Showing papers on "Mycelium published in 1969"

Carbohydrate Metabolism During Morphogenesis of Coprinus lagopus (sensu Buller)

Abstract: The occurrence and properties of enzymes of carbohydrate metabolism were studied during dikaryotic fruiting of the mushroom Coprinus lagopus. Enzymes of hexose monophosphate catabolism, sugar alcohol (polyol) dehydrogenases (DH), and trehalase occurred throughout development. The ratio of xylitol DH to sorbitol DH was greater than unity in both monokaryotic mycelium and dikaryotic fruit body caps, whereas this ratio decreased in the stipe (stalk) tissue. Xylitol DH and sorbitol DH were both dependent upon nicotinamide adenine dinucleotide (NAD) and showed maximal activity at pH 9. Two separate enzymes were suspected on the basis of preferential utilization of the NAD analogue, thionicotinamide-NAD, by xylitol DH, and this feature was consistent throughout development. An appraisal of the carbohydrate pool revealed trehalose and glucose, with the former predominant in the stipe and the latter in excess in the cap of dikaryotic fruit bodies. Trehalase activity in dialyzed enzyme extracts showed pH optima at acid and alkaline pH levels in monokaryotic mycelium, dikaryotic stipes, and cap tissues.

Effects of herbicides on the growth of soil fungi

Abstract: Summary Three methods have been used to investigate the effects of a number of commercial herbicides on the growth of certain soil fungi: measurements of hyphal extension across agar plates; measurements of hyphal extension along sterilized plant material; and manometric techniques. Three points, in particular, emerged from these studies. First, that there was no stimulation of fungal growth. Herbicide interference in growth included suppression of spore germination, inhibition of the rate of linear extension of the mycelia, and abnormalities in growth habit and in patterns of spore production. Secondly, that some herbicides (e.g. linuron and paraquat) were more fungitoxic than others (e.g. MCPA and simazine) to a range of organisms. Thirdly, that there were differences between fungi in their sensitivity to individual herbicides. All three methods have shown consistent differences between fungi in their ability to tolerate paraquat. Trichoderma viride, in particular, has been found to be sensitive to paraquat. The inhibitory effects were observed at concentrations well within the range likely to be experienced in the field.

Translocation of C^(14)-Labeled Compounds in Mycorrhizae and It Implications in Interplant Nutrient Cycling

Abstract: Loblolly pine (Pinus taeda L.) seedlings were grown axenically in mycorrhizae synthesis cultures with either the symbiont Pisolithus tinctorius (Pers.) Coker and Couch or Thelephora terrestris (Ehrh.) Fr. Glassware was designed to allow synthesis of mycorrhizae on two seedlings physically separated except for a bridge formed between the two root systems by mycorrhizal fungus mycelium. Glucose—C14 and sucrose—C14 were used as tracers to investigate movement of labeled compounds from mycorrhizal roots to external mycelium, from external mycelium to roots and from one root system to the other via shared mycelium. Whether applied to foliage as glucose—C14 or sucrose—C14, C14 was readily translocated to pine roots. Transport of C14 from mycorrhizal roots to external hyphae of T. terrestris up to a distance of 12 cm was shown, but only slight movement of C14 occurred into external hyphae of P. tinctorius. The introduction of glucose—C14 and sucrose—C14 to isolated strands of T. terrestris resulted in the movement of C14 from strands to roots. Movement of isotope from one seedling to the other via mutually—shared mycelium did not occur in the synthesis cultures; however, C14 movement between root systems artifically linked by mycelial strands indicated that interplant exchange can take place. Evidence suggests that mycorrhizal fungi such as T. terrestris could be effective in the exchange of organic and possibly other materials between root systems in an ecosystem.

