Adsorption and survival patterns of Escherichia coli and Streptococcus bovis in six New Zealand soils

Abstract

The ability of E. coli and S. bovis to adsorb on to and subsequently survive in sterilised soil slurries at 10°c was examined. These slurries were prepared with samples from 0—10 cm and 10—20 cm depths of Egmont brown loam, Timaru silt loam, Tokomaru silt loam, Taupo sandy silt, Waikiwi silt loam, and Marua clay loam. E. coli was little adsorbed by soil from both depths and survived for 2—3 months, except in Marua soil where survival was limited to 25 days. S. bovis was not adsorbed by samples of Egmont and Timaru soils from either depth, or by samples of Waikiwi and Tokomaru soils from the lower depth. The highest levels of adsorption occurred in slurries of samples from both depths of Marua soil. The highest survival times for S. bovis were up to 1 month in Timan! soil, between 1 and 2 weeks in Waikiwi and Tokomaru soils, less than 1 week in Taupo soil, and only 1 day in Marua soil. A combination of high clay content and low soil pH appeared to be responsible for high adsorption and short survival times for S. bovis and a reduced survival time for E. coli.