Fungi associated with sorghum seeds

Summary A study of the external and internal fungi associated with different varieties ofSorghum seeds has been made. The varieties tested included eighteen local varieties and twelve newSorghum varieties obtained from the Rockefeller Foundation. The external fungi were studied by preparing suspensions of superficial fungi and growing on potato dextrose agar. The internal fungi were studied by planting surface sterilized seeds on P.D.A. and pure cultures of all these fungi were prepared.The external fungi found to be associated with the different varieties included different species ofPhycomyces, Circinella, Syncephalastrum, Chaetomium, Curvularia, Cladosporium, Helminthosporium, Montospora, Pullularia, Aspergillus, Penicillium, Cephalosporium, Trichoderma, Phoma, Fusarium.The internal fungi recovered from these varieties included species ofChaetomium, Cladosporium, Curvularia, Helminthosporium, Heterosporium, Hormodendron, Pullularia, Alternaria, Aspergillus, Blastomyces, Monilia, Penicillium, Fusarium, Phoma, Phomopsis. Varieties 4403B, 1060 and 503 were found to carry a large number of fungi. Variety Black spanish was found to be entirely free from any internal or external fungus. Varieties which were free from endophytic fungi but possess external fungi only were Kaoling 301, African variety 901 and Shallus 475. Three fungi viz.,Pullularia, Heterosporium, Monilia have been recovered from theSorghum seeds for the first time.     

Colonization and Degradation of Thermally Oxidized High-Density Polyethylene by Aspergillus niger (ITCC No. 6052) Isolated from Plastic Waste Dumpsite

Plastic materials, particularly polyethylene, are the potential source of environmental pollution. In the present study, a fungal strain was isolated from plastic waste dumpsites capable of adhering to high-density polyethylene (HDPE) surface. The fungal strain was identified as Aspergillus niger (ITCC no. 6052). A visible increase in the growth of the fungi was observed on the surface of the polyethylene when cultured in minimal medium at 30°C and 120 rpm, for 1 month. Approximately 3.44% reduction (gravimetrically) in mass and 61% reduction in tensile strength of polyethylene was observed after 1 month of incubation with fungal isolate. Scanning electron microscope analysis showed hyphael penetration and cracks on the surface of polyethylene. A thick network of fungal hyphae forming a biofilm was also observed on the surface of the plastic pieces. The efficient biofilm formation on polyethylene surface by Aspergillus niger (ITCC no. 6052) is attributed to its high cell surface hydrophobicity. This study indicated that Aspergillus niger (ITCC no. 6052) has ability to degrade thermally oxidized polyethylene.     

Mould biodiversity in homes I. Air and surface analysis of 130 dwellings

Summary Air and surface sampling to quantify and identify fungi were conducted over a 10-year period in 130 Belgian homes, including flats and houses. Homes were selected based on the medical files of allergic, mostly asthmatic patients to assess possible mould responsibility in the aetiology of the disease. Air sampling was done with Reuter centrifugal air sampler using different sampling times and incubation temperatures to detect mesophilic and thermotolerant or thermophilic fungi. More than 50 genera were detected, withCladosporium, Penicillium andAspergillus being the most common. The main species detected wereAspergillus versicolor, several species ofPenicillium, Cladosporium sphaerospermum andCladosporium herbarum. Surface sampling was conducted concomitant with air sampling. Surfaces with and without visible mould growth were tested equally by Rodac contact plates or swabs. AlthoughCladosporium herbarum was shown to be a common species in indoor environments by air sampling, it was not detected by surface sampling from visible mould growth. This finding suggests that its presence in dwellings is from an outdoor origin and not indicative of indoor proliferation.Aspergillus versicolor, Cladosporium sphaerospermun, andPenicillium chrysogenum were the most common species isolated from surfaces showing visible mould growth.     

