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Production of extracellular enzymes in the entomopathogenic fungus Verticillium lecanii  [PDF]
Saba Hasan,Anis Ahmad,Abhinav Purwar,Nausheen Khan
Bioinformation , 2013,
Abstract: This study investigates the mechanisms as well as strategies for purification and characterization of potential enzymes involved in pathogenesis of entomopathogenic fungi. The test strain of Verticillium lecanii that was screened, during the present investigation, proved to be an efficient producer of protein and polysaccharide degrading enzymes (amylase, protease, and lipase), hence indicating versatility in biochemical mechanisms. Halo zones produced colony growth of V. lecanii on agar confirmed activity of protease, amylase and lipase enzyme by the V. lecanii isolate. Enzymatic Index (EI) observed were: Protease – 2.195, Amylase- 2.196, Lipase- 2.147. Spectrophotometric analysis of enzymatic activity of V.lecanii at five different pH – 3, 5, 7, 9, 11 revealed that highest proteolytic activity of the V. lecanii isolate was reported at pH 7 and 9 whereas proteolytic activity was minimum at acidic pH 3. Maximum amylolytic activity of V. lecanii on the 7th day of inoculation was at pH 3 i.e. in an acidic environment in contrast to neutral pH 7. Maximum lipolytic activity of V. lecanii was found at pH 7. Since enzyme production in entomopathogenic fungi is specific and forms an important criterion for successful development as well as improvement of mycoinsecticides, hence a significant conclusion from the present analysis is the degree of variation in secretion of enzymes in test strain of Verticillium lecanii.
Isolation and characterization of a chitinase gene from entomopathogenic fungus Verticillium lecanii
Zhu, Yanping;Pan, Jieru;Qiu, Junzhi;Guan, Xiong;
Brazilian Journal of Microbiology , 2008, DOI: 10.1590/S1517-83822008000200022
Abstract: entomopathogenic fungus verticillium lecanii is a promising whitefly and aphid control agent. chitinases secreted by this insect pathogen have considerable importance in the biological control of some insect pests. an endochitinase gene vlchit1 from the fungus was cloned and overexpressed in escherichia coli. the vlchit1 gene not only contains an open reading frame (orf) which encodes a protein of 423 amino acids (aa), but also is interrupted by three short introns. a homology modelling of vlchit1 protein showed that the chitinase vlchit1 has a (α/β)8 tim barrel structure. overexpression test and enzymatic activity assay indicated that the vlchit1 is a functional enzyme that can hydrolyze the chitin substrate, so the vlchit1 gene can service as a useful gene source for genetic manipulation leading to strain improvement of entomopathogenic fungi or constructing new transgenic plants with resistance to various fungal and insects pests.
Patogenicidade de fungos hifomicetos aos pulg?es Aphis gossypii Glover e Myzus persicae (Sulzer) (Hemiptera: Aphididae)
Loureiro, Elisangela de S.;Moino Jr., Alcides;
Neotropical Entomology , 2006, DOI: 10.1590/S1519-566X2006000500014
Abstract: the aphids aphis gossypii and myzus persicae are cosmopolitan, poliphagous and damage cultivated plants. the effects of the entomopathogenic fungi beauveria bassiana (isolate ibcb 66), metarhizium anisopliae (isolate ibcb 121), paecilomyces fumosoroseus (isolate ibcb 141) and lecanicillium (= verticillium) lecanii (isolate jab 02) on third instar nymphs of a. gossypii and m. persicae were evaluated in the laboratory at 25°c, 70 ± 10% rh and 12h photophase. the aphids were transferred to petri dishes with a foliar disk (cotton or pepper) with a layer of 1 cm tick of agar-water. the fungi were applied in a suspension containing 1.0 x 106 to 1.0 x 108 conidia/ml. in the control treatment 1 ml of sterilized water was added to the foliar disks. the mortality of aphids was evaluated daily. b. bassiana and m. anisopliae caused 100% mortality at the seventh day after inoculation, for both species. l. lecanii was the fungus that provided mortality later in the aphids and m. persicae was more susceptible to both fungi than a. gossypii.
