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1.
Germinating turnip seeds were used as baits to measure changes in colonizing floras of the spermosphere in glasshouse soil boxes following fumigation. The spermosphere mycoflora of the untreated soil was always dominated by Fusarium, Pythium, and Gliocladium spp. Methyl bromide, chloropicrin, and MBC33 (a 67:33 mixture of methyl bromide and chloropicrin), applied in polyethylene bags at a rate of 2·5 ml/cubic foot of soil, greatly reduced colonization by Fusarium and Pythium spp. for 120 days. Fungi and actinomycetes recolonizing treated soils were more active than in untreated soils, and each fumigant induced a characteristic recolonization pattern. The spermosphere of methyl bromide-treated soil was initially dominated by actinomycetes and later by Penicillium spp. In chloropicrin-treated soil, Trichoderma and later Penicillium spp. dominated, and in soil treated with MBC 33, Penicillium and Trichoderma spp. were co-dominant. Dilution plates, made at the same time from the same soil, indicated a close correlation between inoculum density of different fungi in the soil and their inoculum potentials towards the spermosphere. 相似文献
2.
Summary The antagonistic effect of six Pleurotus spp. strains was studied in confrontation with three strains of Trichoderma spp. Pleurotus strains were cultivated on sterile coffee pulp, with and without a Trichoderma inoculant. Laccase, Mn peroxidase and endoglucanase activities were determined during incubation. Laccase production was also studied by PAGE analysis to detect enzymatic isoforms. Results show that the presence of Trichoderma induced a significant increase in oxidase production by the Pleurotus strains. Nevertheless, Trichoderma was not observed to induce laccase isoforms. 相似文献
3.
Robert Messner Eva M. Kubicek-Pranz Andrea Gsur Christian P. Kubicek 《Archives of microbiology》1991,155(6):601-606
Monoclonal antibodies have been used to determine the presence of cellobiohydrolases I and II (CBH I and II), and endoglucanase I (EG I) on the surface of conidia from Trichoderma reesei QM 9414 and RUT C-30, and 8 other Trichoderma species. For this purpose, proteins were released from the conidial surface by treatment with a non-ionic detergent (Triton X-100 and -octylglucoside), followed by SDS-PAGE/Western blotting and immunostaining. Both CBH I and II were clearly present, but — unlike in extracellular culture fluids from Trichoderma — CBH II was the predominant cellulase. In T. reesei EG I could not be detected. The higher producer strain T. reesei RUT C-30 exhibited a higher conidial level of CBH II than T. reesei QM 9414. In order to assess the importance of the conidial CBH II level for cellulase induction by cellulose, multiple copies of the chb2 gene were introduced into the T. reesei genome by cotransformation using PyrG as a marker. Stable multicopy transformants secreted the 2- to 4-fold level of CBH II into the culture medium when grown on lactose as a carbon source, but their CBH I secretion was unaltered. Upon growth on cellulose, both CBH I and CBH II secretion was enhanced. Those strain showing highest cellulase activity on cellulose also appeared to contain the highest level of conidial bound CBH II. CBH II was also the predominant conidial cellulase in various other Trichoderma sp. However, roughly the same amount of conidial bound CBH II was detected in all strains, although their cellulase production differed considerably. 相似文献
4.
The survival of Botrytis cinerea in sterile and unsterile soil at different temperatures and relative air humidities was investigated in south‐eastern Spain. Conidia survived only 7 days at 40°C but, depending on relative humidity, for 30–90 days at 22°C. High air humidity (95%) was needed to maintain soil humidity (8%) at a level that favoured conidial survival. Conidia survived better in sterile soil than in unsterile soil, probably because of the presence in the latter of soil microorganisms antagonistic to B. cinerea. Survival of conidia in environmental conditions simulating those in a greenhouse was less than 28 days. Results showed that B. cinerea conidia cannot survive over summer in south‐eastern Spain, and other primary sources of inocula are discussed. 相似文献
5.
el-Komy HM 《Folia microbiologica》2001,46(1):25-30
The survival ofHerbaspirillum spp. cells added directly or encapsulated in alginate beads and colonization of wheat roots was evaluated in soil microcosms.
