两株真菌降解菜籽饼中植酸的研究

利用选择性培养基从土壤中分离到两株能降解植酸的丝状真菌。这些菌株能利用肌醇作为唯一的碳源和能源而生长。在液态发酵中植酸的降解率分别为74．4％和95．0％;在固态发酵中植酸的降解率为40％左右。某些金属离子对菌株的降解率的提高具有一定的促进作用。对温度、pH和水分等影响因子也进行了初步的探讨。经初步鉴定,这两株菌株中有一株为拟青霉（Paecilomycessp）,另一株为青霉（Penicilliumsp．）,它们均不产黄曲霉素素。     

Effect of Host Plant on the Potential ofPaecilomyces fumosoroseus(Deuteromycotina: Hyphomycetes) for Controlling the Silverleaf Whitefly,Bemisia argentifolii(Homoptera: Aleyrodidae) in Greenhouses

We determined host plant effect on susceptibility of the silverleaf whitefly,Bemisia argentifolii, to the entomopathogenic fungusPaecilomyces fumosoroseus. Whiteflies were reared on three vegetable species (cucumber, cabbage, and tomato) and three cultivars of tomato (Heatwave, Better Boy, and Rutgers). Second instars were sprayed with 5 × 10⁴conidia/cm²ofPfr97, aP. fumosoroseusstrain, used as a microbial control agent of whiteflies. Trials were conducted in an experimental greenhouse, where temperature and relative humidity were adjusted to favor infection (22–33°C, and 68–100% RH). Larval susceptibility to fungal infection was high and not significantly affected by the host plant. Mortality was > 70% 1 week after treatment and increased further during the second week. Percentages of cadavers with subsequent production of conidia observed in the greenhouse did not vary significantly either with the host vegetable species (85–93% 7 days after treatment and 99–100% 14 days after treatment), or with the cultivar of tomato (96–97% 7 days after treatment and 99–100% 14 days after treatment). After incubation under optimal laboratory conditions, the percentages based on the total number of sporulating cadavers (includingin situsporulating individuals and cadavers sporulating afterin vitroincubation) were not significantly influenced either by host vegetable or cultivar of tomato. According to the conditions prevailing in the series of experiments with the three vegetable species or in the series of experiments with the three cultivars of tomatoes, the production of newly formed conidia varied from approximately 10,000 to 18,000 conidia/cadaver. However, in both series, there was no significant influence of the host vegetable species or cultivar. The survival of the newly formed conidia harvested 7 days following treatment reached more than 50% but was not affected by host plant. These results indicate thatP. fumosoroseusshows potential as a microbial control agent for controllingB. argentifoliion greenhouse crops.     

拟青霉属的一个新种

从湖南省桃江县采集的亚香棒虫草(Cordyceps hawkesii Gray)的新鲜子座、单子囊孢子及其寄主,一种蝙蝠蛾(Hepialus sp.)的僵死幼虫,培养获得拟青霉属的一个新种,命名为霍克斯拟青霉(Paecilomyces hawkesii Xiao,T.B.Li et Q.T.Chen,sp.nov.)。本文报道该菌的形态学特征及其与近缘种肉色拟青霉(P.carneus)的关系,并认为它可能是亚香棒虫草的无性阶段。     

不同品种大豆培养基对蝙蝠蛾拟青霉菌丝体代谢成分的影响

以不同品种大豆为培养基对蝙蝠蛾拟青霉代谢成分影响进行研究,筛选出最佳大豆品种,为蝙蝠蛾拟青霉标准化生产提供参考。首先对15个不同大豆品种培养基的主成分含量进行测定,同时对各品种大豆培养基培养的蝙蝠蛾拟青霉菌丝体生物量、菌丝体腺苷含量及腺苷总量进行测定。采用非靶向代谢组学方法对不同品种大豆培养基培养的蝙蝠蛾拟青霉菌丝体中的代谢成分进行研究。结果表明,15个不同品种大豆豆饼中的粗蛋白和粗脂肪含量以及对应培养基培养的蝙蝠蛾拟青霉菌丝体腺苷含量均有显著性差异(P<0.05),其中9号品种大豆培养基培养的菌丝体腺苷含量最高为(1 089.35±25.51) mg/kg, 5号的最低为(60.68±9.56) mg/kg, 5号、9号和10号培养的菌丝体之间存在显著性差异(P<0.05)。代谢组学研究表明,5号、9号和10号菌丝体代谢成分相对含量差异较大。其中9号菌丝体丙氨酸、谷氨酸、天冬氨酸等氨基酸,水苏糖、半乳糖等糖类,以及三羧酸循环产物2-氧代丁酸、柠檬酸等代谢物相对含量显著高于5号和10号菌丝体。KEGG富集分析表明,9号培养基通过促进天冬氨酸及谷氨酸代谢通路,可增加天冬氨酸和...     

