Article Info Received : 08.12.2015 Accepted : 20.01.2016 The aim of this work is to study the ability of several isolates belonging to Rhizobacteria (Pseudomonas and Bacillus) collected from several chickpea growing areas in Algeria, to control the mycelium growth of Fusarium oxysporum f. sp. ciceris. Interesting isolates were characterized for their morphological characteristics, physiological and biochemical activities as potential bio-control agent. Fungal inhibition tests were performed using plate assay and each isolate were tested for the production of protease, cyanide hydrogen, indole acetic acid, antifungal volatile and extracellular compound. According to API 50 CH, we are able to identify six Bacillus species (B. subtilis, B. circulans, B. lentus, B. aneurinilyticus, B. firmus, B. licheniformis; and with API 20NE test we have identified three Pseudomonas species (P. aeruginosa, P. luteola, P. fluorescens). The ability of bacterial isolates was varied in production of Protease, Gelatinase, Amylase, Cellulase, Acid Indole acetic, Lipase, Catalase and Cyanid Hydrogen. This is traduced in different rate of inhibition growth due to various extracellular compounds, where B61 (Bacillus aneurinilyticus) and P39 (Pseudomonas luteola) and P70 (Pseudomonas fluorescens) were the most efficient with 77 and 55.5% respectively, while B39 (Bacillus firmus) and P41 (Pseudomonas luteola) were the most efficient by volatile compounds with 70.5 and 77.5% respectively. Our results indicate that these bacteria isolates can be used in the biocontrol of Fusarium oxysporum f. sp. ciceris.

This study aimed to isolate rhizobacteria belonging to the genus Pseudomonas with plant-growth-promoting properties that can be used in the control of chickpea wilt disease caused by Fusarium oxysporum f. sp. ciceris (Foc). The production of antifungal compounds by the isolated rhizobacteria was assessed against two Foc isolates, coded Foc-S1 and Foc-S2. Strains E1FP13, E1FP4, and E1PP7 were the most effective against Foc-S1, with percentages of 52.77%, 48.37%, and 47.97%, respectively, while E1PP6, E1FP13, and E1PP15 were the most effective against Foc-S2 with percentages of 52.20%, 52.09%, and 45.38%, respectively. All five isolates were identified as Pseudomonas species using 16S rRNA sequencing. The microscopic examination of the impact of the Pseudomonas strains on Foc revealed that all five strains caused morphological changes in Foc, such as granulation and condensation of the cytoplasm, fragmentation, and deformation of the hyphae. The strains produced several plant-growth-promoting compounds, such as cellulase, hydrogen cyanide, indole acetic acid, ammonia, siderophores, lipase, protease, and solubilized phosphate. They were also able to significantly increase chickpea growth and reduce wilt disease, with E1FP13 resulting in the highest disease reductions of 55.77% (Foc-S1) and 53.33% (Foc-S2). The results revealed that our isolates can make promising biocontrol agents for controlling chickpea wilt disease.

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Fusarium head blight is an important disease of durum wheat which requires several fungicide treatments of seeds to achieve satisfactory control. The current study was carried out to evaluate commercially available fungicides in vitro for their efficacy against eighteen Fusarium spp. isolates collected from different fields in the north-eastern part of Algeria. The morphological and molecular characterization reveals the presence in wheat seeds of the main species complexes F. acuminatum, F. equiseti, F. avenaceum, F. solani, F. culomorum, F. incarnatum-equiseti, as well as F. tricinctum species complex and F. chlamydosporum species complex. Antifungal activity of fungicides shows that all triazoles tested have proven their effectiveness in inhibiting the mycelial growth of various strains of Fusarium tested. However, their sensitivity varies between them significantly (p<0.05) depending on the dose applied and period of exposure to each fungicide. The results showed that tebuconazole (Raxil and T?buzole) and the combination fludioxonil + difenoconazole greatly reduced the mycelial growth of Fusarium isolates by 84.31%, 82.94%, 81.33%, respectively, as compared to difenoconazole alone (73.16%) at the recommended dose after five days of exposure. Regarding their effect on conidia germination, tebuconazole was more effective than fludioxonil + difenoconazole, which leads to deformation of cell wall structure and fragmentation of conidia. These results will provide useful information to select suitable fungicides for seed treatment and management of wheat head blight disease.

The present work was carried out to enhance biomass production of Spirulina (Arthrospira platensis Gomont) in a modified medium and to investigate “in vitro” its ability to produce antimicrobial substances against pathogenic bacteria and phytopathogenic fungi. The antibacterial activity was evaluated by the solid medium diffusion method on two pathogenic bacteria (Bacillus cereus & Klebsiella sp.), And the antifungal activity was evaluated on three phytopathogenic fungi (Alternaria solani, Cladosporium sp., Fusarium culmorum). The antibacterial test showed that the aqueous extract produced by S. platensis was more active against Gram-positive than on Gram-negative bacteria, the highest antibacterial activity was recorded against Bacillus cereus. Moreover, the Antifungal test showed that the aqueous extract was active against all three tested fungi and the highest antifungal activity was recorded against F. culmorum with over 90% inhibition of mycelial growth. The results of this research proved that cyanobacteria could be a good source for the production of antimicrobial agents which could be effective when compared with contemporary antimicrobial compounds and it can be used in the Biocontrol of several plant fungal diseases.