Cells entrapped in alginate in the presence of JNFb-broth and introduced into unplanted non-sterile clay loamy and sandy soils
survived better than cells added directly to the same soils after 50 d incubation. On amendment by JNFb broth and/or skim
milk the entrapped cells survived better than those prepared in water. Encapsulated cells survived better in a heavier textured
soil (clay-loamy) than in a lighter (sandy) soil. Wheat plants growing in microcosms inoculated with various bead types from
day 0 to day 30 exhibited high levels of histosphere colonization, nitrogenase activity (in situ) measured by acetylene reduction assay, plant dry mass and total N content but no symptoms of mottled stripe disease were
observed. Comparable results of growth criteria and nitrogenase activity, but relatively lower bacterial populations, were
obtained with wheat grown for 45 d after the inoculant had been introduced into the soil with different bead types. 相似文献
6.
Conidial movement of nontoxigenic Aspergillus flavus and A. parasiticus in peanut fields following application to soil 总被引:1,自引:0,他引:1
The use of nontoxigenic strains of Aspergillus flavus and A. parasiticus in biological control effectively reduces aflatoxin in peanuts when conidium-producing inoculum is applied to the soil surface.
In this study, the movement of conidia in soil was examined following natural rainfall and controlled precipitation from a
sprinkler irrigation system. Conidia of nontoxigenic A. flavus and A. parasiticus remained near the soil surface despite repeated rainfall and varying amounts of applied water from irrigation. In addition,
rainfall washed the conidia along the peanut furrows for up to 100 meters downstream from the experimental plot boundary.
The dispersal gradient was otherwise very steep upstream along the furrows and in directions perpendicular to the peanut rows.
The retention of biocontrol conidia in the upper soil layers is likely important in reducing aflatoxin contamination of peanuts
and aerial crops such as corn and cottonseed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
7.
Stefania Galletti Eleonora Sala Onofrio Leoni Pier Luigi Burzi Claudio Cerato 《Biological Control》2008,45(3):319-327
Biofumigation by Brassicaceae green manure or seed meal incorporation into soil is an ecological alternative to chemical fumigation against soil-borne pathogens, based on the release of glucosinolate-derived compounds. This study aimed at investigating the tolerance of the beneficial fungus Trichoderma to these compounds in view to combined utilization with Brassica carinata seed meal (BCSM). Forty isolates of Trichoderma spp. were tested in vitro for tolerance to toxic volatiles released by BCSM and in direct contact with the meal. They were found to be generally less sensitive than the assayed pathogens (Pythium ultimum, Rhizoctonia solani, Fusarium oxysporum), even if a fungistatic effect was observed at the highest dose (10 μmole of sinigrin). Most of them also were able to grow on BCSM and over the pathogens tested. A preliminary experiment of integrating BCSM with Trichoderma in soil was carried out under controlled conditions with the patho-system P. ultimum—sugar beet. BCSM incorporation increased pathogen population, but reduced disease incidence, probably due to indirect mechanisms. The greatest effect was achieved when BCSM was applied in combination with Trichoderma, regardless of meal ability to release isothiocyanate. These findings suggest that disease control can be improved by this integrated approach. This study also highlighted that a reduction of allyl-isothiocyanate concentration in soil could occur due to the activity of some Trichoderma isolates. This effect could protect resident or introduced Trichoderma isolates from depressing effects due to the biocidal compounds, but, on the other hand, could reduce the efficacy of biofumigation against target pathogens. 相似文献
8.
In vitro, tests were conducted at 10°C and 5°C against sclerotia of Botrytis cinerea with 58 isolates of Trichoderma spp., highly antagonistic at 24°C but differing in their cold tolerance. Some isolates macerated and colonized sclerotia even at 5 °C. With 19 isolates of Trichoderma spp. less than 10 % of the sclerotia remained viable after 42 d at 5 °C. Conidia ol some Trichoderma spp. germinated at 5 °C within a few days and reached germination rates higher than 80 %. It seems to be feasible to use selected isolates of Trichoderma spp. for biological control of sclerotia of ß. cinerea also during the colder season. 相似文献
9.
