scholarly journals Controle biológico da queima-das-bainhas em arroz pela microbiolização de sementes com bactérias antagonistas

2007 ◽  
Vol 32 (5) ◽  
pp. 381-386 ◽  
Author(s):  
Juliane Ludwig ◽  
Andréa B. Moura

Objetivou-se avaliar o efeito de oito isolados bacterianos pré-selecionados de Pseudomonas synxatha, P. fluorescens, Bacillus subtilis, Bacillus sp. e Stenotrophomonas malthophilia no controle da queima-das-bainhas do arroz, causada por Rhizoctonia solani. Sementes da cultivar El Passo L144 foram imersas em suspensão (A540=0,5) de cada um dos isolados e agitadas por 30 min a 10ºC. Sementes imersas somente em solução salina e em salina mais fungicida (Carboxin + Thiran) foram utilizadas como testemunhas. Foram semeadas 10 sementes por vaso, em quatro repetições, dispostas em delineamento completamente casualizado. Foram realizados três ensaios, sendo que no primeiro foi possível selecionar três isolados como promissores, com reduções na severidade da doença atingindo 50, 33,3 e 16,7 %, respectivamente. Estes isolados foram utilizados nos ensaios posteriores, instalados em casa de vegetação e conduzidos até o ponto de colheita, onde foi possível observar o efeito biocontrolador propiciado, principalmente, pelo isolado de P. fluorescens DFs223, com reduções significativas na severidade da doença chegando a 88 e 91,7% no segundo e terceiro ensaios respectivamente. Em ambos os ensaios, houve incremento tanto do número de panículas quanto do número de perfilhos e da massa seca de raízes em até 42,8, 81,2 e 113% respectivamente, nas plantas tratadas com o isolado de P. fluorescens DFs223.

Nova ◽  
2011 ◽  
Vol 9 (16) ◽  
pp. 177 ◽  
Author(s):  
Cristian Layton ◽  
Edna Maldonado ◽  
Luisa Monroy ◽  
Lucía Constanza Corrales Ramírez MSC ◽  
Ligia Consuelo Sánchez Leal MSC

El presente estudio documental evalúa el efecto biocontrolador del género <em>Bacillus sp </em>contra hongos fitopatógenos de plantas, particularmente, a través de relaciones antagónicas inductoras de muerte celular en términos inminentemente naturales. <em>Fusarium oxysporum </em>se encuentra muy relacionado con casos de marchitez vascular y pudrición de raíz en variedad de plantas, obstrucción de los vasos que permiten la circulación vegetal hasta causar amarillamiento de las hojas por imposibilidad en el transporte de nutrientes, causal de grandes pérdidas económicas en el campo agrícola nacional. Se han establecido varios mecanismos para controlar este hongo micelial dentro de las que se encuentran el uso extensivo y variable de agroquímicos y pesticidas, práctica que por sus efectos nocivos con el medio ambiente se ha comenzado a reemplazar por empleo de especies del género <em>Bacillus. </em>La acción biocontroladora de este género bacteriano esta mediada por su perfil bioquímico ya que son productores de múltiples metabolitos biológicamente activos, en el caso de <em>Bacillus subtilis </em>de Iturin A y fengycin y en <em>Bacillus brevis de gramicidina S </em>(1-5) son capaces de inhibir el desarrollo y crecimiento normal de otros microorganismos, lo que sugiere su utilización para el biocontrol de plagas en aras al fortalecimiento de los actuales estándares de calidad en los procesos ambientales.


2020 ◽  
Vol 16 (1) ◽  
pp. 37-48
Author(s):  
Ratna Sari Dewi ◽  
Giyanto Giyanto ◽  
Meity Suradji Sinaga ◽  
Dadang Dadang ◽  
Bambang Nuryanto

