Faba bean (Vicia fabae L.) is one of the most economic legume crops in Egypt. The antifungal effects of different concentrations of Chitosan and silver nanoparticles (20 ppm, 40 ppm, 60 ppm, 80 ppm and 100 ppm) were studied against aggressive isolates of Botrytis fabae and Alternaria alternata causing chocolate spot disease and Alternaria leaf spot disease respectively. Under laboratory conditions, the application of five concentrations of Chitosan nanoparticles and silver nanoparticles to the cultures of B. fabae and A. alternata showed significant inhibition of mycelial growth. Number of spores/ml decreased with increasing of nanoparticle concentration. Mycelial weight of fungal pathogens also decreased. The lesion growth was suppressed by increasing in the concentration of nanoparticles with significantly different relative to control using detached leaf test. Under greenhouse conditions, chitosan and silver nanoparticles were sprayed in concentrations 60 ppm, 80 ppm, and 100 ppm on faba bean plants. The tested nanoparticles showed significant effect against B. fabae and A. alternata relative to control. The obtained results indicated that the highest reduction of chocolate spot severity was obtained with treatment by 100 ppm of silver nanoparticles (52.94%) followed by chitosan nanoparticles 80 ppm (50.59%). While the application of 100 ppm of chitosan nanoparticles was highly efficient against Alternaria leaf spot where the reduction in disease severity (67.13%) followed by 100 ppm silver nanoparticles which caused reduction rate (61.5%). The obtained results indicated the possibility of using chitosan and silver nanoparticles as a substance in the manufacturing of fungicides to minimize the impact of chocolate spot and Alternaria leaf spot diseases in faba bean. However, further experimental trials under field conditions and safety evaluation studies are needed before the nanoparticles types and concentrations can be used as potential antifungal agents.

Brown leaf spot is one of the prevalent diseases caused by Alternaria alternata in different growing areas of potato worldwide. Eight A. alternata isolates were screened from forty-two isolates collected from different potato growing regions in four Egyptian governorates viz, North Sinai (Baloza), Beheira (El-Nubaria and Wadi El-Natrun), Ismailia (Abu Suweir, Fayed and Tell El-Kebir), Sharqia (New Salheya and El-Husseiniya). The virulence of the isolates was tested based on the Per cent of Disease Index (PDI) which ranged from 28.2% to 70.3% PDI by Alternaria isolates of Baloza and Fayed respectively. Two bacterial strains "Brevibacillus formosus strain DSM 9885, and Brevibacillus brevis strain NBRC 15304 were selected to control of A. alternata. The bacterial strains have a higher inhibitory effect on mycelial development and spore germination of A. alternata. To determine the effects of the bacterial strains on disease index and severity, the most virulent of A. alternata isolates were selected for greenhouse experiments where the potato plants were sprayed with bacterial strains individually and mixture treatments. Superior effect of treatments in disease reduction was observed when the two bacterial strains were combined. The effect of leaf age was studied where the leaf position has significant effect on disease progress. The changes of soluble protein in potato leaves due to Brevibacillus strains application were studied. Protein profiling by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) revealed that the plant treated with mixture of biocontrol agents able to synthesize some new proteins with maximum number of bands followed by treatment by B. formosus strain. The presence or absence of the bands in protein profiling might be responsible for resistance response against A. alternata in potato. The present work suggests that use of B. formosus strain DSM 9885, and B. brevis strain NBRC 15304 could be considered as potential management tools for reducing the impact of A. alternata causing brown leaf spot disease on potato.

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The genus Bacillus and related genera are distributed vastly in nature and contain thermophilic, psychrophilic, alkalophilic, acidophilic, and halophilic bacteria that utilize a wide range of carbon sources for autotrophs or heterotrophic growth. A lot of bioactive metabolites have been detected, as bioactive compounds produced by biocontrol agents such as the bacterial genus of Brevibacillus. In this review, we summarize the general characteristics and properties of the Brevibacillus genus as biocontrol agents, taxonomy, phylogeny, identification and the impact of Brevibacillus as a biological control agent of plant disease combat and soil bioremediation.