Ultrastructure of Dimorphic Transformation in Paracoccidioides brasiliensis

Abstract: The fine structure of Paracoccidioides brasiliensis undergoing temperature-dependent transformation from mycelium to yeast and vice versa (M right harpoon over left harpoon Y) was studied. The transitional form to mycelium from the yeast appears as an elongated bud that extends from the yeast and which has a mixture of characteristics from both the yeast and the mycelium. The transitional form to yeast from the mycelium starts with enlargement of the interseptal spaces and cracking of the outer electron-dense layer of the cell wall of the hypha. Later the interseptal spaces tend to become round and separate. In M --> Y only few interseptal spaces seem to transform. The yeast is produced by self-transformation of the hypha. In Y --> M a new structure is formed and the yeast dies. Intrahyphal hyphae are observed during the transformation from M --> Y, and intrayeast hyphae during the Y --> M. Due to the high mortality and breakage observed in both types of transformations, we believe that wound of the yeast or the mycelium could elicit this phenomenon.

The fatty acid composition of sporangiospores and vegetative mycelium of temperature-adapted fungi in the order mucorales.

Abstract: SUMMARY: The lipid content and fatty acid composition of sporangiospores and vegetative mycelium of mesophilic, thermotolerant and thermophilic fungi in the Mucorales were examined. In each fungus the spores contained less lipid than the vegetative mycelium. The mesophiles accumulated less lipid in spores and mycelium than did thermotolerants and thermophiles. No unusual fatty acids were detected by gas-liquid chromatography in the lipids of spores or mycelium. The fatty acid compositions of spores and vegetative mycelium were qualitatively very similar, but spore lipids were always more highly saturated than mycelial lipids. Lowering growth temperature from 48 to 25° increased the synthesis of unsaturated fatty acids in the spores and the mycelium of the thermotolerant and thermophilic fungi examined.

Environmental effects on microbial turnover of some mineral elements: Part I—Abiotic factors

Abstract: Some effects of biotic factors (forest floor, microflora, litter fauna) on mineral cycling on artificial and natural substrates were measured using radionuclides Leaching and immobilization of 134Cs in the leaves of four species of tree were positively related During the first weeks of decay all species except mulberry showed net immobilization In fresh litter of tulip poplar rates of leaching of 137Cs and microbial activity, as well as immobilization of 137Cs, were higher than in one-year-old litter Mixing of litter with 137Cs and litter without 137Cs did not affect 137Cs movement Concentration factors for Cs of several representative soil organisms in vitro and in fungal fruiting bodies in the field which derived their Cs from the substrate varied from < 01 to 80 The maximum concentration of 134Cs and 60Co by Trichoderma viride in shaken cultures occurred after about 5 days A change from net immobilization to net mineralization of 137Cs by the natural flora of tulip poplar leaves occurred after 10 days of growth Presumably ageing of microbial tissue increased release of minerals more than it did uptake which resulted in reduced immobilization in time Mineral accumulation by long-lived fungal fruiting bodies and mycelium, however, continued for several weeks Five millipedes on l g of entire white oak leaves tagged with 134Cs accumulated in 18 days 9% of the initial 134Cs in their tissue; reduced microbial immobilization from 24 to 11% of the initial 134Cs, presumably by reducing mycelium growth; and increased leaching from 26 to 30% of the initial 134Cs as a result of leaf fragmentation It was concluded that biotic as well as abiotic factors greatly affect mineral turnover by the microflora Further knowledge of such effects may open ways to control the mineral kinetics in the environment

Saprophytic development of the flax rust Melampsora lini, race No. 3

Abstract: A medium containing 0.1% yeast extract (Difco) in addition to sucrose, inorganic salts, and chelated iron supported saprophytic growth of Melampsora lini (Pers.) Lev., race No. 3. Cultures were started with sterile uredospores from rust-infected flax tissue cultures and were maintained for over 5 months through up to eight transfers. In some aging parts of living mycelial cultures, single one-celled teliospores were formed on aerial hyphae, and in other parts composed of dense masses of firm, small cells, clusters of uredospore-like structures were found. Growth and survival of mycelium were better when 4% sucrose was used instead of glucose, and when 500 mg/l of K2HPO4 was present in addition to the routinely used potassium monophosphate. Spore production was increased by raising the yeast extract concentration to 0.2%.

The effects of various lipids on growth of mycelium of Agaricus bisporus.

