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1.
Katherine Muñoz Mario Vega Gisela Rios Rolf Geisen Gisela H. Degen 《Mycotoxin Research》2011,27(4):239-247
Ochratoxin A (OTA) is one of the most widespread mycotoxins, and is produced by several Aspergillus or Penicillium species. Human exposure to OTA is mainly by intake of contaminated food, with cereal products, followed by coffee and red
wine as the main sources of OTA. In this study, the OTA production of four ochratoxigenic fungi (two Aspergillus and two Penicillium species) was investigated in four different media, i.e. wheat and coffee model media as food-based media and two standard laboratory media (malt extract glucose agar, MEA and yeast
extract sucrose agar, YES). Colony growth was documented and OTA concentrations in cultures were determined at day 2, 4 and
8 of incubation at 25°C by high-performance thin-layer chromatography (HPTLC) and high-performance liquid chromatography (HPLC).
OTA production clearly depended upon time of incubation, fungal species, and medium composition. On coffee based medium, moderate
OTA levels were produced by A. ochraceus BFE635 (9.8 μg/g) and by A. niger BFE632 (10.6 μg/g) on day 8 of incubation. In wheat-based medium, these strains produced much more OTA than in coffee. The
highest OTA concentration (83.8 μg/g on day 8) was formed by A. ochraceus BFE635 followed by the other Aspergillus niger BFE632 (49 μg/g). Lower OTA levels were produced by P. verrucosum BFE550 and P. nordicum BFE487, in both wheat and in YES medium, whilst OTA was hardly detectable in coffee and in MEA in case of P. nordicum. Colony growth of the tested strains on different media was not indicative of OTA production. Guttation droplets developed
on wheat-based medium with the Aspergillus strains within a week, and this phenomenon coincided with the high OTA amounts formed by these species. Results from this
study add to our knowledge on the behaviour of ochratoxigenic fungal species when cultured on food based media. 相似文献
2.
F. W. Wang R. H. Jiao A. B. Cheng S. H. Tan Y. C. Song 《World journal of microbiology & biotechnology》2007,23(1):79-83
Among 67 endophytic fungi isolated from Quercus variabilis, 53.7% of endophytic fungal fermentation broths displayed growth inhibition on at least one test microorganism, such as pathogenic
fungi (Trichophyton rubrum, Candida albicans, Aspergillus niger, Epidermophyton floccosum, Microsporum canis) and bacteria (Escherichia coli, Bacillus subtilis, Pseudomonas fluorescens). Moreover, 19.4% of strains showed a broader antimicrobial spectrum, such as Aspergillus sp., Penicillium sp., Alternaria sp., 20.9% of strains showed strong inhibition (+++) to pathogenic bacteria, while only 7.5% displayed that to test fungi.
The most active antifungal strain I(R)9-2, Cladosporium sp. was selected and fermented. From the broth, a secondary metabolite, brefeldin A was obtained. This is the first report
on the antimicrobial potentials of endophytic fungi residing in Q. variabilis and isolation of brefeldin A produced by Cladosporium sp. 相似文献
3.
Claudia Ordóñez-Valencia Alejandro Alarcón Ronald Ferrera-Cerrato Laura Verónica Hernández-Cuevas 《Mycoscience》2009,50(5):380-387
Bicarbonates are often utilized in the food industry to avoid fermentation and to improve pH, flavor, and texture. In the
same manner, bicarbonates have been demonstrated to control postharvest phytopathogens; however, there are no reports describing
the effects of these chemical compounds either on soil-borne pathogens such as Sclerotinia sclerotiorum or on antagonist fungi such as Trichoderma species. This study evaluated the antifungal effect of increasing concentrations (0, 2, 4, 6, 8, 10, 25, and 50 mM) of potassium
bicarbonate (KHCO3) on the growth of Trichoderma sp. strain R39 and S. sclerotiorum under in vitro systems. Applications of KHCO3 greater than 8 mM significantly inhibited (P < 0.001) the growth of both fungi. Concentrations of KHCO3 lower than 25 mM did not affect the antagonistic effect of Trichoderma on the growth of S. sclerotiorum; however, this fungal interaction was not observed when exposed to 50 mM KHCO3 because of its strong inhibition of fungal growth. In addition, KHCO3 concentrations higher than 8 mM caused significant (P < 0.001) reduction of the sclerotium formation of S. sclerotiorum. Sclerotium germination and de novo sclerotium formation were significantly (P < 0.001) inhibited as the concentrations of KHCO3 increased. Results show the potential benefits of potassium bicarbonate for controlling both growth and development of S. sclerotiorum, although it also exerts negative effects on the Trichoderma strain that is a natural antagonist to S. sclerotiorum. 相似文献
4.
