Mucor Hiemalis Research Articles

A new genus of the Piptocephalidaceae (Zoopagales) from Japan

A previously undescribed haustorial mycoparasite of Mucorales was studied at the light-microscopic level, based on dural cultures with three hosts, Mucor hiemalis, Mortierella remanniana, and Cunninghamella elegans. Sporangial and zygosporic development of the parasite are described and illustrated, and salient features of the fungus are compared with those of Piptocephalis and Syncephalis. The new fungus appears more nearly related to Piptocephalis in possessing similar hyphal and haustorial characteristics, dichotomously branched sporangiophores, and a nearly identical form of zygospore. Like a few species of Piptocephalis, the fungus lacks a head-cell, and it forms branched merosporangia one or two terminally on ultimate branches of the sporangiophore. However, merosporangial development in the fungus is unique for the Piptocephalidaceae in that it proceeds by a process of sequential acropetal budding leading to the formation of a more or less highly branched, moniliform sporangiole. Sporangiospores mature simultaneously, are multinucleate, and are liberated by merosporangial disarticulation. Because of its distinctive merosporangium, the Japanese isolate is placed in a new genus and species, huzuhaea moniliformis.

Experimental model for in vitro hydroxylation; micromycetes mucor hiemalis compared to liver microsomal fraction

Experimental model for in vitro hydroxylation; micromycetes mucor hiemalis compared to liver microsomal fraction

Mycoflora of bean, broad bean, lentil, lupine and pea seeds in Saudi Arabia

Using the seed-plate method on glucose-Czapek's agar at 28 °C (±2 °C), 24 genera and 60 species in addition to two varieties were collected from bean, broad bean, lentil, lupine and pea seeds. The most frequent genera were Aspergillus (16 species + two varieties), Penicillium (14 species), Rhizopus (1 species) and Yeasts, followed by Fusarium (3 species), Mucor (4 species) and Drechslera (3 species). From the preceding genera, Aspergillus niger, A.flavus, Penicillium citrinum, Rhizopus stolonifer, Fusarium moniliforme or F. oxysporum, Mucor hiemalis or M. racemosus and Drechslera spicifera were the most prevalent species.

Microbial production of ethylene in desert soils

Ethylene production was monitored in 12 desert soils. In all but two soils with high organic matter content, C 2H 4 production was low. Statistical analysis showed a good correlation between organic matter content and C 2H 4, production. Minimum levels of C 2H 4 were observed in saline and sodic soils. Addition of l-methionine to soil significantly increased C 2H 4 formation, indicating its possible role as a precursor for C 2H 4. Addition of salt to the high C 2H 4-producing soils suppressed C 2H 4 production most probably because of a direct effect on C 2H 4-producing microorganisms through toxic salt levels, high osmotic pressure, increased pH or a combination of these factors. Leaching of four saline soils and subsequent incubation resulted in significant increases in C 2H 4 in two soils. Ethylene producers, previously inhibited by salinity, were probably reactivated when the salts were removed. A Fusarium isolated from the high C 2H 4-producing soil, produced the most C 2H 4 in pure culture followed by isolates belonging to the genera Aspergillus, Penicillium, Curvularia and Rhizopus. A sterilized saline soil produced significant C 2H 4 when inoculated with spores of Mucor hiemalis or the Fusarium isolate, indicating an originally low population of C 2H 4-producing organisms in the saline soil. The two high organic matter soils when sterilized and similarly inoculated produced only a fraction of the C 2H 4 produced in non-sterilized samples, indicating the involvement of a number of species in the production of C 2H 4 in these soils.

Effects of volatile oils from aromatic shrubs on soil microorganisms

Volatile oils from Thymus capitatus, Satureja thymbra and, to a lesser extent, Rosmarinus officinalis stimulate soil respiration. The S. thymbra oil is fungistatic to the germination of Penicillium citrinum spores in soil, and to mycelial growth of Mucor hiemalis in liquid culture. Addition of the S. thymbra oil and, to a lesser extent, R. officinalis oil to soil result in increased bacterial numbers. Bacteria appear to use the oils as carbon and energy sources. Thus the oils appear to have an ecological effect by shifting the soil population balance from fungi to bacteria.

