Isolation, identification, and characterization of ground water bacteria

Abstract

Ground water is an increasingly significant source of potable water and is one of the least studied ecosystems on earth. Assessment of man's impact on this resource requires knowledge of the microbial populations present. Over 500 bacteria were isolated from well water samples on a low nutrient medium (R2A). Gram-negative, rod shaped, nonmotile bacteria predominated. Acinetobacter spp. comprised 54% of the total isolates. Direct counts using ep i f 1 uorescent microscopy revealed that representative isolates grew significantly in filtered well water. Growth of Acinetobacter sp. was significantly enhanced in water enriched with low concentrations (100 ug carbon/liter or 1000 ug carbon/liter) of glucose, acetate, succinate, or pyruvate. The growth and survival of an Acinetobacter sp., an opportunistic pathogen, in water had not previously been described. Bacterial survival studies conducted on water samples from 19 wells throughout the Tucson basin revealed the presence of a significant population of bacteria capable of rapid growth and survival in unamended native well water.