Colonization of the Biocontrol Bacterial Strain DJB5 against Aspergillus flavus in Maize Grains

PurposeTo understand the colonization of the biocontrol bacterial strain DJB5 in maize grains and its regularities.

MethodPlasmid pHT01-P43GFPmut3a was transformed into DJB5 cells for fluorescence tagging by natural transformation. The stability of plasmid, growth tendency and biofilm-forming ability of DJB5-GFP were tested, and the control efficiency difference between DJB5 and DJB5-GFP strains was analyzed using plate antagonism bio-assay and grain storage experiment.

ResultPlasmid pHT01-P43GFPmut3a could keep stable, and its introduction had no significant negative load on DJB5 growth and biocontrol activity. The storage experiment showed that under different grain moisture contents and storage temperatures, the number of DJB5-GFP increased with the increase of grain moisture contents and was as high as 10⁷ CFU/g (orders of magnitude) at the grain moisture content of 30%; colonization was greater at storage temperature ranging from 28 ℃ to 35 ℃ than that below 28 ℃ and above 35 ℃. The result indicated that DJB5 had the potential for controlling Aspergillus flavus on maize grains during post-harvest storage.