A global approach to asses stress response of the bioregenerative life support system organism Rhodospirillum rubrum under space-flight related environmental conditions.

In view of long haul space exploration missions, the development of regenerative life support systems is a condition sine qua non to increase the crew autonomy and decrease the cost associated to the mass embarked. Therefore, in the late 80’s, the European Space Agency initiated the MELiSSA project (Micro-Ecological Life Support System Alternative). MELISSA has been conceived as a micro-organisms and higher plant process enabling high recycling efficiency. Nevertheless, the organisms inhabiting the the MELISSA system need to perform their tasks as optimally as possible (Fig. 1). A number of stresses such as temperature variation, water deprivation, oxidative stress, UV and ionizing radiations, light variation, supernatant of the previous compartment, genomic evolution during long-time culturing and gene transfer can indeed affect the capabilities of the micro-organisms as well as the efficiency of the whole bioregenerative loop. Thus, the detection of functional and genetic instability due to stress in all bioreactors of the MELiSSA loop is considered to be of primordial importance. In this paper a global approach is put forward to analyse the stress response of R. rubrum ATCC25903, using whole cell flow cytometry analysis, mass spectrometry analysis and microarray gene expression profiling.