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1.
Mating-type genes were cloned and sequenced in the heterothallic phytopathogenic fungus Exserohilum monoceras, a candidate bioherbicide for the control of Echinochloa weeds in rice fields. Using PCR-based methods, we determined both idiomorphs and flanking regions of these genes. The structural
organization of the E. monoceras
Mat locus was similar to that of other heterothallic ascomycetes. The MAT1-1-1 gene was 1191 bp and encoded a predicted protein of 379 amino acids with an α box domain. The MAT1-2-1 gene was 1093 bp and encoded a predicted protein of 345 amino acids with a high mobility group box domain. Expression of
both MAT genes was detected under vegetative and invasive growth conditions. MAT-specific primers were developed to assess the mating-type frequency of E. monoceras field isolates. Both mating types were observed in Japanese field isolates. Analysis of mating types and sexual hybridization of E. monoceras could provide useful approaches for the conventional genetic manipulation of this fungus to produce a more efficient bioherbicide. 相似文献
2.
Shereen Sabet Lamine Diallo Lauren Hays Woosung Jung Jesse G. Dillon 《Extremophiles : life under extreme conditions》2009,13(4):643-656
Solar salterns are extreme hypersaline environments that are five to ten times saltier than seawater (150–300 g L−1 salt concentration) and typically contain high numbers of halophiles adapted to tolerate such extreme hypersalinity. Thirty-five
halophile cultures of both Bacteria and Archaea were isolated from the Exportadora de Sal saltworks in Guerrero Negro, Baja
California, Mexico. 16S rRNA sequence analysis showed that these cultured isolates included members belonging to the Halorubrum, Haloarcula, Halomonas, Halovibrio, Salicola, and Salinibacter genera and what may represent a new archaeal genus. For the first time, metabolic substrate usage of halophile isolates was
evaluated using the non-colorimetric BIOLOG Phenotype MicroArray™ plates. Unique carbon substrate usage profiles were observed,
even for closely related Halorubrum species, with bacterial isolates using more substrates than archaeal cultures. Characterization of these isolates also included
morphology and pigmentation analyses, as well as salinity tolerance over a range of 50–300 g L−1 salt concentration. Salinity optima varied between 50 and 250 g L−1 and doubling times varied between 1 and 12 h.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
3.
Everardo A. Menezes Walderez Gambale Mahasti S. Macedo Dulcineia S. P. Abdalla Claudete R. Paula Julio Croce 《Mycopathologia》1995,131(2):75-81
In a previous study with airborne mould extracts we verified thatDrechslera (Helminthosporium) monoceras presented stronger reactions than those presented by 42 other moulds isolated in São Paulo city. In the present study, we evaluated the biochemical composition and the antigenicity of crude extracts obtained from vegetative and conidial stage ofD. monoceras using Czapeck broth (CB) modified and tris-HCl for extraction. The maximum values of total proteins and lipids were verified in the crude extract obtained in the 28th day of growth, and maximum values of carbohydrates were observed in the extracts of the 16th, 22nd and 26th days. The fractionated proteins by SDS-PAGE presented bands with molecular weights between 14.4 to 67 Kd; the 28th day extract showed a larger number of bands. The carbohydrates and amino acids were characterized by thin-layer chromatography. The antigenicity of the crude extracts was verified by immunodiffusion reaction in agar against rabbit hyperimmune sera. Precipitation lines were observed in all studied extracts and common antigenic molecular populations. Based on the above results, the 28th day extract was selected to verify the induction of IgE antibody responses in immunizations of Balb/c and cAF-1 mice, and titer by passive cutaneous anaphylaxis test using Wistar rats. The maximum titers obtained were 160 in cAF-1 mice and 1.280 in Balb/c mice. The results suggest that the 28th day extract contains allergenic fractions and should be chosen for future studies related to fractionation, characterization and standardization in diagnostic methods and immunotherapy.Part of the thesis of E.A. Menezes to get degree of Doctor Fractionation and characterization of allergenic extract ofDrechslera (Helminthosporium) monoceras. 相似文献
4.
Denture stomatitis is often treated with antifungal agents but recurrences or new episodes are common, and certain episodes
can be resistant. New triazoles, such as posaconazole and voriconazole, may represent useful alternatives for management.