Abstract: Growth of mycelium of Agaricus bisporus was stimulated by the addition of lipids to the basal medium. The addition of 9 commercial vegetable oils and beef and pork tallow caused increased growth of the same approximate magnitude. Esters of oleic and linoleic acid and oil additions with equivalent oleic and linoleic acid concentrations resulted in similar increased growth of mycelium. It is suggested that these fatty acids are largely responsible for the stimulation of growth caused by the vegetable oils. The growth of 5 isolates of A. bisporus was stimulated while that of one was not.

Studies on the Decomposition of Raffinose by α-Galactosidase of Mold

Abstract: A mold which produced α-galactosidase and little invertase was isolated and identified as Mortierella vinacea. α-Galactosidase formation of the mold was induced by galactose, melibiose, raffinose and lactose. Among these inducers lactose showed the most stimulative effect. α-Galactosidase was produced by either Koji method or submerged culture method, but in the latter most α-galactosidase was found in the mycelium fraction.Hydrolysis of raffinose in beet molasses was studied with the α-galactosidase in the mycelium fraction and about 80% of raffinose was found to be hydrolyzed by the enzyme preparation.

The relation between growth, conidiation and trehalase activity in Neurospora crassa.

Abstract: The extent to which trehalose is accumulated in the vegetative mycelium of strains of Neurospora crassa is significantly affected by conidiation. In heavily conidiating strains a rapid decrease in mycelial trehalose occurs following the initiation of conidiation. Meanwhile, trehalase activity in the vegetative mycelium of heavily conidiating strains increases rapidly following the initiation of conidiation, although apparently it is not directly caused by the sporulation process. High levels of both trehalase and trehalose appear concomitantly in the newly formed conidia. MANY OBSERVATIONS attest to the fact that changes in the nutrient level affect the sporulation of fungi and other microorganisms (Hawker, 1957; Halvorson, 1962). Therefore, we began studies with Neurospora in which the changes in hydrolytic enzymes involved in sugar metabolism including trehalase and invertase were studied in relation to conidiation. That the activity of these enzymes in Neurospora possibly was influenced by the level of nutrients and related to conidium formation was suggested by the work of Hill and Sussman (1964). Thus the germination of conidia was accompanied by the rapid diminution of the activity of these two enzymes, and upon the leveling off of growth and the formation of conidia increased activity became evident. The ubiquity of trehalose in the fungi and its prominent role as an endogenous source of energy suggested that there might be a connection between the formation of conidia and the synthesis of trehalase, which in turn might be regulated by the supply of exogenous sugar. The results of these studies are presented in two papers, the first devoted to the relation between trehalase and conidiation and the second to the means through which trehalase synthesis is controlled. MIETHODS AND MATERIALS-Strain 69-1113A (T8) of Neurospora crassa was the standard strain with which most of the experiments were performed. Another wild-type strain, 73a, was used occasionally to supplement the data obtained with strain 69-1113A. Mutant strains used are listed in Table 1. With the exception of strains UN1107A and B2A which were obtained from Dr. R. H. Davis, 1 Received for publication 25 March 1969. This study was supported by a N. I. H. Predoctoral Fellowship and constitutes a portion of the thesis submitted as a requirement for the Ph.D. degree of the primary author. 2Present address: Department of Science, Northeast Missouri State College, Kirksville, Mo. University of Michigan, Ann Arbor, mutant strains were obtained from the Fungal Genetics Stock Center, Department of Biological Sciences, Dartmouth College, Hanover, N. H. Standing cultures were grown in 30 ml of a liquid minimal medium containing 2 % sucrose and 2 % Vogel's minimal supplement (Vogel, 1956) in 125-ml Erlenmeyer flasks at 262-24 C. Continuous light was provided by two F48T12/CW fluorescent tubes (General Electric) set at 4Y2 inches above the tops of the flasks. These conditions are subsequently referred to as standard growth conditions. Inoculum for aconidial and slowly conidiating strains was prepared by homogenizing mycelial mats of approximately 100 mg dry weight in a sterile Waring Blendor for 1 min in 100 ml sterile distilled water. This preparation remained viable for several days when stored at 4 C. Conidial suspensions were used as inoculum for the other strains. Cultures were harvested in duplicate. Young, or slow-growing cultures were separated from the growth medium by filtration through a Buichner funnel, washed several times with distilled water, dried, and weighed. Larger mycelial mats were first placed in approximately 1 liter of distilled water before the final washing and drying in a Buichner funnel. When conidia and aerial hyphae were present, they were scraped from the mycelial mat with a spatula and discarded except when the dry weight of the entire culture was desired. The early stages of conidiation are often accompanied by the production of large amounts of aerial hyphae bearing very few conidia. These may be readily harvested by lightly scraping the surface of the mycelium or side of the flask with a spatula. As the conidia begin to appear, a tuft of aerial hyphae may be removed from the flask with forceps, placed on paper and the portion bearing the conidia cut off with a razor blade and discarded. As more conidia are pro-

