Production of biomass by indigenous bacteria found in hypersaline oil‐reservoir brine was limited by a fermentable carbon and phosphorus source. The addition of polymeric carbohydrates, such as maltodextrins, along with organic phosphates stimulated production of a flocculent and sometimes slimy biomass, which was not produced from simple sugars. Maltodextrins also stimulated production of lower levels of the end‐products acetate and ethanol. Injection of indigenous bacteria into sandstone cores followed by phosphate and maltodextrin resulted in a >90% reduction in the in‐depth permeability of a sandstone core, whereas treatment with glucose resulted in primarily face‐plugging of a sandstone core. These corns tarch maltodextrins and organic phosphate esters have application as nutrients for stimulation of biomass necessary for selective plugging of reservoir rock by microbial populations found in a hypersaline oil reservoir.