In vitro activities of amphotericin B, nystatin, miconazole, fluconazole, itraconazole, posaconazole and voriconazole against
150 oral Candida (101 C. albicans, 18 C. tropicalis, 12 C. glabrata, 11 C. guilliermondii, 4 C. parapsilosis, 2 Saccharomyces cerevisiae, 1 C. dubliniensis and 1 C. krusei) from 100 denture wearers were tested by the CLSI M27-A3 method. Resistant isolates were retested by Sensititre YeastOne
and Etest. Most antifungal agents were very active. However, 4 C. glabrata (33.3%), 2 C. tropicalis (11.1%), 6 C. albicans (5.6%) and 1 C. krusei were resistant to itraconazole. Posaconazole was active against 143 yeast isolates (95.3%): 6 C. albicans (5.9%) and 1 C. tropicalis (5.6%) were resistant. Geometric mean MICs were 0.036 μg/ml for C. parapsilosis, 0.062 μg/ml for C. albicans, 0.085 μg/ml for C. tropicalis, 0.387 μg/ml for C. guilliermondii and 0.498 μg/ml for C. glabrata. Voriconazole was active against 148 isolates (98.7%) with geometric mean MICs ranging from 0.030 μg/ml for C. parapsilosis, 0.042 μg/ml for C. albicans, 0.048 μg/ml for C. tropicalis, 0.082 μg/ml for C. guilliermondii, to 0.137 μg/ml for C. glabrata. Only 2 C.
albicans (2%) were resistant to voriconazole showing cross-resistance to other azoles. Posaconazole and voriconazole have excellent
in vitro activities against all Candida isolates and could represent useful alternatives for recalcitrant or recurrent candidiasis. 相似文献
5.
R. Khushiramani S. K. Girisha P. P. Bhowmick Indrani Karunasagar Iddya Karunasagar 《World journal of microbiology & biotechnology》2008,24(10):2263-2268
Outer membrane proteins (Omps) are located at host–bacterial interface and are important for host immune responses and as
targets for drug therapy. In the present study, outer membrane protein profiling of 40 isolates of Aeromonas spp. (A. hydrophila, A. trota, A. caviae, A. veronii biovar sobria, A. jandaei and A. schubertii) obtained from different sources was done using SDS-PAGE, PCR and Western blotting techniques. The 3–4 high intensity bands
at the region of 25–45 kDa were obtained in all the isolates with minor differences. Twenty Omp patterns (M1–M20) were obtained.
The isolates were further tested for omp specific PCR and Omp specific antibody based Western blot. Positive reaction was obtained in 35 isolates of Aeromonas using ompTS-PCR and anti-OmpTS antibodies based Western blot. Primers specific for omp48 and antibodies to Omp48 reacted with 32 isolates. One mutant of A. hydrophila (AB-3-5-2 mutant) and 4 clinical isolates (one A. jandaei and three A. schubertii) were negative for both the genes. When both the assay systems were tested with bacterial cultures other than Aeromonas spp., anti-OmpTS antibodies were specific for Aeromonas spp. whereas, the anti-omp48 antibodies gave reaction with Escherichia coli and other Gram negative non-aeromonads. From the results we conclude the usefulness of OmpTS for identification of virulent
Aeromonas spp. and Omp48 as a potential recombinant vaccine candidate for Gram negative opportunistic infection of fish. Omp profiling
can be a useful molecular marker for characterizing Aeromonas isolates. 相似文献
6.
Santiago IF Alves TM Rabello A Sales Junior PA Romanha AJ Zani CL Rosa CA Rosa LH 《Extremophiles : life under extreme conditions》2012,16(1):95-103
A total of 564 isolates of endophytic fungi were recovered from the plants Deschampsia antarctica and Colobanthus quitensis collected from Antarctica. The isolates were screened against parasites Leishmania amazonensis and Trypanosoma cruzi and against the human tumour cell lines. Of the 313 fungal isolates obtained from D. antarctica and 251 from C. quitensis, 25 displayed biological activity. Nineteen extracts displayed leishmanicidal activity, and six inhibited the growth of at
least one tumour cell line. These fungi belong to 19 taxa of the genera Alternaria, Antarctomyces, Cadophora, Davidiella, Helgardia, Herpotrichia, Microdochium, Oculimacula, Phaeosphaeria and one unidentified fungus. Extracts of 12 fungal isolates inhibited the proliferation of L. amazonesis at a low IC50 of between 0.2 and 12.5 μg ml−1. The fungus Phaeosphaeria herpotrichoides displayed only leishmanicidal activity with an IC50 of 0.2 μg ml−1, which is equivalent to the inhibitory value of amphotericin B. The extract of Microdochium phragmitis displayed specific cytotoxic activity against the UACC-62 cell line with an IC50 value of 12.5 μg ml−1. Our results indicate that the unique angiosperms living in Antarctica shelter an interesting bioactive fungal community
that is able to produce antiprotozoal and antitumoral molecules. These molecules may be used to develop new leishmanicidal
and anticancer drugs. 相似文献
7.