C. X. Zhang X. Zhao Y. X. Jing T. Chida H. Chen S. H. Shen 《World journal of microbiology & biotechnology》2008,24(10):2179-2181
Bacillus subtilis KB-1111 and KB-1122 were studied to illustrate their phenotypic and biological properties. Comparison of KB-1111 with KB-1122
in morphology was carried out by microscopy and agar plate assays. Biological assay of the test strains showed that they may
possess different physiological pathways from those of reference strain ATCC6501. The assessment of antagonism against the
indicator fungi showed that both test strains had broad antifungal characteristics against eight phytopathogenic fungi. Of
those fungal species, Magnaporthe grisea P131, Sclerotinia sclerotiorum, and F. oxysporium exhibited high sensitivity to the test strains. 相似文献
5.
Using molecular karyotyping and genetic hybridization analysis, two new polymeric β-fructosidase genes, SUC9 and SUC10, were identified in the yeast Saccharomyces cerevisiae, which are located on chromosome XIV and on the chromosome XVI/XIII doublet, respectively. The genes are responsible for
fermentation of sucrose and raffinose. The SUC gene genotypes of strains VKM Y-1831 and DBVPG 1340 are SUC2 SUC9 and suc2
0
SUC10, respectively. suc2
0 is a silent sequence. The scientific and applied significance of SUC genes is discussed. 相似文献
6.
Cereal grain is a major component of food and feed in large parts of the world. The microbial flora on cereal grains may interfere
with hygiene and storage stability, palatability and bioavailability of minerals and proteins may depend on the composition
of the microbial population. Therefore, it is of primary interest to control the microbial species present on cereal grain.
Inoculation of the biocontrol yeast Pichia anomala to cereal feed grain improved feed hygiene by reduction of moulds and Enterobacteriaceae, and enhanced the nutritional value by increasing the protein content and reducing the concentration of the antinutritional
compound phytate. P. anomala strains showed a high phytase activity, for some strains also considerable extracellular phytase activity was observed. A certain maximum in biomass concentration was never exceeded indicating cell density induced growth inhibition of P. anomala. 相似文献
7.
Esterases are known for their involvement in several physiological processes and high degree of polymorphism, in many organisms.
Such polymorphism has been used to characterize species and species groups and to study genetic changes occurred in their
evolutionary history. In the present study, the esterase patterns of 19 strains from 10 species representative of the five
subgroups of the saltans species group were analyzed using polyacrylamide gel electrophoresis and α- and β- naphthyl acetates as substrates. Fifty-one
esterase bands were detected and classified as 31 α-esterases, 18 β-esterases and two α/β-esterases. On the basis of the inhibition
patterns using Malathion and eserine sulfate, 34 bands were classified as carboxylesterases, 14 as acethylesterases and three
as cholinesterases. Ten gene loci were tentatively established on the basis of data on band position in the gel, substrate
preference and inhibition pattern. Twenty bands were species-specific, the remaining being shared by species from the same
or different subgroups. Bands detected exclusively in males and bands with a different frequency or degree of expression between
sexes were also detected. In the gels prepared for analysis of gene expression in the body parts (head, thorax and abdomen),
the degree of expression of the β-esterases was higher in the thorax, while the α-esterases were expressed predominantly in
the abdomen and thorax. A global view of the data available at present on the esterases of the species from the saltans group and their degree of polymorphism are presented, as well as the possibility of using some β-esterases, because of their
characteristics in the gels, as markers for species identification. 相似文献
8.
