Lactococcus lactis subsp. lactis as a biocontrol agent against phytopathogens causing rice bacterial leaf blight

Area of Science:

• Agricultural Microbiology
• Plant Pathology
• Biotechnology

Background:

• Bacterial leaf blight (BLB) causes significant rice yield losses globally.
• Chemical controls for BLB pose environmental and health risks.
• Lactic acid bacteria (LAB) offer a sustainable alternative for crop protection.

Purpose of the Study:

• To investigate the antimicrobial efficacy of Lactococcus lactis subsp. lactis (RBX7) against BLB pathogens.
• To identify antimicrobial compounds produced by RBX7.
• To evaluate RBX7 as a biocontrol agent for rice BLB.

Main Methods:

• Agar well diffusion, time-kill assays, and detached leaf assays were used to assess antimicrobial activity.
• Scanning electron microscopy (SEM) visualized pathogen cell damage.
• Metabolomic profiling (LC-MS/MS-QTOF) identified antimicrobial compounds.
• In planta experiments confirmed efficacy in rice seedlings.

Main Results:

• RBX7 cell-free supernatant (CFS) and live culture inhibited Xoo and Pan growth.
• SEM revealed pathogen cell rupture and shrinkage upon RBX7 treatment.
• Metabolomic analysis identified cefixime, cinchonidine, antimycin A, and bufalin as potential antimicrobial agents.
• In planta assays demonstrated significant suppression of BLB symptoms.

Conclusions:

• Lactococcus lactis subsp. lactis (RBX7) exhibits potent antimicrobial activity against rice BLB pathogens.
• RBX7 represents a safe and sustainable biocontrol strategy for managing BLB.
• This research supports the use of LAB in sustainable agriculture and achieving development goals.