Mississippi State University
Haque, Zahur Z.
Sharma, Chander Shekhar
Date of Degree
Graduate Thesis - Open Access
Master of Science
College of Agriculture and Life Sciences
Department of Food Science, Nutrition and Health Promotion
Previous findings showed that Listeria monocytogenes exhibits higher heat tolerance to thermal exposure at 60°C when pre-exposed to sublethal heat stress at 48°C for 30/60 min. The objective of this study was to investigate the morphological changes that occurred in L. monocytogenes serotype 1/2a cells as visualized by transmission electron microscopy (TEM) after exposure to sublethal heat stress at 48°C for 60 min and in combination with lethal concentration of carvacrol for 30 min. The TEM micrographs revealed thickening of cell wall and cell membrane, and clumping of cytoplasm when subjected to sublethal heat stress followed by carvacrol treatment. These studies indicate that L. monocytogenes cells when adapted to heat stress may alter its morphology to protect themselves against carvacrol. Further studies will investigate the effect of increased contact time with carvacrol and with other essential oils on the ultrastructural changes in L. monocytogenes cells adapted to heat stress.
Saha, Sulagna, "Transmission Electron Microscopy Study of Listeria Monocytogenes Serotype 1/2A Cells Exposed to Sublethal Heat Stress and Carvacrol" (2015). Theses and Dissertations. 4778.