Four gram positive and two gram negative bacteria were used for the antibacterial activity
assay. E. coli (O157:H7), S. typhimurium (LT2), S. aureus (Mu50), L. monocytogens (EDGE), E.
faecalis and M. smegmatis (LM143) were obtained from the public culture collection (ATCC or
DSMz). Before each use, frozen stock cultures of bacteria were thawed and grown in a
chemically defined medium (CDM) (Jensen and Hammer, 1993) at 37°C for 20 h under aerobic
and anaerobic conditions (6% hydrogen, 20% CO2 and balanced with nitrogen). The cultures
were inoculated using overnight culture of each bacterium at OD600nm = 0.1 in 150 µl of CDM
with (2% of the zingiberaceous extract) or without zingiberaceous extract and performed in 96
wells microplate. The kinetic growths were performed in CDM at 37°C for 30 h using microplate
reader, and 72 h for M. smegmatis in aerobic (Beckman Coulter DTX 800/880 microplate reader)
and anaerobic conditions (Biotek ELx808 microplate reader). Each experiment was conducted in
three replicates