Acute oral intragastric pathogenicity and toxicity in mice of <Emphasis Type="Italic">Paecilomyces fumosoroseus</Emphasis> isolated from whiteflies

Paecilomyces fumosoroseus, monospore culture EH-506/3, isolated in Mexico from Bemisia tabaci whitefly was tested for acute oral intragastric pathogenicity and toxicity in CD-1 mice. Animals were inoculated by gavage with only one dose (10⁸ conidia/animal) of viable (72 mice), heat-killed (24 mice) fungus and compared to 18 control mice. Clinical observations were done daily; mycological and histological tests were performed during necropsies at days 3, 10, 17, and 21 after the inoculation. No mice were clinically ill or died. At the end of the study, their mean weight corresponded to healthy adults. Positive fungal cultures of feces were obtained only 24 h after inoculation. Positive cultures were found in 15 out of 360 organs (liver, spleen, kidney, brain, lung) in 12 of 72 mice inoculated with viable conidia. Gross pathology exhibited splenomegaly and liver paleness in mice inoculated with viable and heat-killed fungus. Non-germinated conidia were observed in studied organs, without any pathological tissue reaction, suggesting no mycological or histopathological evidence of fungal multiplication. The fungus was able to persist, but did not cause permanent damage to the host. This study supports the non-pathogenic/toxic status of P. fumosoroseus EH-506/3 when administered intragastrically in mice.     

Impact of carbon and nitrogen nutrition on the quality, yield and composition of blastospores of the bioinsecticidal fungus Paecilomyces fumosoroseus

The impact of growing cultures of Paecilomyces fumosoroseus in liquid media containing four combinations of glucose and casamino acids (8 g l^–1 or 80 g l^–1 glucose, 1.32 g l^–1 or 13.2 g l^–1 casamino acids) was evaluated, based on blastospore production, germination rate, viability after freeze-drying and short-term storage stability. When blastospores were produced using a high casamino acid concentration, blastospore yields and germination rates were significantly higher (13.2–18.5×10⁷ blastospores ml^–1, 50–60% germination after 4 h), compared to cultures grown in media containing lower casamino acid concentrations (0.4–2.3×10⁷ blastospores ml^–1, 10–20% germination after 4 h). Chemical analyses of blastospore composition showed that accelerated blastospore germination may be related to increased proteinaceous reserves rather than to glycogen or lipid accumulation. Tolerance to freeze-drying by blastospores suspended in spent medium was enhanced by a high initial casamino acid concentration in the culture medium (75% survival) and by the residual glucose concentrations in the spent medium. Under the conditions of this study, the storage stability of blastospores of P. fumosoroseus was unaffected by the nutritional condition in which they were produced.     

Viability of Heterodera glycines Exposed to Fungal Filtrates

Filtrates from nematode-parasitic fungi have been reported to be toxic to plant-parasitic nematodes. Our objective was to determine the effects of fungal filtrates on second-stage juveniles and eggs of Heterodera glycines. Eleven fungal species that were isolated from cysts extracted from a soybean field in Florida were tested on J2, and five species were tested on eggs in vitro. Each fungal species was grown in Czapek-Dox broth and malt extract broth. No toxic activity was observed for fungi grown in Czapek-Dox broth. Filtrates from Paecilomyces lilacinus, Stagonospora heteroderae, Neocosmospora vasinfecta, and Fusarium solani grown in malt extract broth were toxic to J2, whereas filtrates from Exophiala pisciphila, Fusarium oxysporum, Gliocladium catenulatum, Pyrenochaeta terrestris, Verticillium chlamydosporium, and sterile fungi 1 and 2 were not toxic to J2. Filtrates of P. lilacinus, S. heteroderae, and N. vasinfecta grown in malt extract broth reduced egg viability, whereas F. oxysporum and P. terrestris filtrates had no effect on egg viability.     

Hyalohyphomycosis caused byPaecilomyces variotii: a case report,animal pathogenicity and ‘in vitro’ sensitivity

A case of cutaneous infection in a 25-year-old male caused byPaecilomyces variotii is described. Animal pathogenicity studies with normal and cortisone-treated mice revealed the predeliction ofP. variotii for skin and liver in both normal and cortisone-treated mice and for lungs and heart only in immunosuppressed mice. 5-fluorocytosine gave the best MIC value forP. variotii in vitro. This report documents for the first time thatP. variotii causes cutaneous infection.     

Optimization of Culture Medium for Sporulation and Biomass Production of a Nematophagous Fungus: Consideration of Nutritional and Environmental Conditions

This study reports the effects of various nutritional and environmental factors on sporulation and biomass of Paecilomyces lilacinus IPC‐P. These factors included carbon and nitrogen sources, carbon‐to‐nitrogen ratios, mineral elements and vitamins together with water potentials, temperatures, dark/light cycles and pH. On the basis of these results, together with a ‘two‐step’ cultivation and orthogonal method, the culture conditions for sporulation of this fungus were optimized. The spore suspension was inoculated on a basal medium (sucrose 19.00 g/l, soy peptone 4.06 g/l, K₂HPO₄ 1.00 g/l, KCl 0.50 g/l, MgSO₄ 0.50 g/l, FeSO₄ 0.01 g/l, agar 13.00 g/l) for 4 days, before being transferred to a sporulation medium (dextrin 2.27 g/l, urea 2.13 g/l, CaCl₂ 3.00 g/l, ZnSO₄·7H₂O 0.01 g/l, agar 13.00 g/l) for a further 4 days under the following environmental conditions: ?3.9 MPa/pH 7/light 24 h/temperature 29°C; these conditions were altered to ?0.3 MPa/pH 6/light 24 h/temperature 23°C in order to obtain better biomass yields. The data presented provide information on the nutrient and environmental requirements of this fungus, which will be essential for its commercial production.