Preparation of CFS of the Selected Bacilli Colonies

The selected colonies were inoculated in MRS broth and sub-cultured three times at 37°C for 18 h with agitation at 185 rpm, and the tubes were tilted at 45 degrees during incubation. The third subculture was transferred to an Eppendorf tube (Eppendorf, Hamburg, Germany) and was centrifuged at 16000 g for 5 min. The supernatant was filter-sterilized using Millex 0.22 μm non-pyrogenic filters (Merck Millipore Ltd., Co., Cork, Ireland). The pH of the CFS was measured after filter-sterilization and compared against an MRS control.