INFLUENCE OF IRON, GROWTH TEMPERATURE AND PLASMIDS ON SIDEROPHORE PRODUCTION IN AEROMONAS-HYDROPHILA

Aeromonas hydrophila strains obtained from diarrhoeal samples of human patients (19 isolates) and freshwater ponds (11 isolates) were analys ed for siderophore production, Both clinical and environmental isolate s showed significantly increased siderophore production under iron-lim iting conditions both at 28 degrees C and at 37 degrees C, Clinical is olates consistently produced higher levels of siderophores than did th e environmental isolates, The role of plasmids in moderating sideropho re production was studied after curing with acridine orange, Treatment with acridine orange for 24 h removed the larger plasmids but the sma ller plasmids (<5 MDa), more common in the environmental isolates, wer e resistant to curing, As found in the untreated isolates, the cured c linical isolates produced higher mean levels of siderophores than the cured environmental isolates, Siderophore production in A, hydrophila was significantly influenced by iron-limiting cultural conditions and the source of isolates, but plasmid content and growth temperature at 28 degrees C or 37 degrees C had little effect on production, The basi s for the greater production of siderophores in clinical isolates than in environmental isolates needs further study.