Association between Chrysosporium pannorum and Mucor hiemalis in Poa flabellata litter

Mucor hiemalis was frequently isolated from the litter of Poa flabellata where it apparently grows as a secondary sugar fungus in association with Chrysosporium pannorum.

Antimicrobial Properties of Calcium Peroxide in Relation to Its Potential Use as a Seed Dressing

Calcium peroxide, in a formulation with calcium hydroxide, inhibited the growth of fungi and bacteria in liquid shaken culture. The formulation (‘CaO2’) was effective against spore germination, but less so against hyphal growth on solid or liquid media. With the exception of Mucor hiemalis, similar amounts of Ca(OH)2 alone were not effective; the antimicrobial activity of the formulation depends only partly on its alkalinity. Of the fungi tested, M. hiemalis had the greatest peroxidase activity and showed most resistance to ‘CaO2’ The production of H2O2 and free radicals by ‘CaO2’ may in part account for its action. ‘CaO2’ increased overall carbon release from axenic wheat seed, especially at 17 and 21% (v/v) O2 concentrations, but fructose and glucose exudations were inhibited. Total carbohydrate released was not affected. Sucrose exudation was detected from ‘CaO2’-treated seed, but not from untreated seed. The major form of carbon released from seeds was not carbohydrate and possibly originated from the seed coat. Although exudates supported substantial fungal and bacterial growth, the antimicrobial properties of the formulation suggest that it has potential as a plant protection chemical.

Effect of triglycerides on the production of lipids and lipase by Mucor hiemalis.

The effect of triglycerides on the growth of Mucor hiemalis and the production of lipase and mycelial lipids was studied. Addition of 1% triglycerides to the fermentation medium was best for the mycelial as well as the broth lipase production. The added triglycerides seemed to be utilized through the formation of free fatty acids, and towards the end of the growth phase most of the triglycerides and their hydrolysis products were utilized. The mycelial lipase activity was maximum (66 U/g dry mycelium) at the end of the growth phase, while the maximal broth lipase activity (204 U/100 mL) was achieved after the cell lysis had started. The lipids produced per gram mycelia were high initially (260 mg/g dry weight at 48 h), reducing gradually later. With increase in growth the maximum mycelial lipids per 100 mL of culture medium was obtained after 96 h (176 mg/100 mL). The various fractions detected in the mycelial lipid extracts were sterol esters, triglycerides, free fatty acids, diglycerides, sterols, monoglycerides, phosphatidyl ethanolamine, phosphatidyl choline, and small amounts of an unknown polar lipid at all the stages of fermentation studied. Proportion between total neutral and total polar lipids remained nearly constant throughout fermentation.

A Naturally Occurring Developmental Synergism between the Cellular Slime Mold, Dictyostelium mucoroides and the Fungus, Mucor hiemalis

We here report the second record of a developmentally aberrant strain of a cellular slime mold from natural populations and demonstrate that this Dictyostelium mucoroides variant is capable of undergoing normal morphogenesis in the presence of the phycomycete fungus, Mucor hiemalis. The synergism is induced by an extracellular product(s) which is diffusable through thin agar membranes and is released by the fungus. The presence of the fungus not only induces stalk formation in this stalkless variant, but also increases the rate of sorocarp formation in 3 of 5 additional species of cellular slime molds assayed.

A NATURALLY OCCURRING DEVELOPMENTAL SYNERGISM BETWEEN THE CELLULAR SLIME MOLD, DICTYOSTELIUM MUCOROIDES AND THE FUNGUS, MUCOR HIEMALIS

We here report the second record of a developmentally aberrant strain of a cellular slime mold from natural populations and demonstrate that this Dictyostelium mucoroides variant is capable of undergoing normal morphogenesis in the presence of the phycomycete fungus, Mucor hiemalis. The synergism is induced by an extracellular product(s) which is diffusable through thin agar membranes and is released by the fungus. The presence of the fungus not only induces stalk formation in this stalkless variant, but also increases the rate of sorocarp formation in 3 of 5 additional species of cellular slime molds assayed.

Purification and properties of glutathione peroxidase from Mucor hiemalis.