Detection and identification of moulds in dutch houses and non-industrial working environments

The mycoflora of indoor non-industrial environments is reported from “case” studies in The Netherlands. Both air sampling by a RCS-Reutcr centrifugal air sampler and surface sampling by swabs and cellotape preparations were carried out in homes, archives and libraries, musea, offices and schools. Common species encountered in these indoor environments are Aspergillus versicolor, Penicillium brevicompactum, P. chrysogenum, Cladosporium spp. and the xerophilic fungi Eurotium spp. and Wallemia sebi. Aspergillus fumigatus, Scopulariopsis spp. and Stachybotrys chartarum were occasionally isolated. It is not always possible to detect the mycoflora growing on surfaces by air sampling. Therefore direct microscopical examination and sampling from surfaces in addition to air sampling is strongly recommended for the detection of viable moulds in indoor environments. Selection of the most suitable media for isolation of fungi is discussed.     

Physico-Chemical Properties of Linseed Oil as Affected by Various Seed-Borne Fungi

The effect of six seed-borne fungi on linseed oil was studied. Alternaria alternate, Aspergillus flavus, Aspergillus repens, Fusarium culmorum and Torula allii reduced oil content while Cladosporum herbarum slightly increased it. All fungi increased the free fatty acid content and saponification number linseed oil. Iodine number was decreased except in Cladosporium herbarum and Fusarium culmorum. Aspergillus flavus was the most destructive parasite in altering quantity and quality of linseed oil.     

米曲霉异源蛋白表达系统研究进展及展望

米曲霉作为一种重要的工业微生物,在异源蛋白表达方面已有广泛应用,受限于被表达蛋白的修饰及分泌过程,目前实际生产使用的基因供体主要局限于其他真菌,尤其是丝状真菌。当外源基因来源于植物、昆虫和哺乳动物时,米曲霉所生产的异源蛋白产量及生物活性往往不尽如人意。本文综述了米曲霉作为宿主表达异源蛋白的研究进展,包括其现有的遗传操作手段及异源表达方面的应用及探索,重点介绍了应用过程中面临的挑战和解决策略,另外,对米曲霉表达异源蛋白的应用前景及发展方向进行了展望。     

Chitinolytic Activity of Filamentous Fungi

The chitinolytic activity of nine species of filamentous fungi, classified with seven genera (specifically, Aspergillus, Penicillium, Trichoderma, Paecilomyces, Sporotrichum, Beaueria, and Mucor), was studied. When cultured in liquid medium containing 1% crystalline chitin, all fungi produced extracellular chitosans with activity varying from 0.2 U/mg protein (Sporotrichum olivaceum, Mucorsp., etc.) to 4.0–4.2 U/mg protein (Trichoderma lignorum, Aspergillus niger).     

Some cases of onychomycosis from North India in different working environments

Three fungi, Alternaria humicola, A. pluriseptata and Aspergillus niger are being reported as new probable etiologic filamentous fungi, causing onychomycosis. The morphology and physiology of these fungi is discussed.     

Analysis of the ionic interaction between the hydrophobin RodA and two cutinases of Aspergillus nidulans obtained via an Aspergillus oryzae expression system

Hydrophobins are amphipathic secretory proteins with eight conserved cysteine residues and are ubiquitous among filamentous fungi. In the fungus Aspergillus oryzae, the hydrophobin RolA and the polyesterase CutL1 are co-expressed when the sole available carbon source is the biodegradable polyester polybutylene succinate-co-adipate (PBSA). RolA promotes the degradation of PBSA by attaching to the particle surface, changing its structure and interacting with CutL1 to concentrate CutL1 on the PBSA surface. We previously reported that positively charged residues in RolA and negatively charged residues in CutL1 are cooperatively involved in the ionic interaction between RolA and CutL1. We also reported that hydrophobin RodA of the model fungus Aspergillus nidulans, which was obtained via an A. oryzae expression system, interacted via ionic interactions with CutL1. In the present study, phylogenetic and alignment analyses revealed that the N-terminal regions of several RolA orthologs contained positively charged residues and that the corresponding negatively charged residues on the surface of CutL1 that were essential for the RolA–CutL1 interaction were highly conserved in several CutL1 orthologs. A PBSA microparticle degradation assay, a pull-down assay using a dispersion of Teflon particles, and a kinetic analysis using a quartz crystal microbalance revealed that recombinant A. nidulans RodA interacted via ionic interactions with two recombinant A. nidulans cutinases. Together, these results imply that ionic interactions between hydrophobins and cutinases may be common among aspergilli and other filamentous fungi.

