Mycotoxin Producing Potential of Fungi Associated with Dry Shrimps

Among 114 fungi isolated from 20 dry shrimp samples, 27 isolates were capable of producing mycotoxins. Aspergillus and Penicillium were-the-predominant fungi. Two of 3 Aspergillus flavus could produce aflatoxin B₁ and G₁ on yeast extract sucrose medium and on surface sterilized dry shrimps. For other toxigenic species, toxicity was found mostly in the chloroform extracts of cultures. Visibly mouldy dry shrimps had significantly higher moisture content than the non-mouldy ones. Most of the fungi were isolated from mouldy samples.     

Yeasts and Yeast-Like Fungi Associated with Tree Bark: Diversity and Identification of Yeasts Producing Extracellular Endoxylanases

A total of 239 yeast strains was isolated from 52 tree bark samples of the Medaram and Srisailam forest areas of Andhra Pradesh, India. Based on analysis of D1/D2 domain sequence of 26S rRNA gene, 114 strains were identified as ascomycetous; 107 strains were identified as basidiomycetous yeasts; and 18 strains were identified as yeast-like fungi. Among the ascomycetous yeasts, 51% were identified as members of the genus Pichia, and the remaining 49% included species belonging to the genera Clavispora, Debaryomyces, Kluyveromyces, Hanseniaspora, Issatchenkia, Lodderomyces, Kodamaea, Metschnikowia, and Torulaspora. The predominant genera in the basidiomycetous yeasts were Cryptococcus (48.6%), Rhodotorula (29%), and Rhodosporidium (12.1%). The yeast-like fungi were represented by Aureobasidium pullulans (6.7%) and Lecythophora hoffmanii (0.8%). Of the 239 yeast strains tested for Xylanase, only five strains of Aureobasidium sp. produced xylanase on xylan-agar medium. Matrix-assisted laser desorption ionization-time of flight analysis and N-terminal amino-acid sequence of the xylanase of isolate YS67 showed high similarity with endo-1-4-β-xylanase (EC 3.2.1.8) of Aureobasidium pullulans var. melanigenum. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

RAPD技术应用于紫杉醇产生菌的分类鉴定

紫杉醇是一种用于癌症治疗的特效药物,微生物发酵法是生产紫杉醇的有效方法,采用RAPD技术对4株紫杉醇产生菌的遗传差异进行分析,重新从分子水平对其进行了进一步的分类鉴定;并将为下一步的基因工程育种工作中的基因定位和分子克隆提供丰富可靠的分子标记。     

Detection and Identification of Fungi Intimately Associated with the Brown Seaweed Fucus serratus

The filamentous fungi associated with healthy and decaying Fucus serratus thalli were studied over a 1-year period using isolation methods and molecular techniques such as 28S rRNA gene PCR-denaturing gradient gel electrophoresis (DGGE) and phylogenetic and real-time PCR analyses. The predominant DGGE bands obtained from healthy algal thalli belonged to the Lindra, Lulworthia, Engyodontium, Sigmoidea/Corollospora complex, and Emericellopsis/Acremonium-like ribotypes. In the culture-based analysis the incidence of recovery was highest for Sigmoidea marina isolates. In general, the environmental sequences retrieved could be matched unambiguously to isolates recovered from the seaweed except for the Emericellopsis/Acremonium-like ribotype, which showed 99% homology with the sequences of four different isolates, including that of Acremonium fuci. To estimate the extent of colonization of A. fuci, we used a TaqMan real-time quantitative PCR assay for intron 3 of the beta-tubulin gene, the probe for which proved to be species specific even when it was used in amplifications with high background concentrations of other eukaryotic DNAs. The A. fuci sequence was detected with both healthy and decaying thalli, but the signal was stronger for the latter. Additional sequence types, representing members from the Dothideomycetes, were recovered from the decaying thallus DNA, which suggested that a change in fungal community structure had occurred. Phylogenetic analysis of these environmental sequences and the sequences of isolates and type species indicated that the environmental sequences were novel in the Dothideomycetes.     