Selenium-independent glutathione peroxidase was purified from a cell-free extract of Mucor hiemalis by ammoniumsulfate fractionation, column chromatographies on DEAE-Sephadex and hydroxylapatite, and gel filtration on Bio-Gel P-100. The purified enzyme was homogeneous on ultracentrifugation. The enzyme had a molecular weight of 45, 000 and an isoelectric point of 5.2. The enzyme could reduce cumenehydroperoxide and r-butyl hydroperoxide, but could not reduce hydrogen peroxide. The enzymewas highly specific for glutathione as a hydrogen donor. Mucor glutathione peroxidase was proved to be different from mammalian selenium-dependent glutathione peroxidase I and selenium-independent glutathione peroxidase II in some physicochemical and enzymatic properties.

Production of glutathione peroxidase by Mucor hiemalis.

The distribution of glutathione peroxidase was investigated among microorganisms. Glutathione peroxidase was found in the cell-free extracts of molds belonging to the genus Mucor, and Mucor hiemalis showed the highest enzyme activity. The glutathione peroxidase production by M. hiemalis was almost completely associated with the mycelial growth. The addition of oxidants such as hydroperoxides and antioxidants such as glutathione and α-tocopherol did not significantly affect the enzyme production.

Production of lipids and lipase activity during growth of Mucor hiemalis

Production of lipids and lipase activity by a strain of Mucor hiemalis known to have potential for high lipase activity was studied in a medium containing glucose as the carbon source. Most of the glucose was utilized by the end of the growth phase when the mycelium showed maximal lipase activity (17 U/g dry mycelium) as well as maximal lipid content (13 mg/g dr*** mycelium). Maximal broth lipase activity (76 U/100mL) was observed after cell lysis had begun. The fractions identified in the mycelial lipid extracts were sterol esters, triglycerides, fatty acids, diglycerides, sterols, monoglycerides, phosphatidylethanoamine, phosphatidylcholine, phosphatidylserine, and an unknown polar lipid. The proportion between the neutral and the polar lipids was only 0.06 at 44 h, increasing gradually to 1.51 at 164 h of fermentation. A relationship between the production of lipase and the neutral lipids appears to exist.

Photochemical interaction of dictamnine, a furoquinoline alkaloid, with fungal DNA.

The furoquinoline alkaloid dictamnine has been shown to provoke lethal damage to filamentous fungi in near ultraviolet light. The phototoxicity was more pronounced against Mucor hiemalis and Mucor ramannianus than against Fusarium graminearum and Penicillium italicum. In vitro, labeled dictamnine was shown to form covalent monoadducts with purified DNA from M. hiemalis in the presence of long-wave ultraviolet light. Addition of [3H]dictamnine to cultures of the same organism showed photobinding with the fungal DNA in vivo. These results support the suggestion made earlier, on the basis of in vitro experiments with calf thymus DNA, that DNA represents a major cellular target in vivo for the phototoxicity of the alkaloid.

THE EFFECT OF BIPYRIDYL HERBICIDES ON THE LOSS OF NUTRIENTS FROM FUNGI

SummaryParaquat and diquat cause rapid loss of potassium and phosphate from Aspergillus niger, Penicillium frequentans, Mucor hiemalis and Zygorrhynchus heterogamus. The rate of loss is greater at higher concentrations of herbicide, particularly from Zygorrhynchus and Mucor. A brief incubation in paraquat or diquat is followed by sustained loss of potassium when colonies of the four species are transferred to water. Sodium azide also stimulates loss of potassium but thisceases when colonies are transferred to water. Paraquat enhances the level of malondialdehyde, a breakdown product of membrane fatty acids, in Zygorrhynchus and Mucor. These results are discussed with reference to the possible mode of action of bipyridyl herbicides in fungi.

Promotion and Inhibition of Soil Aggregate Stabilization by Micro-organisms

Microbial cells in suspension were added to two soils. After drying, the degree of aggregation and stability of the aggregates to water was estimated by adding water, shaking and measuring turbidimetrically the particles remaining in suspension. In a silt loam (Hamble series), Azotobacter chroococcum, Lipomyces starkeyi and Pseudomonas sp. all promoted the stabilization of aggregates, this being related to the number of cells added, but Mucor hiemalis inhibited the process. In a clay soil (Denchworth series), Mucor hiemalis and Pseudomonas sp. both promoted stabilization. The stabilization of the silt loam by Lipomyces starkeyi was also produced by the polysaccharide extracted from the cell.

Coprophilous fungi of the horse.

