LAUSR

BACKGROUND Biocontrol strategies are of significant concern for their application in crops. Various green practices have been designed, but almost all of them had delivery constraints. Especially, to design biocontrol strategies against Sclerotium oryzae in flooded rice fields, the active agent should be retained on the plant leaves by spreading application, nevertheless, the direct application onto the water produces the biocontrol agent dilution. Then an effective delivery model was needed. This work aimed to evaluate the effects of chitosan Molecular Weight on the formation of positively charged Pseudomonas fluorescens-Chitosan complex as floating microcarrier against Sclerotium oryzae. To this end, three different sizes of chitosan (Molecular Weights 20000; 250000; 1250000 g/mol) at different pH values (4, 6, and 7) were tested. The electrostatic interaction was analyzed through ζ-potential measurement. An adjustment of the experimental values was carried out for making predictions. The bacteria antifungal activity into the carrier with different chitosan MW was analyzed. RESULTS Our results suggest that it is possible to form a bacteria-chitosan complex with a net positive charge at the conditions that improve the bacteria incorporation to the microcarrier technology, without harmful the bacteria viability and its antifungal activity. In this sense, high chitosan MW (1250000 g/mol) at pH 6 is preferable for the designed microcarrier technology. CONCLUSION Our findings provide relevant information about bacteria-chitosan interaction and especially can be useful in biocontrol programs that involved these two components and, in such occasions where the bacteria adsorption to an anionic carrier or anionic surfaces is desirable. This article is protected by copyright. All rights reserved.