Spreading vinasse on soil enhances the risk of anaerobiosis and changes in microbial biodiversity. Our aims were to check whether the return to aerobic conditions after an anaerobic event eliminates anaerobic effects on the amounts of fungi, bacteria and archaea, as well as on bacterial molecular diversity. Batch incubations of ferralsol slurry were performed according to the sequence aerobiosis (7 d), anaerobiosis (0, 2, 7, 14, 21 or 28 d), aerobiosis (28 d), rum vinasse being supplied at the beginning of anaerobiosis. Bacteria and archaea were enumerated combining microscopic observations to quantitative PCR, fungal biomass was measured by ergosterol extraction, and bacterial molecular biodiversity was investigated by PCR-SSCP. The main biotransformations were characterized through gas and solute changes. During the initial aerobic period, no great change was observed. During anaerobiosis, the main biotransformations were fermentations and true acetogenesis, Fe(III), Mn(IV) and SO4-- reductions and CH4 production. During this period, the fungal biomass stayed roughly constant as well as bacteria density number, whereas archaea density number increased. Bacterial molecular diversity was reduced during the first 4 d of anaerobiosis with the emergence of some populations, and then became more complex but different from the initial ones. After the return to aerobiosis, fungal biomass presented transient increases and decreases (no data for archaea and bacteria). After 28 d of aerobiosis, fungal biomass was negatively correlated to the duration of the anaerobic period, and could be lower or higher than the soil initial value. Trends on bacteria and archaea were uncertain. Similarly as during anaerobiosis, bacterial molecular diversity was reduced during the first days of aerobiosis with the emergence of other populations, and then became more complex. Final molecular diversity resembles the initial molecular diversity of the soil all the more the duration of the anaerobic period was short.