Mycological Peptone Research Articles

Effect of Phanerochaete chrysosporium on transformations of urea, sulphur-coated urea and peptone in soil

Growth of the bioremediation fungus Phanerochaete chrysosporium in non-sterilised soil stimulated the release of sulphate and ammonium from added sulphur-coated urea and also significantly increased ammonium release (but not subsequent nitrification) from added urea. The mineralisation of mycological peptone to ammonium in soil and its subsequent oxidation to nitrate was also generally stimulated following inoculation. The results show that following inoculation, P. chrysosporium influences the transformation of natural or fertiliser compounds in soils. The possibility that such changes may occur should be considered when P. chrysosporium is added to soils solely for the purposes of bioremediation.

Efficient production of phialoconidia of Verticillium lecanii for biocontrol of cucumber powdery mildew, Sphaerotheca fuliginea

A method is described that yields over 3 • 10 9 phialoconidia/ml of VerticiIlium lecanii. Additional keyword: mycoparasites. Spore production of mycoparasitic fungi may vary considerably and mass production of fungal conidia for biological control often meets with problems. Some mycoparasites do not produce sufficient inoculum for small-scale experiments (Hijwegen, 1988). Usually, special studies on cultivation methods are required as demonstrated for Ampelomyces quisqualis by Schmitz-Elsherif (1990). Verticillium lecanii (Zimm.) Vi6gas strain Fyto 88.1, isolated from Sphaerotheca fuliginea (Schlecht.: Fr.) Poll. (Hijwegen, 1988), can easily be grown and sporulates well on most solid media such as agars containing potato-dextrose broth, malt extract plus mycological peptone, oat meal, chitin or skimmed milk. In this way productions of 1-4 • 107 conidia/cm 2 (0.5-2 • 109 conidia/petridish) can be obtained. When, however, 8 • 101~ conidia were required every week for a greenhouse experiment, (Verhaar and Hijwegen, unpublished) surface grown cultures were inadequate and other methods of cultivation were investigated. V. lecanii was grown at 20 ~ and 135 rpm in liquid media containing milled, autoclaved oat meal, skimmed milk or malt extract plus mycological peptone. Yields of conidia were rather low. Conidium production was enhanced by raising the incubation temperature to 25 ~ Yeast cell walls and malt extract plus mycological peptone gave a good yield of conidia. These media were, however, surpassed by far by growing V. lecanii in autoclaved oat meal suspension. V. lecanii has been reported to produce only blastoconidia in liquid culture (Latg6 et al., 1986). After consulting Dr W. Gums, CBS, Baam this was investigated using our strain Fyto 88.1. In our experiments submerged mycelium, producing micro-verticils with micro-phialides carrying normal phialoconidia, was formed in liquid culture. Budding was not observed. Conidia produced in liquid culture could not be distinguished microscopically in size or shape from conidia produced on solid oat meal medium. In 1% oat meal more mycelium was formed than in 3% oat meal. This raises the question whether oat meal contains substances that influence the mycelium--conidia ratio. To investigate conidium production quantitatively, 0.8 cm 2 pieces of agar with mycelium from the margin of a growing culture of V. lecanii were added to 300-ml Erlenmever flasks containing 100 ml of 1, 2, or 3% milled and autoclaved oat meal (Quaker I~IO

Nutritional and environmental factors affecting biomass and oospore production of the biocontrol agent Pythium oligandrum

Biomass and oospore production by Pythium oligandrum were examined in a defined glucose-asparagine medium. Optimal biomass production occurred between 20 and 35°C, with little growth below 10°C or above 35°C. Biomass production was maximal between pH 6.0 and 7.5 and was totally inhibited at pH 4.5 and 9.5. Apart from urea, all tested simple and complex nitrogen sources were utilized, but the greatest biomass production was with l-asparagine, l-arginine, l-aspartate, l-glutamate, mycological peptone, and autoclaved yeast as nitrogen sources. Growth occurred on most carbon sources tested, but only d-glucose, maltose, and trehalose were used extensively. The C : N ratio affected both biomass and oospore production with low ratios (5–30 : 1) most favorable for oospore production. Oospore production was initiated prior to total depletion of nutrients from the medium. THe implications of these findings for the production of biocontrol inoculum and the use of P. oligandrum in the field are discussed.

Effect of oleic acid on vegetative growth of the aphid-pathogenic fungusErynia neoaphidis

The aphid-pathogenic fungus Erynia neophidis grew on a semi-defined medium containing 16 g·1−1 glucose, 3 g·1−1 yeast extract and 5 g·1− mycological peptone only when the medium was supplemented with low concentrations of certain fatty acids. Of these, oleic acid fulfilled the growth requirement at a concentration of 0.02% (v/v), but higher concentrations were toxic, causing complete loss of viability of cultures at a concentration of 0.2% (v/v) in liquid medium and at 4% (v/v) on solid medium. The reduced viability of the fungus in liquid culture compared to that on equivalent solid medium, and at low inoculum density compared to high inoculum density in liquid medium, is explicable in terms of this toxicity.

Effect of oleic acid on vegetative growth of the aphid-pathogenic fungus Erynia neoaphidis

The aphid-pathogenic fungus Erynia neophidis grew on a semi-defined medium containing 16 g·1 −1 glucose, 3 g·1 −1 yeast extract and 5 g·1 − mycological peptone only when the medium was supplemented with low concentrations of certain fatty acids. Of these, oleic acid fulfilled the growth requirement at a concentration of 0.02% (v/v), but higher concentrations were toxic, causing complete loss of viability of cultures at a concentration of 0.2% (v/v) in liquid medium and at 4% (v/v) on solid medium. The reduced viability of the fungus in liquid culture compared to that on equivalent solid medium, and at low inoculum density compared to high inoculum density in liquid medium, is explicable in terms of this toxicity.

