Formulation of Coniothyrium minitans for biocontrol of white mold caused by Sclerotinia sclerotiorum

O fungo Sclerotinia sclerotiorum, agente causal do mofo-branco, tem controle dificultado pela longevidade de seus escleródios no solo. Uma estratégia alternativa de controle é o uso do fungo antagonista Coniothyrium minitans, que parasita os escleródios de S. sclerotiorum e reduz a incidência da doença. O objetivo deste trabalho foi desenvolver uma formulação com C. minitans capaz de controlar o mofo-branco. Para tanto, picnídios deste fungo foram encapsulados com diferentes polímeros (alginato de sódio e pectina cítrica), caulim e substratos naturais (farinha de trigo e celulose). Das combinações obtidas, a formulação que continha 0,5% de alginato, 1,5% de celulose e 5% de caulim apresentou os melhores resultados quanto à viabilidade do fungo e controle da doença. Os grânulos da formulação armazenados a 4ºC apresentaram 100% de viabilidade do fungo. Nos grânulos armazenados a 28ºC, o fungo perdeu capacidade de crescer após os primeiros dois meses. O fungo formulado foi capaz de esporular sobre os grânulos incubados em meio de cultura BDA e no solo, como também foi capaz de reduzir a incidência da doença.Sclerotinia sclerotiorum, causal agent of white mold, maintains its resistant structures viable for many years in the soil, and its control is difficult. An alternative method for controlling it is the use of Coniothyrium minitans, an antagonistic fungus efficient in attacking the sclerotia. The objective of this work was to develop a method to encapsulate picnidia of C. minitans to control the white mold, using different polymers, such as alginate and pectin supplemented with wheat flour or cellulose and kaolin. Picnidia of C. minitans formulated in alginate 0.5%, cellulose 1.5%, and kaolin 5% survived better at 4 than at 28ºC when stored during two months. After this period, only the formulation stored at 4ºC maintained its viability. When the formulation was stored at 28ºC, the fungus lost its ability to grow after two months. The fungus formulated grew abundantly on the pellets when they were inoculated on PDA. They also reduced completely the disease incidence in infested soil

ISOLATION AND CHARACTERIZATION OF CARBENDAZIM DEGRADING Trichoderma harzianum RIFAI MUTANTS

Mutants of Trichoderma harzianum Rifai, obtained after ultraviolet (UV) light exposure, showed high resistant to the fungicide benomyl. A mutant (2B6) was capable of degrading carbendazim, other fungicide of the benzimidazole fungicide. This mutant degraded 41.5% of the molecule within five days. This and others mutants (2B1 and 2B2) presented variation in size and frequency of uni-nucleated and/or bi-nucleated spores compared to the wild type. Four primers generated RAPDs patterns that allowed the mutant to be differentiated from the wild-type. It is concluded that using UV mutagenization, it is feasible to obtain strains of T. harzianum with improved pesticide degradation ability

Controle biológico da murcha de berinjela causada por Verticillium albo-atrum

The antagonistic activity of Trichoderma species against Verticillium wilt of eggplant was evaluated. The studies were undertaken in vitro and in vivo. A clearly defined zone, in which the growth of the pathogen was inhibited, was observed with some isolates of Trichoderma in vitro. The best results of the btocontrol under greenhouse conditions were obtained with Trichoderma hamatum and with the isolate T3 of Trichoderma sp. In a field experiment, T. lignorum and the isolate significantly reduced the disease. The mutants of Trichoderma, obtained by UV irradiation, were not efficient in controlling the disease.O controle biológico de Verticillium albo-atrum Reinke & Berth., agente causai da murcha de berinjela (Solanum melongena L.), foi feito em condições de laboratório e em condições de campo. Os melhores isolados de Trichoderma foram aqueles que apresentaram, em placas de Petri, uma zona de inibicão bem evidente. Trichoderma hamatum e o isolado T3 de Trichoderma reduziram sensivelmente a incidência da doença em condições de casa-de-vegetação. No campo, T. lignorum e o isolado T3 propiciaram os melhores resultados. Os mutantes de Trichoderma, obtidos por irradiação ultravioleta, não foram eficientes no biocontrole de Verticillium

