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1.
Forty-five fungal isolates from moldy supermarket foods were tested for toxicity to brine shrimp, and twenty-two of these isolates were subsequently tested for toxicity to chicken embryos. Highly toxigenic fungi were Cladosporium sphaerospermum from a bakery product, Fusarium oxysporum from carrots, F. solani from cabbage, Aspergillus niger and Penicillium corylophilum from bread, P. cyclopium and P. herguei from corn meal, P. lanosum from onions,P. steckii from chocolate syrup, Penicillium sp. from jelly, and Rhizopus nigricans isolates from sweet potato, applesauce, and strawberries. Approximately one-third of the fungal cultures were moderately to highly toxigenic to brine shrimp and chicken embryos, while several additional cultures were slightly toxigenic.  相似文献   

2.
Thermophilic Fungi: Their Physiology and Enzymes   总被引:19,自引:0,他引:19       下载免费PDF全文
Thermophilic fungi are a small assemblage in mycota that have a minimum temperature of growth at or above 20°C and a maximum temperature of growth extending up to 60 to 62°C. As the only representatives of eukaryotic organisms that can grow at temperatures above 45°C, the thermophilic fungi are valuable experimental systems for investigations of mechanisms that allow growth at moderately high temperature yet limit their growth beyond 60 to 62°C. Although widespread in terrestrial habitats, they have remained underexplored compared to thermophilic species of eubacteria and archaea. However, thermophilic fungi are potential sources of enzymes with scientific and commercial interests. This review, for the first time, compiles information on the physiology and enzymes of thermophilic fungi. Thermophilic fungi can be grown in minimal media with metabolic rates and growth yields comparable to those of mesophilic fungi. Studies of their growth kinetics, respiration, mixed-substrate utilization, nutrient uptake, and protein breakdown rate have provided some basic information not only on thermophilic fungi but also on filamentous fungi in general. Some species have the ability to grow at ambient temperatures if cultures are initiated with germinated spores or mycelial inoculum or if a nutritionally rich medium is used. Thermophilic fungi have a powerful ability to degrade polysaccharide constituents of biomass. The properties of their enzymes show differences not only among species but also among strains of the same species. Their extracellular enzymes display temperature optima for activity that are close to or above the optimum temperature for the growth of organism and, in general, are more heat stable than those of the mesophilic fungi. Some extracellular enzymes from thermophilic fungi are being produced commercially, and a few others have commercial prospects. Genes of thermophilic fungi encoding lipase, protease, xylanase, and cellulase have been cloned and overexpressed in heterologous fungi, and pure crystalline proteins have been obtained for elucidation of the mechanisms of their intrinsic thermostability and catalysis. By contrast, the thermal stability of the few intracellular enzymes that have been purified is comparable to or, in some cases, lower than that of enzymes from the mesophilic fungi. Although rigorous data are lacking, it appears that eukaryotic thermophily involves several mechanisms of stabilization of enzymes or optimization of their activity, with different mechanisms operating for different enzymes.  相似文献   

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根据嗜热真菌生境特点,从采集的600多份标本中分离鉴定到嗜热真菌15种,其中分离获得半知菌8种。对8种半知菌的形态特征进行了系统综合描述。  相似文献   

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Fourteen samples of retail purchases of snuff were examined for the presence of viable thermophilic fungi; four species were found.  相似文献   

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Ten thermophilic bacterial strains were isolated from manure compost. Phylogenetic analysis based on 16S rRNA genes and biochemical characterization allowed identification of four different species belonging to four genera: Geobacillus thermodenitrificans, Bacillus smithii, Ureibacillus suwonensis and Aneurinibacillus thermoaerophilus. PCR-RFLP profiles of the 16S-ITS-23S rRNA region allowed us to distinguish two subgroups among the G. thermodenitrificans isolates. Isolates were screened for thermotolerant hydrolytic activities (60–65°C). Thermotolerant lipolytic activities were detected for G. thermodenitrificans, A. thermoaerophilus and B. smithii. Thermotolerant protease, α-amylase and xylanase activities were also observed in the G. thermodenitrificans group. These species represent a source of potential novel thermostable enzymes for industrial applications.  相似文献   

7.
To determine a thermotolerant fungus strain for decolorization of alcohol distillery wastewater (ADW), 38 fungus strains were studied. Capacity for ligninolytic enzyme production was examined at 35 and 43C on agar media containing 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) and MnCl2. At 43°C, four Pycnoporus coccineus strains showed a higher potential for ADW decolorization both on agar media and in liquid media. Immobilized mycelia on polyurethane foam removed about threefold more total phenol than did free mycelia under conditions of shaking at 43°C. Moreover, immobilized mycelia removed nearly 50% more color than did free mycelia.  相似文献   