产黄酮甘蔗叶内生真菌的分离与鉴定

采用显色反应、薄层层析色谱和紫外吸收光谱法,对甘蔗叶内16株内生真菌的代谢产物进行黄酮类化合物检测。结果共筛选到3株能够产黄酮类化合物的内生真菌(GZ-1、GZ-4和GZ-5)。依据真菌的形态特征及ITS序列分析,鉴定结果表明菌株GZ-1、GZ-5为棘孢曲霉(Aspergillus aculeatus),菌株GZ-4为黑曲霉(Aspergillus niger)。     

紫杉醇产生菌分离的研究

报道了1993年从东北红豆杉树(Taxuscuspidata Sieb.et     

Fungi Associated with Softening of Bisulfite-Brined Cherries

Softening of sound, calcium bisulfite-brined cherries was induced fairly quickly by brining them with cherries rotted by Aspergillus niger, Cytospora leucostoma, and Penicillium expansum, but not with cherries rotted by a variety of other microorganisms, including Alternaria sp., Aspergillus oryzae, Aureobasidium pullulans, Botrytis cinerea, Cladosporium sp., Mucor racemosus, Rhizopus stolonifer, and Sclerotinia fructicola. Rapid softening was correlated with the presence of a bisulfite-stable polygalacturonase, as demonstrated by a cup-plate test. A survey of naturally rotted cherries suggests the involvement of a bark-canker fungus, C. leucostoma, in softening of commercially brined cherries in the Pacific Northwest.     

Rapid Isolation of DNA from Dry and Fresh Samples of Plants Producing Large Amounts of Secondary Metabolites and Essential Oils

The presence of certain metabolites has been observed to interfere with DNA isolation procedures and downstream reactions such as DNA restriction, amplification and cloning. The chemotypic heterogeneity among species may not permit optimal DNA yields with a single protocol, and thus, even closely related species may require different isolation protocols. Here we describe the essential steps of a rapid DNA isolation protocol that can be used for diverse medicinal and aromatic plants, which produce essential oils and secondary metabolites such as alkaloids, flavanoids, phenols, gummy polysaccharides, terpenes and quinones. The procedure is applicable to dry as well as fresh plant tissues. This protocol, in our experiments, permitted isolation of DNA from tissues of diverse plant species and produced fairly good yields. The isolated DNA proved amenable to PCR amplification and restriction digestion.     

红树林内生真菌多样性及其应用潜能

红树林是分布于热带和亚热带潮间带的湿地林,为多样化的生物群落提供了必要的栖息之所。内生真菌是指一类生活于健康宿主体内,而不引起宿主组织发生任何病变的真菌,它们不仅在维护整个生态系统的平衡中起着重要作用,而且还具有多样化的应用潜能。文中在总结了红树林内生真菌多样性的基础上,对红树林内生真菌在工业、农业和医药业上的应用潜能进行了探讨,旨在为后续红树林内生真菌的研究提供一定的参考依据。     

Occurrence of Ochratoxin A-Producing Fungi in Commercial Corn Kernels in Argentina

Potentially ochratoxigenic Aspergillus and Penicillium species were identified and the natural occurrence of ochratoxin A (OTA) in corn kernels was evaluated. Likewise, the capacity to produce OTA by Aspergillus section Nigri and Circumdati was investigated. A total of 50 corn samples for human consumption was collected in the south of Córdoba Province. The surface-disinfected method for mycobiota determination was used. The OTA detection was performed by HPLC. OTA production was tested in strains belonging to section Nigri and Circumdati. Statistical analysis demonstrated that the specie A. flavus was isolated in higher frequency (p<0.01) from corn kernels in DRBC and DG18 media. The percentage of corn kernels contaminated by A. niger var. niger was similar in DRBC and DG18 media. The frequency of grains contaminated by A. flavus and A. niger var. awamori was higher than A. niger var. niger and A. japonicus var. japonicus (p<0.01) in DG18 media. The other potentially ochratoxigenic species, A. ochraceus, was isolated between 5% and 10% of the corn kernels in DG18 and DRBC media, respectively. The OTA producing species P. verrucosum was not isolated. All samples of corn were OTA negative (<1 ng g⁻¹). Thirty strains (25%) of the black Aspergillus were OTA producers. From four strains of A. ochraceus isolated, only one produced OTA. Due to the storage variable conditions could not be adequate in this substrate, the presence of ochratoxigenic strains of section Nigri and OTA needs to be evaluated for a longer time to establish the toxicological risk for human beings. The contamination of stored corn kernels with A. flavus and Aspergillus section Nigri was significant.     

