Epiphytic Bacteria from Sweet Pepper Antagonistic In Vitro to Ralstonia solanacearum BD 261, a Causative Agent of Bacterial Wilt

Microorganisms

Martin Makgose Maboko¹  Casper Nyaradzai Kamutando²  Olubukola Oluranti Babalola³  Olayinka Ayobami Aiyegoro⁴  Tshifhiwa Paris Mamphogoro⁴ 

[1] Crop Science Unit, Agriculture Research Council—Vegetable and Ornamental Plants, Private Bag X293, Roodeplaat, Pretoria 0001, South Africa;Department of Plant Production Sciences and Technologies, University of Zimbabwe, P.O. Box MP167, Mount Pleasant, Harare 0263, Zimbabwe;Food Security and Safety Niche Area, Faculty of Natural and Agricultural Sciences, North-West University, Private Bag X2046, Mmabatho 2735, South Africa;Gastro-Intestinal Microbiology and Biotechnology Unit, Agriculture Research Council-Animal Production, Private Bag X02, Irene, Pretoria 0062, South Africa;

关键词: antagonists;    biological control;    epiphytes;    sweet pepper;    16S rRNA genes;    Ralstonia solanacearum;   

DOI  :  10.3390/microorganisms9091947

来源: DOAJ

【 摘 要 】

Biological control of plant pathogens, particularly using microbial antagonists, is posited as the most effective, environmentally-safe, and sustainable strategy to manage plant diseases. However, the roles of antagonists in controlling bacterial wilt, a disease caused by the most devastating and widely distributed pathogen of sweet peppers (i.e., R. solanacearum), are poorly understood. Here, amplicon sequencing and several microbial function assays were used to depict the identities and the potential antagonistic functions of bacteria isolated from 80 red and green sweet pepper fruit samples, grown under hydroponic and open soil conditions, with some plants, fungicide-treated while others were untreated. Amplicon sequencing revealed the following bacterial strains: Bacillus cereus strain HRT7.7, Enterobacter hormaechei strain SRU4.4, Paenibacillus polymyxa strain SRT9.1, and Serratia marcescens strain SGT5.3, as potential antagonists of R. solanacearum. Optimization studies with different carbon and nitrogen sources revealed that maximum inhibition of the pathogen was produced at 3% (w/v) starch and 2,5% (w/v) tryptone at pH 7 and 30 °C. The mode of action exhibited by the antagonistic isolates includes the production of lytic enzymes (i.e., cellulase and protease enzymes) and siderophores, as well as solubilization of phosphate. Overall, the results demonstrated that the maximum antimicrobial activity of bacterial antagonists could only be achieved under specific environmental conditions (e.g., available carbon and nitrogen sources, pH, and temperature levels), and that bacterial antagonists can also indirectly promote crop growth and development through nutrient cycling and siderophore production.

【 授权许可】

Unknown