Bacillus thuringiensis: a natural endophytic bacterium found in wild plants

Area of Science:

• Microbial Ecology
• Bacteriology
• Biological Pest Control

Background:

• Bacillus thuringiensis is widely used in biological pest control.
• Its natural habitat and ecological role remain poorly understood.
• Research is needed to define its niche beyond agricultural applications.

Purpose of the Study:

• To investigate the endophytic nature of Bacillus thuringiensis in wild plants.
• To isolate and characterize wild-type Bacillus thuringiensis strains from plant tissues.
• To determine the ecological role and potential insecticidal activity of endophytic strains.

Main Methods:

• Surface sterilization of plant leaves from 110 wild plant species.
• Isolation and culturing of endophytic microflora.
• Identification and characterization using 16S rRNA, hag, MLST, cry gene sequencing, Bc-RepPCR, and protein analysis.

Main Results:

• 22 isolates exhibited Bacillus thuringiensis morphology; 10 were confirmed as Bacillus thuringiensis sensu stricto.
• Identified subspecies included kurstaki, nigeriensis, and thuringiensis.
• Limited toxicity observed against mosquito larvae, Caenorhabditis elegans, and Manduca sexta.

Conclusions:

• Bacillus thuringiensis can naturally exist as an endophytic bacterium within wild plants.
• Endophytic strains may have a different ecological role and reduced insecticidal activity.
• Further research is required to elucidate the ecological significance of endophytic Bacillus thuringiensis.