Mucor Hiemalis Research Articles

Implications of ethylene production by bacteria for biological balance of soil

ETHYLENE in soil causes fungistasis1, affects the growth of bacteria, actinomycetes and nematodes (unpublished data) and consequently must influence many soil biological processes. Mucor hiemalis has been proposed as a major producer of ethylene in soil2 although earlier work suggested that facultative anaerobes may be involved3. Our studies show clearly that the main production of ethylene in soil is by spore-forming bacteria in anaerobic microsites. These bacteria seem to be an integral part of a self-regulating cycle in soil controlling microbial activity and with far-reaching implications for the biological balance of soil.

Mode of Ethylene Formation by Mucor hiemalis

Mode of Ethylene Formation by Mucor hiemalis

A Study on Variability in Mucor hiemalis and Related Species

A Study on Variability in Mucor hiemalis and Related Species

Occurrence of trans-phytoene in microorganisms grown in the absence of carotenogenesis inhibitors

Cultures of two blue green mutants of Rhodospirillum rubrum and cultures of Mucor hiemalis grown anaerobically in the light show the presence of trans-phytoene. An hypothesis is advanced for the biological occurence of this natural isomer of phytoene.

Humoral encapsulation in Diptera (Insecta): defence reactions ofChironomuslarvae against fungi

Humoral encapsulation is an effective defence reaction against fungal pathogens. The development of injected spores in the haemocoele ofChironomuslarvae may be completely (Aspergillus niger) or partially (Mucor hiemalis) prevented by this reaction. The encapsulation proceeds very rapidly; within 5 min of injection most of the spores are enclosed in a solid capsule. Disintegrating blood cells may participate in the formation of capsule substance, but this is not usually the case. Encapsulation also occurs within the cuticle against invading hyphae ofBeauveria bassiana. Histochemical tests show that the capsule substance does not consist of polysaccharides; some tests for proteins and all tests for melanin were positive. The significance of melanin formation and the biochemistry of the phenoloxidase system in insects is discussed in detail. The data presented lead to the conclusion that humoral encapsulation is based upon an activation of phenoloxidases and that the capsule substance represents a polyphenol—protein complex. In contrast to current opinion, the formation of melanin in cellular as well as in humoral encapsulation is not considered to be a secondary process, independent of the actual encapsulation procedure. Instead, the authors interpret the presence of melanin as an indication of the activity of phenoloxidases which cause the formation of a capsule substance on the surface of the parasites.

Formation of Ethylene by a Soil Fungus

SUMMARY: Methionine is a substrate for ethylene formation in Mucor hiemalis, but glucose is also required for maximal ethylene production. The formation of ethylene from these substrates in a defined mineral salts medium was studied both with sealed shaken flasks and with a chemostat. Oxygen promoted growth and ethylene production per unit weight of organism. That anaerobic conditions appear to be necessary to observe ethylene accumulation in the soil is probably because soil anaerobiosis mobilizes the substrates required for ethylene biosynthesis.

Metabolic products of microorganisms 123. Thraustomycin, a new antifungal nucleoside antibiotic from Streptomyces exfoliatus.

A new nucleoside antibiotic, inhibiting the growth of fungi, could be isolated from Streptomyces exfoliatus. The antibiotic was found by a screening method based on the inhibition of zygospore formation of Mucor hiemalis. It is composed of equal amounts of adenine, L-leucine, and an unusual tetrahydroxy-monocarbonic acid, C11H14O9 with properties similar to a carbohydrate.

A study of the kinetics of hyphal extension and branch initiation of fungal mycelia.

Growth of Mucor hiemalis, Geotrichum candidum, Aspergillus nidulans, Neurospora crassa and Penicillium chrysogenum was studied by time lapse photography. The total hyphal length of the mycelium of each species increased at an exponential rate; in M. hiemalis exponential growth continued until the mycelium had a total hyphal length in excess of 10 mm. After spore germination there was an initial phase of discontinuous tip production followed by a phase of ‘continuous’ tip production. The hyphal length and number of tips possessed by a mycelium increased exponentially at approximately the same specific growth rate. The amplitude of the oscillations in the length of the hyphal growth unit of a mycelium decreased progressively during mycelial growth and eventually the growth unit attained a more or less constant value. The results support the hypothesis that mycelial growth involves the duplication of a ‘growth unit’ which consists of a tip and a certain mean length of hypha.

