Detection of antibiotic resistant genes in cherry tomato entophytic bacteria and transfer of GFP marked bacteria in plantation model

Objective  To investigate the prevalence of antibiotic resistant genes of endophytic bacteria in cherry tomatoes sold in Guangzhou, and discuss the possibilities of resistant genes transferring into cherry tomatoes based on GFP-tagged Escherichia coli artificial plantation model.

Method  The endophytic bacteria in commercially available cherry tomatoes was identified by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). Polymerase chain reaction was used to qualitatively detect the prevalence of resistant genes including chloromycetin (cmlA), tetracycline (tetA and tetM), sulfonamide (sul1, sul2 and sul3) and quinolones (oqxA, oqxB, qnrB, qnrS and qepA). The GFP-tagged E. coli artificial plantation model was used to detect target GFP-bacteria in cherry tomato fruits, leaves and roots, and explore the possibilities of entophytic bacteria and GFP tag transferring into cherry tomatoes.

Result  Enterobacter and Klebsiella accounted for a relatively high proportion in 52 endophytic bacterial strains, and almost all strains carried oqxB gene with a total positive rate of 92.31%. The endophytic bacterial strain containing GFP tag was isolated from the fruit collected on the 27th day in artificial plantation model.

Conclusion  oqxB gene is most prevalent in cherry tomato endophytic bacteria. The antibiotic resistant genes can transfer into cherry tomato fruits through root irrigation.