The colonization of Bacillus thuringiensis strains in bryophytes

Abstract

In our previous study, several Bacillus thuringiensis (Bt) strains were isolated from bryophyte samples, indicating that bryophytes could serve as Bt reservoirs in the wild. SFR13 is a wild strain isolated from the bryophyta Physcomitrium japonicum. In order to understand its ecological properties, green fluorescent protein (GFP)-labelled SFR13 (SFR13GFP) was generated to evaluate the colonization capability in bryophytes, using dynamic tracing and cell counting to observe the process and patterns of colonization. Our results showed that genetic stability, growth curve dynamics, and insecticidal crystal production were not affected by GFP expression in Bt. Fluorescence microscopy was used to track the dynamic distribution of SFR13GFP. Distribution patterns showed that SFR13GFP can establish stable and long-term colonization in leaves and stems by the 26th day after inoculation. A better understanding of how Bt colonizes plants in the wild will not only result in increased knowledge of plant–microbe interactions but will also lead to a more successful and reliable use of bacterial inoculants.