Chapter XVI The Evaluation of Mycelial Growth

Abstract: Publisher Summary This chapter presents of overview of the evaluation of mycelial growth Difficulties in the evaluation of the growth of mycelial organisms, such as fungi and actinomycetes, arise from the nature of the mycelium itself Yeasts and bacteria have a rapid rate of reproduction At the end of growth, the cells usually form a fairly stable suspension, though sometimes they undergo autolysis Fungi and actinomycetes grow much more slowly, the threads extending and changing in composition as they age The composition of the mycelium is continually changing The mycelium may also store reserve substances and fats, so that a weight increase can occur without the formation of new cells or without consumption of nitrogen Growth may be evaluated by measuring increases in weight or by the quantity of nitrogen being removed from the medium Another point of importance is that mycelial cultures are often grown on complex media containing chalk as a buffer, such media contain a good deal of insoluble material that interferes with the determination of mycelial weight This is often the case with media used for industrial fermentations, and attempts must be made to correct for this source of error in growth determinations The chapter also provides reasons for measuring mycelial growth and the choice of method

Induction of sporulation of Alternaria porri f. sp. Solani by inhibition of its vegetative development

Abstract: Alternaria porri (Ellis) Cif. f. sp. solani (Ellis & Mart.) Neerg. on potato and tomato plants kept under continuously moist conditions either in dark or in light or in photoperiods covered the leaves with mycelium, but produced no or few spores. Under all light conditions, interrupting the continuously moist period with 1–3 days of dryness resulted in abundant sporulation. In tomatoes, the highest sporulation occurred when the final day of moisture started with a 12-h light period. Formation of secondary spores in vitro was induced by treatments which interfered with normal germination of mother spores. These treatments included application of toxins, deficiency in nutrients, shocks of high and low temperatures, intermittent drying and exposure to high osmotic pressure. It was concluded that sporulation may be induced by various factors which partially inhibit the vegetative development of the fungus.

Destruction of hair by Chrysosporium keratinophilum.

Abstract: The means by which the keratinolytic fungus Chrysosporium keratinophilum (Frey) Carmichael attacks and destroys human and bovine hair in vitro are described While fronded mycelium plays a part, especially in the attack on the cuticle, the destruction of the cortex is mainly by boring hyphae which are at first typical of those of non-keratinolytic fungi but later penetrate the hair in all directions giving rise to large individual cells, wide-celled columns, and masses of mycelium of extraordinarily varied morphology True perforating organs as found in the dermatophytes were never seen, neither was erosion of the keratin around the mycelial elements demonstrable It is concluded that the fungus digests keratin in a manner chemically distinct from the dermatophytes and that on this difference may depend the difference in the morphology of the digesting mycelium In certain ways this is intermediate between that of non-keratinolytic fungi and of true dermatophytes, thus providing support for the hypothesis that the latter may have evolved from the former

Untersuchunge über Stoffwechselbeziehungen zwischen Parasit und Wirt am Beispiel von Puccinia graminis var. tritici auf Weizen