Venkatesh Chaturvedi Ashok Kumar 《International biodeterioration & biodegradation》2011,65(7):961-971
In the present investigation, an attempt has been made to isolate and identify SDS-degrading bacteria from different detergent contaminated ponds situated in Varanasi city, UP, India. Initial survey of ponds indicated that these ponds were contaminated with detergents. Employing enrichment technique in minimal medium (PBM) with SDS as a sole carbon source, a total of 24 isolates were recovered from 7 detergent contaminated ponds. Studies on rates of SDS degradation indicated that the rate of SDS degradation varied from 97.2% to 19.6% after 12h incubation under identical conditions. An estimation of alkyl sulfatase activity indicated that the activity varied from 0.168 ± 0.004 to 0.024 ± 0.005 μmol SDS/mg protein/min. Molecular characterization of these isolates was performed on the basis of ARDRA and ERIC PCR, which indicated that these isolates were broadly divided in 8 groups. Some selected isolates were identified on the basis of 16S rDNA sequencing. It was found that these isolates belonged to Pseudomonas aeruginosa, Pseudomonas mendocina, Pseudomonas stutzeri, Pseudomonas alcaligenes, Pseudomonas pseudoalcaligenes, Pseudomonas putida and Pseudomonas otitidis respectively. Among these isolates P. aeruginosa, P. putida and P. otitidis have been previously shown to degrade and metabolize SDS, the rest of the isolates appear to be new. 相似文献
8.
The tolerances of 20 Beauveria bassiana isolates derived from host insects worldwide to UV-B irradiation were assessed quantitatively in multi-dose bioassays. Conidial
suspensions of the isolates smeared on glass slides were exposed to the gradient UV-B doses of 0.1–1.6 J cm−2 (D), which generated from 0.75 to 10.17 min irradiation of weighted 312-nm wavelength at 2.0–2.61 mW cm−2. Irradiated conidia were then incubated for 24 h at 25°C under saturated humidity. The ratio of germination at each dose
over that in the blank control was defined as survival index (I
s). For all isolates, the I
s − D observations fit well with the survival model I
s = 1/[1 + exp(a + bD)] (0.94 ≤ r
2 ≤ 0.99) generated widely spanned lethal doses of 0.154–0.928, 0.240–1.139, and 0.383–1.493 J cm−2 for their losses of 50%, 75%, and 95% viabilities, respectively. These were far below the solar UV-B dose of 2.439 J cm−2 measured in a sunny day during the summer. The large variation of UV-B tolerance among the isolates indicates a necessity
to select UV-tolerant candidates for formulations applied to insect control during summer. The highly efficient bioassay method
was developed to measure accurately the UV-B tolerances of fungal biocontrol agents as lethal doses. 相似文献
9.
Barua S Tripathi S Chakraborty A Ghosh S Chakrabarti K 《Indian journal of microbiology》2011,51(3):369-376
The effect of fluctuations of salinity in three different seasons on diazotrophic populations and N2 fixation in six mono cropped rice field soils of the coastal region of the Gangetic delta of West Bengal, India, was studied.