H. R. Zabihi G. R. Savaghebi K. Khavazi A. Ganjali M. Miransari 《Acta Physiologiae Plantarum》2011,33(1):145-152
We have recently indicated the plant growth promoting activities of Pseudomonas sp. as well as their alleviating effects on some soil stressors such as salinity. This is because in recent years, biological
fertilizers have received special attention by scientists in sustainable agriculture. Accordingly, it is pertinent to specify
the beneficiary level of such soil bacteria on plant growth including phosphorous (P) uptake. Hence, the objectives were to
determine: (1) the plant growth promoting effects of the tested Pseudomonas sp., and (2) its combined effects with different P fertilization rates on the nutrient uptake (N, P, and K) and yield of
wheat (Triticum
aestivum L.) under greenhouse and field conditions. The experiments were factorially arranged on the basis of a completely randomized
block design with three replicates and were conducted at the Research Farm of Agriculture and Natural Resources Research Center
of Khorasan, Mashhad, Iran. P was fertilized at three levels including 0, 25 and 50 kg/ha P2O5. Pseudomonas sp. including Pseudomonas
fluorescens 153, P. fluorescens 169, P.
putida 4, and P.
putida 108 were tested. Activities such as production of ACC deaminase and IAA-like products, as well as P solubilization were among
the most important activities of the tested Pseudomonas sp. Such bacterial effects greatly enhanced wheat growth and yield under greenhouse and field conditions. The results also
showed that the effects of Pseudomonas sp. on wheat nutrient uptake and the effects of bacteria as well as P fertilization on wheat yield were significant. P.
putida 108 was the most effective strain enhancing wheat P uptake and grain yield under greenhouse (96 and 58%) and field (80 and
37%) conditions, respectively. Hence, although Pseudomonas sp. could be a suitable replacement for high P fertilization, however, the optimum wheat yield resulted when the bioinoculants
are combined with 50% (25 kg/ha P2O5) P fertilization. This finding has great agricultural and environmental implications. 相似文献
9.
Based on the results of genetic analysis and molecular karyotyping, a total of 11 strains involved in fermentation processes
employed in various regions of Africa were identified as representatives of the species Saccharomyces cerevisiae. These stains exhibited a high degree of chromosomal polymorphism. The obtained fertile genetic lines of the studied African
strains may be of considerable interest for evolutionary genetics and breeding of yeasts of the genus Saccharomyces. 相似文献
10.
Emira Noumi Mejdi Snoussi Hajer Hentati Kacem Mahdouani Lucas del Castillo Eulogio Valentin Rafael Sentandreu Amina Bakhrouf 《Mycopathologia》2010,169(4):269-278
Several virulence factors in Candida albicans strains such as production of hydrolytic enzymes and biofilm formation on surfaces and cells can contribute to their pathogenicity.
For this, control of this opportunistic yeast is one of the factors reducing the nosocomial infection. The aim of this study
was to investigate biofilm formation on polystyrene and polymethylmethacrylate and the production of hydrolytic enzymes in
Candida albicans strains isolated from the oral cavity of patients suffering from denture stomatitis. All strains were identified by macroscopic,
microscopic analysis and the ID 32 C system. Our results showed that 50% of the total strains produced phospholipase. Furthermore,
protease activity was detected in seven (35%) strains. All Candida albicans strains were beta haemolytic. All C. albicans strains adhered to polystyrene 96-well microtiter plate at different degrees, and the metabolic activity of C. albicans biofilm formed on polymethylmethacrylate did not differ between tested strains. The atomic force micrographs demonstrated
that biofilm of Candida albicans strains was organized in small colonies with budding cells. 相似文献
11.
Hao Zhang Yuping Ran Dongming Li Yongfang Liu Yun Xiang Ruifeng Zhang Yaling Dai 《Mycopathologia》2010,169(5):373-380
We describe the first case of cutaneous infection caused by Chaetomium atrobrunneum and Clavispora lusitaniae in a one-and-a-half-year-old boy with acute and severe inflammation around his left eyelid. He presented to our outpatient
center with a 6-day history and previously ineffective antibacterial therapy. Scanning electron microscopy (SEM) revealed
hyphae and spores were on the surface of the crusty exudates and also penetrated into it, and the microbiology study further
showed their characteristic cultural features. Fungal isolates were identified by the amplification and sequencing of the
26S RNA gene and of the ITS region, as C. lusitaniae and C. atrobrunneum. Up until now, most known clinical records of these rare species have shown them as agents of deep mycosis. Due to the emergency
situation, medications were administered promptly and confirmed by subsequent fungal identification and successful therapeutic
outcome. This article illustrates the importance of recognizing fungal infections, especially those caused by uncommon pathogens.