Formation de phytoene all- trans chez Mucor hiemalis

When grown in the presence of carotenogenesis inhibitors, Mucor hiemalis synthesizes, particularly in the light, but also in the dark, a mixture of phytoene isomers, the configuration of which has been studied with ultraviolet, infrared and especially NMR spectroscopy. The inhibitor action mechanism is not well established, but we have been able to show that the inhibitors might behave as phytoene sensitizers in vitro as well as in vivo. This made us suppose that a phytoene part arises from the photoisomerization without enzymatic intervention. Therefore, we must emphasize particularly the presence of small quantities of trans-phytoene in the light and in the absence of inhibitors. In conclusion the trans-isomer seems to be synthesized normally in the cell.

Culture turbidity as a measure of mould growth

Culture turbidity is evaluated as a parameter of mould growth. The growth kinetics of Geotrichum candidum, Verticillium agaricinum, Mucor hiemalis and Fusarium avenaceum as measured by changes in culture turbidity were similar to those observed for unicellular micro-organisms. The doubling time for G. candidum at 30° was 1·1 h; this is believed to be the fastest recorded growth rate for a , eucaryotic organism. V. agaricinum and F. avenacearum produced spores during growth in submerged culture.

A preliminary study of the growth of fungi and bacteria from temperate and antarctic soils in relation to temperature

The growth of fungi isolated from a lowland temperate site (Roudsea Wood National Nature Reserve), an upland temperate moorland (Moor House National Nature Reserve) and an oceanic Antarctic island (Signy, S. Orkneys) was compared at 1, 14 and 25°C. This showed that low temperatures caused greatest retardation of growth in fungi from the warmest site (Roudsea) and least from the coldest site (Signy Island). At Moor House, fungi which were isolated most frequently in winter were able to grow better at 1°C than summer forms. The fungal flora of Signy Island was restricted and consists of cold tolerant cosmopolitan species which have been selected by or become adapted to the prevailing low temperatures. Of fungi isolated from any two of the sites, Mortierella alpina and Mucor hiemalis showed temperature adaptation correlated with prevailing site temperature, while Trichoderma viride, Penicillium thomii, and P. frequentans showed no adaptation. The growth of bacteria isolated from Moor House and Signy Island was also compared at 1,13 and 25°C, and 56 per cent of the Moor House isolates grew best at 25°C compared with 2 per cent of the bacteria from Signy Island. The majority of the latter grew best at 13°C and were Gram-negative rods.

Inhibition of fungal sporulation by aflatoxin.

The fungi Penicillium expansum, Aspergillus niger, Cladosporium herbarum, Thamnidium elegans, Mucor hiemalis and Rhizopus nigricans were cultivated on filter disks containing various concentrations of crude aflatoxin or coumarin. After 3 days the rate of sporulation was noted. 100 μg/disk aflatoxin inhibits the sporulation of all fungi with the exception of P. expansum which was only slightly influenced. 10 μg/disk aflatoxin also exerts a restricting influence on most of the fungi, whereas at 1 μg/disk aflatoxin the quantity of newly formed spores was nearly equal to the toxin-free controls. In comparison with the action of coumarin it is evident that the influence of aflatoxin is specific for that toxin and not or only in a small degree dependent on an action of the coumarin nucleus itself.

Turgor pressure of fungal mycelia

The osmotic water potential and turgor pressure of fungal mycelia were determined by thermocouple psychrometry. The water potential ( ψ ) of intact aerial mycelia was assumed to be the same as that of the growth substrate: the osmotic water potential ( ψ s ) of the mycelia was determined by psychrometric measurement of the water potential of disrupted samples of the mycelia. Turgor pressure ( ψ p ) of the mycelia was calculated by difference ( ψ p =ψ-ψ s ). The effect of decreasing substrate water potential on the turgor pressure, osmotic water potential and colony growth rate of Mucor hiemalis and Aspergillus wentii was evaluated, using sucrose and KCl to control substrate water potential. Mycelial turgor pressure ranged from 4 to 11 bar for M. hiemalis and 12 to 18 bar for A. wentii but showed no consistent relationship to growth rate or to substrate and osmotic water potential. The results indicate that solute-induced growth retardation of M. hiemalis probably involves an inhibitory influence of low internal osmotic water potential.

The alkaoids of fungi. I. The formation of ergoline alkaloids by representative mold fungi.

Examination of different species of local fungi, grown on two nutritive solutions of different composition, for alkaloid formation was investigated. The formation of alkaloids was confined to four species, namely: Geotrichum candidum, Mucor hiemalis, Aspergillus flavus and Rhizopus nigricans. A comparative study of the growth as well as the formation of alkaloids by these species and by Claviceps purpurea NRRL was carried out. Methods were also described with which the different alkaloids produced by the experimental strains were identified. Peptides as well as clavine type alkaloids were detected in all cases except with Mucor hiemalis where a compound corresponding to ergosine was the only alkaloid present.

