Design of a biodegradable carrier for the application of controller bacteria on air–water interfaces

BACKGROUND The formulation of a biodegradable carrier which effectively concentrates microorganisms on air–water interfaces is proposed. This avoids the dispersion of bacteria into the bulk liquid phase and at the same time prevents their sedimentation. This formulation can be used in biocontrol and bioremediation treatments where the target is at the position of the air–water interface, as in the case of the treatment of rice diseases caused by Sclerotium oryzae and Rhizoctonia complex. The carrier is an oil‐in‐water (O/W) emulsion which contains lecithin and chitosan in both phases at different proportions. In a stable formulation, bacteria that are adsorbed onto the surface of oil droplets are carried with them and flowed upward to the air–water interface, due to buoyancy forces. RESULTS When using the biodegradable carrier, it is possible to recover at least 15‐fold more bacteria from the air–water interface than in the case of using the aqueous formulation. CONCLUSION The emulsion O/W is applied to the surface by dripping, resulting in a homogeneous two‐dimensional film distribution. With this application device, the number of bacteria at the air–water interface is significantly increased. © 2019 Society of Chemical Industry There is continued need for new formulations to pest biocontrol. This develop can help to vehiculate bacteria on a biodegradable formulation when the pest is in the air–water interface.