8.
Thirteen thermohilic genera and 19 species in addition to one variety of each of M. pulchella and H.grisea were collected from wheat and broad-bean straw composts at 45 °C. In wheat and broad-bean, all thermophilic fungi were completely checked between 4–9 days, and 1–8 days composting when the temperature ranged between 58 ° and 67 °C, and 58 ° and 70 °C respectively, and reappeared, represented by P. duponti, M. albomyces, T. lanuginosus and S. thermophile, after 9 or 10 days composting when the temperature decreased to 51.5 °–54 °C. Wheat and broad-bean straw composts were analyzed biochemically to follow the changes in ethanol and diastase soluble, hemicellulose, cellulose and lignin fractions during composting.  相似文献   

9.
A study was performed on the numbers and species diversity of thermophilic fungi (growing at 45 °C in vitro) in 38 nests of 9 species of wetland birds, taking into account the physicochemical properties of the nests and the bird species. It was found that in nests with the maximum weight (nests of Mute Swan), the number and diversity of thermophilic fungi were significantly greater than in other nests, with lower weight. The diversity of the thermophilic biota was positively correlated with the individual mass of bird and with the level of phosphorus in the nests. The dominant species within the mycobiota under study was Aspergillus fumigatus which inhabited 95 % of the nests under study, with average frequency of ca. 650 cfu g?1 of dry mass of the nest material. In a majority of the nests studied (nests of 7 bird species), the share of A. fumigatus exceeded 50 % of the total fungi growing at 45 °C. Significantly higher frequencies of the fungal species were characteristic of the nests of small and medium-sized piscivorous species, compared with the other bird species. The number of A. fumigatus increased with increase in the moisture level of the nests, whereas the frequency of occurrence of that opportunistic pathogen, opposite to the general frequency of thermophilic mycobiota, was negatively correlated with the level of phosphorus in the nest material, and with the body mass and length of the birds. The authors indicate the causes of varied growth of thermophilic fungi in nests of wetland birds and, in particular, present a discussion of the causes of accumulation of A. fumigatus, the related threats to the birds, and its role as a source of transmission in the epidemiological chain of aspergillosis.  相似文献   

10.
赵春青  李多川 《菌物研究》2008,6(3):133-135
从采自海南的标本中分离到2个中国大陆新记录种——嗜热子囊菌(Thermoascus aurantiacus)和黄褐毁丝霉(Myceliophthora hinnulea),并进行了形态学描述。研究标本保存于山东农业大学植物病理学标本室(HSAUP)。  相似文献   

11.
木聚糖酶是一类木聚糖降解酶系,在食品、饲料领域应用广泛.本实验对实验室前期保存的一株产木聚糖酶真菌TL01进行形态学、18S rDNA及产酶鉴定,其结果表明TL01为梳棉状嗜热真菌(Thermomyces lanuginosus),以木糖为底物,测得粗酶液酶活为0.250±0.03 U/mL.对其两种主要的木聚糖酶基因(xyn11A和xyl43)进行克隆并对其编码蛋白(Xyn1 1A和Xy143)进行了生物信息学分析.Xyn11A预测蛋白分子量24.36 kD,等电点为4.77,含有19个氨基酸的信号肽序列,属于亲水性蛋白,无跨膜结构域,其二级结构主要是无规则卷曲(44.89%);Xyl43蛋白分子量38.24 kD,等电点为5.23,编码的胞内蛋白属于亲水性蛋白,无跨膜结构域,无规则卷曲(59.76%)是其主要的二级结构.本研究通过对Th.lanuginosus TL01的xyn11A和xyl43基因克隆及其编码蛋白的生物信息学分析,为后续进一步构建高效表达工程菌株奠定了基础.  相似文献   

