Abstract |
The bacterial microflora of two shallow aquifers in Oklahoma was characterized by direct observation with light (LM) and electron microscopy (EM), by plating, and by examination of colony morphology and distribution. Total cell counts varied only slightly from sample to sample, whereas colony counts varied widely. Colony counts on nutritionally-rich (NR) media were lower than on low-nutrient (LN) media, especially in samples from the saturated zone. The variety of colony types growing on NR media depth decreased with depth. Cell morphologies of bacteria grown aerobically on plates included short rods, cocci, and actinomycete-like forms. Direct LM observation of sediments revealed short, rod-shaped and coccoid bacterial cells. EM observation of bacteria released from the samples revealed that 85-90% of them were coccoid, Gram-positive, Arthrobacter-like organisms some of which were dividing or contained completed division septa. (Copyright (c) 1985, American Society for Microbiology.) |