Abstract: Rust infected wheat plants were incubated with different 14C-labelled amino acids. Uredospores that were formed during the incubation contained 14C-activity. By analysis of these spores it was investigated whether the parasitic mycelium of Puccinia graminis takes amino acids from the host. It could be demonstrated that the applicated amino acids were taken up directly from the wheat leaf. The carbon sceletons of applicated lysine and arginine showed only little randomization of 14C-activity. Glutamic acid, alanine and glycine isolated from uredospore protein showed a very strong alteration of the original label. The pools of free amino acids in the host and the parasite are in isotope equilibrium. This demonstrates, that synthesis of amino acids in the mycelium is quantitatively not important. By following the kinetics of incorporation of an amino acid it could be demonstrated that the amino acids enter the parasite as free amino acids and not in the form of proteins.

Some investigations on the mycorrhiza of calluna, erica and vaccinium*

Abstract: SUMMARY The symbiosis of endotrophic fungi with Calluna, Erica and Vaccinium species was studied in artificially infected seedlings and cuttings. The fungi investigated are not species-specific, e.g., a fungus isolated from the European Vaccinium oxycoccus can serve the North American V. macrocarpon as a symbiont. When added to sterile cuttings the fungus stimulates root formation, and both with seedlings and cuttings it enhances growth. These symbiotic fungi have cellulase and pectinase. The process of penetration into the epidermis has been studied electron microscopically. The protoplast of an invaded epidermal cell is not killed by the fungus which eventually is digested by the living plant cell. The fungus cannot invade the subepidermal cells, probably because the secondary cell wall of the latter consists of, or contains, multiple layers of suberin. However, break-down products of the digested mycelium may not be prevented by the suberin layer from being assimilated, as radioactive serine was found to be taken up when applied ca. 1 cm from the tip of the root.

A regulatory system controlling inhibition in the sexual cycle of neurospora

Abstract: A cross made by adding conidia to protoperithecia on a mycelium of opposite mating type inhibits a subsequent cross on the same mycelium, or on an adjacent mycelium connected either by hyphae or medium. The inhibitory activity reaches a steady rate of movement through the area of the second cross from the area of the first cross and brings about either total or partial inhibition of the second cross, depending upon certain controllable variables; translocation of the activity occurs primarily through the hyphae but to a lesser degree through the medium as well. Total inhibition is not a result of modification of the medium by the first cross, such as depletion of nutrients or change in pH. An uncrossed mycelium which received activity from a crossed mycelium becomes inhibited either irreversibly or, to a certain extent, reversibly, depending upon the degree of activity received; in either event, transmission of this passive activity may occur from this mycelium to an outgrowing mycelium on fresh medium. T...

Effects of ozone on growth, lipid metabolism, and sporulation of fungi. [Colletotrichum lindemuthianum; Alternaria oleraceae]

Abstract: Fumigations with ozone at concentrations of 10 pphm or more for 4 hr repeated daily for 4 days suppressed radial growth and spore production of Colletotrichum lindemuthianum, the most sensitive species studied. Neither radial nor mass growth of Alternaria oleraceae, a more tolerant species, was inhibited by 60 pphm ozone, although spore production was significantly accelerated. Since ozone did not affect spore viability, the inoculum potential was greatly enhanced. Histological effects of ozone included loss of pigmentation in C. lindemuthianum and abundant formation of light-refractive globules in the hyphae. Chemical analyses of mycelial mats showed an average 28% decrease in neutral lipid content of ozone-fumigated cultures. No differences were detectable in fatty acid composition of fumigated cultures. While some lipids may have leaked into the substrate, it was suspected that ozone penetrated into vital sites within the cell-oxidizing sulfhydryl groups, thereby suppressing lipid synthesis. The actual degree of suppression in fumigated hyphae may have been greater than indicated, since much of the mycelia analyzed grew within the substrate and was not directly subjected to ozone. 14 references.