Biotransformation of Domestic Wastewater Treatment Plant Sludge by Two-Stage Integrated Processes -Lsb & Ssb

The study of biotransformation of domestic wastewater treatment plant (DWTP) sludge was conducted in laboratory-scale by two-stage integrated process i.e. liquid state bioconversion (LSB) and solid state bioconversion (SSB) processes. The liquid wastewater sludge [4% w/w of total suspended solids (TSS)] was treated by mixed filamentous fungi Penicillium corylophilum and Aspergillus niger, isolated, screened and mixed cultured in terms of their higher biodegradation potential to wastewater sludge. The biosolids was increased to about 10% w/w. Conversely, the soluble [i.e. Total dissolve solid (TDS)] and insoluble substances (TSS) in treated supernatant were decreased effectively in the LSB process. In the developed LSB process, 93.8 g kg-1of biosolids were enriched with fungal biomass protein and nutrients (NPK), and 98.8% of TSS, 98.2% of TDS, 97.3% of turbidity, 80.2% of soluble protein, 98.8% of reducing sugar and 92.7% of chemical oxygen demand (COD) in treated sludge supernatant were removed after 8 days of treatment. Specific resistance to filtration (1.39x1012 m/kg) was decreased tremendously by the microbial treatment of DWTP sludge after 6 days of fermentation. The treated biosolids in DWTP sludge was considered as pretreated resource materials for composting and converted into compost by SSB process. The SSB process was evaluated for composting by monitoring the microbial growth and its subsequent roles in biodegradation in composting bin (CB). The process was conducted using two mixed fungal cultures, Trichoderma harzianum with Phanerochaete chrysosporium 2094 and (T/P) and T. harzianum and Mucor hiemalis (T/M); and two bulking materials, sawdust (SD) and rice straw (RS). The most encouraging results of microbial growth and subsequent solid state bioconversion were exhibited in the RS than the SD. Significant decrease of the C/N ratio and germination index (GI) were attained as well as the higher value of glucosamine was exhibited in compost; which clearly implied that the increased bioconversion occurred in the treated process. Comparatively, superior composts were produced by T/P at 50-60 days of SSB. Significantly lower heavy metals (Pb, Cd, Cr, Ni, Cu and Zn) were recorded in chemical analysis of the end products (composts) after SSB, in comparison to the USA’s recognized limits for application in municipal solid waste (MSW).Keywords: Liquid state bioconversion, solid state bioconversion, domestic wastewater sludge, filamentous fungi, biosolids and compost.

A kinetic study of the growth of Aspergillus nidulans and other fungi.

SUMMARY The growth kinetics of Aspergillus nidulans, Mucor hiemalis and Penicillium chrysogenum on solid media and in submerged culture were studied. Growth of A. nidulans colonies on solid medium can be divided into the four phases of lag, exponential, deceleration and constant growth rate. The growth kinetics of A. nidulans in submerged culture were similar to those commonly found for unicellular micro-organisms. The effects on colony radial growth rate, of glucose concentration, medium depth, oxygen partial pressure and temperature were studied. The radial growth rate of glucose-limited colonies of A. nidulans increased linearly with the log. of the initial glucose concentration. The effects of glucose concentration on internode length, hyphal density and hyphal diameter were also studied. At glucose concentrations above 1 % (w/v) there was an inverse relation between the radial growth rate of A. nidulans colonies and their peripheral hyphal density. The relations between colony radial growth rate (Kr ) and germ tube specific growth rate (α g ) on solid media and specific growth rate in submerged culture (α s ) were investigated. Direct proportionality between Kr and α s of A. nidulans was found by varying specific growth rate by temperature changes. The germ tubes of A. nidulans conidia grew exponentially at a rate which was about 2·3 times as great as the specific growth rate of the organism in submerged culture. The colony radial growth rates of the three moulds could not be used as a measure of their relative specific growth rates in submerged culture.

