Survival of Escherichia coli in Stream Water in Relation to Carbon Dioxide and Plant Photosynthesis

During a study of the survival of Escherichia coli in a chalk stream and in the laboratory, the organism ceased to grow in filtered stream water if air free of atmospheric carbon dioxide was passed over the culture. Fewer E. coli cells grew with the alga Stichococcus bacillaris in the light than in the dark. In the stream, low numbers of the organism were associated with plant blooms (macrophytes and microphytes). It is suggested that the numbers of E. coli in natural waters may sometimes be determined by the content of dissolved carbon dioxide which itself must be affected by the volume of photosynthesizing green cells.