Studies of interactive effects between iron and musty-odor producing cyanobacteria

最近自来水公司面临的一个问题是霉味，这是由蓝藻产生的土豆素或2-甲基异龙脑引起的。为了阐明产霉味蓝藻的生长机理，研究了在不含EDTA的CT培养基中，铁对大孢鱼腥藻、细嫩鱼腥藻、螺旋鱼腥藻、细小振荡藻和短振荡藻生长的影响。然而，在不含EDTA的CT培养基中，短乳杆菌生长良好，并能产生Geosmin。因此，短链乳杆菌能够利用胶体铁、磷酸铁，甚至是氧化铁来生长。这表明，在无螯合剂的介质中，短乳杆菌有望产生一种特定的高亲和力铁络合剂(铁载体)。在BPDS存在下，Fe(II)螯合剂短链霉菌和P.tenue能够生长，而大孢子菌和O.tenuis则不能生长。此外，在含有微生物铁载体(去铁胺B)或过量的强Fe(III)螯合剂(如EDDHA和HBED)的培养基中，短链青霉能够生长，而其他4种蓝藻不能生长。以柠檬酸铁为铁源时，即使在高铁水平(28微米)下，也能显着抑制微囊藻的生长。目前的研究表明，与其他4种蓝藻相比，短藻能够利用多种形式的铁作为铁源，而且吸收铁的能力更强。Tenuis似乎对其生长所能利用的铁形态有特定的要求。

A recent problem for water utilities is musty-odor, which is caused by geosmin or 2-methylisoborneol produced by cyanobacteria. In order to clarify the mechanism of growth of musty-odor producing cyanobacteria, the effect of iron, an essential element, on the growth of Anabaena macrospora, Phormidium tenue, Anabaena spiroides, Oscillatoria tenuis and Oscillatoria brevis was studied.The growth was suppressed for A.macrospora, A.spiroides, P.tenue and O.tenuis in the EDTA-free CT medium. However, O.brevis grew well and produce geosmin in the EDTA-free CT medium. Thus, O.brevis showed an ability to utilize colloidal iron, iron(III) phosphate and even iron oxides for its growth. This indicates that O.brevis would be expected to produce a specific high affinity iron chelator (siderophore) in the chelator-free medium. In the presence of BPDS, a strong Fe(II) chelator, O.brevis and P.tenue were able to grow, but A.macrospora and O.tenuis were not. Furthermore, O.brevis was capable of growing in the medium containing a microbial siderophore (desferrioxamine B) or excess of strong Fe(III) chalators such as EDDHA and HBED, although the other 4 cyanobacteria were not able to grow. The growth of O.tenuis was remarkably suppressed at even high levels of iron (28 muM as Fe) when iron citrate was used as the iron source. The present studies indicate that O.brevis can utilize a wide variety of iron forms as the iron sources and more excellent ability of iron absorption compared with other 4 cyanobacteria. O.tenuis seems to have specific requirements for the iron form it can utilize for growth.