12.
Pearl millet is widely consumed in regions of Africa and Asia, and is increasingly being grown as an alternative grain in drought-prone regions of the United States. Pearl millet and corn were grown in dryland conditions at Tifton, Georgia, USA and grains were compared for pre-harvest infection by potentially toxigenic fungi and contamination by mycotoxins. Corn hybrids Agripro 9909 and Pioneer 3146, and pearl millet Tifgrain 102 were grown in 2000 and 2001; pearl millet HGM 100 was included in the test in 2001. Hybrids were sown on multiple planting dates in each year to induce variation in flowering time. Host species differed in the frequency of isolation of potentially toxigenic fungal species in both years. Across years, corn hybrids were more prone to infection by Aspergillus flavus Link (maximum isolation frequency = 8.8%) and Fusarium moniliforme Sheldon sensu lato (maximum isolation frequency = 72.8%), with corresponding greater concentrations of aflatoxins (maximum concentration = 204.9 μg kg−1) and fumonisins (maximum concentration = 34,039 μg kg−1). Pearl millet was more prone to infection by F. semitectum Berk. & Ravenel (maximum isolation = 74.2%) and F. chlamydosporum Wollenweb & Reinking (maximum isolation = 33.0%), and contamination by moniliformin (maximum contamination = 92.1 μg kg−1). Beauvericin (maximum concentration = 414.6 μg kg−1) was present in both hosts. Planting date of corn affected aflatoxin and beauvericin contamination in 2000, and fumonisin concentration in 2001. The observed differences in mycotoxin contamination of the grains, which are likely due to host-specific differences in susceptibility to pre-harvest mycoflora, may affect food safety when the crops are grown under stress conditions.  相似文献   

13.
Thermotolerant and thermostable laccases   总被引:1,自引:0,他引:1  
Laccases are phenol-oxidizing, usually four-copper containing metalloenzymes. For industrial and biotechnological purposes, laccases were among the first fungal oxidoreductases providing larger-scale applications such as removal of polyphenols in wine and beverages, conversion of toxic compounds and textile dyes in waste waters, and in bleaching and removal of lignin from wood and non-wood fibres. In order to facilitate novel and more efficient bio-catalytic process applications, there is a need for laccases with improved biochemical properties, such as thermostability and thermotolerance. This review gives a current overview on the sources and characteristics of such laccases, with particular emphasis on the fungal enzymes.  相似文献   

14.
Toxigenic Escherichia coli   总被引:1,自引:1,他引:0  
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15.
嗜热毛壳菌Chaetomium thermophilum CT2是一种土壤腐生菌,可产生具有重要工业生产价值的纤维素酶类。RACE-PCR获得嗜热毛壳菌纤维二糖水解酶Ⅱ(CBHⅡ)的编码基因(cbh2)。DNA序列分析表明cbh2的开放阅读框由1428个碱基组成,编码476个氨基酸。推断的氨基酸序列包含一个典型真菌纤维素酶的糖结合域(CBD)、催化域(CD)以及二者之间富含脯氨酸和羟基氨基酸的连接桥。根据氨基酸序列推算该酶分子量为53kD,属于糖苷水解酶第六家族,具有该家族催化保守区的典型特征。PCR扩增cbh2的成熟蛋白编码基因,利用基因重组的方法构建可在毕赤酵母分泌表达系统中表达纤维二糖水解酶蛋白的重组表达载体,并转化毕赤酵母得到重组子。在毕赤酵母醇氧化酶AOX1基因启动子的作用下,重组蛋白得到高效表达,小规模发酵量达1.2 mg/mL。经硫酸铵沉淀、DEAESepharose Fast flow阴离子层析等步骤纯化了该重组表达蛋白。SDS-PAGE得到重组蛋白分子量为67kD,与从嗜热毛壳菌中纯化的该酶分子量一致。该重组纤维二糖水解酶作用的最适合温度50℃,最适pH4.0,在70℃的半衰期为30min,具有较好的热稳定性。  相似文献   

16.
Stool specimens were examined from 40 children with diarrhea who were under three years of age to determine the incidence of enterotoxigenic Escherichia coli in endemic diarrhea. Heat-labile E. coli enterotoxin was assayed in the very sensitive and reproducible cultured adrenal tumor cell system. Toxigenic E. coli were isolated from only one stool specimen and in this case infection with Shigella dysenteriae was also present. None of the eight classic enteropathogenic E. coli isolates were positive in the adrenal assay. This study suggests that heat-labile enterotoxin-producing E. coli are not an important cause of endemic childhood diarrhea in Southern California.  相似文献   

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Twenty-two species of thermophilic fungi were isolated from mushroom compost. Scytalidium thermophilum was present in the compost ingredients, fresh straw, horse droppings, and drainage from compost and dominated the fungal biota of compost after preparation. Of 34 species of thermophilic fungi tested, 9 promoted mycelial growth of Agaricus bisporus on sterilized compost: Chaetomium thermophilum, an unidentified Chaetomium sp., Malbranchea sulfurea, Myriococcum thermophilum, S. thermophilum, Stilbella thermophila, Thielavia terrestris, and two unidentified basidiomycetes. These species will be considered for future experiments on inoculation and more controlled preparation of compost.  相似文献   

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