Sele??o de isolados de Verticillium lecanii para o controle de Cinara atlantica
Leite, Maria Silvia Pereira;Penteado, Susete do Rocio Chiarello;Zaleski, Scheila Ribeiro Messa;Camargo, Joelma Melissa Malherbe;Ribeiro, Rodrigo Daniel;
Pesquisa Agropecuária Brasileira , 2005, DOI: 10.1590/S0100-204X2005001100013
Abstract: the aim of this study was to evaluate the pathogenicity of verticillium lecanii isolates against cinara atlantica, and the lc50 of the best strain. for selection tests, nymphs of c. atlantica were placed on individual pine seedling with 20 isolates and one control, in a total of 21 treatments and ten replicates. for the lc50 estimation it was used the cg 904 strain with six concentrations and ten replicates. vl 6, cg 902 and vl 2 produced the highest mortality, of 72.22%, 67.34% and 67.31%, respectively. the control plot showed mortality of 15.6%. the lc50 of the cg 904 strain indicated mortality of 100% at the concentration of 108 conidia ml-1; lc50, 2x105 conidia ml-1; and lt50, 4.4 days.
Effect of Storage Conditions of Formulations on Viability of Verticillium lecanii (Zimmerman) Viegas and its Virulence to Brevicoryne brassicae (L.)
Ali Derakhshan,R.J. Rabindra,B. Ramanujam
Journal of Biological Sciences , 2008,
Abstract: Studies were conducted on the effect of culture media, storage temperature and moisture content on viability and virulence of Verticillium lecanii to Brevicoryne brassicae. Among nine media evaluated, Molasses Yeast Broth (MYB) plus 2% Polyethylene Glycol (PEG) maintained the fungus viability higher than other media followed by MYB plus 1% PEG and rice powder. Viability in refrigerator temperature was significantly higher than in room temperature. Among three moisture levels tested, viability at 5 and 10% were on par and were significantly higher than at 15%. Viability over time decreased and the differences in viability among the three storage times were significant. Storage time and media had significant effect on aphid mortality. Mortality decreased over storage time but the rate of decrease in aphid mortality was less than the rate of decrease in the fungal viability.
b-n-acetylglucosaminidase production by Lecanicillium (Verticillium) lecanii ATCC 26854 by solid-state fermentation utilizing shrimp shell
Barranco Florido,Esteban; Bustamante Camilo,Patricia; Mayorga-Reyes,Lino; González Cervantes,Rina; Martínez Cruz,Patricia; Azaola,Alejandro;
Interciencia , 2009,
Abstract: lecanicillium (verticillium) lecanii produced chitinases using shrimp shell as inducer. maximum production of b-n-acetylglucosaminidase was measured at 80h. enzyme stability was obtained at temperatures ranging from 30 to 40°c and maximum activity at 50°c, ph 6.0. enzyme activity increased with ba2+, co2+, fe3+ and zn2+. bioassays against the phytopathogenic fungus oidium spp. showed mycelial and germination inhibition. sds-page electrophoresis of the partially purified extract revealed four bands of 70, 58, 45 and 31kda and this extract showed activity of b-n-acetylglucosaminidase through zymogram analysis. chitinases produced by l. lecanii are potentially useful against phytopathogenic fungi, insects and chitosan bioconversions.
Crescimento e esporula??o de isolados de Verticillium lecanii sob diferentes fatores ambientais
Monteiro, Antonio Carlos;Barbosa, Claudio Camargo;Correia, Ant?nia do Carmo Barcelos;Pereira, Gener Tadeu;
Pesquisa Agropecuária Brasileira , 2004, DOI: 10.1590/S0100-204X2004000600007
Abstract: this research aimed to evaluate the growth and sporulation of two verticillium lecanii (zimm.) viégas isolates cultivated on solid medium with different initial ph values (4, 5, 6, 7, 8 and 9), exposed to different temperatures (19, 22, 25, 28 and 31oc) and photoperiods (0, 12 and 24 hours). there was no substantial effect of the initial ph values on growth and sporulation of both isolates twenty days after inoculation, except at ph 4.0 in which the growth was significantly reduced. absence of light promoted the best growth of jab 02 (32.70 mm) and jab 45 (32.67 mm) isolates but there was no effect of photoperiod on sporulation. the best temperatures for growth of jab 02 were 19, 22 and 25oc and for jab 45, 19 and 25oc. the latter isolate sporulated most at 19 and 22oc and there was no effect of temperature on sporulation of jab 02. none of the isolates developed at 31oc.