A total of 1267 microfungi, including 35 Myxomycetes, were recorded from the fecal samples of the 60 horses; of these 395 were found on 20 saddle-horse feces, 363 on 20 race-horses and 509 on 20 working horses. Eighty two species representing 53 genera were recorded; of these 7 were Zygomycetes, 18 Ascomycetes, 1 Basidiomycetes and 25 Fungi Imperfecti: 2 Myxomycetes. Common coprophilous fungi are in decreasing order Pilobolus kleinii, Saccobolus depauperatus, Mucor hiemalis, Lasiobolus ciliatus, Podospora curvula, Petriella guttulata, M. circinelloides, Coprinus radiatus, Dictyostelium mucoroides, Sordaria fimicola, C. miser, C. stercorariusm, Acremonium sp., Coprotus granuliformis, Graphium putredinis, Iodophanus carneus, Chaetomium murorum, Podospora communis, P. inaequalis, P. setosa, Saccobolus versicolor and Cladosporium cucumerinum. Species of Myrothecium verrucaria, Actinomucor elegans, Kernia nitida, Spiculostilbella dendritica and Mucor parvispora were found exclusively in working-horses feces. Badhamia sp., Anixiopsis stercoraria, Echinobotryum state of D. stemonitis, Geotrichum candidum and Oidiodendron sp. were found only in saddle-horses feces. Chlamidomyces palmarum, Philocopra sp. were found exclusively in race-horses feces. Notes on infrequent or interesting fungi include Thamnostylum piriforme, Phialocephala dimorphospora, Rhopalomyces elegans and Spiculostilbella dendritica.

Myxothiazol, a new antibiotic interfering with respiration.

Myxothiazol, a new antibiotic from the myxobacterium Myxococcus fulvus, inhibited the growth of many yeasts and fungi at concentrations between 0.01 and 3 micrograms/ml. It was generally inactive against bacteria. The inhibitory effect was cytostatic. With Candida albicans, Saccharomyces cerevisiae, and Mucor hiemalis, the growth inhibition was neutralized by glucose. Soon after being added to a cell suspension, the compound almost completely blocked oxygen consumption.

Control of hyphal orientation in colonies of Mucor hiemalis

This is a study of factors controlling the development of hyphae of Mucor hiemalis on a plane uniform agar surface, whereby a single germ tube elongating linearly gives rise to a colony enlarging symmetrically on an approximately uniform front through 360° from its centre. Most branches arise closely behind an existing elongating hyphal tip, and only a small number are formed on older parts of hyphae. The observed distances between successive points of of origin of hyphae fit a γ distribution with estimated shape parameter 1.5 and an estimated scale parameter of 0.011μm. The observed angles at which branches diverged from their parents' axes ranged within a normal distribution (mean 56° σ 17°). The first formed hyphae extend at about 20 μm per h for about 1 h after germination. Subsequently some stop growing permanently or temporarily; variation in the rates of elongation at the remaining tips, and at those branches formed after this first hour fits a half normal curve (mean 85 μm h−1). Growing hyphal tips repel each other, the maximum distances between tips at which this interaction has been seen range from about 10 μm to about 20 μm. No appreciable reorientation has been seen when living tips come close to dead ones, or if they approach agar sites from which another growing tip has been removed. The effects of moving growing tips close to older parts of the mycelium are less regular. Half of 68 observed cases stopped elongating, approximately one quarter (16) grew away from the older hyphae before making contact, approximately one quarter (18) crossed the older hyphae with no visible change in direction. Analysis of patterns produced by computer simulation indicates that the circular shape is the expected result of any system having the observed variation in branching and rates of elongation. No other controlling factor is needed to explain the patterns seen. In particular there is no evidence that orientating interactions between hyphal tips have any biologically important effect on colony shape. The amount to which the observed variation could be increased or reduced without affecting the growth patterns in any biologically important way is being studied.

Myxothiazol, an antibiotic from myxococcus fulvus. (myxobacterales) I. cultivation, isolation, physico-chemical and biological properties.

Myxothiazol (AB-Mx f16-1), a new antifungal antibiotic, is produced by the myxobacterium Myxococcus fulvus strain Mx f16. It is active against many filamentous fungi, and completely inhibits growth of Mucor hiemalis at a concentration of 2 micrograms/ml. The molecular formula of myxothiazol was determined to e C25H33N3O3S2.