1,720,986 research outputs found
Efficacy of cell free supernatant from Bacillus subtilis ET-1, an Iturin A producer strain, on biocontrol of green and gray mold
No full textThe present study deals with the control of two important postharvest fruit diseases by application of the supernatant obtained from Bacillus subtilis strains ET-1. The bacteria, B. subtilis was grown in a bench-scale bioreactor and a cell free supernatant (CFS) rich in Iturin A was produced. During the entire bacterial culture time, it has been observed that Iturin A production started at the end of the exponential growth phase and a maximum concentration of 422 mg L−1 was observed after 57 h. CFS was then used to evaluate, both in vitro and in vivo, for its antifungal activity against P. digitatum and B. cinerea the agents responsible for the green and gray mold, respectively. Concerning in vitro studies, it has been observed that the antifungal activity of CFS was correlated to Iturin A concentration. The minimum concentration of Iturin A within CFS, necessary to inhibit P. digitatum and B. cinerea, was 6.60 and 3.30 mg L−1, respectively. The application of CFS on lemon and strawberry fruit artificially inoculated with P. digitatum and B. cinerea proved to be highly effective in the control of rot diseases. Compared to the positive control, in the CFS treated trials a significant decrease of disease incidence (up to 68.6% and 74.1%, in lemon and strawberry respectively) was recorded. It is also important to emphasize that the CFS treatment has drastically prevented the expansion of the fungal mycelium on the diseased fruits. The strong antifungal activity together with its already known characteristics related to high biodegradability and low toxicity, suggest that Iturin A could be a successful alternative to synthetic fungicide usage in postharvest disease control. However, it is important to do further research on large scale basis to evaluate the Iturin A production and extraction by B. subtilis ET-1 in order to study the possible formulations for its ideal application. © 2017 Elsevier B.V
Bioethanol and biomethane potential production of thirteen pluri-annual herbaceous species
No full textThe research aimed to study and characterize, in a four-year study, thirteen pluri-annual herbaceous species for their potential bioethanol and biomethane production. The highest biomass yield was obtained with Arundo donax followed by Miscanthus x giganteus. Biomass cellulose content had median values ranging from 23.1% (Symphytum x uplandicum) to 45.4% (Lythrum salicaria), hemicellulose from 9.4% (Iris pseudacorus) to 36.8% (Glyceria maxima) and lignin from 2.6% (G. maxima) to 14.5% (Helianthus tuberosus and L. salicaria). The best ethanol and methane median yields were achieved by A. donax (3.5 Mg ha−1 and 8227 m3 ha−1, respectively) followed by M. x giganteus (3.2 Mg ha−1 and 4446 m3 ha−1, respectively). Methane transformation showed a higher energy output than ethanol with values ranging from 1 GJ ha−1 (Phalaris arundinacea) to 508 GJ ha−1 (A. donax) and from 1 GJ ha−1 (P. arundinacea) to 624 GJ ha−1 (A. donax) for ethanol and methane, respectively. Results showed that A. donax and M. x giganteus are the most interesting species for bioethanol and biomethane production. © 2018 Elsevier B.V
Arundo donax refining to second generation bioethanol and furfural
Full text linkBiomass-derived sugars are platform molecules that can be converted into a variety of final products. Non-food, lignocellulosic feedstocks, such as agroforest residues and low inputs, high yield crops, are attractive bioresources for the production of second-generation sugars. Biorefining schemes based on the use of versatile technologies that operate at mild conditions contribute to the sustainability of the bio-based products. The present work describes the conversion of giant reed (Arundo donax), a non-food crop, to ethanol and furfural (FA). A sulphuric-acid-catalyzed steam explosion was used for the biomass pretreatment and fractionation. A hybrid process was optimized for the hydrolysis and fermentation (HSSF) of C6 sugars at high gravity conditions consisting of a biomass pre-liquefaction followed by simultaneous saccharification and fermentation with a step-wise temperature program and multiple inoculations. Hemicellulose derived xylose was dehydrated to furfural on the solid acid catalyst in biphasic media irradiated by microwave energy. The results indicate that the optimized HSSF process produced ethanol titers in the range 43–51 g/L depending on the enzymatic dosage, about 13–21 g/L higher than unoptimized conditions. An optimal liquefaction time before saccharification and fermentation tests (SSF) was 10 h by using 34 filter paper unit (FPU)/g glucan of Cellic® CTec3. C5 streams yielded 33.5% FA of the theoretical value after 10 min of microwave heating at 157◦ C and a catalyst concentration of 14 meq per g of xylose
Influence of Phenotypic Dissociation in Bacillus subtilis Strain ET-1 on Iturin A Production
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Occurrence and inheritance of resistance to Fusarium oxysporum f. sp. melonis in local germplasm of Cucumis melo
No full textEssential oil of Calamintha nepeta (L.) Savi subsp. nepeta is a potential control agent for some postharvest fruit diseases
No full textThe antifungal activity of essential oil from Calamintha nepeta (L.) Savi subspecies nepeta was investigated against some destructive fungal pathogens of postharvest fruit. A preliminary in vitro assay was used to assess the inhibitory effect using vapour contact and direct contact of the essential oil against Botrytis cinerea, Penicillium digitatum, Monilia laxa and Penicillium italicum. Both methods demonstrated that the essential oil was effective against all the fungal species tested in a dose-dependent manner, although the antifungal activity was more potent with the vapour contact test. Additional in vivo tests confirmed the efficacy of the vapour phase of the essential oil against P. digitatum and M. laxa on clementine and plum fruit, respectively. Total control of both brown rot and green mould was achieved on artificially inoculated fruit at doses of 133.3 μL L. Furthermore, excellent control efficacy, similar to that obtained with conventional fungicides, was achieved at a dose of 66.6 μL L. Chemical analysis of the essential oil by gas chromatography-mass spectrometry showed that pulegone (44.7%), menthone (16.4%), piperitenone (13.3%) and piperitone (6.01%) were the major constituents. These results suggest that the essential oil of C. nepeta subsp. nepeta has the potential to be used by vapour diffusion as an alternative biocontrol agent to conventional fungicides for postharvest management. However, it is important to do further research to validate these results under conditions that mimic commercial facilities and to optimise the application of essential oil vapours
Effect of powdery mildew on yield of susceptible and resistant tomatoes under greenhouse conditions
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