Tobacco mosaic virus in Pythium spec

Abstract: Cultures of the soil inhabiting fungusPythium spec. were inoculated in vitro with tobacco mosaic virus. Virus could be demonstrated in the mycelia from 4 days on after inoculation. In 15 days old cultures the virus concentration in the mycelium was higher than in the liquid culture medium. It is not yet clear whether the virus only accumulates, or also multiplies in the mycelium. After growth on solid medium infected mycelia still contained virus indicating that the virus is able to persist and possibly also to multiply in the hyphae.

The role of sclerotial rind in the germinability of sclerotia of Sclerotium rolfsii

Abstract: Punctured sclerotia of Sclerotium rolfsii Sacc. germinated more rapidly than unpunctured ones, especially on water agar. Discs of agar with mycelium and sclerotia in different stages of development were transferred to medium supplemented with 14C-iodoacetic acid. The radioisotope was not incorporated into mature sclerotia. It was concluded that the sclerotial rind is a mechanical barrier preventing uptake of nutrients from the medium.

Behaviour of α-aminoadipylcysteine and glutamylcysteine in the presence of intact and disrupted mycelium of a Cephalosporium sp

Abstract: 1. delta-(l-alpha-Aminoadipyl)-l-cysteine, the corresponding d- and dl-alpha-aminoadipyl isomers, delta-(dl-alpha-amino[6-(14)C]adipyl)-l-cysteine and gamma- and alpha-l-glutamyl-l-cysteine were synthesized. 2. The behaviour of delta-(l-aminoadipyl)-l-cysteine and the corresponding d- and dl-alpha-aminoadipyl isomers was studied in the presence of suspensions of intact mycelium of a Cephalosporium sp., suspensions treated ultrasonically and extracts obtained by grinding with alumina. 3. With intact mycelium the l-alpha-aminoadipyl isomer was removed more rapidly from the extracellular fluid than the corresponding d-isomer. 4. Addition of delta-(dl-alpha-amino[6-(14)C]adipyl)-l-cysteine to suspensions of intact mycelium led to the labelling of extracellular and intracellular penicillin N and cephalosporin C, but also to extensive hydrolysis of the dipeptide. 5. Broken-cell systems hydrolysed delta-(l-alpha-aminoadipyl)-l-cysteine and the corresponding d-alpha-aminoadipyl isomer, but the former was hydrolysed more readily than the latter. 6. gamma- and alpha-l-Glutamyl-l-cysteine were also hydrolysed but delta-(l-alpha-aminoadipyl)-l-cysteinyl-l-valine was not. 7. Only part of the enzyme activity in broken-cell systems responsible for the hydrolysis of delta-(alpha-aminoadipyl)-l-cysteine was present in the supernatant obtained on centrifugation at 20000g. 8. Possible implications of these findings are discussed.

Studies on the Decomposition of Raffinose by α-Galactosidase of Mold:Part I. α-Galactosidase Formation and Hydrolysis of Raffinose by the Enzyme Preparation

Abstract: A mold which produced α-galactosidase and little invertase was isolated and identified as Mortierella vinacea. α-Galactosidase formation of the mold was induced by galactose, melibiose, raffinose and lactose. Among these inducers lactose showed the most stimulative effect. α-Galactosidase was produced by either Koji method or submerged culture method, but in the latter most α-galactosidase was found in the mycelium fraction.Hydrolysis of raffinose in beet molasses was studied with the α-galactosidase in the mycelium fraction and about 80% of raffinose was found to be hydrolyzed by the enzyme preparation.

In Vitro Culture of Pisolithus Tinctorius Mycelium

Abstract: (1969). In Vitro Culture of Pisolithus Tinctorius Mycelium. Mycologia: Vol. 61, No. 1, pp. 195-198.

Isocitrate lyase in Coprinus lagopus (sensu Buller).

Abstract: Isocitrate lyase activity was detected in cell-free extracts of both a monokaryon and a dikaryon of Coprinus lagopus sensu Buller grown in media containing either acetate or glucose as carbon source. The activity in extracts of mycelium grown in an acetate medium was greater than that in extracts of mycelium grown in a glucose medium but marked differences between extracts of monokaryons and dikaryons grown in similar media were not observed. The isocitrate lyase activity could be largely sedimented by centrifugation at 10 000 × g for 20 minutes.

