Isolation, screening and molecular identification of antagonistic bacteria against Colletotrichum gloeosporioides in mango

Abstract

The study was conducted at the Postharvest and plant Biotechnology laboratory, Department of Horticulture, Patuakhali Science and Technology University, Patuakhali, Bangladesh during the period from January to July 2017 to isolate, screening and molecular identification of antagonistic bacteria against anthracnose of mango. All treatments were arranged in a completely randomized design (CRD) with replications and repeated twice. Epiphytic bacteria, isolated from leaf and fruit surfaces of mango, were tested as biocontrol agent against anthracnose disease caused by Colletotrichum gloeosporioides wherein 20 strains were confirmed as antagonistic. Molecular characterization of the three potential strains of bacteria were done by the amplification of 16S rDNA gene following the extraction of genomic DNA, polymerase chain reaction (PCR) amplification, gel electrophoresis and gel documentation. The PCR amplified products and the genomic DNA samples were sent to the Macrogen Company through Sunchon National University, Seoul, South Korea for molecular identification by sequence analysis. Among the 20 antagonistic bacteria screened in vitro by dual and concomitant tests, two isolates, namely GB6 (PSTU-Hort-8), and GB19 (PSTU-Hort-14) were recognized as antagonistics to the test fungus. Using the molecular identification systems, isolated bacterial strains PSTU-Hort-8 was identified as B. subtilis with National Center for Biotechnology Information (NCBI) accession numbers MW659188; on the other hand, strain PSTU-Hort-14 was identified as Stenotrophomonas rhizophila with NCBI accession number MW659190.