Pure Fungal Cultures Research Articles

Effects of NH4 + on the growth and K+ (86Rb) uptake of various ectomycorrhizal fungi in pure culture

Effects of NH4 + on the growth and K+ (86Rb) uptake of various ectomycorrhizal fungi in pure culture

Mold Inhibitory Activity of an N-Oxime Ether

A N-oxime ether (CG-97967), representative of a new class of mold inhibitors that have promising in vitro activity, was tested for activity in unaltered corn meal. Using inhibition of the production of respiratory CO2 as the criterion of antifungal activity, the N-oxime ether was equal or superior to propionic acid in three batches of corn meal. Further testing against pure cultures of fungi, yeast, and bacteria revealed that the experimental compound was unstable and was inactivated by heating, which caused an oxidative decarboxylation. These results suggest that use of the N-oxime ether would be inappropriate in pelleted poultry feed.

Synergistic antimicrobial effect of ethanol, sodium chloride, acetic acid and essential oil components.

Ethanol, NaCl, acetic acid and essential oil components were examined for their synergistic antimicrobial effects, using air-borne microorganisms and pure cultures of fungi. Antimicrobial assays were carried out at 27°C, using 2% glucose Sabouraud agar. In order to completely suppress the growth of all the contaminating air microorganisms for over 20 days, more than 8% (by volume) ethanol, 25% (wt/vol) NaCl, or 0.2% (by volume) acetic acid was required in the medium. All essential oil components examined, at a concentration of 1 or 2mM, were only moderate or very weak in antimicrobial effect. However, when these substances were applied in pairs, in threes and in fours, they exhibited a potent antimicrobial effect at relatively or considerably lower concentrations. The combination of 3% ethanol, 0.05% acetic acid and 1mM perillaldehyde, and thecombination of as low as 0.5% ethanol, 2% NaCl, 0.05% acetic acid and 0.5mM perillaldehyde were sufficient to suppress completely the growth of all contaminating air microorganisms for over 20 days. The combination of 3% ethanol, 3% NaCl and 0.5mM perillaldehyde or 0.05% acetic acid was also fairly potent in this respect. Other essential oil components, such as citral, citronellol, geraniol, cuminaldehyde and eugenol, were as effective as perillaldehyde ; L-menthol, linalool and D-carvone were somewhat less effective ; and hydrocarbons (D-limonene, α-pinene, β-pinene, camphene, β-myrcene and p-cymene), citronellal, 1, 8-cineole, anethole and vanillin were very weak or almost completely ineffective in this respect. Similar synergistic antimicrobial effects of these substances were also observed when using pure cultures of fungi as inocula. Our results strongly suggest that combinations of ethanol, NaCl, acetic acid and certain essential oil components, each at a considerably lower concentration, are applicable for effective preservation of foods without applying synthetic preservatives or other antimicrobial substances uncommon in usual foods.

Synergistic Antimicrobial Effect of Ethanol, Sodium Chloride, Acetic Acid and Essential Oil Components

Ethanol, NaCl, acetic acid and essential oil components were examined for their synergistic antimicrobial effects, using air-borne microorganisms and pure cultures of fungi. Antimicrobial assays were carried out at 27°C, using 2% glucose Sabouraud agar. In order to completely suppress the growth of all the contaminating air microorganisms for over 20 days, more than 8% (by volume) ethanol, 25% (wt/vol) NaCl, or 0.2% (by volume) acetic acid was required in the medium. All essential oil components examined, at a concentration of 1 or 2mM, were only moderate or very weak in antimicrobial effect. However, when these substances were applied in pairs, in threes and in fours, they exhibited a potent antimicrobial effect at relatively or considerably lower concentrations. The combination of 3% ethanol, 0.05% acetic acid and 1 m.M perillaldehyde, and the combination of as low as 0.5% ethanol, 2% NaCl, 0.05% acetic acid and 0.5 mM perillaldehyde were sufficient to suppress completely the growth of all contaminating air microorganisms for over 20 days. The combination of 3% ethanol, 3% NaCl and 0.5 mM perillaldehyde or 0.05% acetic acid was also fairly potent in this respect. Other essential oil components, such as citral, citronellol, geraniol, cuminaldehyde and eugenol, were as effective as perillaldehyde; L-menthol, linalool and D-carvone were somewhat less effective; and hydrocarbons (D-limonene, a-pinene, /?-pinene, camphene, /?-myrcene and /?-cymene), citronellal, 1,8-cineole, anethole and vanillin were very weak or almost completely ineffective in this respect. Similar synergistic antimicrobial effects of these substances were also observed when using pure cultures of fungi as inocula. Our results strongly suggest that combinations of ethanol, NaCl, acetic acid and certain essential oil components, each at a considerably lower concentration, are applicable for effective preservation of foods without applying synthetic preservatives or other antimicrobial substances uncommon in usual foods.