The average pH, ECe, organic carbon and total nitrogen of the soils ranged from 4.99–7.08, 2.02–19.58 dSm−1, 4.68–12.03 g kg−1 and 0.44–1.70 g kg −1, respectively. The average log colony forming units of the bacterial populations and N2-fixation in the soils varied from 4.61 to 5.86 and 2.74 to 4.52 mg N2 fixed 50 ml −1 culture media respectively, with the lowest value recorded in summer. Recovery of microorganisms and N2- fixation gradually decreased with extraneous addition of NaCl in the culture media. All the eight isolates were Gram positive,
spore and capsule formers. They could utilize glucose, sucrose, mannitol, starch, citrate and nitrate, and were catalase and
gelatinase positive, but indole, methyl red and Vogues Proskauer reaction negative. The organisms produced alkaline reaction
on TSI agar slant. The acetylene reduction assay of the isolates at 0 and 1% NaCl in the culture media were 4.51–164.52 and
1.72–100.6 nmole C2H4 ml−1 culture media in 72 h, respectively. The isolates could fix 2.42–4.45 and 2.04–4.08 mg N2 fixed 50 ml−1 culture media at 0 and 1% NaCl in the culture media respectively. 16S rDNA sequences of the isolates were similar to the
species: Bacillus sp. isolate 28A, Bacillus sp. MOLA 87, Bacillus sp. By113 (B)Ydz-dh, Bacillus sp. PN13, Bacillus licheniformis strain RH101, Bacterium Antarctica 14, Bacillus sp. PN13 and Bacillus megaterium. 相似文献
10.
Diversity of lactic acid bacteria and yeasts in Airag and Tarag,traditional fermented milk products of Mongolia 总被引:2,自引:1,他引:1
Koichi Watanabe Junji Fujimoto Masae Sasamoto Jamyan Dugersuren Tseveendori Tumursuh Shirchin Demberel 《World journal of microbiology & biotechnology》2008,24(8):1313-1325
We used culture- and molecular-biology-based methods to investigate microbial diversity in the traditional Mongolian fermented
milks “Airag” (fermented mare’s milk) and “Tarag” (fermented milk of cows, yaks, goats, or camels). By rRNA or functional
gene sequencing, we identified 367 lactic acid bacteria (LAB) strains and 152 yeast strains isolated from 22 Airag and 31
Tarag samples. The total concentration of LAB in Airag (107.78 ± 0.50 c.f.u. ml–1; mean ± SD) was significantly lower (P < 0.01) than in Tarag (108.35 ± 0.62 c.f.u. ml−1), whereas the total concentration of yeasts in Airag (107.41 ± 0.61 c.f.u. ml-1) was significantly higher (P < 0.01) than in Tarag (105.86 ± 1.29 c.f.u. ml-1). Lactobacillus helveticus and Lactobacillus kefiranofaciens were isolated from Airag as the predominant LAB strains at levels of about 107 c.f.u. ml−1, whereas Lactobacillus delbrueckii subsp. bulgaricus, L. helveticus, and Streptococcus thermophilus were the predominant isolates from Tarag at about 107 c.f.u. ml−1. The lactose-fermenting Kluyveromyces marxianus was isolated predominantly from Airag as its major alcoholic fermentation component. Non-lactose-fermenting yeasts such as
Saccharomyces cerevisiae, Issatchenkia orientalis, and Kazachstania unispora were the predominant isolates from Tarag, at about 105 c.f.u. ml−1. The apparent geographic differences in the L. kefiranofaciens and S. thermophilus contents of Tarag strongly suggested that differences among the animal species from which the milk was sourced, rather than
geographic distances, were the most important factors influencing the diversity of the microbial composition of traditional
fermented milks in Mongolia. 相似文献
11.
Ahmet Yilmaz Coban Ugur Demırpek Tuba Yıldırım Yeliz Tanrıverdı Caycı Tanil Kocagoz Belma Durupınar 《World journal of microbiology & biotechnology》2011,27(8):1901-1904
In this study, it was aimed to evaluate colorimetric Quicolor ES agar for the rapid detection of methicillin resistance and
to determine susceptibility and resistance breakpoint zone diameters for cefoxitin by using 51 methicillin susceptible Staphylococcus aureus (MSSA) and 63 methicillin resistant S. aureus (MRSA) isolates. In the study, while oxacillin and cefoxitin results were obtained within 4–7 h (5.5 h in average) for MSSA
isolates, the results of MRSA isolates were obtained within 5.5–9 h (6.6 h in average) for both antibiotics on QC ES agar.
QC ES agar is an inexpensive medium for rapid detection (4–9 h) of methicillin resistance by disc diffusion method using oxacillin
or cefoxitin. Additional studies for further evaluation of the efficiency of QC-ES agar in rapid determination of methicillin
resistance in S. aureus may be beneficial. 相似文献
12.