Bacterial Communities Associated with the Surfaces of Fresh Fruits and Vegetables

Fresh fruits and vegetables can harbor large and diverse populations of bacteria. However, most of the work on produce-associated bacteria has focused on a relatively small number of pathogenic bacteria and, as a result, we know far less about the overall diversity and composition of those bacterial communities found on produce and how the structure of these communities varies across produce types. Moreover, we lack a comprehensive view of the potential effects of differing farming practices on the bacterial communities to which consumers are exposed. We addressed these knowledge gaps by assessing bacterial community structure on conventional and organic analogs of eleven store-bought produce types using a culture-independent approach, 16 S rRNA gene pyrosequencing. Our results demonstrated that the fruits and vegetables harbored diverse bacterial communities, and the communities on each produce type were significantly distinct from one another. However, certain produce types (i.e., sprouts, spinach, lettuce, tomatoes, peppers, and strawberries) tended to share more similar communities as they all had high relative abundances of taxa belonging to the family Enterobacteriaceae when compared to the other produce types (i.e., apples, peaches, grapes, and mushrooms) which were dominated by taxa belonging to the Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria phyla. Although potentially driven by factors other than farming practice, we also observed significant differences in community composition between conventional and organic analogs within produce types. These differences were often attributable to distinctions in the relative abundances of Enterobacteriaceae taxa, which were generally less abundant in organically-grown produce. Taken together, our results suggest that humans are exposed to substantially different bacteria depending on the types of fresh produce they consume with differences between conventionally and organically farmed varieties contributing to this variation.     

Fungi Associated with Root Rot of Winter Wheat in Alabama

Winter wheat plants were sampled during the spring and autumn to identify fungi associated with root rot in Alabama. Samples were taken from 61 fields in the major wheat-producing areas of the state; 179 fungi were isolated, identified, and tested for pathogenicity. Of the fungi identified, 46 (26%) were Gaeumannomyces graminis var. tritici , 37 (21%) were Cochtiobolus sativus , and 55 (31%) were Fusarium species of which 37 (21%) were Fusarium oxysporum . Other fungi identified that were pathogenic on wheat were Rhizoctonia solani, Sderotium rolfsii , and Pythium spp. G. g. var. tritier was the main pathogen associated with diseased root and lower stem tissue of wheat in Albama.     

Biosynthesis of Ochratoxin A

Biosynthesis of ochratoxin A by Aspergillus ochraceus Wilh. was investigated by radiolabeling experiments in which phenylalanine-1-(14)C and sodium acetate-2-(14)C were supplied to the fungus in sucrose-yeast extract medium. Results showed that phenylalanine was incorporated unaltered into the phenylalanine moiety of ochratoxin A, whereas the isocoumarin moiety of ochratoxin A was mostly derived via acetate condensation.     

Biosynthesis of Ochratoxin A

Biosynthesis of ochratoxin A by Aspergillus ochraceus Wilh. was investigated by radiolabeling experiments in which phenylalanine-1-¹⁴C and sodium acetate-2-¹⁴C were supplied to the fungus in sucrose-yeast extract medium. Results showed that phenylalanine was incorporated unaltered into the phenylalanine moiety of ochratoxin A, whereas the isocoumarin moiety of ochratoxin A was mostly derived via acetate condensation.     

The Penicillium commune Thom and Penicillium clavigerum Demelius Fungi Producing Fumigaclavines A and B

The type strains Penicillium clavigerum VKM F-447 and P. commune VKM F-3233 are found to produce fumigaclavines A and B. Of the seven other strains of these species, only two strains, P. commune VKM F-3088 and F-3491, possess the ability to synthesize these alkaloids. It is suggested that the five other strains under study either lost such an ability or require very specific conditions for the synthesis of these alkaloids.     