Pestalotiopsis menezesiana on greenhouse plantings of Cissus rhombifolia with notes on related fungi occurring on Vitaceae

Pestalotia menezesiana Bres. & Torr., reported to cause dieback of rooted cuttings of Cissus rhombifolia Vahl in Ontario greenhouses, is redisposed in Pestalotiopsis and a description of the fungus in pure culture is provided. Eight other species assigned originally to Pestalotia and occurring on Vitaceae are discussed. A key is presented to differentiate these species on the basis of conidial morphology. The following new combinations are proposed: Truncatella pitospora (da Costa & da Camara) Bissett, Pestalotiopsis uvicola (Speg.) Bissett, and Pestalotiopsis quadriciliata (Bubák & Dearness) Bissett.

シソと食塩の食品防腐作用における相乗効果について

Antimicrobial effect of perilla was examined, using microorganisms from air and pure cultures of fungi and bacteria. Either 0.01% ether-extract of perilla leaves or 10% NaCl allowed considerable growth of microorganisms on usual agar media. However, it was found that in agar media containing more than 5% NaCl, the ether-extract of perilla leaves at a concentration of 0.01% completely inhibited growth of many kinds of microorganisms. This synergistic antimicrobial effect of perilla and NaCl concentrations may offer a useful tool for preserving some foods without applying any synthetic preservative.

Fungal Feeding by Enchytraeidae (Oligochaeta) in a Tropical Woodland in Orissa, India

The food preference of three species of Enchytraeidae were examined by three techniques: (1) Squash preparations; (2) Culturing of gut contents; (3) Selective feeding on pure fungal cultures. Enchytraeids ingested large amount of organic material and fungi. Fungal material formed some 30% of the gut contents. Anteclitellar part of the body contained significantly higher percent of plant and fungal material than the postclitellar part. Analysis of gut contents showed that Rhizopus nigricans, Syncephalastrum racemosum, and Trichoderma viride are generally digested by enchytraeids while Penicillium steckii and Aspergillus niger are not digested. Isolations made from postclitellar gut content did not generally give rise to fungal colonies except for Aspergillus niger and Penicillium steckii.

Abiotic factors affecting the toxicity of lead to fungi.

The toxicity of lead (Pb) to fungi in pure culture was influenced by several abiotic factors: pH, inorganic anions, clay minerals, and particulate (humic acid) and soluble organic matter. The toxicity of Pb was potentiated under acidic conditions (pH 5 and 6), and phosphate or carbonate anions reduced the toxicity, apparently as a result of the formation of sparingly soluble Pb salts. Clay minerals (montmorillonite greater than attapulgite greater than kaolinite) and particulate humic acid protected against the toxicity of Pb, presumably as the result of sorption, by cation exchange of the Pb to the exchange complexes, which reduced its availability for uptake by the fungi. Soluble organics, such as tryptone, yeast extract, cysteine, succinic acid, and increasing concentrations of neopeptone, also reduced the toxicity of Pb.

