2. Materials and Methods
2.1. Bacterial Strains
L. ivanovii was isolated from local food industry. L. innocua, E. coli and Salmonella spp. were
obtained from the department of medical science, ministry of public health, Thailand. Listeria and non
Listeria cultures were multiplied in shake tubes using Tryptic Soy Broth (TSB) and amplified to reach the
final cell density at approximately 109 CFU/mL. Serial dilutions were done to achieve the desired initial
cell concentration at 10 9 CFU/mL prior to perform selective enrichment studies.
2.2. Media preparation
Selective enrichment media were prepared according to the manufacturers’ recommendation. Fraser
enrichment broth (FB), UVM modified enrichment broth (UVM), morpholinepropanesulfonic acid-
buffered Listeria enrichment broth (MOPS-BLEB), selective enrichment broth (SEB) and Palcam broth
(PB) were included in this study. To determine cell density at different stages of incubation, Tryptic Soy
Agar (TSA) was utilized to enumerate viable cell counts for both Listeria and non Listeria strains. If
applicable, most media were sterilized using an autoclave at 121 C for 15 min. Selective and inhibitory