Pseudomonas Aeruginosa in Drinking Water

SUMMARY: The literature concerning antagonism between Pseudomonas aeruginosa and Escherichia coli , the natural habitat of the former and its potential pathogenicity, has been briefly surveyed. Experimental work showed that the two organisms can coexist in pure water, but in mixed cultures in peptone water Ps. aeruginosa can inhibit E. coli , though not in the early stages of growth and only within a critical range of peptone concentration. Ps. aeruginosa might therefore reduce the coli‐aerogenes content in grossly polluted water but would not normally interfere with the determination of the actual coli‐aerogenes content at the time of sampling. Water supplies containing many Ps. aeruginosa but few or no coli‐aerogenes bacteria were found to be relatively common in Northern Israel and in view of the faecal origin of the former, and its potential pathogenicity, it is concluded that this organism should be taken into account, as well as coli‐aerogenes bacteria, in assessing the suitability of water for drinking purposes.