Mycotoxicological investigations on Zambian maize

In Zambia there is a statutory requirement that visually diseased kernels should not constitute more than 2% of maize intended for human consumption. Four samples of Zambian maize containing 1·8, 5·4, 13·0 and 20·3% visually diseased kernels were subjected to mycological and chemical analyses and to toxicity trials in ducklings and rats. For all the samples the dominant fungi isolated from surface-sterilized kernels were Fusarium moniliforme Sheldon and Diplodia macrospora Earle, and the most prevalent fungus isolated from prepared maize meals was F. moniliforme. The level of fungal invasion of both kernels and meal was significantly lower for the 1·8%-diseased sample than for the other three. Protein and essential amino acid content tended to increase as the level of diseased kernels increased. None of the samples contained chemically detectable amounts of aflatoxins, ochratoxins, sterigmatocystin, cyclopiazonic acid or zearalenone. Although no samples were lethal to either ducklings or rats, body-weight gains were higher in male and female rats fed the 1·8%-diseased sample for 6 months than in those given the other test diets, the difference being statistically significant in the males. Of seven pure cultures of fungi isolated from the maize samples, five, including F. moniliforme and D. macrospora, were acutely toxic to ducklings and rats. In view of the indications that unidentified Fusarium and Diplodia toxins present in Zambian maize containing more than 1·8% visually diseased kernels reduce the growth rate of rats fed such samples for 6 months, it is recommended that the 2% maximum level of visually diseased kernels acceptable in Zambian maize for human consumption should be maintained.

Pesticide -- Plant Disease Interactions: Effect of Cycloate on Growth of Rhizoctonia solani

CAMPBELL, C. L., and J. ALTMAN. 1977. Pesticide -plant disease interactions: effect of cycloate on growth of Rhizoctonia solani. Phytopathology 67: 557-560. Linear growth of Rhizoctonia solani after 72 hr at 20 C was in steamed soil amended with 4 Mg!g cycloate, colonization significantly less on all nutrient concentrations of potato- of 5-mm-long mature bean hypocotyl segments by R. solani dextrose agar amended with cycloate (S-ethyl N-ethylthio- was slightly greater than in soil without cycloate. At 16 and 32 cyclohexanecarbamate) from 10 to 100 /ig/ml, than in Ag/g cycloate, colonization of hypocotyl segments was controls without cycloate. Rate of growth of mycelium of R. significantly less than in nonamended controls in both solani was less in Czapek-Dox broth with 1 g yeast steamed and raw soil. Colonization of sterile sugar beet seeds extract/liter amended with 4 or 8 btg/ml cycloate, than in by R. solani also was less with 8, 16, and 32 jg/g cycloate controls. In raw soil amended with 4 and 8 Mg! g cycloate, and than in controls. Herbicides are becoming more important in modern growth of the fungus in pure culture in the presence of agriculture. Although much research is done to evaluate Dacthal. the phytotoxicity of herbicides to economic crop plants, Altman (1) and Altman and Ross (2) observed both in questions remain concerning the effects of herbicides on field and greenhouse work that an interaction, leading to soil microorganisms including soil-borne plant increased disease incidence, existed between sugar beet pathogens. (Beta vulgaris L.) seedling damping-off caused by R. Rodriguez-Kabana et al. (11) using rates ranging from solani and certain herbicides used in sugar beet culture those considered likely to accumulate in soil under field which included cycloate, pebulate, and pyrazon. The applications to others much higher than would be authors concluded that this interaction could in part expected, found that in liquid culture, diuron had little explain poorer stands of plants in certain herbicideeffect on the mycelial production of Rhizoctonia solani treated fields compared with stands in nontreated fields. Kfihn. EPTC generally had little effect on the growth of The purpose of this work was to investigate the effect of R. solani, although the fungus initially was inhibited by cycloate (S-ethyl N-ethylthiocyclohexanecarbamate) this herbicide. Atrazine inhibited mycelial production on R. solani. This herbicide currently is recommended for throughout the 22-day trial period, but paraquat use as a preplant treatment for sugar beets in Colorado increasingly inhibited the fungus as herbicide and in all other intermountain states in which sugar beets concentration increased, are grown. Ebner (5) found that R. solaniwas sensitive to diuron at 125 #g/ml and to linuron at 60 and 125 Ag/ml. In media MATERIALS AND METHODS

Vital staining of fungi in pure cultures and in soil with fluorescein diacetate

A method for vital staining of fungal mycelium with fluorescein diacetate (FDA) is described. In experiments with pure cultures, good correlation was obtained between relative staining efficiency, growth rate, and respiration. FDA thus appears to be a true vital stain, in that it stains only metabolically active mycelia. In fresh soil suspensions stained with FDA, brightly fluorescent hyphae and portions of hyphae were observed. The applicability of the method for measurement of active mycelium in the soil is discussed.