Nutritional requirements for the fungus Alternaria alternata

 Uma linhagem de Alternaria alternata (ALT A) foi cultivada em meio sintético com diferentes fontes de C, N e vitaminas. O crescimento micelial foi avaliado durante sete dias após a semeadura e a esporulação no décimo dia de incubação. O meio sintético básico suplementado com biotina, NH4Cl e os carboidratos maltose e glicose suportaram um bom crescimento micelial (em média 0,75 cm/dia). Galactose e arabinose induziram significativamente a produção de esporos (mL-1), da ordem de 5,0 x103 e 4,1 x 103, respectivamente. Nas diferentes fontes de vitamina e N não houve diferenças significativas quanto ao crescimento micelial e à esporulação.A strain of Alternaria alternata (ALT A) was tested using different sources of C, N and vitamins in order to find a medium for its growth and sporulation. The mycelial growth was evaluated for seven days after sowing and the sporulation on the tenth day of incubation. Among various C, N and vitamins compounds tested, highest mycelial growth was achieved with maltose and glucose (C), NH4Cl (N) and biotin, with an average ratio of 0.75 cm/day. Sporulation reached highest values with galactose and arabinose (5.0 x 103 and 4.1 x 103 conidia mL-1, respectively). Others vitamins and N compounds did not influence the growth and sporulation

INDUÇÃO DA ENZIMA PIROCATECASE POR Acinetobacter baumanii ENVOLVIDA NA BIODEGRADAÇÃO DO HERBICIDA DIURON

Uma linhagem de Acinetobacter baumanii, isolada da rizosfera de cana-de-açúcar, cultivada em solos tratados com Diuron foi incubadada em diferentes substratos para verificar a presença de catecol 1,2- dioxigenase (pirocatecase). Diferentes indutores foram adicionados ao meio de cultura (glicose, benzoato de sódio, Diuron, dicloroanilina, benzoato de sódio + glicose, benzoato de sódio + dicloroanilina, Diuron + glicose). As células bacterianas, obtidas pelo processo fermentativo, foram coletadas após centrifugação e rompidas por sonicação para extração da enzima intracelular. A linhagem apresentou alta atividade enzimática quando benzoato de sódio ou benzoato de sódio + glicose ou benzoato de sódio + dicloroanilina foram adicionados ao meio de cultura. A atividade enzimática acompanhou a produção de biomasa. No estudo da cinética de crescimento, usando Diuron como fonte de carbono e em três diferentes pH, essa linhagem apresentou melhor resultado quando cultivada em pH 6,8. Verificou-se pela avaliação da capacidade de A. baumanii transformar o Diuron, que o metabólito 3,4-dicloroanilina (3,4-DCA) não foi produzido. PYROCATECHASE INDUCED BY Acinetobacter baumanii INVOLVED IN THE BIODEGRADATION OF THE HERBICIDE DIURON Abstract An Acinetobacter baumanii strain, isolated from Diuron treated sugarcane rhizosphere, was grown in different substrates in order to determine the catechol 1,2-dioxygenase (pyrocatechase) presence. Different inducers were added to the culture media (glucose, sodium benzoate, Diuron, dichloroaniline, sodium benzoate plus glucose, sodium benzoate plus dichloroaniline, and Diuron plus glucose). The bacterial cells were harvested by centrifugation and disrupted by sonication for intracellular enzyme extraction. The strain showed high activity of pyrocatechase when sodium benzoate or sodium benzoate plus glucose or sodium benzoate plus dicloroaniline were added to the culture media. The enzymatic activity followed the biomass production. According to the growing kinetics study using Diuron as a carbon source, and with three different pH, this strain showed the best result when growed at pH 6.8. Estimating the A. baumanii capacity of transforming Diuron, it was observed that the 3,4-dichloroaniline (3,4-DCA) metabolite was not produced

Changes in hyphal morphology due to chitosan treatment in some fungal species

In this work, changes in the hyphal morphology due to chitosan treatment in some fungal species were studied. Scanning electron microscope (SEM) observations revealed that chitosans with molar fraction of acetyl groups (F A 0.16 and 0.18) and degree of polymerization (DP 1,089 and 1,242) had a direct effect on the morphology of the chitosan-treated fungi, reflecting its potential for causing a delay in the growth of Alternaria alternata (500 µg × mL-1), Botrytis cinerea (1,000 µg × mL-1), Penicillium expansum (1,000 µg × mL-1) and Rhizopus stolonifer (500 µg × mL-1). Mycelial aggregation and structural changes such as excessive branching, swelling of the cell wall and hyphae size reduction were observed in the micrographs.637646Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