Erythritol Metabolism in Wild-Type and Mutant Strains of Schizophyllum commune

Abstract: Erythritol uptake and metabolism were compared in wild-type mycelium and a dome morphological mutant of the wood-rotting mushroom Schizophyllum commune. Wild-type mycelium utilized glucose, certain hexitols, and pentitols including ribitol, as well as d-erythrose, erythritol, and glycerol as sole carbon sources for growth. The dome mutant utilized all of these compounds except d-erythrose and erythritol. Erythritol- or glycerol-grown wild-type mycelium incorporated erythritol into various cellular constituents, whereas glucose-grown cells lagged considerably before initiation of erythritol uptake. This acquisition was inhibited by cycloheximide. Dome mycelium showed behavior similar to wild-type in uptake of erythritol after growth on glucose or glycerol, except that erythritol was not further catabolized. Enzymes of carbohydrate metabolism were compared in cell extracts of glucose-cultured wild-type mycelium and dome. Enzymes of hexose monophosphate catabolism, nicotinamide adenine dinucleotide (NAD)-dependent sugar alcohol dehydrogenases, and reduced nicotinamide adenine dinucleotide phosphate (NADPH)-coupled erythrose reductase were demonstrated in both. The occurrence of erythrose reductase was unaffected by the nature of the growth carbon source, showed optimal activity at pH 7, and generated NAD phosphate and erythritol as products of the reaction. Glycerol-, d-erythrose-, or erythritol-grown wild-type mycelium contained an NAD-dependent erythritol dehydrogenase absent in glucose cells. Erythritol dehydrogenase activity was optimal at pH 8.8 and produced erythrulose during NAD reduction. Glycerol-growth of dome mycelium induced the erythritol uptake system, but a functional erythritol dehydrogenase could not be demonstrated. Neither wild-type nor dome mycelium produced erythritol dehydrogenase during growth on ribitol. Erythritol metabolism in wild-type cells of S. commune, therefore, involves an NADPH-dependent reduction of d-erythrose to produce erythritol, followed by induction of an NAD-coupled erythritol dehydrogenase to form erythrulose. A deficiency in erythritol dehydrogenase rather than permeability barriers explains why dome cannot employ erythritol as sole carbon source for mycelial growth.

Germination of chlamydospores of Fusarium oxysporum f. sp. pisi race 1 in the rhizosphere, and penetration of the pathogen into roots of a susceptible and a resistant pea cultivar

Abstract: Germination of chlamydospores ofFusarium oxysporum f. sp.pisi race 1 in the rhizosphere of pea seedlings and red clover seedlings grown in natural soil heavily infested with the pathogen, was highest in percentage along the actively growing parts of the roots. At these sites, exudation of ninhydrinpositive substances and reducing sugars was most intense with seedlings grown in vitro. No significant difference in the percentage of germinating chlamydospores ofFusarium oxysporum f. sp.pisi race 1 were observed in the rhizosphere soil and on the root surface of homologous parts of roots of seedlings and mature plants of a susceptible ‘Rondo’ and a resistant ‘Rovar’ pea cultivar grown in natural soil heavily infested with the pathogen. Differences in the growth of mycelium of the pathogen on the root surface, or in the attachment of the mycelium to the root surface of both cultivars were not observed. Epidermis and cortex cells of roots of both cultivars reacted on penetration by the pathogen by producing a cellulose thickening of the cell wall, which later became infiltrated with a ligning-like material. A selective effect on the activities of the pathogen in the rhizosphere, on the root surface and in the epidermis and cortex in relation to resistance thus could not be demonstrated. Formation of new chlamydospores from germ tubes of germinating chlamydospores was frequently observed in the rhizosphere of the susceptible and resistant pea cultivar and in the rhizosphere of red clover seedlings.

[Host-parasite metabolic relationship between puccinia graminis var. tritici and triticum vulgare (Wheat) : II. Uptake of hexoses from the host].

