Morphological, biochemical and molecular identification of rhizobacteria isolates with potential for biocontrol of fungal plant pathogens

Abstract

Rhizobacteria have huge potential for biocontrol activity against many plant pathogens. Isolation and identification are therefore crucial to understand their microbial diversity and ecological importance. The study sought to identify eight yam (Dioscorea sp.) rhizobacterial isolates found to be inhibitory in a previous study to several fungal pathogens, using polyphasic approach (morphological, biochemical, and molecular approaches). Morphological and biochemical characterizations were carried out at the Noguchi Memorial Institute for Medical Research (NMIMR), Legon-Accra, Ghana while the Molecular characterization was done at Functional Biosciences Inc., Wisconsin, USA. Morphological and biochemical characters determined were texture, consistency, the morphology of cell growth on nutrient agar, citrate utilization, catalase reaction, Gram reaction, and endospore formation. Molecular identification was achieved through the amplification and sequencing of the 16SrRNA and gyrB regions of the eight rhizobacterial genomic DNA followed by BLAST analysis. Sequencing data were also deposited at GenBank to obtain accession numbers for the rhizobacteria. All the eight bacterial isolates were shown to possess rod-shaped bacilli cells, Gram-positive, and were endospore producers. The amplification of the 16SrRNA and the gyrB regions of the bacterial DNA and subsequent BLAST of these two regions revealed that they were all members of the Bacillus subtilis group at percentage similarity between 99-100%. Four out of the eight isolates were, Bacillus subtilis, three were B. amyloliquefaciens and the last, B. velezensis. Sequence data of both the 16SrRNA and gyrB deposited at the GenBank provided GenBank accession numbers for nucleotide sequence of 16SrRNA as GenBank MT535846-MT535853 and gyrB as GenBank MT908225-MT908232 respectively. This is the first attempt to identify these rhizobacteria, which have huge potential as fungal antagonists of many plant pathogens in Ghana. � 2021 Informa UK Limited, trading as Taylor & Francis Group.