Comparative Analysis of Oxidative Stress During Aging of Kluyveromyces marxianus in Synthetic and Whey Media Priyanka Saini 1 & Arun Beniwal 1 & Shilpa Vij 1 Received: 6 December 2016 /Accepted: 28 February 2017 # Springer Science+Business Media New York 2017 Abstract During the aging of yeast culture, Kluyveromyces marxianus undergoes a number of changes in physiology and these changes play a significant role during fermentation. Aged stationary phase cells were found to contain more reactive oxygen species. Additionally, the level of oxidant is counteracted by the antioxidant defense system of the cells. Comparison of 3-day-old culture of K. marxianus with 45-day stationary phase culture represents an increased level of ROS inside the cells. Moreover, a decrease in glutathione content was observed over the set of the incubation period. The increased level of superoxide dismutase (SOD) and catalase also revealed that there is oxidative stress during the long period incubation of the stationary phase cells of K. marxianus. The actual phenomenon of aging in dairy yeast K. marxianus is a complex process, but the present study signifies that role of antioxidant defense system during aging in stationary phase cells of K. marxianus. Keywords Kluyveromyces marxianus . Oxidative stress . Glutathione . Catalase . Free radicals Introduction Individual cells of yeast Kluyveromyces marxianus are subjected to finite life span after undergoing a series of cell division. K. marxianus is a model cell factory used during fermentation-related studies on whey, but no study has been conducted on aging process taking place in K. marxianus [1]. This strain offers numerous advantages from industrial point of view and may further be used as a model organism during experimentation on aging on higher eukaryotes. Moreover, the aging process occurring in K. marxianus is an important physiological process taking place in dairy yeast apart from its relevance in aging of higher eukaryotes. Appl Biochem Biotechnol DOI 10.1007/s12010-017-2449-9 * Shilpa Vij shilpavijn@yahoo.co.in 1 Dairy Microbiology Division, National Dairy Research Institute, Karnal 132001, India