The spatial and seasonal distribution of microscopic fungi in Arable soils

The results from comprehensive, regularly repeated analyses of soil fungi in two wheat-field soils were examined for information about preferential colonization of microhabitats and for seasonal variation in numbers of fungi. Using a soil washing technique, a limited number of species was found with significant preference for organic particles. The majority of species, however, were equally well or better represented on mineral particles. In some cases, where a slightly higher percentage of isolations was found on organic particles, the results for a series of analyses were nevertheless more constant for mineral particles. The latter are, therefore, to be preferred for soil fungus analyses. An exception must be made, however, for Fusarium spp., Mucor hiemalis, and Gaeumarmomyces graminis, which showed a more pronounced predilection for organic particles. Seasonal variation could not be demonstrated for most species, since the variation within a plot was almost as high as that between different sampling dates. Slight increases in the summer months were observed for Verticillium nigrescens and some of the most common species in these soils, but only in V. nigrescens was the seasonal effect statistically significant.

Experimental studies on microfungi from decaying stems of Heracleum sphondylium and Urtica dioica

All of twenty fungi which were members of the primary microfloras of decaying stems of Heracleum sphondylium L. and Urtica dioica L. and four out of six members of the secondary microfloras were able to utilize cellulose as a nutrient in artificial culture. Mucor hiemalis and Rhizopus arrhizus , both secondary microflora species, failed to utilize it. Of nine prominent primary microflora species, the spores of five were able to germinate at or below 93·2% R.H. The rest required higher humidities. Stachybotrys atra and Torula herbarum were unable to grow on pieces of sterilized stem substrate that were not saturated with water, but seven other species could. Bright daylight favoured pycnidium production by Phoma acuta, P. complanata , and Phomopsis asteriscus , but inhibited production of conidia by T. herbarum and of chlamydospores by Cephalosporium sp.I. The other four fungi tested were indifferent to brightness of illumination These characteristics in respect of water relations and sensitivity to illumination are correlated with, and may be partly responsible for, the patterns of distribution of these fungi on decaying stems of H. sphondylium and U. dioica .

Growth and Metabolism of Fungi in an Atmosphere of Nitrogen

SUMMARY Strains of 13 species of fungi isolated in relatively large numbers from sewage sludges, polluted waters, organically enriched soils and similar habitats were incubated under 100% prepurified nitrogen gas in liquid culture with the reductant sodium formaldehyde sulfoxylate. Incubation was carried out in 25-ml conical flasks in Case anaero jars. Growth and removal of carbon from the medium were measured at weekly intervals by oven dry weight determinations on cell crops collected on membrane filters, and with a Beckman carbon analyzer. Except for Geotrichum candidum, Fusarium oxysporum and F. solani, all strains used demonstrated a definite requirement for vitamins under the anaerobic or microaerophilic conditions of the test. Greatest amount of growth activity was demonstrated by Geotrichum candidum, Fusarium oxysporum, F. solani and Mucor hiemalis. The fungi most sensitive to a 100% nitrogen gas atmosphere were Phoma herbarum, Rhodotorula mucilaginosa and Candida parapsilosis. Intermediate species included: Aspergillus niger, A. fumigatus, Aureobasidium pullulans, Phialophora jeanselmei, Penicillium oxalicum and P. brevicompactum (used in combination), and Trichoderma viride, in descending order. It was shown that strains of those fungi tested are able to metabolize organic substances and produce cell tissue under the conditions of the experiment and that therefore they may be carrying out similar activities in microaerophilic or even anaerobic conditions in sewage treatment systems and similar habitats. The objectives of this investigation were to study the effects of elemental nitrogen on the survival, growth, and metabolic activity (utilization of carbohydrate) of common fungi associated with polluted waters. For a long time fungi have been considered to be obligate aerobes that require some molecular oxygen for growth, sporulation, germination and essential developmental activities. In spite of the statements that fungi fail to grow at very low or zero oxygen pressures (Matsumoto, 1921; Denny, 1933; Kuhn, 1938; Smith, 1946; Skinner et al., 1947; Preston and McClellan, 1948; and Pine, 1954; among others), quantitative relations of growth and oxygen supply vary considerably among different species and strains and some fungi have a wide range of oxygen tension that gives maximum growth. The optimum amount of oxygen has been shown to vary from species to species, and strains of many species are observed to develop in one or more stages of their life cycle in less than the amount available in air. Literature on the oxygen requirements of

The localization of some enzymes in the mycelium of Mucor hiemalis.

Histochemical staining for dehydrogenases in mycelium of Mucor hiemalis has shown characteristic localizations of these enzymes. Alcohol dehydrogenase is almost totally localized in the chlamydospores, in developing sporangia and in the columellae of intact and ruptured sporangia. Malate, isocitrate (NAD-and NADP-linked) and glutamate (NAD- and NADP-linked) dehydrogenases are localized in hyphae showing the early stages of sexual and asexual reproduction.