Virendra Kumar Sanchita Haldar Koshlendra K. Pandey Rana P. Singh Achuit K. Singh Prabhash C. Singh 《World journal of microbiology & biotechnology》2008,24(7):1003-1009
Early blight (Alternaria solani) is an important disease causing severe damage in tomato. The eleven isolates of A. solani designated as So, Dh, Sh, Va-5, Ka, Ma, Hy, Ba-1, My, Va-3 and Mi were collected from different agroclimatic conditions and
these isolates were characterized for cultural, morphological, pathogenic and molecular variations. The pigmentation varied
from yellow, brown, black, brownish to greenish black in isolates of A. solani on potato dextrose agar medium. In general, radial growth of all isolates ranged between 14.9 mm and 32.2 mm on PDA and 24.3 mm
to 53.7 mm on three selective media i.e., ASM, V-8 juice agar and V-8 juice agar (synthetic) on the fourth day. The fastest
radial growth was recorded in the So isolate and slowest in the Ka isolate on PDA, while isolates Dh, Ba-1 and Va-3 were recorded
to be faster in growth on ASM, V-8 juice agar and V-8 juice agar (synthetic) medium. The thickness of conidiogenous hyphae
varied between 1.17 μ and 9.56 μ, with maximum in the Va-5 and Ma isolates. Most of the isolates showed smooth mycelial growth
with circular and irregular margin and without concentric zonation. Sporulation was not found in any of the isolates on four
different nutrient media, whereas conidiogenous hyphal length was observed in V-8 juice agar medium only. Based on the pathogenicity,
isolates of A. solani were rated as virulent or less virulent based on percentage disease incidence data. Molecular variability studies were also
done to find out the best annealing temperature and eighty-six primers were screened to select for maximum polymorphism of
DNA. The best annealing temperature was recorded between 32.5 °C and 34.0 °C for the pathogen, and most efficient amplification
and polymorphism of DNA was found with random primer 5′-CGCGTTCCTG-3′. 相似文献
13.
Jennifer Loveland-Curtze Vanya Miteva Jean Brenchley 《Extremophiles : life under extreme conditions》2010,14(1):61-69
Three novel orange, ultramicrobacterial isolates, UMB10, UMB14, and UMB34T were isolated from enrichment cultures inoculated with a melted 3,043 m deep Greenland ice core sample. Phylogenetic analysis
of the 16S rRNA gene sequences indicated that the isolates belonged to a single species within the genus Chryseobacterium. They were most closely related to Chryseobacterium aquaticum (99.3%), Chryseobacterium soli (97.1%), and Chryseobacterium soldanellicola (96.9%). Genomic hybridization showed low levels of relatedness between UMB34T and C. aquaticum and C. soldanellicola (19–30%) and C. soli and Chryseobacterium jejuense (45–56%). Comparative genomic fingerprinting analysis using the enterobacterial repetitive intergenic consensus (ERIC) sequence
showed nearly identical banding patterns for the three isolates and these patterns were distinct from those of C. aquaticum, C. soldanellicola, C. soli, and C. jejuense. The cells were short rods, lacked flagella, had cell volumes of <0.1 μm3, formed buds and smaller protrusions (blebs), produced copious extracellular material and a flexirubin type pigment. UMB34T produced acids from carbohydrates and utilized glucose and maltose although it did not assimilate mannose. The DNA G + C
was 39.6–41.6 mol%. Based on the differences from validly named Chryseobacterium species, it was concluded that these isolates represent a new species for which the name, Chryseobacterium greenlandense is proposed. The type strain is UMB34T (=CIP 110007T = NRRL B-59357). 相似文献
14.
