Permeable (sandy) marine sediments are dynamic environments, with oxic-anoxic boundaries constantly changing due to wave oscillations and tidal cycles. As such, this environment selects for metabolically flexible bacteria such as facultative anaerobes; capable of utilizing different electron acceptors and donors based on availability. Typically, anoxic degradation of organic matter proceeds through fermentation to volatile fatty acids (VFA), which are then oxidized to CO2 via terminal respiration processes. However, this is not the case in high energy sands, where fermentation is the dominant carbon degradation pathway and remains uncoupled from respiration after transient anoxia. Build-up of VFA such as acetate, a major fermentation by-product, is therefore expected, yet to date we have observed no significant accumulation in anoxic sediments and our understanding of the fate of the organic fermentation products remains incomplete. Our work suggests facultative anaerobes are storing organic carbon intracellularly in the form of lipid granules such as polyhydroxyalkanoates (PHA) or triacylglycerol (TAG). Using pure culture incubations of facultative anaerobes isolated from dynamic sandy sediments, we show cells under anoxia have increased fatty acid content, major components of storage lipids. Furthermore, imaging of these cells using cryo electron microscopy (cryoEM) shows two different types of storage granules and other irregularities when compared to cells grown under oxic conditions. While prior work has shown acetate assimilation can be significant in anoxic sandy sediments, this study is the first to provide evidence of distinct facultatively anaerobic bacteria storing intracellular storage compounds following periods of fermentation remaining uncoupled to respiration.