ABSTRACT
Klebsiella pneumoniae isolated from oil well waters reduced in size in response to nutrient starvation. The cells remained viable during starvation and later were able to grow rapidly when stimulated by nutrients. The heterotrophic potential, culture absorbance and extracellular polysaccharide production decreased during cell starvation whereas an initial increase in colony-forming units was observed on agar plates. Transmission electron microscopy (TEM) after 24 d revealed that the cells had changed to small rods or cocci between 0.5 by 0.25 micron and 0.87 by 0.55 micron. When transferred to half-strength brain heart infusion medium, TEM showed cell division and rod-shaped cells after 45 min and full resuscitation within 4 h. Cell response was much slower in sodium citrate medium and resuscitation took 8 h.