马尔尼菲篮状菌分泌蛋白的鉴定及功能预测分析

目的 鉴定马尔尼菲篮状菌(TM)的分泌蛋白,并初步分析其生物学功能.方法 基于质谱技术对TM菌株(ATCC18224)培养上清进行分泌蛋白组鉴定,利用生物信息学手段预测所鉴定蛋白的亚细胞定位和信号肽剪切位点,以及分析其生物学功能和信号通路.结果 通过2次独立重复实验,共鉴定得到21个分泌蛋白;功能注释结果显示分泌蛋白主...     

成都市区三个功能区气传真菌的定量研究

作者使用液体吸收定量采样法,于1987年在成都市三个功能区进行了一年的气传真菌检测工作。调查表明,成都市区空气中常年飘散着较高浓度的真菌孢子,浓度变化范围为870.37～7592.59个/m~3,高峰在4月和10月。经分离鉴定,气传真菌分属36属和群。其中,酵母、枝孢霉属、青霉属、曲霉属、短梗霉属及无孢菌群为优势气传真菌。对空气中黄曲霉群菌株初筛结果,产毒菌占33.49％。     

Disseminated aspergillosis due to Aspergillus flavus in an experimental model: efficacy of azole therapy

The aim of this investigation was to create a reproducible experimental model of disseminated Aspergillus flavus aspergillosis, and to compare the relative therapeutic efficacies of itraconazole and fluconazole in this model. Temporarily immunosuppressed male Wistar rats received intravenous challenge by A. flavus conidia. Treatment was initiated 24 h later with oral itraconazole (1 mg kg-1 BW day-1), oral fluconazole (1 mg kg-1 BW day-1) or excipient only (infected-untreated rats); this was continued for 10 days. At this time, although 100% mortality had occurred among all infected-untreated rats, no mortality was noted among the control-uninfected, infected-itraconazole-treated or infected-fluconazole-treated rats. After killing, essential organs were processed for microbiological and histopathological studies. Aspergillus flavus was recovered in high colony counts from the organs of infected-untreated rats (lungs > liver > brain > kidneys), but in significantly lower colony counts, or not at all, from the organs of itraconazole-treated and fluconazole-treated rats. Histopathological alterations were pronounced in tissues of infected-untreated rats, but less so in treated rats. These data suggest that administration of itraconazole or fluconazole sufficiently early may prevent, or retard, progression of lesions in disseminated aspergillosis.     

Aspergillus endocarditis presenting as femoral artery embolism

Fungal valvular endocarditis is an unusual cause of endocarditis, yet very important because of its historically poor prognosis. We report two fatal cases of fungal valvular endocarditis following cardiovascular surgery, presenting as femoral artery embolism. Aspergillus terreus and A. flavus were the causative agents of endocarditis in the two patients. Diagnosis was established very early by culture of the emboli and was confirmed later by isolation of the same Aspergillus species from the resected valve tissue.     

Crystallization,Morphology, and Enzymatic Degradation of Polyhydroxybutyrate/Polycaprolactone (PHB/PCL) Blends

Two types of mixtures were prepared by solution blending: high molecular weight polyhydroxybutyrate (PHB)/poly(ε‐caprolactone) (PCL) and PHB/low molecular weight chemically modified PCLs (mPCL). The morphology, crystallization, and enzymatic degradation of the blends were studied by differential scanning calorimetry, polarized light optical microscopy, scanning electron microscopy, ¹H NMR, and weight loss measurements. In addition, enzymatic degradation studies were performed by an exposure to Aspergillus flavus. High molecular weight PHB/PCL blends were found to be immiscible in the entire composition range. Phenomena such as PCL fractionated crystallization and a decrease in PHB nucleation density were detected. When PHB was blended with mPCLs, the blends were partially miscible; two phases were formed, but the PHB‐rich phase exhibited clear signs of miscibility through a depression of both the T_m and the T_g of the PHB component (which was stronger with lower molecular weight mPCL), and an increase in the growth rate of PHB spherulites in the blends as compared to neat PHB or to the PHB component in the PHB/PCL blends. The biodegradation by a exposure to A. flavus showed that the blends are synergistically attacked in comparison to the homopolymers. Two factors may influence the improved degradation rate of the blends: the dispersion of the components and their crystallinity that was reduced in view of the fractionated crystallization and impurities transfer. In the case of the PHB/mPCL blends, the increased miscibility between the components caused a reduction in the degradation rate.

     

Neuroaspergillosis in an immunocompetent patient

Aspergillosis of the central nervous system (CNS) is an uncommon infection, mainly occurring in immunocompromised patients. We report a case of neuroaspergillosis caused by Aspergillus flavus in an immunocompetent patient presenting as a space-occupying lesion of the CNS. The patient was responding favorably to voriconazole at the time of this report.     

