At least 20-40% of annual losses of avocado crops are caused by pathogenic fungi.The chemical treatments of these diseases are inefficient,cause environmental pollution and are increasingly restricted by international...At least 20-40% of annual losses of avocado crops are caused by pathogenic fungi.The chemical treatments of these diseases are inefficient,cause environmental pollution and are increasingly restricted by international laws.This work aimed to assess the biocontrol capacity of a bacterial extract to protect avocado fruits and plants from pathogen infections.Extracts from the bacterial isolate Serratia sp.ARP5.1 were obtained from liquid fermentations in a biorreactor.A body rot postharvest infection model with Colletotrichum gloeosporioides on fruits was developed.Moreover,packaging conditions were simulated using the bacterial extract and the commercial fungicide prochloraz as a positive control.Additionally,seedlings infections with Phytophthora cinnamomi were performed on two types of avocado(West Indian race and cv.Hass).The Area Under Disease Progress Curve(AUDPC) was recorded using the bacterial extract and a commercial product with fosetyl-aluminium as treatments.The bacterial extract significantly reduced infections by C.gloeosporioides on injured avocado fruits at 31.1 μg mL^-1.Intact fruits were also protected against body rot infections at the same concentration and showed no significant differences with the commercial fungicide.On the other hand,AUDPC in the seedlings was significantly reduced with the extract treatment at 3 μg mL^-1 compared to the control.However,a possible phytotoxicity effect of the extract was evidenced in the seedlings and confirmed by pathogen recovery and tests on Raphanus sativus seedlings.Finally,formulations of the extracts(emulsion and emulsifiable concentrate) were prepared,and bioactive stability was assessed for 8 wk.The emulsion formulates demonstrated very stable bioactivity against P.cinnamomi.The extract and the emulsion formulate showed promising results for the control of avocado pathogens.New bioproducts based on this type of active principles could be developed for the benefit of avocado industry.展开更多
This study investigated the protective effects of secondary bacterial metabolites, produced by Pseudomonas sp. (bacterium strain LN), on citrus canker disease caused by Xanthomonas axonopodis pv. citri (Xac 306). The ...This study investigated the protective effects of secondary bacterial metabolites, produced by Pseudomonas sp. (bacterium strain LN), on citrus canker disease caused by Xanthomonas axonopodis pv. citri (Xac 306). The LN bacteria strain was cultured in liquid medium and the supernatant free-cells was treated with methanol (AMF) and ethyl acetate (AEF), respectively, and then the extract was concentrated, filtrated, lyophilized and fractionated by vacuum liquid chromatography (VLC). After VLC, eight fractions were obtained. All fractions’ activity against Xac 306 by agar well diffusion assay and minimum inhibitory concentration but in different concentrationswere tested. Cytotoxicity effects were observed in all fractions in 50 μg·mL-1 concentration. The comet assay demonstrated that the fractions EAF, VLC2 and VLC3 presented no genotoxic effects at tested concentrations. In plants only VLC3 showed significant results (p<0.05), reducing the incidence of citrus canker lesions.展开更多
This work evaluated the effect of secondary bacterial metabolites produced by Pseudomonas sp LV strain in control of Lactobacillus sp. population in the microcosm of the vat during ethanol fermentation. The fraction F...This work evaluated the effect of secondary bacterial metabolites produced by Pseudomonas sp LV strain in control of Lactobacillus sp. population in the microcosm of the vat during ethanol fermentation. The fraction F4 produced by Pseudomonas aeruginosa was extracted with dichloromethane and fractionating by vacuum liquid chromatography obtained in a methanol phase. The evaluation of antibiotic activity of F4 fraction mixed or not with sulphuric acid and Kamoram?. The antibiotic activity of F4 fraction was determined as well as the fermentation efficiency. Also was determined yeast cell viability, budding formation, the viability of budding cells, and number of populations of Saccharomyces cerevisiae and Lactobacillus sp. The results showed that the F4 fraction had high selective antibiotic activity against Lactobacillus sp. but not for S. cerevisae, and no inhibitory effect was observed in the fermentation process by yeast. Also F4 fraction decreased flocculation and foam formation. The F4 has an antibiotic activity against Lactobacillus sp. and should be used as an alternative to control bacteria contamination and foam and flocculation formation in the fuel ethanol fermentation process. The F4 fraction could reduce the use of antibiotics in the control of Lactobacillus sp. population during the fuel ethanol production.展开更多
Bacterial spot caused by Xanthomonas arboricola pv. pruni (Xap) is considered as a major problem in peach orchards. Copper and antibiotics are used to control, and biocontrol should be a new alternative with low envir...Bacterial spot caused by Xanthomonas arboricola pv. pruni (Xap) is considered as a major problem in peach orchards. Copper and antibiotics are used to control, and biocontrol should be a new alternative with low environment impact. The objective was evaluated by the antibiotic activity of the metabolite produced by Pseudomonas aeruginosa LV strain. The free cells supernatant was fractionated with a serial organic solvent with crescent polarity and a dichloromethane phase was concentrated and lyophilised, and after was fractionated using vacuum liquid chromatography. The antibiotic activity of the F3 fraction containing an organometallic compound was tested on Xap in vitro and in a greenhouse conditions. Plants were sprayed with F3 before or after Xap infection and the results showed changes in exopolysaccharides and cell morphology. The F3 concentration of 450 μg·mL-1 was more effective. The results showed that F3 fraction could be a new alternative to control bacterial spot.展开更多