     

Bio-activity of fungal culture filtrates against root-knot nematode egg hatch and juvenile motility and their effects on growth of mung bean (Vigna radiata L. Wilczek) infected with the root-knot nematode,Meloidogyne incognita

Culture filtrates of selected soil fungi, namely Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Fusarium oxysporum, Penicillium vermiculatum and Rhizopus nigricans exhibited variable response to egg hatching and mortality of the root-knot nematode, Meloidogyne incognita. Higher concentrations of the culture filtrates of all the fungi inhibited egg hatching and proved to be toxic to the juveniles of M. incognita. In addition, development of the gall and multiplication of M. incognita were also found adversely affected in varying degrees on all the plants of Vigna radiata treated with the filtrates. The culture filtrate of A. niger showed highest toxicity to the nematode than those of any other fungus tested. Soil drench application of the culture filtrates gave better seedling growth and least nematode multiplication in comparison to seed soaking treatment.     

Effect of fungi–termite interaction on the chlorophyll content of three rice varieties grown on ultisol soil of Ikenne,south-west Nigeria

The effect of fungi–termite interaction on three rice varieties was conducted in a screen house at the Africa Rice Center (AfricaRice) Ibadan, Nigeria. Of the 10 fungi species (Fusarium verticilloides, Trichoderma sp., Aspergillus niger, Aspergillus flavus, Macrophoma sp., Neurospora sp., Botryodiplodia theobromae, Penicillum sp., Rhizopus sp. and Sclerotium rolfsii) isolated from termites, soil and rice plants, F. verticilloides, Trichoderma sp. and B. theobromae were used for the interaction study. Each fungus was inoculated singly and in combinations with termite into the root of each rice variety in potted soil. Leaf samples were taken to measure the chlorophyll content which is a major parameter to estimate effect of termite–fungi interaction. The chlorophyll content of the inoculated rice plants was significantly reduced when compared with the control. Fungi interaction with termite had significant reduction on the chlorophyll content. The synergistic relationship between the fungi and the termite was discussed.     

Aspergillus on tree nuts: incidence and associations

California exports tree nuts to countries where they face stringent standards for aflatoxin contamination. Trade concerns have stimulated efforts to eliminate aflatoxins and Aspergillus flavus from almonds, pistachios and walnuts. Incidence of fungi on tree nuts and associations among fungi on tree nuts were studied. Eleven hundred pistachios, almonds, walnuts and brazil nuts without visible insect damage were plated on salt agar and observed for growth of fungi. Samples came both from California nut orchards and from supermarkets. To distinguish internal fungal colonization of nuts from superficial colonization, half the nuts were surface-sterilized before plating. The most common genera found were Aspergillus , Rhizopus and Penicillium . Each species of nut had a distinct mycoflora. Populations of most fungi were reduced by surface sterilization in all except brazil nuts, suggesting that they were present as superficial inoculum on (rather than in) the nuts. In general, strongly positive associations were observed among species of Aspergillus ; nuts infected by one species were likely to be colonized by other species as well. Presence of Penicillium was negatively associated with A. niger and Rhizopus in some cases. Results suggest that harvest or postharvest handling has a major influence on nut mycoflora, and that nuts with fungi are usually colonized by several fungi rather than by single species. This revised version was published online in June 2006 with corrections to the Cover Date.     

