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 Tomato bacterial wilt and canker caused by Clavibacter michiganensis subsp. michiganensis (Cmm) is an economically important seed-borne disease in the major tomato growing regions all over the world. Also, this disease is present in northern, northwestern, and central provinces of Iran. This study aimed to isolate fluorescent pseudomonads with efficient antagonistic activity against Cmm from tomato rhizosphere and rhizoplane. In the present study, ninety six fluorescent pseudomonads were isolated from rhizosphere and rhizoplane of tomato plants using King’s medium B agar and tested for antagonistic activity against Cmm by co-inoculation culture in vitro. Seed and roots of tomato transplants were inoculated with representative antagonistic strains and planted in the soil infected by Cmm in greenhouse. The incidence and severity of the disease were assessed on tomato as well as growth parameters. Nineteen strains exhibited inhibitory activity against Cmm in vitro and two selected strains (M1R1 and H1R1) were identified as Pseudomonas putida based on their phenotypic characteristics and partial 16S rRNA gene sequences. These two strains produced siderophore and hydrogen cyanide. In greenhouse, strain M1R1 reduced the disease incidence by 30% and 40% in Superluna and Falat cultivars, respectively. Strain H1R1 reduced the disease incidence by 20% only in Falat cultivar. Strains M1R1 and H1R1 decreased the disease severity by 52.93 % and 10.60 % in Superluna and 47.90 % and 42.88 % in Falat cultivars, respectively. Strain M1R1 increased the growth parameters, including fresh and dry weight, and height of the inoculated plants significantly in comparison with control. These results indicated that rhizospheric fluorescent pseudomonads could be effective agents in the biocontrol of tomato bacterial wilt and canker disease.
 

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  The aim of this work was identified lactic floraas a traditional fermented food and then evaluates antimicrobial activities of some strains. A total of 140 Gram-positive and catalase-negative isolates were subjected to grouping by physiological and biochemical tests and carbohydrates fermentation. Based on the resultsthese 140 isolateswere dividedinto 9 groups. Two or three isolated were selected from each group and 16S rRNA was amplified using universal primers. Diversity of lactic acid bacteria in horreh was as followings:Lactobacillus fermentum (30.00%),Lactobacillus plantarum (28.57%), Lactobacillus brevis (15.00%), Weissellacibaria(8.57%),Enterococcus (faecium and faecalis) (7.14 %), Leuconostoc (citreumand mesenteroides subsp.Mesenteroides) (6.42%) and Pediococcus pentosaceus (4.28%). Antagonistic activity of 20 isolates (strains) of lactic acid bacteriaobtained fromhorreh was evaluated against food- borne bacteria. Sixteen isolates in Agar spot method and 14 isolates in well diffusion assayshowed antibacterial activity against at least one of these indicators. Eight isolates including:Ent. faecium (1), Ent. faecalis (1), P. pentosaceus(1) and Lb. plantarum (2) exhibited  the  highest  antagonistic  activity toward Listeria innocoa. Antagonistic activity of cell free supernatant (CFS) from Lb. plantarum showed the highest thermal stability. Also, two isolates belonging to:Ent. faecium, Ent. Faecalis presented antibacterial activity at pH=7. Only, the supernatant of Lb. plantarum was not influenced by proteinase K.The results showed that the supernatant of some isolatestestedcan be used as a bio preservative in food products.

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 Seventy five bacterial strains were isolated from cucurbits rhizosphere and examined for antagonistic activities against Macrophomina phaseolina isolate 44, the causal agent of melon charcoal root rot disease. The results of screening strains including B2, B11, B12 and BKN showed high potential of antagonistic activities against the pathogen in laboratory experiments. Inhibition of mycelial growth varied from 54.3 to 62.22%, 39.43 to 54.82%, 78.52 to 100%, and 64.45 to 88.89% in dual culture, volatile metabolite, antibiotic production, and cell free culture tests, respectively. In greenhouse experiment, seed treatment with strain B2 significantly (P= 0.01) controlled the disease by increasing plant growth indices including height, shoot and root fresh weight, shoot and root dry weight by 37.98, 36.27, 32.97, 34.44, and 30.39%, respectively, as compared to the control. The biochemical and physiological tests as well as gyrA sequence confirmed these four strains as Bacillus amyloliquefaciens. Results indicated that strain B2 could be an important new biological control agent for charcoal root rot disease of melon.