Beauveria bassiana conidia were stored in sterile and nonsterile soil under various temperature, relative humidity, soil water content, and pH regimes. Survival of the conidia was primarily dependent on temperature and soil water content. Conidia half-lives ranged from 14 days at 25°C and 75% water saturation to 276 days at 10°C and 25% water saturation. Conidia held at ?15°C exhibited little or no loss in viability regardless of water content, relative humidity, or pH. Conidia were not recoverable after 10 days from soils held at 55°C. Conidia survival in nonsterile soil that was amended with carbon sources, nitrogen sources, or combinations of carbon and nitrogen was greatly decreased and loss was often complete in less than 22 days whereas sterile soil treated in the same manner showed dramatic increases in number, demonstrating that B. bassiana is capable of growth in sterile soil. The obvious fungistatic effect in amended nonsterile soils was possibly related to Penicillium urticae which was routinely isolated from the soils and is shown to produce a water-soluble inhibitor of B. bassiana. The fungistatic effect was shown to be an active inhibition rather than due to competition. 相似文献
10.
Whole cells of the methanogen Methanosarcina barkeri were immobilized in an alginate network which was crosslinked with Ca2+ ions. The rates of methanol conversion to methane of entrapped cells were found to be in the same range as the corresponding rates of free cells. Furthermore, immobilized cells were active for a longer period than free cells. The particle size of the spherical alginate beads (1.2 mm-3.7 mm ?) and thus diffusion had no obvious influence on the turnover of methanol. The half-value period for methanol conversion activity determined in a buffer medium was approximately 4 days at 37°C for entrapped cells. The apparent Km value K for such cells was nearly 140mM and the Vmax value was about 1.2 μmol methanol/min/mg entrapped protein. Therefore the high rates of methanol degradation measured, e.g., 0.5 μmol methanol/min/mg entrapped protein, indicated that the immobilization technique preserved the cellular functions of this methanogenic bacterium. 相似文献
11.
F. R. S. Paixão E. R. Muniz L. P. Barreto C. C. Bernardo G. M. Mascarin C. Luz 《Biocontrol Science and Technology》2017,27(3):324-337
The thermotolerance of oil-based conidial formulations of Metarhizium anisopliae s.l. (IP 46) and Metarhizium robertsii (ARSEF 2575) were investigated. Conidia of IP 46 or ARSEF 2575 were suspended in different adjuvants and exposed to 45?±?0.2°C for 4, 6, 8 or 24?h; their viability was then assessed after 48?h incubation at 27?±?1°C. Conidia heated in pure mineral or vegetable oil exhibited mean relative viability exceeding 70% after 8?h of heat exposure, whereas low germination (≤20%) was observed when conidia were heated in water (Tween 80® 0.01%), carboxymethyl cellulose gel or emulsifiable oils (Graxol® or Assist®) and exposed to heat for 6 or 8?h. In addition, conidia of IP 46 suspended in either pure mineral or canola oil and exposed to heat for 48?h had moderate viability, 57% or 41%, respectively. Unstable oil-in-water emulsions showed a higher percentage of conidia incorporated into oil micellae, while the stable emulsions had higher percentage of conidia outside the oil micellae. The thermotolerance of conidia formulated in stable emulsions, however, did not differ from that of conidia formulated in unstable emulsions. The present study highlights possibilities to alleviate the deleterious effects of heat stress towards Metarhizium spp. conidia applied for controlling arthropod pests and vectors through oil-based formulations. 相似文献
12.
We tried to polymerize d-glucose to cellotriose, the smallest substrate for β-1,4-glucan synthesis by the β-transglycosylase of Trichoderma longibrachiatum, without participation of high energy compounds such as nucleotide sugars. A commercial β-glucosidase (sweet almond) showed a typical condensation reaction of d-glucose, producing cellobiose when it was entrapped in a visking tube and incubated in 30% d-glucose solution. The reaction was done with immobilized enzyme covalently bound to Polyacrylamide beads, and entrapped enzyme. Cellobiose (21.0 mg) was obtained from 30 g of d-glucose in a 3-day reaction, where 0.29 unit of the entrapped enzyme preparation was incubated with 100 ml of 30% d-glucose at pH 6.0 and 41°C. Gentiobiose was also produced in the mixture as a minor product. The immobilized β-glucosidase (Sumizyme C) preparation covalently bound to Polyacrylamide beads could catalyze a transglucosylation reaction to produce cellotriose from cellobiose in a good yield without production of gentiobiose. The transfer reaction was optimal at pH 4.8 and 30°C. Cellotriose (11.2 mg) was produced from the reaction mixture containing 68 mg of cellobiose and the enzyme preparation (0.1 unit) after 24-hr of incubation at the optimal conditions. Both immobilized β-glucosidases, sweet almond and Sumizyme C, may be used repeatedly without any loss of the initial activity. 相似文献
13.
