Abstract
A recent problem for water utilities is musty-odor, which is caused by geosmin or 2-methylisobomeol produced by cyanobacteria.
In order to clarify the mechanism of growth of musty-odor producing cyanobacteria, the effect of iron on the growth ofAnabaena macrospora, Phormidium tenue, Oscillatoria trnuidand Oscillatoria breviswas studied.
The growth of A.macrnspora, P. tenueandO. tenuiswas suppressed at low levels of colloidal iron (1μMas Fe) in the EDTA-free CT medium, However, at high levels of iron (18μMas Fe) using colloidal iron kept in a refrigerator, A. macrnsporaandP.tenuewere able to grow althoughO. tenuiscould not When autoclaved colloidal iron was used as the iron source, none of the cyanobacteria exceptO. breviswere able to grow.
The effect of spongy or powdery iron on the growth of cyanobacteria was also invesdgated.A macrospora, P tenue and O.breviswere capable of growing in media containing spongy or powdery iron, which release Fe (II) continuously, but the growth ofO. tenuiswas suppressed.
The culture experiments and photoreduction of Fe (III) to Fe (II) show thatA. macrospora, P. tenueandO. bneviscan utilize iron even in the absence of EDTA if there are large amounts of iron present in a form photoreducible to Fe (II) . However, O. tenuiswas found to require chelated and photoreducible iron for its growth.
The present results and previous studies {Water Sci. Technol., 25 (2) : 207-216 (1992) } indicate thatO. brevishas the ability to utilize a wide variety of iron forms such as Fe (III) -EDTA, Fe (II) -BPDS, Fe (III) -Desferrioxamine B (microbial siderophore) chelates, colloidal iron, iron oxides (Fe2O3, Fe3O4), spongy iron and powdery iron. On the other hand, O. tenuisseems to have specific requirements for the form of iron it can utilize for growth.