Limitations in the routine identification procedures and therapeutic options of this emerging opportunistic agent are also
discussed in this report. 相似文献
12.
Ineke van Gremberghe Pieter Vanormelingen Katleen Van der Gucht Antoniya Mancheva Sofie D’hondt Luc De Meester Wim Vyverman 《Hydrobiologia》2009,635(1):147-155
We conducted a laboratory experiment to investigate the influence of Daphnia infochemicals on growth rate, microcystin production, colony formation and cell size of eight Microcystis strains isolated from two lakes. The strains were characterized genetically by their 16S-23S rDNA ITS sequence. The experiment
was composed of four treatments: (1) a control using filtered WC medium, (2) addition of Scenedesmus obliquus culture medium filtrate, (3) addition of Daphnia magna culture medium filtrate and (4) addition of sodium octyl sulphate, a commercially available Daphnia infochemical. Our results showed that sympatric strains differed strongly for the measured functional traits, while no correlations
between traits were found. Between-strain differences in growth rate, microcystin production, colony formation and cell size
were generally larger than the differences in phenotypes observed between treatments. Despite this, several strains reacted
to the infochemicals by changing functional trait values. Daphnia culture medium filtrate and, to a lesser extent, sodium octyl sulphate had a negative influence on the growth rate of half
of the strains and stimulated microcystin production in one strain, but the latter effect was not Daphnia-specific as Scenedesmus culture medium filtrate had the same effect. Daphnia culture medium filtrate also induced colony formation in one strain. Our data suggest that Daphnia infochemicals generally have a weak influence on growth rate, microcystin production and colony formation of Microcystis strains as compared to the inter-strain variability, while existing inducible effects are highly strain-specific. 相似文献
13.
Some strains of white rot fungi, non-lignolytic fungi and litter-decomposing basidiomycetes have been recognized as PAH degraders.
The purpose of our research was to enlarge the scope of PAH-degrading fungi and explore the huge endophytic microorganism
resource for bioremediation of PAHs. In this study, phenanthrene was used as a model PAHs compound. Nine strains of endophytic
fungi isolated from four kinds of plant from Eupharbiaceae were screened for degradation of phenanthrene. The endophytic fungus Ceratobasidum stevensii (strain B6) isolated from Bischofia polycarpam showed high degradation efficiency and was selected for further studies. Into the fungal culture, 100 mg l−1 phenanthrene was added, and after 10 days of incubation, about 89.51% of the phenanthrene was removed by strain B6. Extracellular
ligninolytic enzyme activities of strain B6 were tested. The results showed that manganese peroxidase [MnP] was the predominant
ligninolytic enzyme and that its production was greatly induced by the presence of phenanthrene. To confirm the involvement
of MnP in phenanthrene degradation, promotion and inhibition studies on MnP in different concentration level of Mn2+ and NaN3 were performed. Additionally, fungal mycelium-free and resuspended experiments were carried out. The results showed no apparent
correlation between MnP activity and phenanthrene degradation. The mycelium and fresh medium were the crucial factors affecting
the degradation of phenanthrene. To date, this is the first report on PAH degradation by Ceratobasidum stevensii. This study suggests that endophytic fungi might be a novel and important resource for microorganisms that have PAH-degrading
capabilities. 相似文献
14.
