IJSRP, Volume 4, Issue 10, October 2014 Edition [ISSN 2250-3153]
Mohd Nizam Lani, Zaiton Hassan and Son Radu
Survival and growth of Listeria monocytogenes L56 (IMR isolate) was studied in trypticase soy broth (TSB) grown at 37ºC before being subjected to three selected sublethal stress temperatures (55ºC, 28ºC and 4ºC). The morphological changes and motility as affected by temperature stresses were determined using Scanning Electron Microscopy (SEM) and motility media, respectively. For this purpose, 10 ml broth containing L. monocytogenes previously grown in 300 ml of TSB at 37ºC at log phase (12 hour) and stationary phase (19 hour) to 55ºC, 28ºC and 4ºC were taken every 2 h intervals for measurement of morphological changes and motility. A total of 180 cells were measured lengthwise at 9,500x Scanning Electron Microscopy (SEM) magnification using SEMafore for each temperature treatments. The study demonstrated cells of both log and stationary phase of stressed temperature of L. monocytogenes showed a significant variation in morphology.