The decay pattern of Phellinus tremulae (Bond.) Bond, et Borisov in Populus tremula L.

The distribution of Phellinus tremulae in stems of Populus tremula was studied visually, macroscopically as well as microscopically, and by means of isolation of the fungus in pure culture. Evidence suggests that P. tremulae occurs alone in most of the tree. Microorganisms associated with P. tremulae in the wood are suggested to be independent invaders or secondary invaders. A dark reaction zone was formed in certain parts of the wood and consisted microscopically of melanized hyphes and brown material in the ray cells. An inner wood, formed as a result of the death of nearby brandies, is apparently the main part infected by P. tremulae, and its outer border may basically limit the spread of the fungus in the trunk. The formation of “heartwood” in aspen is discussed, and a suggested outline shown for the infection and decay processes caused by the fungus.

Microbial utilization of Pinus radiata bark.

A screening program using suspensions of ground bark in mineral salts media, or extracts prepared from ground bark by treating with hot water, sulfuric acid, ammonium hydroxide, or sodium hydroxide, yielded more than 200 pure cultures of fungi, yeasts, and bacteria. Only 38 of these have good growth on liquid bark media. All were filamentous fungi, although many bacteria and yeasts were among the cultures that failed to give appreciable growth. Species of Penicillium, Scopulariopsis, Aspergillus, Trichoderma, Cladosporium, and Fusarium were among the most actively growing cultures. Cell biomass yields, as measured by cell nitrogen determination, were too low for economic production of single cell protein.

2,4,6‐trichloroanisole in broiler house litter: A further cause of musty taint in chickens

AbstractTwo unknown components in extracts of broiler house litter were identified as 2,4,6‐trichloroanisole and 2,4,6‐trichlorophenol; the latter compound was also found in extracts of fresh wood shavings. Experiments with pure cultures of fungi isolated from the litter demonstrated that these microorganisms were capable of methylating 2,4,6‐trichlorophenol to the chloroanisole. A musty taint in broiler chickens was shown to be due to the presence of 2,4,6‐trichloroanisole.

Microbial Utilization of Pinus radiata Bark

A screening program using suspensions of ground bark in mineral salts media, or extracts prepared from ground bark by treating with hot water, sulfuric acid, ammonium hydroxide, or sodium hydroxide, yielded more than 200 pure cultures of fungi, yeasts, and bacteria. Only 38 of these have good growth on liquid bark media. All were filamentous fungi, although many bacteria and yeasts were among the cultures that failed to give appreciable growth. Species of Penicillium, Scopulariopsis, Aspergillus, Trichoderma, Cladosporium, and Fusarium were among the most actively growing cultures. Cell biomass yields, as measured by cell nitrogen determination, were too low for economic production of single cell protein.

Detection of mycotoxins in foodstuffs by use of chick embryos.

A method of extracting fungal cultures with aqueous methanol and hexane is described. The extract from 100 grams of foodstuff, or pure fungal cultures on cereals (maize, wheat and rye), was inoculated into groups of twenty fertile hens eggs, both into the air sac and into the yolk, which were then incubated through to hatch at twenty-two days. The results show good sensitivity to aflatoxin and sporidesmin. The fungal cultures are recorded as toxic (below 50% hatch) non toxic (above 68% hatch) and doubtful. Five isolates ofAspergillus repens isolated from one batch of mouldy hay gave a high (43%) incidence of deformed embryos. This method is suggested as a general biological test for toxicity in foodstuffs.