Saat ini teknologi pengendalian hayati penyakit utama padi terus berkembang. Dalam pengembangan teknologi pengendalian hayati, mekanisme penghambatan patogen dalam perkembangan penyakit pada suatu populasi tumbuhan dalam area tertentu menjadi hal yang penting. Penelitian bertujuan mendapatkan bakteri agens hayati potensial dalam pengendalian penyakit penting padi di antaranya yang disebabkan Pyricularia oryzae, Xanthomnas oryzae pv. oryzae, Rhizoctonia solani, Burkholderia glumae, dan Drechlera oryzae, berdasarkan mekanisme antagonisme, kemampuan menginduksi ketahanan dan mendukung kebugaran tanaman, serta kompatibilitas antaragens hayati. Ralstonia pickettii TT47, Pseudomonas fluorescens P12, Chromobacterium sp. T51118, Bacillus subtilis 451 dan 154, serta Streptomyces sp. T51105 dibuktikan memiliki mekanisme antibiosis dengan menghasilkan metabolit sekunder dan senyawa volatil. Berdasarkan uji produksi enzim kitinolitik Chromobacterium sp. dan Streptomyces sp. memiliki mekanisme lisis. Aktivitas antibiotik R. pickettii dan P. fluorescens tergolong kuat terhadap P. oryzae dengan penekanan secara berurutan sebesar 79.68% dan 77.59% pada uji biakan ganda. Penekanan pertumbuhan miselium P. oryzae dan R. solani pada uji volatil mencapai 100% oleh Chromobacterium sp. Semua agens hayati umumnya mampu menginduksi ketahanan dan mendukung kebugaran tanaman. Uji kompatibilitas menunjukan R. pickettii, P. fluorescens, dan Chromobacterium sp. bersifat kompatibel. Dari hasil penelitian diperoleh tiga bakteri agens hayati dengan kategori unggul, yaitu P. fluorescens P12, R. pickettii TT47, dan Chromobacterium sp. T51118. Ketiganya mampu menekan pertumbuhan patogen, menginduksi ketahanan dan mendukung kebugaran tanaman, memiliki patogen sasaran yang lebih beragam, serta bersifat kompatibel.


2021 ◽  
Vol 43 (3) ◽  
pp. 27-35
Author(s):  
Pham Viet Cuong ◽  
Nguyen Phuong Hoa

The bacteria capable of fixing atmospheric nitrogen were isolated from cassava cultivated soils of Vietnam. The potential isolates were identified by analyzing the 16S rRNA gene and by morphological, biochemical, cultural characteristics. The selected isolates were assigned to the species Bacillus sp. DQT2 M17, Bacillus subtilis DTAN6 M17, and Bacillus megaterium DSHB I8. The effect of culture conditions on the nitrogen-fixing activity of three selected isolates were studied and the obtained results showed that the highest amount of accumulated ammonia was detected after 6 days of incubation at 35 oC, pH 7.0 with sucrose as a carbon source. The selected strains could be exploited as inoculants for microbial fertilizer production.


2016 ◽  
Vol 7 (1) ◽  
pp. 1 ◽  
Author(s):  
Amran Muis ◽  
Arcadio J. Quimio

Rhizoctonia solani Kuhn. causing banded leaf and sheath blight diseases is one of the important fungi of corn world wide. The fungus is commonly controlled by using fungicide because no resistant variety available. The objective of the study was to develop a seed treatment formulation of the selected Bacillus subtilis to control R. solani in corn. The study was conducted in the Department of Plant Pathology, College of Agriculture, University of the Philippines Los Bañòs, College, Laguna from May 2004 to August 2005, using sweet corn var. IPB Supersweet as test plant. Corn seeds were surface sterilized for 10 minutes in 1% sodium hypochlorite solution and 5% ethanol, washed thrice with sterile distilled water and air-dried. The seeds were coated with formulated B. subtilis BR23 and used for several experiments, such as evaluation for their germination and growth in the laboratory, effectively on R. solani in the baked and nonbaked field soil under greenhouse condition, and in the microplots artificially infested with R. solani. The treatment was compared with other standard seed treatment of synthetic fungicides such as captan (10 g per kg seeds) and metalaxyl (10 g per kg seeds). The experiments were designed in a completely random design with three replications. Parameters observed were seed germination, plant height, disease scores, and plant yield. Laboratory formulated B. subtilis BR23 used as seed treatment had no detrimental effects on seed germination and seedling vigor. In microplots artificially infested with a selected highly virulent R. solani, seed treatment with the same formulation increased grain yield by 27% compared to that of the control captan seed treatment with 14.4%. The studies showed the potential of B. subtilis BR23 for commercialization as a seed treatment for the control of banded leaf and sheath blight disease (R. solani) in corn.