基金the Faculty of Health Sciences from the Institution University Colegio Mayor de Antioquia and the General System of Royalties from Antioquia,Colombia,for funding this projectthe National University of Colombia and the Doctoral Fellowship Program(567)from Colciencias
文摘At least 20-40% of annual losses of avocado crops are caused by pathogenic fungi.The chemical treatments of these diseases are inefficient,cause environmental pollution and are increasingly restricted by international laws.This work aimed to assess the biocontrol capacity of a bacterial extract to protect avocado fruits and plants from pathogen infections.Extracts from the bacterial isolate Serratia sp.ARP5.1 were obtained from liquid fermentations in a biorreactor.A body rot postharvest infection model with Colletotrichum gloeosporioides on fruits was developed.Moreover,packaging conditions were simulated using the bacterial extract and the commercial fungicide prochloraz as a positive control.Additionally,seedlings infections with Phytophthora cinnamomi were performed on two types of avocado(West Indian race and cv.Hass).The Area Under Disease Progress Curve(AUDPC) was recorded using the bacterial extract and a commercial product with fosetyl-aluminium as treatments.The bacterial extract significantly reduced infections by C.gloeosporioides on injured avocado fruits at 31.1 μg mL^-1.Intact fruits were also protected against body rot infections at the same concentration and showed no significant differences with the commercial fungicide.On the other hand,AUDPC in the seedlings was significantly reduced with the extract treatment at 3 μg mL^-1 compared to the control.However,a possible phytotoxicity effect of the extract was evidenced in the seedlings and confirmed by pathogen recovery and tests on Raphanus sativus seedlings.Finally,formulations of the extracts(emulsion and emulsifiable concentrate) were prepared,and bioactive stability was assessed for 8 wk.The emulsion formulates demonstrated very stable bioactivity against P.cinnamomi.The extract and the emulsion formulate showed promising results for the control of avocado pathogens.New bioproducts based on this type of active principles could be developed for the benefit of avocado industry.
基金the National Council of Scientific and Technological Development(CNPq)who enabled the execution of this study by conceding PIBIC,M.Sc.,PhD and Productivity in research grants.
文摘This study investigated the protective effects of secondary bacterial metabolites, produced by Pseudomonas sp. (bacterium strain LN), on citrus canker disease caused by Xanthomonas axonopodis pv. citri (Xac 306). The LN bacteria strain was cultured in liquid medium and the supernatant free-cells was treated with methanol (AMF) and ethyl acetate (AEF), respectively, and then the extract was concentrated, filtrated, lyophilized and fractionated by vacuum liquid chromatography (VLC). After VLC, eight fractions were obtained. All fractions’ activity against Xac 306 by agar well diffusion assay and minimum inhibitory concentration but in different concentrationswere tested. Cytotoxicity effects were observed in all fractions in 50 μg·mL-1 concentration. The comet assay demonstrated that the fractions EAF, VLC2 and VLC3 presented no genotoxic effects at tested concentrations. In plants only VLC3 showed significant results (p<0.05), reducing the incidence of citrus canker lesions.
基金the National Council of Scientific and Technological Development(CNPq)who enabled the execution of this study by conceding PIBIC,MSc.,Ph.D and Productivity in research grants.
文摘This work evaluated the effect of secondary bacterial metabolites produced by Pseudomonas sp LV strain in control of Lactobacillus sp. population in the microcosm of the vat during ethanol fermentation. The fraction F4 produced by Pseudomonas aeruginosa was extracted with dichloromethane and fractionating by vacuum liquid chromatography obtained in a methanol phase. The evaluation of antibiotic activity of F4 fraction mixed or not with sulphuric acid and Kamoram?. The antibiotic activity of F4 fraction was determined as well as the fermentation efficiency. Also was determined yeast cell viability, budding formation, the viability of budding cells, and number of populations of Saccharomyces cerevisiae and Lactobacillus sp. The results showed that the F4 fraction had high selective antibiotic activity against Lactobacillus sp. but not for S. cerevisae, and no inhibitory effect was observed in the fermentation process by yeast. Also F4 fraction decreased flocculation and foam formation. The F4 has an antibiotic activity against Lactobacillus sp. and should be used as an alternative to control bacteria contamination and foam and flocculation formation in the fuel ethanol fermentation process. The F4 fraction could reduce the use of antibiotics in the control of Lactobacillus sp. population during the fuel ethanol production.
文摘Bacterial spot caused by Xanthomonas arboricola pv. pruni (Xap) is considered as a major problem in peach orchards. Copper and antibiotics are used to control, and biocontrol should be a new alternative with low environment impact. The objective was evaluated by the antibiotic activity of the metabolite produced by Pseudomonas aeruginosa LV strain. The free cells supernatant was fractionated with a serial organic solvent with crescent polarity and a dichloromethane phase was concentrated and lyophilised, and after was fractionated using vacuum liquid chromatography. The antibiotic activity of the F3 fraction containing an organometallic compound was tested on Xap in vitro and in a greenhouse conditions. Plants were sprayed with F3 before or after Xap infection and the results showed changes in exopolysaccharides and cell morphology. The F3 concentration of 450 μg·mL-1 was more effective. The results showed that F3 fraction could be a new alternative to control bacterial spot.