Hua Zhang Rui Xia Zhou Li Jing Zhang Ruo Yu Wang Li Zhe An 《Journal of Plant Biology》2007,50(3):336-343
A novel late embryogenesis abundant (LEA) gene (AY804193), namedCbLEA, has now been isolated fromChorispora bungeana. This rare alpine subnival plant can survive sudden snowstorms and low temperatures. The full-lengthCbLEA is 842 bp, with an open reading frame encoding 169 ami no acids. The putative molecular weight ofCbLEA protein is 17.9 kDa, with an estimatedpl of 6.45. To investigate the functioning of thisCbLEA protein in cold-stress tolerance,CbLEA was introduced into tobacco under the control of the CaMV35S promoter. Second-generation (R1) transgenic tobacco plants exhibited significantly increased tolerance to cold. These transgenics maintained lower malondialdehyde
(MDA) contents and electrolyte leakage (EL) but their relative water content (RWC) was significantly higher compared with
non-transgenic plants under chilling stress. Further experimental results showed that non-transgenic plants had severe freezing
damage after exposure to -2°C for 1 h, whereas the transgenics suffered only slight injury under the same conditions. Moreover,
survival was longer in the latter genotype at that temperature. The extent of increased cold tolerance was positive correlated
with the level ofCbLEA protein accumulation, and was also reflected by the delayed development of damage symptoms. This indicates thatCbLEA is an excellent stress tolerance gene, and holds considerable potential as a new molecular tool for engineering improved
plant genetics. 相似文献
15.
Ching-Nan Lin Wan-Jr Syu Wei-Sheng W Sun Jenn-Wei Chen Tai-Hung Chen Ming-Jaw Don Shao-Hung Wang 《Journal of biomedical science》2010,17(1):84
Plumbagin is found in many herbal plants and inhibits the growth of various bacteria. Escherichia coli strains are relatively resistant to this drug. The mechanism of resistance is not clear. Previous findings showed that plumbagin
treatment triggered up-regulation of many genes in E. coli including ahpC, mdaB, nfnB, nfo, sodA, yggX and ygfZ. By analyzing minimal inhibition concentration and inhibition zones of plumbagin in various gene-disruption mutants, ygfZ and sodA were found critical for the bacteria to resist plumbagin toxicity. We also found that the roles of YgfZ and SodA in detoxifying
plumbagin are independent of each other. This is because of the fact that ectopically expressed SodA reduced the superoxide
stress but not restore the resistance of bacteria when encountering plumbagin at the absence of ygfZ. On the other hand, an ectopically expressed YgfZ was unable to complement and failed to rescue the plumbagin resistance
when sodA was perturbed. Furthermore, mutagenesis analysis showed that residue Cys228 within YgfZ fingerprint region was critical for
the resistance of E. coli to plumbagin. By solvent extraction and HPLC analysis to follow the fate of the chemical, it was found that plumbagin vanished
apparently from the culture of YgfZ-expressing E. coli. A less toxic form, methylated plumbagin, which may represent one of the YgfZ-dependent metabolites, was found in the culture
supernatant of the wild type E. coli but not in the ΔygfZ mutant. Our results showed that the presence of ygfZ is not only critical for the E coli resistance to plumbagin but also facilitates the plumbagin degradation. 相似文献
16.
Lam Hoang Kyung Sik Song In Koo Rhee Jeong Hoe Kim Sangman Lee 《Journal of Plant Biology》2007,50(4):514-516
To analyze the growth inhibitory mechanism of a 2-aminobenzoic acid (2-AA) derived fromBacillus cereus EJ-121, we treatedArabidopsis thaliana plants with 2-AA, 2-AA analogs, auxin (NAA), a known auxin transport inhibitor [2,3,5-triiodobenzoic acid (TIBA)], and an
ethylene action inhibitor [silver thiosulfate (Ag)]. Root development was significantly inhibited by 50 μM 2-AA, whereas the
growth of bacteria and yeast was undeterred. The application of two 2-AA analogs - 3-aminobenzoic acid (3-AA) and 4-aminobenzoic
acid (4-AA) - did not impairArabidopsis root growth at concentrations below 100 μM. These results suggest that the effect of 2-AA is not due to its chemical structure,
but because of its conversion to another metabolite, IAA. To confirm this, we supplemented TIBA in the growth medium, and
found that the degree of inhibition was significantly reduced. Similarly, when plants were co-treated with 100 μM Ag, the
negative effect of 50 μM 2-AA was greatly diminished. All of these observations support the proposal that this inhibition
results from the conversion of 2-AA to IAA. Furthermore, the increased auxin level leads to a rise in ethylene synthesis,
which then blocks root growth and, ultimately, retards overall plant development. 相似文献
17.