Root-surface mycoflora of cassava (Manihot esculenta) and post harvest rot of the tubers

The root-surface mycoflora of cassava were isolated from roots washed in serial changes of sterile distilled water and plated out on potato-dextrose agar. A small group of fungi which included Aspergillus niger, Botryodiplodia theobromae, Fusarium solani, Penicillium javanicum, Penicillium sp., and Trichoderma sp. were found to be consistently associated with the root surface. While the isolates, B. theobromae and F. solani were found to be aggressively pathogenic on freshly harvested cassava tubers causing extensive rot, A. niger was only mildly so. The root-surface mycoflora, therefore, includes fungi which have been reported as the most important in postharvest deterioration of the tubers. The removal of the rhizoplane microflora by surface-sterilization using calcium hypochlorite or Clorox and subsequent incubation in loosely tied polyethylene bags extended the storage life of the tubers considerably.     

Comparison of four media for the isolation ofAspergillus flavus group fungi

Four agar media used to isolate aflatoxin producing fungi were compared for utility in isolating fungi in theAspergillus flavus group from agricultural soils collected in 15 fields and four states in the southern United States. The four media wereAspergillus flavus andparasiticus Agar (AFPA, 14), the rose bengal agar described by Bell and Crawford (BCRB; 3), a modified rose bengal agar (M-RB), and Czapek's-Dox Agar supplemented with the antibiotics in BC-RB (CZ-RB). M-RB was the most useful for studying the population biology of this group because it permitted both identification of the greatest number ofA. flavus group strains and growth of the fewest competing fungi. M-RB supported an average of 12% moreA. flavus group colonies than the original rose bengal medium while reducing the number of mucorales colonies and the number of total fungi by 99% and 70%, respectively. M-RB was successfully employed to isolate all three aflatoxin producing species,A. flavus, A. parasiticus andA. nomius, and both the S and L strains ofA. flavus. M-RB is a defined medium without complex nitrogen and carbon sources (e.g. peptone and yeast extract) present in BC-RB. M-RB should be useful for studies on the population biology of theA. flavus group.Abbreviations M-RB Modified Rose Bengal Agar - CZ-RB Czapeks Rose Bengal Agar - BC-RB Bell and Crawford's Rose Bengal Agar - AFPA Aspergillus flavus andparasiticus agar     

Studies on seed-borne fungi of wheat in seed health testing programme

Seed mycoflora associated with wheat was studied on different media with a particular reference to Blotter and potato dextrose agar (PDA) procedures of ISTA. Seed-borne fungi, viz. Fusarium moniliforme, Rhizopus spp., Mucor spp., Alternaria alternata, Aspergillus niger, Aspergillus flavus, Curvularia lunata, Drechslera spp, Alternaria spp. and Penicillium spp., were isolated from the variety HD264. Blotter method was found to be the best media for the isolation of mycoflora whether borne externally or internally. Total number and frequency of occurrence of fungi were recorded. The effect of seed treatment with different chemicals and eco-friendly botanicals was analysed on germination, and growth, better percentage of seed germination and reduction in fungal pathogen were due to biochemical seed treatment.     

The mycoflora and incidence of aflatoxin,zearalenone and sterigmatocystin in dairy feed and forage samples from Eastern India and Bangladesh

The mycoflora of a range of mixed ruminant feed and forage samples collected in Eastern India and Bangladesh were determined. Most fungi isolated from the samples were those associated with low moisture contents. Several potentially mycotoxigenic fungi and thermotolerant species were present particularly in the rice straw. The most frequently isolated fungi were: Aspergillus versicolor (Vuill.) Tiraboschi, Penicillium citrinum Thorn, Eurotium species, Wallemia sebi (Fr.) v. Arx, Aspergillus penicilloides Speg. and yeasts. Fusarium moniliforme Sheldon and Cladosporium species were prevalent in straw but not other feeds. Levels of certain individual fungi, particularly thermotolerant types, were higher in Bangladesh rice straw although overall counts were similar to those of the Indian samples. Mycotoxin analyses for aflatoxins, zearalenone and sterigmatocystin were carried out. Aflatoxins were detected in significant amounts in some feed samples from Eastern India but not in rice straw from India and Bangladesh. Zearalenone occurred in a Paspalum straw sample and three other feed samples from India and sterigmatocystin was detected in three rice straw samples from Bangladesh.     

