.0%). Similarly to bacteria, C. elegans oxidized fluorene at the C-9 position of the five-member ring to form an alcohol and the corresponding ketone. In addition, C. elegans produced the novel metabolite 2-hydroxy-9-fluorenone.     

Biotransformation of chlorpromazine and methdilazine by Cunninghamella elegans.

When tested as a microbial model for mammalian drug metabolism, the filamentous fungus Cunninghamella elegans metabolized chlorpromazine and methdilazine within 72 h. The metabolites were extracted by chloroform, separated by high-performance liquid chromatography, and characterized by proton nuclear magnetic resonance, mass, and UV spectroscopic analyses. The major metabolites of chlorpromazine were chlorpromazine sulfoxide (36%), N-desmethylchlorpromazine (11%), N-desmethyl-7-hydroxychlorpromazine (6%), 7-hydroxychlorpromazine sulfoxide (36%), N-hydroxychlorpromazine (11%), 7-hydroxychlorpromazine sulfoxide (5%), and chlorpromazine N-oxide (2%), all of which have been found in animal studies. The major metabolites of methdilazine were 3-hydroxymethdilazine (3%). (18)O(2) labeling experiments indicated that the oxygen atoms in methdilazine sulfoxide, methdilazine N-oxide, and 3-hydroxymethdilazine were all derived from molecular oxygen. The production of methdilazine sulfoxide and 3-hydroxymethdilazine was inhibited by the cytochrome P-450 inhibitors metyrapone and proadifen. An enzyme activity for the sulfoxidation of methdilazine was found in microsomal preparations of C. elegans. These experiments suggest that the sulfoxidation and hydroxylation of methdilazine and chlorpromazine by C. elegans are catalyzed by cytochrome P-450.