Bacteriophage As a Promising Biocontrol Agent for Pectobacterium Carotovorum, Inciting Potato Soft Rot Disease

Document Type : Original Article

Authors

1 Biology Department, Faculty of Education, Ain Shams Univ., Egypt.

2 Microbiol. Department Faculty of Agriculture, Ain Shams Univ., Egypt.

3 plant pathology dep,Fac.Of,Agriclutre,Benha Unv.

Abstract

Pectobacterium carotovorum subsp < em>. carotovorum (Pcc)is the main causative of soft rot disease in a vast variety of vegetables and crops worldwide. Currently, phage therapy used to be a safe biological opportunity for manipulating plant bacterial infections. Hence, this study was designed to isolate and identify Pcc isolates and their specific phages. Twenty Pcc isolates were isolated from diseased potato roots and soil cultivated with various crops. Pcc isolates were identifiedbased on morphological and biochemical characteristics. Pathogenicity studies revealed that healthy potato tubers were responsive to soft rotted Pectobacterium. Twenty-three specific bacteriophages for isolated Pcc were isolated from infected potato tubers, soil and sewage and drainage water samples and then, identified via spot and plaque assay techniques. The phages confirmed various morphological plaques ranging from 1.0 to 5.0 mm in diameter, then purified for establishing the morphological properties using TEM and genetic variability using restriction enzyme pattern. The obtained phages have the ability to prevent biofilm formation of Pcc isolates with percentages of 98.5, 81.0, 81.6 and 97.0 for Pcc1, Pcc2, Pcc3 and Pcc4, respectively. Applying of phages cocktail on potato tubers caused a reduction in soft rot indications and disease severity by about 7.0, 15.0, 17.5 and 15.0%. Nevertheless, the short longevity of phages on host plants is considered one of the obstacles to their application. So, some phages formulations were prepared to increase their longevity, among them the formula containing phages, corn flour (0.5%) and sucrose (5%) (v/w) was the most efficient one for improving phage longevity at room temperature and decreased the disease severity to 5.0, 10.0, 15.0 and 13.0% for Pcc1, Pcc2, Pcc3 and Pcc4, respectively compared to Pcc isolates on potato tubers.

Keywords