A study of field drain ochre deposits. 2. The distribution of micro-organisms

Abstract

SummarySheathed filamentous bacteria,Leptothrixspp. andGallionellaspp., were observed in ochre samples from sites in England and Wales.Thiobacillus ferrooxidanswas found in acidic samples (pH < 4·0) and in ochre from drainage water of near neutral pH suggesting that it can contribute to ochre formation over a wide range of drainage water pH, Heterotrophic bacteria capable of growing in artificial media of low pH and complexdegrading heterotrophic bacteria were also isolated. Some ochre deposits could be described as either pyritic or filamentous but the majority of samples fell between these extremes and had various combinations ofT. ferrooxidans, sheathed filamentous bacteria and other heterotrophic bacteria.