Biological control of postharvest fungal rot of yam (<Emphasis Type="Italic">Dioscorea</Emphasis> spp.) with<Emphasis Type="Italic">Bacillus subtilis</Emphasis>

The potential of isolates of Bacillus subtilis from yam farm soil to control rot of yam in storage barns was investigated. Yam tubers inoculated in vivo with B. subtilis showed no rot while those inoculated with Aspergillus niger, Botryodiploidia theobromae or Penicillium oxalicum showed considerable rot. The set of yams in which B. subtilis and the fungi were simultaneously inoculated produced rot whereas those in which B. subtilis was inoculated a day before the fungi was inoculated were totally reduced or free of rot. Many fewer fungi were isolated from the surface of tubers treated with B. subtilis than from the untreated (control) and there was high recovery of B. subtilis (99–100%) throughout the period of storage. Rot build up was faster in uninoculated control tubers or those inoculated with a spoilage fungus, while those treated with the antagonist were totally reduced or free of rot. The culture filtrate of B. subtilis prevented spore germination in some spoilage fungi. The importance of this study in relation to farmers in developing countries is discussed.     

Fibrinolytic activity of some fungi isolated from self-heated composted fertilizer

Mesophilic fungi isolated from organic fertilizer compost samples accounted for 70.94% of the total fungal count, while thermophilic and thermotolerant fungi constituted 29.05% of that count. Eight mesophilic fungal species, namelyAspergillus niger, Monilia sitophila, Paecilomyces divaricata, Penicillium chrysogenum, P. fellutanum, Scopulariopsis brevicaulis, S. brumptii andZygorhynchus japonicus; two thermophilic fungiHumicola grisea andOidiodendron flavum and three thermotolerant speciesAspergillus fumigatus, Thermomyces lanuginosus andZygorhynchus vuilleminii were isolated during the study. Most of the tested fungi showed a proteolytic activity and liquified gelatin in the test tube method and in cup plates. The thermophilic fungusO. flavum was the most potent proteolytic fungus. The comparative fibrinolytic assay revealed the following sequence in the ability of the tested fungi to hydrolyse fibrin:O. fiavum>S. brevicaulis>H. grisea>A. fumigatus>T. lanuginosus.     

Mycobiota of the giant oyster <Emphasis Type="Italic">Crassostrea gigas</Emphasis> (Thunberg, 1787) (Bivalvia) from the Peter the Great Bay of the Sea of Japan

Mycological investigation of the Pacific (giant) oyster Crassostrea gigas (Thunberg, 1793) (Bivalvia) from the Peter the Great Bay of the Sea of Japan was carried out. The taxonomic composition of filamentous fungi associated with C. gigas was studied. The taxonomic composition of the fungi associated with the giant oyster included 22 species of filamentous fungi of which 17 species were identified. The latter belonged to six genera: Alternaria, Aspergillus, Botrytis, Fusarium, Penicillium, and Trichoderma. The distribution of filamentous fungi in the internal organs of the bivalve mollusk was studied.     

On factors influencing fruit-set and sterility in arecanut (Areca Catechu Linn.)

Summary (1) Histological studies on the stigmas of female flowers of areca indicate the possibility of the stigmatic surfaces being impacted upon by air spora. The presence of spores or hyphae together with pollen grains has been shown in stigmatic surface.(2) Air spora of arecanut plantation chiefly consist ofAspergillus, Penicillium, Actinomycetes, Mucor, Alternaria, Cladosporium andBacteria.(3) The types of fungi, bacteria and actinomycetes adhering to the stigma are isolated.(4) The metabolites of the fungi, bacteria and actinomycetes isolated from the stigmas of arecanut flowers inhibit,in vitro, considerably the germination of pollen grains and rate of growth of pollen tubes. In certain instances there is no germination of the pollen grains in the metabolites of fungi, bacteria and actinomycetes. In view of the results the significance of the air spora in affecting the normal course of pollination and fertilization is discussed.