Accumulation of betaine and ectoine in osmotic stress adaptation of biocontrol agents against Fusarium verticillioides in maize

Abstract

The aims of this study was to examine the effect of the osmotic (NaCl) water stress on, growth and accumulation of endogenous compatible solutes of Bacillus amyloliquefaciens and Micro- bacterium oleovorans, biocontrol agents against Fusarium verticillioides. Triptic soya broth me- dia were modified ionically to 0.99; 0.98; 0.97 and 0.96 aw with NaCl. The endogenous contents of the intracellular compatible solutes glycine- betaine and ectoine were quantified. Cells grown under ionic solute stress showed accumulation of significant amounts of both amino acids in all treatments. The growth rate of F. verticillioides was decreased significantly by interaction with B. amyloliquefaciens and M. oleovorans phy- siologically adapted at 0.96 aw. This study have demonstrated the ability to synthesize betaine and ectoine under high-osmolality conditions of B. amyloliquefaciens and M. oleovorans cells. Such ecophysiological manipulation, especially to water stress, may increase the potential for biological control of F. verticillioides at field under wider aw conditions.