Chaganti Subba Rao Reddy Shetty Prakasham Adari Bhaskar Rao Jhillu S. Yadav 《World journal of microbiology & biotechnology》2008,24(8):1411-1415
The role of functionalized alginate gels as immobilized matrices in production of l (+) lactic acid by Lactobacillus delbrueckii was studied. L. delbrueckii cells immobilized in functionalized alginate beads showed enhanced bead stability and selectivity towards production of optically
pure l (+) lactic acid in higher yields (1.74Yp/s) compared to natural alginate. Palmitoylated alginate beads revealed 99% enantiomeric
selectivity (ee) in production of l (+) lactic acid. Metabolite analysis during fermentation indicated low by-product (acetic acid, propionic acid and ethanol)
formation on repeated batch fermentation with functionalized immobilized microbial cells. The scanning electron microscopic
studies showed dense entrapped microbial cell biomass in modified immobilized beads compared to native alginate. Thus the
methodology has great importance in large-scale production of optically pure lactic acid. 相似文献
14.
Production of cyclodextrins (CDs) by immobilized cells of the alkaliphilic Bacillus agaradhaerens LS-3C with integrated product recovery was studied. The microorganism was entrapped in polyvinyl alcohol-cryogel beads and used as a convenient source of immobilized cyclodextrin glycosyltransferase (CGTase). On activation by incubation in the cultivation medium containing 1% (w/v) starch, the entrapped cells multiplied and secreted CGTase with an activity of 2–3 mg -cyclodextrin h–1 g–1 beads. The immobilized biocatalyst exhibited maximum activity at pH 9 and 50 °C, and formed cyclodextrins comprising 92–94% -CD and remaining -CD. The cyclodextrin product from the immobilized cell bioreactor was continuously recovered by adsorption to Amberlite XAD-4 in a recycle batch mode. The product adsorption was facilitated at low temperature while hot water was used for elution. 相似文献
15.
Protoplasts were isolated from thalli of Ulva pertusa using a mixed enzyme solution of 2.0% Cellulase Onozuka R-10, 2.0% Macerozyme R-10, and 2.0% Driselase. Isolated protoplasts regenerated cell walls, developed into thalli, and propagated in large numbers under aeration in the preparative scale-culture system. Typical bioflavor compounds produced from the regenerated plants, as well as from field-collected plants, were found to be long chain aldehydes, which gave a typical seaweed odor. The long chain aldehydes were formed enzymatically from unsaturated fatty acids and released into the culture fluid. A Percoll/mannitol discontinuous density gradient separation of the heterogeneous protoplasts led to a selection of cell lines with high production of bioflavor. The cells that regenerated from protoplasts were immobilized by polymer matrices such as alginate, -carrageenan, agarose, and agar. Living cells entrapped in alginate beads in aerated cultures survived best. However, the beads started to breakdown after two months. The immobilized cells demonstrated a higher bioflavor production than did the cultured cells. 相似文献
16.
We studied the mechanisms of adherence of Blastomyces dermatitidis conidia to murine bronchoalveolar macrophages and the ability of the conidia to elicit an increase in macrophage O
inf2
sup-
production, using an avirulent fungal strain. The number of cell associated conidia was counted by visual inspection of 2 hour macrophage monolayers incubated with conidia and O
inf2
sup-
was measured by reduction of ferricytochrome c. Adherence of conidia to bronchoalveolar macrophages was time dependent and reached a plateau after 30 min (36±5%, 51±22%, and 36±17% macrophages with adherent conidia after 15, 30, and 60 min, respectively). Both Ca+2 and Mg+2 were required. The carbohydrates mannose, mannan, fucose, alpha-methylmannoside, beta-glucan, galactose, N-acetylglucosamine and chitotriose (100–1000 g/ml) did not inhibit adherence of conidia to macrophages. Trypsin treatment of macrophages or conidia did not affect binding. Conidia did not stimulate bronchoalveolar macrophage production of O
inf2
sup-
above baseline concentrations (2.0±0.9 vs 0.8±0.5 nmol O
inf2
sup-
, p>0.05). We conclude that murine bronchoalveolar macrophage-B. dermatitidis conidia interactions occur primarily by a non-lectin-like attachment and do not result in the production of macrophage derived O
inf2
sup-
. 相似文献
17.
