Abstract: A microbial process is provided for selectively plugging a high permeability stratum or zone in a subterranean reservoir. Starved bacteria of reduced size are injected into the zone. A poor-nutrient media is either simultaneously or subsequently thereafter injected into the zone to substantially uniformly resuscitate the starved bacteria. Thereupon, the bacteria regain full cell size, proliferate, and commence production of biofilm-forming exocellular polysaccharides. The biofilm is functional to selectively seal off the high permeability zone of the formation and reduce aqueous flow through the zone.