2019 ◽  
Vol 97 (Supplement_2) ◽  
pp. 75-76
Author(s):  
Mariana Boscato Menegat ◽  
Michaela B Braun ◽  
Joel M DeRouchey ◽  
Jason C Woodworth ◽  
Jim Bryte ◽  
...  

Abstract This study evaluated the progeny of sows fed a control or probiotic diet with Bacillus subtilis C-3102 (Calsporin®, Calpis Co. Ltd., Tokyo, Japan) at 500,000 and 1,000,000 CFU/g diet in gestation and lactation, respectively. A total of 358 weaned pigs (DNA 241 × 600) were used in a 42-d trial with 4–5 pigs/pen and 18–19 pens/treatment. Pens were allotted to treatments in a completely randomized design based on BW at weaning. Treatments were a 2×2 factorial with main effects of sow diet (control vs. probiotic) and nursery diet (control vs. probiotic). In the nursery probiotic diet, a product based on probiotic Bacillus subtilis C-3102 at 500,000 CFU/g diet and prebiotics β-glucans and mannan oligosaccharides was included at 0.05% (BacPack ABF™, Quality Technology International, Inc., Elgin, IL). Diets were corn-soybean meal-based. Growth performance and fecal consistency on a 1-to-5 scale were evaluated weekly. Fecal samples were collected for microbial analysis by culture method and bacterial quantification of Bacillus subtilis C-3102, total Bacillus sp., Lactobacillus sp., Clostridium perfringens, Salmonella spp., Enterococcus sp., Enterobacteriaceae, total aerobes, and total anaerobes. Data were analyzed using a linear mixed model (PROC GLIMMIX, SAS®) with pen as experimental unit. There was no evidence for effect of sow diet, nursery diet, or interactions (P > 0.10) on overall nursery growth performance and fecal consistency. However, growth performance from d 21 to 42 and final BW were greater (P < 0.05) in progeny of control-fed sows compared to probiotic-fed sows. Microbial analysis revealed an increase (P < 0.01) in Bacillus subtilis C-3102 and, consequently, total Bacillus sp. in fecal microflora of probiotic-fed pigs. In conclusion, probiotic inclusion to sow diets lowered growth performance of the progeny in late nursery. The probiotic diet provided to sows or nursery pigs did not influence fecal consistency, but altered the fecal microbial population in nursery pigs by increasing total Bacillus sp.


2019 ◽  
Vol 29 (1) ◽  
Author(s):  
Manzoor R. Khan ◽  
Zaki A. Siddiqui

AbstractEffects of Pseudomonas putida and Bacillus subtilis alone, and in combinations for the management of Meloidogyne incognita, Pectobacterium betavasculorum, and Rhizoctonia solani disease complex of beetroot (Beta vulgaris L.), were studied. Application of P. putida or B. subtilis to plants with M. incognita or P. betavasculorum or R. solani singly or in combinations caused a significant increase in plant growth parameters and the activities of defense enzymes. A significant increase in chlorophyll fluorescence attributes, viz., Fv/Fm, ɸPSII, qP, NPQ, and ETR were recorded in plants treated with P. putida or B. subtilis over pathogen-inoculated plants. Inoculation of P. putida results in a higher reduction in galling and nematode multiplication than B. subtilis. Maximum reduction in nematode multiplication and galling occurred when a mixture of P. putida and B. subtilis was used. Soft rot and root rot indices were 3 when Pectobacterium betavasculorum and Rhizoctonia solani were inoculated alone. The disease indices were rated 5 when these pathogens and M. incognita were inoculated in combinations. Inoculation of P. putida/B. subtilis with P. betavasculorum or R. solani reduced soft rot and root rot indices to 2 out of 3, while the use of P. putida + B. subtilis reduced indices to 1. Disease indices were reduced to 2–3 out of 5, when P. putida + B. subtilis were used to plants inoculated with two or three pathogens. The principal component analysis showed significant correlations among the various studied attributes. Two principal components explained a total of 86.1 and 93.4% of the overall data variability. Therefore, the use of P. putida together with B. subtilis had the potential for successful management of disease complex of beetroot.


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