Bruce M. Roll
Roger S. Fujioka
Muruleedhara N. Byappanahalli
2012
<p>High densities of <i>Escherichia coli</i> and enterococci are common in freshwaters on Oahu and other Hawaiian Islands. Soil along stream banks has long been suspected as the likely source of these bacteria; however, the extent of their occurrence and distribution in a wide range of soils remained unknown until the current investigation. Soil samples representing the seven major soil associations were collected on the island of Oahu and analyzed for fecal coliforms, <i>E. coli</i>, and enterococci by the most probable number method. Fecal coliforms, <i>E. coli</i>, and enterococci were found in most of the samples analyzed; log mean densities (MPN ± SE g soil<sup>−1</sup>) were 1.96±0.18, <i>n</i>=61; 1.21±0.17, <i>n</i>=57; and 2.99±0.12, <i>n</i>=62, respectively. Representative, presumptive cultures of <i>E. coli</i> and enterococci collected from the various soils were identified and further speciated using the API scheme; at least six species of <i>Enterococcus</i>, including <i>Enterococcus faecalis</i> and <i>Enterococcus faecium</i>, were identified. In mesocosm studies, <i>E. coli</i> and enterococci increased by 100-fold in 4 days, after mixing sewage-spiked soil (one part) with autoclaved soil (nine parts). <i>E. coli</i> remained metabolically active in the soil and readily responded to nutrients, as evidenced by increased dehydrogenase activity. Collectively, these findings indicate that populations of <i>E. coli</i> and enterococci are part of the natural soil microflora, potentially influencing the quality of nearby water bodies.</p>
application/pdf
10.1264/jsme2.ME11305
en
Japanese Society of Microbial Ecology
Evidence for occurrence, persistence, and growth potential of <i>Escherichia coli</i> and enterococci in Hawaii’s soil environments
article