造血干细胞移植术后继发外生殖器黄曲霉感染一例

目的 报告一例外生殖器黄曲霉感染。方法 对患者的临床资料、真菌学检查、胸部CT检查结果进行分析。结果 患者男,33岁,5个月前确诊为急性髓性白血病M₁型,经化疗诱导缓解后接受异基因造血干细胞移植术。术后7天患者出现发热,38～38.5℃,多种抗生素治疗无效。同时外生殖器部位出现多个圆形水肿性红斑,直径0.2～1cm,中央覆盖黑色焦痂。龟头冠状沟可见糜烂及坏死性皮疹。取皮损渗出物及痂皮作常规真菌检查,分离出黄曲霉。静脉滴注伊曲康唑、局部外用碘伏溶液33天后皮疹治愈。移植术后第137天,胸部CT检查显示右上肺尖一薄壁空洞。结论 该患者为造血干细胞移植术后继发外生殖器黄曲霉感染,感染源可能与肺部病灶有关。     

Potential of Trichoderma spp. for Biocontrol of Aflatoxin-Producing Aspergillus flavus

The inhibitory action of 20 antagonistic Trichoderma isolates against the aflatoxigenic isolate A. flavus ITEM 9 (Af-9) and their efficacy in reducing aflatoxin formation in vitro were examined. Production of metabolites with inhibitory effect by the Trichoderma isolates was also investigated. Antagonistic effect against Af-9 was assessed by inhibition of radial growth of the colonies and by fungal interactions in dual confrontation tests. A total of 8 out of 20 isolates resulted in a significant growth inhibition of 3-day-old cultures of Af-9, ranging from 13% to 65%. A total of 14 isolates reduced significantly the aflatoxin B₁ (AfB₁) content of 15-day-old Af-9 cultures; 4 were ineffective, and 2 increased AfB₁. Reduction of AfB₁ content was up to 84.9% and 71.1% in 7- and 15-day-old cultures, respectively. Since the inhibition of Af-9 growth by metabolites of Trichoderma was not necessarily associated with inhibition of AfB₁ production and vice versa, we investigated the mechanism of reduction of AfB₁ content at the molecular level by examining two strains: one (T60) that reduced both growth and mycotoxin content; and the other (T44) that reduced mycotoxin content but not Af-9 growth. The expression analyses for the two regulatory genes aflR and aflS, and the structural genes aflA, aflD, aflO and aflQ of the aflatoxin biosynthesis cluster indicated that neither strain was able to downregulate the aflatoxin synthesis, leading to the conclusion that the AfB₁ content reduction by these Trichoderma strains was based on other mechanisms, such as enzyme degradation or complexation. Although further studies are envisaged to identify the metabolites involved in the biocontrol of A. flavus and prevention of aflatoxin accumulation, as well as for assessment of the efficacy under controlled and field conditions, Trichoderma spp. qualify as promising agents and possible alternative options to other biocontrol agents already in use.     

3种植物药单体对肺曲霉生物活性实验

目的：探讨3种植物药单体有效活性成分的抗真菌作用,对肺曲霉进行体外生物活性的MIC和MFC实验。方法：采用试管药基法,将桂皮醛、丁香酚、藿香酮倍比稀释成2.5～0.0098μg/mL的浓度,对致病性肺曲霉（烟曲霉、黄曲霉）进行MIC和MFC实验观察。结果：桂皮醛对烟曲霉MIC均值为0.0391μg/mL,黄曲霉MIC均值为0.0781μg/mL,MFC均为0.0781μg/mL;丁香酚对烟曲霉、黄曲霉MIC均值为0.0781μg/mL,MFC0.1562μg/mL;藿香酮对烟曲霉、黄曲霉MIC均值为0.1562μg/mL,MFC0.3125μg/mL;对照组氟康唑对烟曲霉、黄曲霉MIC和MFC均〉2.5mg/mL。结论：3种植物药单体对烟曲霉、黄曲霉均显示有较强的生物活性,其生物活性依次为桂皮醛、丁香酚、藿香酮。氟康唑对烟曲霉、黄曲霉均显示耐药。     

Aspergillus flavus and Total Aflatoxins Occurrence in Dairy Feed and Aflatoxin M1 in Bovine Milk in Aguascalientes,Mexico

Contamination of food chains by toxigenic fungi and aflatoxins is a global problem that causes damage to human health, as well as to crop and livestock production. The objective is to evaluate Aspergillus flavus and total aflatoxins (AFs) occurrence in totally mixed rations (TMRs) for dairy cows and aflatoxin M₁ (AFM₁) in milk for human consumption. Ninety-nine dairy production units located in Aguascalientes, Mexico, were randomly selected, and samples were collected from TMRs, raw milk, and milk marketed in the city in two consecutive agricultural cycles. AFs were quantified in TMRs and milk by indirect enzyme immunoassay and HPLC; aflatoxigenic and molecular (PCR) capacity of monosporic A. flavus isolates in the feed was characterized. All feed, raw, and pasteurized milk samples showed aflatoxin contamination (26.0 ± 0.4 µg/kg, 32.0 ± 1.0, and 31.3 ± 0.7 ng/L, respectively), and a significant proportion (90.4, 11.3, and 10.3%) exceeded the locally applied maximum permissible limits for feed and milk (20.0 µg/kg and 50 ng/L). Aflatoxin contamination in both TMRs and milk indicated a seasonal influence, with a higher concentration in the autumn–winter cycle when conditions of higher humidity prevail. The results obtained suggest the existence of contamination by aflatoxigenic A. flavus and aflatoxins in the diet formulated for feeding dairy cows and, consequently, in the dairy food chain of this region of the Mexican Highland Plateau.