Aerobic respiration of intracellular polyglucose reserves is postulated to playa central role in oxygen adaptive response in obligatory anaerobes like Desulfovibrios, but it has been difficult to probe this event at chemical scale in vivo. Here we present a non-invasive synchrotron infrared (SIR) spectromicroscopy approach to reveal timedependentcomposition and structure changes at a lateral scale of several individual Desulfovirbio vulgaris. The advantage of infrared spectroscopy is that it is non-invasive, and it uses vibration movements of atoms and chemical bonds within functional groups of biomolecules as an intrinsic contrasting mechanism; thus it allows one to immediately detect composition and structure changes within living cells. The advantage of using a synchrotron light source is that its high brightness allows us to detect signals -1000 times weaker then the conventional infrared spectroscopy allows us to. Comparative analysis of SIR spectra of the same individual D. vulgaris exposed to air-level oxygen at different time points reveals chronological information regarding the level of oxidative stress and the extent of cellular injury and repair. These results, together with microscopy images, mark a critical step toward the use of SIR spectromicroscopy as an uninterrupted microprobe at a chemical scale level of physiological events in microbiology applications.