Studies on a wild strain of Schizophyllum commune: Cellulase and xylanase production and formation of the extracellular polysaccharide Schizophyllan

A wild strain of schizophyllum commune (Fr:Fr:) isolated in Bangladesh produced cellulase and xyianase in high yields as well as the exobiopolymer schizophyllan. It was found experimentally that concentrations of 4% Avicel, 3.5% peptone, and 0.5% Ca(NO(3))(2).4H(2)O were optimal for growth and product formation. Bacto-peptone was found to be the most suitable substrate of a number of casein, mycological, and meat peptone preparations for enzyme production. Young plate-culture inocula (4 days) were found to be better than comparatively aged fungal cultures (14 days). With the optimized medium, 5 units filter paper (FP) cellulase, 1244 units xylanase, 108 units beta-glucosidase, and 65 units of carboxymethyl (CM) cellulase per mL culture filtrate were obtained in shake flasks. In a laboratory fermentor the respective enzyme activities were 4.5 units FP-cellulase, 1200 units xylanase, 100 units beta-glucosidase, and 60 units CM-cellulase per mL culture filtrate. A biopolymer, reported to be active against can cerous cells, was an additional product in addition to the enzymes.

Effect of culture shake speed and local oxygenation on the observed maximal accumulation of cytochrome P-450 in Saccharomyces cerevisiae at the fastest growth rate

The yeast Saccharomyces cereoisiae produces a cytochrome P-450 enzyme which is thought to catalyse the Id Yoshida & Aoyama, 1984). Thus oxygen may have an important role in regulating cytochrome P-450 biosynthesis. S . cereoisiae (NCYC 754) was grown at 30°C in an orbital shaker at a series of different shake speeds. The growth medium consisted of 20% (w/v) glucose, 2% (w/v) mycological peptone, 1% (w/v) yeast extract and 0.5% (w/v) sodium chloride. Yeast was inoculated with a wire loop into IOOml of medium in 250ml flasks. Dry weight estimates were obtained by removing samples from the culture, washing the yeast with distilled water and drying at 70°C to constant weight. Cytochrome P-450 was determined directly on whole cells using its reduced carbon monoxide difference spectrum (Omura & Sato, 1964). Fig I shows the effect of growing S. cereoisiae in batch culture at a series of shake speeds on the accumulation of cytochrome P-450 and the growth of yeast. A clear maximum cytochrome P-450 level is observed at 120rev./ min, with the enzyme level per g of yeast decreasing at both slower and faster shake speeds. The maximum yield of cytochrome P-450 occurs at the same shake speed as the maximum growth rate and also the maximum yield of yeast biomass. This suggests a close link between a high yield of cytochrome P-450 and a high growth rate. These interesting findings with the orbital shaker are related to the known effect of agitation in giving enhanced transfer of solutes between the microbial biomass, the bulk medium and the associated gas phase. Transfer rates generally increase with increasing agitation, and an optimal agitation intensity may be expected to correspond to the optimal level of a particular solute. In parallel work, using stirred-tank fermentation (Salihon et al., 1985), cytochrome P-450 yield from S. cereoisiae NCYC 754 showed a clearly defined optimum for agitation. With growth conditions optimized using air as oxygen source, growth under identical conditions, but using air mixed with either nitrogen or oxygen, gave severely reduced enzyme yields, indicating that the agitation optimum found in this work indeed corresponds to optimal dissolved oxygen availability. Blatiak et al. (1983) have previously reported that small h

Studies on the growth of Saccharomycopsis fibuliger on pectic materials

Growth experiments have indicated that the yeast Saccharomycopsis fibuliger is able to utilize pectic materials as a carbon source for cell growth. Small quantities of yeast extract or mycological peptone and maltose are necessary to initiate growth. Cell yields of 35 g/100 g pectin were obtained after modification of the pH value, the concentration of calcium ions and pectin in the growth medium. The optimum pH for cell growth was 4.8, which is similar to the reported optimum for cell growth on starch. Cell yields declined at higher concentrations of pectin, as a result of the reduced rate of oxygen absorption into the growth medium. Neither the concentration of ammonium and phosphate ions nor the type of inorganic nitrogen source significantly affected cell growth within the experimental conditions employed.

Production and Purification of Thermostable Amylase and Protease of Thermomonospora viridis

Maximum yields of amylase were produced by the thermophilic actinomycete Thermomonospora viridis in a modified Simpson and McCoy medium containing 1.5% corn starch and 0.5% mycological peptone with an initial pH 7.0. Best yields of amylase were obtained after incubation for 48 h, when the pH of the medium had risen to 8.2. Amylase was purified 313-fold by precipitation with n-propyl alcohol, dialysis against tap water, adsorption on Ca(3)(PO(4))(2), and fractionation on Sephadex G-100. Protease was produced in nutrient broth containing 0.5% starch and 1.0% corn steep liquor and at an initial pH 7.0. Maximum yields of protease were produced after 42 h. The protease was purified 54-fold by precipitation with n-propyl alcohol, dialysis against tap water, adsorption on Ca(3)(PO(4))(2), and fractionation on Sephadex G-200.

Optimum conditions for initiation of filamentation in Candida albicans

A medium that initially produced filaments from almost all of its Candida albicans blastospore inoculum contained 1% mycological peptone and 0.2% glucose, final pH 7.4-7.5. The medium was inoculated to 10-6 cells/ml and incubated at 40 degrees C. Reversion to secondary blastospores began at a mean of 2.4 h after inoculation. The patterns of utilization of growth nutrients during optimal mycelial growth showed no correlation with the events of filamentation.