M Rantala E Lahti J Kuhalampi S Pesonen A-K J?rvinen L Saijonmaa-Koulumies T Honkanen-Buzalski 《Acta veterinaria Scandinavica》2004,45(1):37
The aim of this study was to evaluate antimicrobial resistance in canine staphylococci, Escherichia coli and enterococci, which were isolated from 22 dogs with pyoderma and a history of previous antibiotic treatment, compared to bacterial isolates from 56 non-treated control dogs. Two isolates of each bacterial species per dog were investigated, if detected. Staphylococcal isolates from dogs with pyoderma (35 isolates) were more resistant to sulphatrimethoprim than the isolates from controls (56 isolates) (57% vs. 25%, p < 0.004). Multiresistance in staphylococci was also more common in dogs with pyoderma (29% vs. 9%, p = 0.02). A similar trend among isolates of E. coli was detected (24 and 74 isolates from treated and control dogs, respectively), but the differences were not significant. Resistance for macrolide-lincosamides was approximately 20% among staphylococci in both groups. Resistance to ampicillin among enterococci was 4%–7%. The age of the dogs might have an impact on resistance: multiresistance among staphylococcal isolates from younger dogs (≤5 years) was more common than in older dogs (≥6 years) (24%, vs. 0%, 63 and 27 isolates, respectively, p = 0.02). Staphylococci in younger dogs were more resistant to tetracycline (48% vs. 11%, p < 0.001) and sulphatrimethoprim (48% vs. 15%, p < 0.01) than those in older dogs. In contrast, the isolates of E. coli from older dogs tended to be more resistant, although a significant difference was detected only in resistance to tetracycline (13% vs. 2% of 40 and 50 isolates respecthely, p = 0.04)). The results of this small study indicate that resistance in canine staphylococci in the capital area of Finland is comparable with many other countries in Europe. Resistance in indicator bacteria, E. coli and enterococci, was low. 相似文献
15.
Buatong Jirayu Phongpaichit Souwalak Rukachaisirikul Vatcharin Sakayaroj Jariya 《World journal of microbiology & biotechnology》2011,27(12):3005-3008
The aim of this work was to select endophytic fungi from mangrove plants that produced antimicrobial substances. Minimal inhibitory
concentrations (MIC) and minimal bactericidal concentrations (MBC) or minimal fungicidal concentrations (MFC) of crude extracts
from 150 isolates were determined against potential human pathogens by a colorimetric microdilution method. Ninety-two isolates
(61.3%) produced inhibitory compounds. Most of the extracts (28–32%) inhibited Staphylococcus aureus (MIC/MBC 4–200/64–200 μg ml−1). Only two extracts inhibited Pseudomonas aeruginosa (MIC/MBC 200/>200 μg ml−1). 25.5 and 11.7% inhibited Microsporum gypseum and Cryptococcus neoformans (MIC/MFC 4–200/8–200 μg ml−1 and 8–200/8–200 μg ml−1, respectively), while 7.5% were active against Candida albicans (MIC/MFC 32–200/32–200 μg ml−1). None of the extracts inhibited Escherichia coli. The most active fungal extracts were from six genera, Acremonium, Diaporthe, Hypoxylon, Pestalotiopsis, Phomopsis, and Xylaria as identified using morphological and molecular methods. Phomopsis sp. MA194 (GU592007, GU592018) isolated from Rhizophora apiculata showed the broadest antimicrobial spectrum with low MIC values of 8–32 μg ml−1against Gram-positive bacteria, yeasts and M. gypseum. It was concluded that endophytic fungi from mangrove plants are diverse, many produce compounds with antimicrobial activity
and could be suitable sources of new antimicrobial natural products. 相似文献
16.
Trine Glad Vibeke Fam Kristiansen Kaare M. Nielsen Lorenzo Brusetti André-Denis G. Wright Monica A. Sundset 《Microbial ecology》2010,60(2):320-330
Dominant colonic bacteria in wild hooded (n = 9), harbour (n = 1) and grey (n = 1) seals were identified using 16S rRNA gene clone libraries (313 clones), revealing 52.7% Bacteroidetes, 41.5% Firmicutes, 4.5% Proteobacteria and 1.0% Fusobacteria. Thirty (77%) of the 39 phylotypes identified were novel, showing <97% sequence similarity to their nearest cultivated relatives.
Mean colonic bacterial cell density, determined by real-time PCR, was high (12.8 log10 cells/g wet wt) for the hooded seals, while the number of methanogenic Archea was low (4.0 log10 cells/g wet wt). The level of ampicillin (ampr) and tetracycline-resistant (tetr) isolates was investigated by cultivation. Aerobic ampr isolates were only detected in colon contents from four hooded seals, whereas aerobic tetr isolates were found in seven of the nine hooded seals. These data provide novel insight to the gut microbiota of Arctic and
sub-Arctic seals living in the wild. 相似文献
17.
