Inhibitory Effect and Morphological Changes by Organic Acids to Bacterial Strains Causing Sugar Beet Soft Root Rot In Vitro

Abdalla, M. E.; Seadh, S. E.; Hamza, S.

doi:10.21608/jppp.2019.40925

Inhibitory Effect and Morphological Changes by Organic Acids to Bacterial Strains Causing Sugar Beet Soft Root Rot In Vitro

Document Type : Original Article

Authors

¹ Plant Pathology Dept., Faculty of Agriculture, Mansoura University

² Plant Pathology Dept., Faculty of Agriculture, Mansoura University.

10.21608/jppp.2019.40925

Abstract

Sugar beet affected by soft rot bacteria and causes great loses in yield. Organic acids are known for their antibacterial and antifungal properties. Three strains of soft rot bacteria, Erwinia carotovora subsp. carotovora (Ecc), Erwinia carotovora subsp. betavasculorum (Ecb) and Burkholderia cepacia (Bc) were treated with acetic, ascorbic and citric acids with concentrations (1.0, 2.5 and 5%) and control was used SDW and antibiotic (Streptomycin 0.015%). The (MIC)of acetic acid for Ecc, Ecb and Bc was determined at concentrations ranging (0.25, 0.35, 0.50, 0.75, 0.80 and 0.90 % V/V); controls were maintained with sterilized water and antibiotic (Streptomycin 0.015%). Determination of inhibitory effect to acetic acid on Ecc by culturing it in NA broth medium to mid-log phase and bacterial suspension (10⁸cfu/ml) was prepared. The cell suspension was incubated at 37^oC for 60 min with acetic acid at a concentration of MIC (0.90 %) then observed using a scanning electron microscope. The organic acid, acetic acid, had highest efficacy in inhibiting the growth of Ecc, Ecb and Bc at concentration 5% with inhibition zone 23 mm. The MIC of acetic acid on Ecc, Ecb and Bc was 0.90 %V/V showed the highest antibacterial activity against bacterial strains, while concentrate 0.25% revealed the lowest inhibitory effect. The cells treated with acetic acid became swell and enlarged in size then explode and smallest, surface roughening and corrugating compared with the control.

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