The phosphotransferase system gene ptsI in the endophytic bacterium Bacillus cereus is required for biofilm formation, colonization, and biocontrol against wheat sharp eyespot.

ABSTRACT

Natural resistance of wheat plants to wheat sharp eyespot is inadequate, and new strategies for controlling the disease are required. Biological control is an alternative and attractive way of reducing the use of chemicals in agriculture. In this study, we investigated the biocontrol properties of endophytic bacterium Bacillus cereus strain 0-9, which was isolated from the root systems of healthy wheat varieties. The phosphotransferase system is a major regulator of carbohydrate metabolism in bacteria. Enzyme I is one of the protein components of this system. Specific disruption and complementation of the enzyme I-coding gene ptsI from B. cereus was achieved through homologous recombination. Disruption of ptsI in B. cereus caused a 70% reduction in biofilm formation, a 30.4% decrease in biocontrol efficacy, and a 1000-fold reduction in colonization. The growth of ΔptsI mutant strain on G-tris synthetic medium containing glucose as the exclusive carbon source was also reduced. Wild-type properties could be restored to the ΔptsI mutant strain by ptsI complementation. These results suggested that ptsI may be one of the key genes involved in biofilm formation, colonization, and biocontrol of B. cereus and that B. cereus wild-type strain 0-9 may be an ideal biocontrol agent for controlling wheat sharp eyespot.