Aims To evaluate the influence of storage conditions on the composition of the bacterial microbiota of living oysters Crassostrea gasar. Methods and ResultsConclusionsThe oysters used in this study came from marine farms (Guaratuba Bay, Brazil) and were exposed to two conditions that simulated different storage situations: immersion in water (group I) and exposure to air (group II). The animals were subjected to five different temperatures (5-25 degrees C), for 10days. The 16S rRNA gene from oysters was amplified and sequenced to determine the taxonomic units and bacterial strains present in the samples. Group I showed higher diversity of bacteria (163genera) rather than group II (104 genera). In all, 59 bacterial genera potentially pathogenic to humans were identified (n=56 in group I and n=45 in group II). The storage conditions having a direct influence on the oyster microbiota. Live C. gasar should be stored exposed to air at 5-25 degrees C, because it favours a lower prevalence of bacteria potentially pathogenic to humans. Significance and Impact of the StudyDuring the oyster commercialization process, some conditions of storage, time and temperature must be followed in order to reduce the prevalence of bacteria potentially pathogenic to humans.