Crescimento e esporula??o de isolados de Verticillium lecanii sob diferentes condi??es nutricionais
Barbosa, Claudio Camargo;Monteiro, Antonio Carlos;Correia, Ant?nia do Carmo Barcelos;Pereira, Gener Tadeu;
Pesquisa Agropecuária Brasileira , 2002, DOI: 10.1590/S0100-204X2002000600011
Abstract: the objective of this work was to determine the best growth and sporulation conditions of two verticillium lecanii (zimm.) viégas, isolates cultivated in different culture medium, c sources, organic and inorganic n sources and c:n ratio. twenty days after inoculation, pda and complete medium provided the best development, and lactose and starch were the best c sources to promote the growth of jab 02 and jab 45 isolates, respectively; jab 02 showed low sporulation while jab 45 sporulated well on glucose and maltose. jab 02 isolate developed well when the organic n source was casitone; jab 45 obtained good development when the tested sources were casitone and peptone, although a low sporulation occurred in presence of tryptone and hydrolysed casein. the inorganic n sources that favoured the best development of isolates were (nh4)2hpo4 and nano3, although jab 02 isolate showed low sporulation. in the c:n ratio analysed, jab 02 isolate developed better on the 60:1 ratio, and the jab 45 isolate on the 5:1, 10:1 and 20:1 ratio. the sporulation of jab 02 isolate was low on all the ratios tested, but there was no effect of the c:n ratio on the sporulation of both isolates.
Pathogenicity and Virulence of Entomogenous Fungus, Verticillium lecanii (Zimm.) Viegas on the Pea Aphid, Acyrthosiphon pisum (Harris)  [cached]
S.A. Safavi,GH.R Rassulian etal
Journal of Science and Technology of Agriculture and Natural Resources , 2002,
Abstract: Pathogenicity and virulence of entomogenous fungus, Verticillium lecanii, was studied on the pea aphid, Acyrthosiphon pisum. Vertalec, a commercial product of V. lecanii, was evaluated under controlled conditions. Second instar nymphs were inoculated with conidial suspensions at concentrations ranging from 104 to 108 conidia/ml, and sterile distilled water (containing wetting agent) as control, then caged on cutted alfalfa stems. Each concentration was replicated three times with 30 aphids treated per replicate. Temperature, relative humidity and photoperiod were maintained at 23±1 °C, %97±3, and 16:8 (L:D), respectively. Aphids were monitored daily over 12 days for mortality and nymph production. All newborn nymphs and dead aphids were removed daily. Vertalec significantly increased aphid mortality (mean mortality because of mycosis increased form %45.55±6.93 at 104 conidia/ml to %95.55±4.45 at 108 conidia/ml). The LC50 value for pathogen was 5.l4×l04 conidia/ml. LT50 values for 105, 106, 107 and 108 conidia/ml were 10, 8, 6.5 and 5 days, respectively. At 104 conidia/ml LT50 value was not determined at experimental period. Ro values significantly decreased with increasing conidial concentration (mean R0 altered from 28.l5±5.38 in control to 5.15±1.81 at 108 conidia/ml). Results indicated that vertalec can be an effective agent against pea aphids. Further studies are recommended for its evaluation under natural conditions.
Crescimento e esporula o de isolados de Verticillium lecanii sob diferentes condi es nutricionais
Barbosa Claudio Camargo,Monteiro Antonio Carlos,Correia Ant?nia do Carmo Barcelos,Pereira Gener Tadeu
Pesquisa Agropecuária Brasileira , 2002,
Abstract: O objetivo deste trabalho foi determinar as melhores condi es de crescimento e esporula o de dois isolados de Verticillium lecanii (Zimm.) Viégas, cultivados em vários meios de cultura, fontes de C, fontes organicas e inorganicas de N e rela es C:N. Após 20 dias de cultivo, BDA e Meio Completo mostraram ser os melhores meios de cultura, e a lactose e o amido foram as fontes de C que mais favoreceram o crescimento dos isolados JAB 02 e JAB 45, respectivamente; baixa esporula o foi apresentada por JAB 02, enquanto JAB 45 obteve boa esporula o em glicose e maltose. JAB 02 desenvolveu melhor quando a fonte organica de N era casitona; JAB 45 obteve bom desenvolvimento em presen a de casitona e peptona, mas houve pouca esporula o em presen a de triptona e caseína hidrolisada. As fontes inorganicas de N que favoreceram o melhor desenvolvimento dos isolados foram (NH4)2HPO4 e NaNO3, porém, JAB 02 apresentou baixa esporula o. Entre as rela es C:N analisadas, JAB 02 obteve melhor crescimento na rela o 60:1 e JAB 45 nas rela es 5:1, 10:1 e 20:1; baixa esporula o foi obtida por JAB 02 nas rela es testadas, mas n o se verificou efeito da rela o C:N do meio sobre a esporula o dos isolados.
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