The test, OD was measured under both aerobic and anaerobic
conditions. It found that under aerobic condition the extracts of Z.
officinale and Zingiber ‘Phlai Chomphu’ showed the effect against L.
monocytogenes while the extracts from Zingiber ‘Phlai Chomphu’, B.
rotunda and K. parviflora showed the effect against M. smegmatis. For
anaerobic condition, the extracts of Z. officinale, Zingiber ‘Phlai
Chomphu’ and A. galanga showed the effect against S. typhimurium
whereas the extracts of K. parviflora showed the effect against S. aureus.
The extracts of Z. montanum, Z. ottensii and Z. zerumbet showed no
antibacterial property while those of Zingiber ‘Phlai Chomphu’ and A.
galanga showed the strongest antimicrobial property