A simple double-layered chrome azurol S agar (SD-CASA) plate assay to optimize the production of siderophores by a potential biocontrol agent Bacillus

摘要

Siderophores, a high-affinity chelating agents for ferric iron, is one of the mechanisms by which biocontrol agents’ act in inhibiting the growth of phytopathogens.?Bacillus subtilisQM3,?a siderophore producer, is a potential biocontrol agent. In this study, a simple double-layered chrome azurol S agar?(SD-CASA)?plate assay was developed. We further studied optimal conditions for detection siderophore production by?B. subtilis?QM3 using various history cultures, pH value, amino acid, and different?carbon-nitrogen ratio as four variables.?After?incubating?different history cultures we found out that the LB medium presented strong significant CAS reaction even for 12 h, and?with the help of?changingvariables?on?SD-CASA plate?assisting?paper-disc diffusion, strain QM3?from LB medium with Fe3+?(10 μmol/L)?showed?difference?interestingly.?In addition, CAS reaction and growth reaction also increased with pH 7.0, tryptophan 10?μmol/L and carbon-nitrogen ratio 5:1. The findings on solid medium were similar as that in liquid medium.?The SD-CASA assay should be a useful tool for screening potential biocontrol microorganisms by siderophore production.