SELEÇÃO DE BACTÉRIAS ENDOFÍTICAS COM AÇÃO ANTAGÔNICA A FITOPATÓGENOS

Muitos métodos rápidos e eficientes de seleção de agentes de biocontrole de fitopatógenos tem sido utilizados, visando reduzir tempo e custo dispendido em testes de campo. Neste trabalho realizou-se uma seleção de isolados endofíticos com potencial de uso no biocontrole de fitopatógenos em testes de antagonismo in vitro. De um total de 95 isolados de bactérias endofíticas do milho, seis foram selecionados quanto à inibição a Pythium aphanidermatum. A essa seleção, foram incluídos um isolado de Bacillus subtilis 0G, Bacillus lentimorbus e Streptomyces sp., para verificação de antagonismo a Rhizoctonia solani, Fusarium moniliforme, Sclerotium rolfsii e Exserohilum turcicum. Verificou-se que os endofíticos B. subtilis 0G, B. lentimorbus e Streptomyces sp., apresentaram ação antagônica superior aos demais, com taxas de inibição entre 32,0% e 53,8%. Dentre os endofíticos do milho, Bacillus agaradhaerens foi o que mais se destacou, com taxas de inibição variando entre 43,7% e 52,3% e indicando uma inespecificidade de ação. Este estudo, embora preliminar, permite vislumbrar a utilização desses endofíticos na supressão de doenças em diferentes sistemas patógeno-hospedeiro em testes subseqüentes, sob condições de casa-de-vegetação e a campo.Several fast and efficient methods of selection of biocontrol agents of plant diseases has been used, to reduce time and cost expended in the field tests. This work took place a selection of isolated endophytics with potential for use in biocontrol of plant pathogens in tests of antagonism in vitro. Out of a total of 95 isolates of bacteria endophytic maize, six were selected on the inhibition to Pythium aphanidermatum. In this selection, were included one isolate of Bacillus subtilis 0G, Bacillus lentimorbus and Streptomyces sp. For verification of antagonism to Rhizoctonia solani, Fusarium moniliforme, Sclerotium rolfsii and Exserohilum turcicum. It was found that the endophytics B. subtilis 0G, B. lentimorbus and Streptomyces sp. showed more antagonic action to the other, with inhibition rates of between 32,0% and 53,8%. Among the endofíticos maize, Bacillus agaradhaerens was what stood out most, with rates of inhibition ranging between 43,7% and 52,3%, indicating a inespecificity of action. This study, though preliminary, to see the use of such endophytics to the elimination of diseases in different host-pathogen systems in subsequent tests under conditions of house-to-vegetation and field

Evaluation of bacterial diversity recovered from petroleum samples using different physical matrices

Unraveling the microbial diversity and its complexity in petroleum reservoir environments has been a challenge throughout the years. Despite the techniques developed in order to improve methodologies involving DNA extraction from crude oil, microbial enrichments using different culture conditions can be applied as a way to increase the recovery of DNA from environments with low cellular density for further microbiological analyses. This work aimed at the evaluation of different matrices (arenite, shale and polyurethane foam) as support materials for microbial growth and biofilm formation in enrichments using a biodegraded petroleum sample as inoculum in sulfate reducing condition. Subsequent microbial diversity characterization was carried out using Scanning Electronic Microscopy (SEM), Denaturing Gradient Gel Electrophoresis (DGGE) and 16S rRNA gene libraries in order to compare the microbial biomass yield, DNA recovery efficiency and diversity among the enrichments. The DNA from microbial communities in petroleum enrichments was purified according to a protocol established in this work and used for 16S rRNA amplification with bacterial generic primers. The PCR products were cloned, and positive clones were screened by Amplified Ribosomal DNA Restriction Analysis (ARDRA). Sequencing and phylogenetic analyses revealed that the bacterial community was mostly represented by members of the genera Petrotoga, Bacillus, Pseudomonas, Geobacillus and Rahnella. The use of different support materials in the enrichments yielded an increase in microbial biomass and biofilm formation, indicating that these materials may be employed for efficient biomass recovery from petroleum reservoir samples. Nonetheless, the most diverse microbiota were recovered from the biodegraded petroleum sample using polyurethane foam cubes as support material.47371272