紫杉醇及其产生菌的研究现状与展望

紫杉醇 (Paclitaxel,商品名Taxol)是一种二萜类衍生物 ,是当前公认的广谱、活性强的抗癌药物之一。1　紫杉醇的发现紫杉醇最早是于 1 971年 ,Wani等[1] 从短枝红豆杉 (Taxusbreviifolia)的树皮中分离得到 ,命名为紫杉醇。随后 ,Schiff等[2 ] 证实紫杉醇具有独特的抗癌机制 ,它作用于细胞微管 (Microtuble) ,通过与微管蛋白N端第 31位氨基酸和第 2 1 7～ 2 31位氨基酸结合 ,诱导和稳定微管蛋白聚合 ,抑制其解聚 ,增加聚合程度 ,使维管束不能与微管组织中心相互连接 ,将细胞周期阻断于G2 M期 ,导致有丝分裂异常或停止 ,阻止癌细胞增殖[3,…     

Identification of Fungi in the Botryosphaeriaceae Family Associated with Stem Blight of Vaccinium spp. in the Southeastern United States

Stem blight is a major disease of blueberry caused by Botryosphaeriaceae fungi. Chemical and cultural management options are limited, putting emphasis on breeding efforts to identify sources of resistance. The efficacy and durability of host resistance could be impacted by the species composition of the pathogen population in a region and by the isolates employed in the screenings used to identify the resistance. Samples (365) were collected from southern highbush (SHB) and rabbiteye blueberry (REB) cultivars from 28 sites in the southeastern US (AL, FL, GA, NC, and SC). Colony morphology identified 86% of the isolates as Botryosphaeriaceae. Conidia morphology and Maximum Likelihood analysis of the Internal Transcribed Spacer rDNA regions (ITS), translation elongation factor one alpha (tef1-α), and β-tubulin were used to identify isolates at genera or species level. A PCR-restriction fragment length polymorphism (PCR-RFLP) test was used to identify isolates to genus. Neofusicoccum and Lasiodiplodia were the predominant genera. N. kwambonambiense, N. ribis, L. theobromae and L. pseudotheobromae were the most common species isolated. Phylogenies conducted with a limited number of isolates indicated non-clonal and potentially diverse populations occur on blueberry that warrant additional study. Botryosphaeria corticis, B. dothidea, and Diplodia seriata were isolated infrequently.     

Treatment of Duodenal Ulcer with Glycyrrhizinic-acid-reduced Liquorice: A MULTICENTRE TRIAL

A double-blind controlled therapeutic trial of glycyrrhizinic-acid-reduced liquorice 760 mg thrice daily for six weeks was carried out on 90 men with relapse of chronic duodenal ulcer. Effects of treatment were judged by the frequency and severity of pain, the amount of alkali consumed, and the doctors'' and patients'' rating of the clinical response. The results do not show any advantage for the active treatment when compared with the placebo.     

Phylogenetic Relationship and Secondary Metabolite Production of Marine Fungi Producing the Cyclodepsipeptides Scopularide A and B

Strains originally affiliated to the genera Scopulariopsis and Microascus were compared regarding the scopularide production in order to investigate their ability to produce the cyclodepsipeptides and select the best suited candidate for subsequent optimisation processes. Phylogenetic calculations using available sequences of the genera Scopulariopsis and Microascus revealed that most of the sequences clustered within two closely related groups, comprising mainly Scopulariopsis/Microascus brevicaulis and Microascus sp., respectively. Interestingly, high yields of scopularide A were exhibited by three strains belonging to S./M. brevicaulis, while lower titres were observed for two strains of Microascus sp. Close phylogenetic distances within and between the two groups supported the proposed combination of both genera into one holomorph group. Short phylogenetic distances did not allow a clear affiliation at the species level on the basis of ribosomal DNA sequences, especially for Microascus sp. strains. Additionally, several sequences originating from strains assigned to Scopulariopsis exhibited a polyphyletic nature. The production pattern is in accordance with the phylogenetic position of the strains and significant production of scopularide B could only be observed for the S./M. brevicaulis strain LF580. Thus, the phylogenetic position marks the biotechnologically interesting strains and matters in optimisation strategies. In conclusion, the ability of all five strains to produce at least one of the scopularides suggests a distribution of the responsible gene cluster within the holomorph group. Setting the focus on the production of the cyclodepsipeptides, strain LF580 represents the best candidate for further strain and process optimisation.