Fungus Metabolites Toxic to Animals

Mycotoxicology deals with diseases in man and animals caused by or resulting from ingestion of foods made toxic by metabolic products of fungi. Of the numerous reviews devoted to this subject over the last ten years, the foll owing are selected: Brook & White (14), Christensen (18 ), Ciegler & Lilleho j (26), Goldblatt (54), Hesseltine (60), Detroy et al (35), Purchase (115), Scott (13 2), Wogan (17 7, 179), Mateles & Wogan (94), and Ciegler et al (25). This review is restricted to those mycotoxins found in feedstuffs (excluding ergot) or in the ingredients of foods and feedstuffs in the field and is little concerned with the host of toxic metabolic products of fungi produced in pure culture in the laboratory. It often is tacitly assumed that if a fungus in pure culture in the laboratory under some conditions produces a compound or compounds in some way toxic to test animals when ingested or otherwise admin istered (including intraperitoneal injection, which by no stretch of the imagination could occur in the feedlot or poultry house) the presence of this same fungus in food or feedstuffs is cause for alarm. This is by no means true; even when a potentia l toxin-p roducing strain of As per gillusfiavus is added to moist grain and allowed to grow, along with the other microflora normally present, it may produce little or no toxin.

Effects of various soil fungi and insecticides on the capacity of Mucor alternans to degrade DDT.

Pure cultures of the fungus Mucor alternans, isolated from DDT-contaminated soils, were able to degrade DDT to water-soluble metabolites. After the addition of fungal spores to DDT-contaminated soils, however, the insecticide-degrading capacity of the fungus was no longer evident. Since under field conditions many species of fungi are simultaneously exposed to mixed residues of pesticidal chemicals, the effects of various species of soil fungi and of various insecticides on DDT degradation by M. alternans were investigated. Experiments were conducted to study the effect of nine fungal species, their stale cell-free media, and various insecticides and related compounds on the capacity of M. alternans to degrade 14C-DDT to water-soluble metabolites. It was found that several pure fungal cultures or some cell-free media, in which mycelia had grown, could also degrade the insecticide. In most cases, however, addition of one of the various fungi to 14C-DDT-treated M. alternans cultures resulted in a total depression of the appearance of water-soluble metabolites in the media. This was due to an accumulation of the metabolites in the mycelium of the other fungus or in an inhibition of metabolite formation. Addition of stale media from various fungi to 14C-DDT-treated M. alternans cultures had various effects on fungal growth and on the capacity of the fungus to degrade the insecticide. Among the insecticides and related compounds tested only lindane, parathion, and Dyfonate caused a reduction in DDT degradation by M. alternans, without severely reducing its vegetative growth.

Effect of Mycorrhizal Fungi on the Growth and Nutrient Status of Slash and Radiata Pine Seedlings

SUMMARY Slash pine (Pinus elliottii var. elliottii Little and Dorman) and radiata pine (P. radiata D.Don) were inoculated with pure cultures of fungi isolated from mycorrhizas of mature pine. All eight species tested, except a Rhizopogon sp. obtained from slash pine, formed mycorrhizas with radiata pine, and all except two unidentified fungi from radiata produced mycorrhizas on slash. The effects of inoculation on yield and nutrient uptake were determined four months after seedlings were transplanted to a sterile peat-sand mixture previously steeped in nutrient solution. Inoculation gave better growth and improved nutrient status even where it did not result in mycorrhiza formation. Unidentified fungi were more effective than Rhizopogon roseolus or Suillus granulatus. Pine seedlings of any one species derived most benefit from inoculation with fungi isolated from that species. The results are discussed in relation to the problems of introducing pure cultures of mycorrhizal fungi into natural soils.

Competitive saprophytic colonization of wheat straw

SUMMARYUsing the ‘Cambridge method’, the effect of temperature on the colonization of wheat straw by Fusarium culmorum, Gibberella zeae, Cochliobolus sativus and C. spicifer was studied. Within the range 10–30 °C, saprophytic colonization by the four fungi was favoured by lower temperatures. This could not be attributed to the effect of temperature on the growth of the fungi in pure culture, but was probably caused by increased antagonism at higher temperatures from the general soil microflora. Contrary to previous indications, C. sativus strongly colonized straw under suitable environmental conditions.