Abstract: Rust infected leaves of wheat plants were incubated with glucose-(14)C. Uredospores which were formed during the application of the tracer were analyzed. All isolated compounds were labeled with (14)C. When germinating uredospores were incubated directly with (14)C-glucose, the isolated glutamic acid, arginine and lysine had practically no radioactivity. These compounds did, however, contain considerable (14)C-activity when they were isolated from uredospores formed on leaves that had been treated with the tracer. We therefore conclude that these amino acids were synthesized in the host and were taken up by the haustoria of the mycelium.High (14)C-radioactivity was also found in all carbohydrates (chitin, glucomannan, polyols etc.). Hexoses isolated from the spore constituents chitin and glucomannan showed the same distribution of radioactivity as the applied glucose-1-(14)C or glucose-6-(14)C. It follows that the rust mycelium takes up glucose or a similar monosaccharide from the wheat plant. The C-6-skeleton is not degraded to smaller metabolites before it is taken up.

Pure culture studies on the aquatic phycomycete, Lagenidium giganteum

Abstract: Lagenidium giganteum Couch has been re-discovered, using chitinous baits, and studied in pure culture In an investigation of its nutrition, chitin utilization has been demonstrated and the significance of this is discussed, as is its highly variable growth on an inorganic nitrogen source Addition of thiamine enhances growth but there is no absolute requirement for this vitamin Typically the fungus grows initially as a septate mycelium but forms separated inflated cells (subthalli) at maturity Subthallus production is closely linked to the source of nitrogen utilized In addition, staled conditions are conducive to subthallus production Under certain conditions germinated zoospores may derive a single subthallus directly, thus reducing the vegetative phase to an olpidioid one Subthalli can usually function as sporangia by producing exit tubes and releasing motile biflagellate zoospores However, they also germinate directly with great readiness, particularly if traces of nutrients are present This capacity to germinate may represent their more important biological role in the life-history of the fungus Conditions conducive to dehiscence were investigated and calcium was shown to be a vital ion in the external environment Although no clear resting stage was observed the vegetative mycelium has a striking capacity both for longevity and for adaptability to growth with minimal nitrogen The cytology of the fungus was also studied

Regulation of NAD-specific alcohol dehydrogenases in Neurospora crassa.

Abstract: Neurospora crassa is capable of synthesizing two different alcohol dehydrogenases. The synthesis of each depends upon the carbon source on which the mycelium is grown. The fermentative alcohol dehydrogenase, consisting of one electrophoretic protein band, is produced when the mycelium is grown on sucrose. The oxidative alcohol dehydrogenase, consisting of at least two isozymes, is synthesized when Neurospora crassa is grown on ethanol as a sole source of carbon. This latter enzyme is repressed by sugars such as glucose or sucrose. The two enzymes have been differentiated (1) electrophoretically, (2) by their substrate specificity, (3) by the ratio of the forward and reverse reactions, and (4) by their thermostability. Extracts from acetate-grown cells indicate a mixture of the two enzymes.

The Changes of Lysine- and Ornithine-lipids in Streptomyces sioyaensis

Abstract: Lysine-lipid (siolipin A) and ornithine-lipid (siolipin B) were found at the same time in Streptomyces sioyaensis. They were also found in mutant strains (Lys‒, Met‒, Try‒, His‒) of Streptomyces sioyaensis. Ratio of siolipin A to siolipin B differed, depending on the culture conditions. The young mycelium contained siolipin A predominantly, while the aged mycelium did much more siolipin B. They also varied according to pH of the broth. As the whole, the effect was more conspicuous in the mycelium from jar fermenter than that from Sakaguchi flasks.

Gluconic acid production

Abstract: Gluconic acid is produced by a fermentation process in which an inoculum of the fungus Aspergillus niger is transferred to a first production medium containing a source of glucose at a time when the glucose oxidase activity of the inoculum is increasing at its maximum rate. The fungus mycelium can be separated from the production medium at harvest time and reused in successive production media without the need for added nutrients until such time as nutrients are needed to revive the glucose oxidase activity.