Effective recombinant strains Pichia pastoris that produce functionally active hybrid of Trigonopsis variabilis D-aminoacids bond with chitin-connecting domain of chitinase A1 of Bacillus circulans (DAOcbd) were obtained. The dependence of DAOcbd production levels from production of the number of copies of “expression
cassette” integrated in the AOX1 locus of recombinant strains was studied. It was indicated that synthesized DAOcbd may be
easily purified and immobilized on chitin sorbents and possessed high specific activity. Produced strains and methods of their
cultivation and DAOcbd extraction may be used for development of technologies of obtaining of biocatalyzers in technological
processes of obtaining of 7-aminocepha-losporane acid. 相似文献
18.
Zoran Maksimović Marina Milenković Dragana Vučićević Mihailo Ristić 《Central European Journal of Biology》2008,3(2):149-154
This paper presents the results of a study on chemical composition and antimicrobial activity of Thymus pannonicus All. (Lamiaceae) essential oil from Vojvodina province (north of Serbia). The investigated oil was hydrodistilled from a flowering plant
and analysed by GC and GC-MS. Fifty-three constituents were identified (>97% of total oil), with geranial (41.42%, w/w) and
neral (29.61%, w/w) as the most prominent. The antimicrobial activity of the oil was evaluated using agar disc diffusion and
broth microdilution method against Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, Escherichia coli, two strains of Klebsiella pneumoniae and two strains of Candida albicans. The essential oil exhibited antimicrobial activity to varying degrees against all tested strains. The maximum activity of
T. Pannonicus oil was observed against E. coli, S. aureus and both tested strains of C. Albicans (MIC = 50 μ/ml, each). Moderate activity was observed against P. aeruginosa and one of the tested strains of K. Pneumoniae (MIC = 200 μ/ml), while E. faecalis and the other strain of K. Pneumoniae expressed a higher degree of resistance (MIC > 200 μ/ml). This study confirms that essential oil of T. pannonicus possesses remarkable in vitro antimicrobial activity against several medicinally important pathogens. This is attributable to lemon-scented citral, a mixture
of geranial and neral, which has well-documented antimicrobial activity against a range of bacteria and fungi. 相似文献
19.
The flagellar protein (flagellin) was isolated and purified from strains of Pseudomonas aeruginosa, Burkholderia cepacia and Stenotrophomonas maltophilia. A significant difference was observed in the molecular weight of different flagellin preparations obtained from these bacterial isolates. Antiserum prepared against S. maltophilia flagellin did not react with flagellin of P. aeruginosa or/and B. cepacia on Immunoblot or in indirect ELISA. In addition the anti-flagellin did not agglutinate P. aeruginosa and B. cepacia. No inhibition of motility of P. aeruginosa and B. cepacia was observed in presence of antiserum; though the latter inhibited the motility of S. maltophilia. The results of the present study prove that no specific relationship existed among all the studied flagellar proteins obtained from closely related bacteria. 相似文献
20.
A rhizobacterium with high antifungal activity was isolated from a potato field at Inneruulalik, South Greenland. Phylogenetic
analysis based on multi locus sequence typing showed that the bacterium was affiliated with strains of Pseudomonas fluorescens. The bacterium, denoted as Pseudomonas
fluorescens In5, inhibited in vitro a broad range of phytopathogenic fungi, and the antifungal activity increased with decreasing temperature.
Microcosm experiments demonstrated that P.
fluorescens In5 protected tomato seedlings from Rhizoctonia solani. Transposon mutagenesis showed that the major cause for the antifungal activity of P. fluorescens In5 was a novel non-ribosomal peptide synthase (NRPS) gene. In addition, transposon mutagenesis showed that P. fluorescens In5 also contained a putative quinoprotein glucose dehydrogenase gene, which was involved in growth inhibition of phytopathogenic
fungi. Although P. fluorescens In5 contained the capacity to synthesize hydrogen cyanide, β-1,3-glucanase, protease, and chitinase, these did not seem to
play a role in the in vitro and microcosm antifungal assays. 相似文献