The effect of space flight irradiation on Saccharomyces cerevisiae growth and respiration

Wild-type Saccharomyces cerevisiae vegetative cells housed in the NASA Microbial Ecology Evaluation Device (MEED) were exposed to solar radiation in space during the transearth Extra Vehicular Activity (EVA) of Apollo 16 [1]. Space parameters in addition to ultraviolet (UV) light, at selected wavelengths and intensities, included weightlessness and stresses encountered during the launch and splashdown. The MEED was designed to examine survival rates of fungi exposed to space flight parameters and UV irradiation in deep space. Ceils recovered for post-flight evaluation were compared with ground and flight controls. Weightlessness and stresses encountered during the launch and splashdown resulted in no variation in fungal viability [2]. In contrast, survival rates varied in relation to UV light exposure parameters [2]. Inhibition of growth and respiration of S. cerevisiae by visible and near-visible light have been reported [3,4]. UV-induced respiratory deficencies have also been reported for S. lactis [5]. The present study examines the effects of UV light exposure in deep space on the ability of S. cerevisiae to grow aerobically and respire on glucose. 2.1. Space flight irradiation