E. Quesada-Moraga E.A.A. Maranhao P. Valverde-García C. Santiago-lvarez 《Biological Control》2006,36(3):274-287
As part of a 3-fold approach to select potential mycoinsecticides for whitefly control, we evaluated infectivity, thermal requirements, and toxicogenic activity of the entomopathogenic fungus Beauveria bassiana (Ascomycota: Clavicipitaceae) under laboratory conditions. Twenty-five native B. bassiana isolates and a commercially available mycoinsecticide (based on B. bassiana) were evaluated for virulence to fourth instar nymphs of sweetpotato whitefly, Bemisia tabaci, and greenhouse whitefly, Trialeurodes vaporariorum, at a concentration of 1 × 107 conidia/ml. All isolates were pathogenic for both whitefly species, whereas mortality rates varied from 3 to 85%. A second series of bioassays was conducted on 10 selected isolates using four 10-fold concentrations ranging from 1 × 105 to 1 × 108 conidia/ml. Median lethal concentrations (LC50) of the four most virulent isolates varied from 1.1 × 105 to 6.2 × 106 conidia/ml and average survival time (AST) of treated nymphs from 5.9 to 7.4 days. T. vaporariorum were significantly more susceptible to all B. bassiana isolates than B. tabaci. The thermal biology of the eight most virulent isolates to both whitefly species was investigated at six temperatures (10–35 °C). The colony radial growth rate was estimated from the slope of the linear regression of colony radius on time and data were then fitted to a modified generalized β function that accounted for 90.5–99.3% of the data variance. Optimum temperatures for extension rate ranged from 23.1 to 27.1 °C, whereas maximum temperatures for fungal growth varied from 31.8 to 36.6 °C. On the basis of their virulence and thermal requirements, three isolates showed promise as candidates for whitefly management in Mediterranean greenhouses. Whilst in vitro production of macromolecular compounds toxic to Galleria mellonella larvae was not a requisite for virulence, ASTs of larvae injected with Sephadex G-25 fractions from candidate isolates ranged from 1.4 to 3.7 days compared with 5–6 days for non-toxic G-25 fractions. In addition, proteinase K treatment significantly reduced their toxic activity suggesting that they were proteins and revealing the potential of these isolates to be further improved through biotechnology to kill the pest more quickly. 相似文献
18.
19.
Mukesh K. Malviya Anita Pandey Pankaj Trivedi Garima Gupta Bhavesh Kumar 《Current microbiology》2009,59(5):502-508
Seventy-eight isolates of actinomycetes were isolated from the soil samples collected from alpine zones of Pindari glacier
region in Indian Himalaya. Following a plate based rapid screening using two test fungi, five efficient isolates (nos. HA1,
HA2, HA6, HA40, and HA142) were selected for further characterization with special reference to their antagonistic properties.
Based on phenotypic and genotypic characters, the isolates were identified up to species level. All the isolates belonged
to the genus Streptomyces. The isolate nos. HA1 and HA2 were S. sampsonii and HA6, HA40 and HA142 were S. griseobrunneus, S. aurantiacus, and S. griseoluteus, respectively. The isolates showed strong antifungal properties against phytopathogenic test fungi in plate assays. All the
isolates hydrolyzed glycol–chitin as a substrate in denaturing conditions showing variable amount of different isoforms. 相似文献
20.
Conidia of Beauveria bassiana and Metarhizium spp. smeared on glass slides were assayed for their responses to irradiation with weighted 312-nm UV-B and 365-nm UV-A at
gradient doses of 0.005–1.1 and 1.0–18.0 J cm−2, respectively. All inverted, sigmoid dose–survival trends showed good fit to a survival model (r
2 ≥ 0.97), yielding respective UV-B LD50s of 0.23–0.59 and 0.05–0.65 J cm−2 for 24 B. bassiana and 36 Metarhizium isolates, and UV-A LD50s of 2.78–10.46 J cm−2 for 24 Metarhizium isolates. Myzus persicae apterae on detached leaves were sprayed with a concentrated spore suspension of B. bassiana or M. anisopliae, followed by exposure to the UV-B doses to cause 10–90% viability losses. These doses caused aphid mortality reductions as
expected but affected neither spray-to-death period nor fungal growth on cadavers. The results highlight the merits of using
UV-tolerant candidates and photoprotection measures in fungal formulations for pest control. 相似文献