Comparative production of ligninolytic enzymes by Phanerochaete chrysosporium and Polyporus sanguineus

The aim of the present study was to compare the effect of a wide range of culture conditions on production of ligninolytic enzymes by Polyporus sanguineus and Phanerochaete chrysosporium . Lignin peroxidase production by P. sanguineus was comparable with that of P. chrysosporium, although the culture conditions giving the highest yield varied greatly between the two fungi. Highest yield of manganese peroxidase by P. sanguineus obtained in 0.5% malt extract medium and peptone or malt extract supplemented mineral salts broth could not be surpassed by P. chrysosporium in any of the optimization experiments. In addition to lignin peroxidase and manganese peroxidase, P. sanguineus also produced laccase, which was best expressed in malt extract medium supplemented with sugarcane bagasse.

First Report of Formosan Michelia Seedling Root Rot Caused by Pythium splendens in Taiwan

Formosan michelia (Michelia compressa (Maxim.) Sargent) is a valuable evergreen tree in Taiwan that is distributed from low to medium (200 to 1,800 m) altitudes. In many nurseries in Taiwan, Formosan michelia seedlings grow poorly or wilt. The etiology of the disease observed in April 2004 in a nursery in Jinshan was investigated. Diseased seedlings with chlorotic leaves and decayed feeder roots lost leaves, died back, and then wilted. The putative pathogen, Pythium splendens Braun, was isolated and identified on a morphological basis (1). P. splendens was isolated from the roots of diseased seedlings on 2% water agar with 100 ppm of ampicillin. Isolates increased daily on potato dextrose agar at 24°C by 27 to 30 mm and on malt extract agar (MEA) by 23 to 25 mm. No zoosporangia and zoospores were produced. The main hyphae were as much as 9 μm wide on MEA. Hyphal swellings were abundant, globose, smooth, terminal, and 33 to 42 μm in diameter, often with dark, densely granulated contents. Attempted matings of four P. splendens isolates in V8 medium failed. To prove pathogenicity, the four isolates were cultured in 300-ml flasks containing 150 ml of 2% malt extract medium at room temperature for 14 days. The mycelia were homogenized in sterile water at 4,500 rpm for 5 min. The suspension was adjusted to 5 × 106 hyphal swellings per ml. Roots of the 2-month-old seedlings were immersed in the suspension for 2 h, whereas the control seedlings were immersed in sterilized water. Five seedlings of each of three replicates were inoculated with one of the four isolates for a total of 60 seedlings. Controls were replicated in the same way. The inoculated plants were transplanted into plastic flowerpots containing sterilized peat and moss and kept in the greenhouse at 20 to 24°C. After 14 days, inoculated seedlings developed symptoms like those of the original plants. The putative pathogen was reisolated from the roots of inoculated plants. Cultures are maintained at the Forest Pathology Lab of the National Taiwan University. To our knowledge, this is the first report of proof of pathogenicity of P. splendens on Formosan michelia seedlings. Reference: (1) A. J. Van der Plaats-Niterink. Stud. Mycol. 21:151, 1981.

Cultivation of tea fungus on malt extract medium

The possibility of application of malt extract as a source of carbohydrate in a medium for tea fungus was investigated. The beverage obtained on such medium was compared with that prepared in a traditional way with sucrose medium. The presence of easily adoptable sugars, glucose and fructose, as dominant in malt medium results in a very effective fermentation, which gives much more sour beverage for the same time and makes it possible to reduce the fermentation period. The obtained beverage has satisfactory sensorial characteristics.

A defined growth medium for the production of chloroperoxidase by Caldariomyces fumago

Ten strains of Caldariomyces fumago and related fungi were found to produce extracellular chloroperoxidase when grown on a glucose – malt extract medium. High enzyme levels and pigment production were observed for C. fumago ATCC 16373 and C. fumago CMI 89362. Removal of malt extract from the medium and the replacement of glucose by fructose as the carbon source provided a defined medium which, by comparison with the complex medium, produced the following results with both fungal strains. Chloroperoxidase was produced to similar levels, with maximum production after 6 days rather than 12 days of growth; pigmentation of the medium was reduced by 90% and the pH of the medium remained constant, thus stabilizing enzyme activity. Addition of urea or proline as a nitrogen supplement to nitrate enhanced enzyme production by strain CMI 89362. Comparison of the two strains indicated that CMI 89362 produced higher levels of chloroperoxidase than ATCC 16373.

Production of Rubratoxin by Penicillium rubrum in a Soy Whey-Malt Extract Medium

Sterile soy whey (1.75% dissolved solids) was fortified with malt extract and inoculated with spore suspensions of Penicillium rubrum strains P-13, 1062, 2120, 2123, and 3290. Samples were incubated quiescently at 28 C from 1 to 28 days and as shake cultures for 3, 5, and 7 days. Rubratoxin was recovered from culture filtrates by alcohol-acetone extraction and resolved by thin-layer chromatography. Toxin was not produced in shake cultures. Rubratoxins A and B were produced in quiescent soy whey cultures of all P. rubrum strains except P. rubrum P-13 which produced only rubratoxin B. Toxin production increased as the concentration of malt extract increased from 0.5 to 10% (w/v). Rubratoxin formation also increased with an increase in incubation time from 3 to 17 days but the amount of toxin in cultures declined rapidly thereafter. Yields of rubratoxin A ranged from 0.83 to 31.53 mg/100 ml in cultures of P. rubrum 1062 and from 1.89 to 22.70, 0.53 to 25.13, and 2.07 to 31.20 mg/100 ml in P. rubrum 2120 2123, and 3290 cultures, respectively. Yields of rubratoxin B ranged from 0.77 to 105.30, 1.03 to 94.83, 2.13 to 91.57, 0.82 to 78.53, and 1.3 to 85.57 mg/100 ml in cultures of P. rubrum 13, 1062, 2120, 2123, and 3290, respectively. After maximum production, toxin content in cultures leveled off and then decreased. Amounts of toxin declined more rapidly than did mold growth (as measured by mycelial dry weight). Although malt extract stimulated fungal growth, toxin production was enhanced more than mold growth.

SOME FACTORS AFFECTING THE GERMINATION OF SPORES OF FOMES IGNIARIUS VAR. POPULINUS (NEUMAN) CAMPBELL, AND THE SIGNIFICANCE OF THESE FACTORS IN INFECTION

Spores of F. igniarius collected from different conks at one time, or from one conk at different times of the year, varied significantly in germinability. However, spores collected from one conk within a 3-day period were judged to be sufficiently consistent for use in comparative tests.Spores germinated best on an 8% malt extract medium buffered at pH 4.0. Only a trace of germination occurred on water agar and none occurred on alkaline media. Stimulation by malt extract appeared to be due partly to the sugar content and partly to an unidentified factor.While extracts of the surface wood of aged wounds contained far less of sugars and amino acids than did extracts of fresh sapwood, germination on the former was consistently better. A lower pH appeared to account for most of this advantage but even when the two types of extract were brought to the same pH better germination occurred on the extract of the aged wound.Spores of F. igniarius germinated well at temperatures in the range 20–35 °C. They varied widely in their ability to germinate after storage. Some samples germinated fairly well after 80 days; others failed to germinate after 10 days.These findings are discussed in relation to the problems of infection.