Two new species of <Emphasis Type="Italic">Neosartorya</Emphasis> from Amazonian soil,Brazil 总被引:1,自引:0,他引:1
Neosartorya indohii and N. tsurutae, two new Neosartorya species isolated from tropical rainforest soil in the Amazonian area, Brazil, are described and illustrated. Neosartorya indohii is characterized by its spreading growth on Czapeks and malt extract agars, light yellow cleistothecia, broadly lenticular ascospores with two conspicuously serrate-incised equatorial crests and tuberculate convex surfaces, and globose to subglobose conidia with a smooth wall. Neosartorya tsurutae is characterized by its spreading growth on Czapeks and malt extract agars, white cleistothecia, broadly lenticular ascospores with four equatorial crests and rugulose-ruminate convex surfaces, and ovoid to broadly ellipsoidal conidia with a smooth wall. 相似文献
18.
Marek Barta Ivona Kautmanová Helena Čičková Ján Ferenčík Štefan Florián Július Novotný 《Biocontrol Science and Technology》2018,28(7):718-735
Two local strains of Beauveria bassiana originally isolated from naturally infected spruce bark beetles in Slovakia were tested for their virulence to Ips typographus (IT) and for their compatibility with a polymeric matrix composed of low-molecular polyethylene. Conidia could be homogenously immobilized in the low-molecular polyethylene matrix with no adverse effect on their viability and infectivity. At constant temperature (25°C), viability of immobilized conidial decreased only by 1–2% after 7 or 14 days when compared with non-formulated conidia. In field conditions, viability of conidia formulated in the matrix was even significantly higher than non-formulated conidia 35 days after their application in traps. Conidia incorporated into the polymeric matrix were infective to IT adults in laboratory bioassays. Mean values of LC50 for native conidia (0.72–2.05?×?106 conidia?ml?1) and conidia immobilized in the polymeric matrix (0.64–1.03?×?105 conidia?mm?2) demonstrated high virulence. The efficacy of the local strains was significantly higher than that of B. bassiana strains from mycoinsecticides (Boverol®, Botanigard® ES and Naturalis-L®). Results showed potential of this polymeric material for its use in microbial control of IT when mixed with conidia of B. bassiana. 相似文献
19.
Jürgen Helbig 《BioControl》2002,47(1):85-99
The yeast Cryptococcus albidus, originally isolated from mature strawberry fruits, was tested for antagonistic activity against Botrytis cinerea, the causal agent of grey mould in strawberries. Conidial germination and germ tube growth of conidia of B. cinerea were inhibited by a cell suspension of the antagonist in aqueous strawberry fruit pulp suspension (1%) after 6 and 24 hours of incubation. Application of a cell suspension (1 × 106 cells/ml) on detached strawberry leaf disks incubated at 10°C reduced incidence and conidiophore density of B. cinerea by 86 and 99%, respectively, but effectiveness was reduced at higher temperatures. Treatments with C. albidus during bloom of strawberries reduced incidence of grey mould on ripe strawberry fruits after harvest by 33, 28 and 21% in three years of field trials. The effectiveness of the yeast was increased when formulation substances (alginate, xanthan and cellulose) were added to the cell suspension. 相似文献
20.
Twelve phytopathogenic Clavibacter michiganensis subsp. michiganensis strains were introduced into non-sterile agricultural loam soil at an inoculum density of about log. 6.0 cfu g–1 dry weight soil. The soil samples were incubated at 22°C under a 12h light, 12h dark cycle and the population densities followed over a 30-day period by plating subsamples of serial dilutions of soil on Brain Heart Infusion agar amended with 0.5% (w/v) yeast extract and 30 g mL–1 nalidixic acid. In 5 soil samples C. michiganensis cfu were not detected after 30 days incubation. Initially, C. michiganensis cfu accounted for about 90% of the cfu recovered but decreased to less than 10% after 30 days. These results suggested that some C. michiganensis strains survive in this particular soil, while other strains exhibit poor survival and/or may be difficult to detect when present in low numbers. 相似文献