Ferric reductase, superoxide dismutase and alkaline phosphatase activities in siderophore producing fungi

Abstract

Enzymes associated with release of iron from internalized ferrated siderophore (ferrisiderophore reductase), with damage to the cell at high iron concentration (superoxide dismutase) and siderophore synthesis (alkaline phosphatase), were examined in 3 test fungi viz., <i>Aspergillus </i>sp. ABp4, <i>Aureobasidium pullulans</i> and <i>Rhizopus </i>sp. Extracellular ferrisiderophore reductase activity was present in all the three fungi, but <i>Aureobasidium pullulans,</i> that showed the highest activity (84.3 μ<i>M </i>min^-1) , was the only one to produce intra-cellular ferric reductase (147.9μ<i>M</i> min^-1) . Superoxide dismutase was produced by <i>Aureobasidium pullulans</i> and <i>Rhizopus </i>sp., but not by <i>Aspergillus </i>sp. ABp4, that showed

intra-cellular enzyme activity in case of ferric reductase and alkaline phosphatase. Maximum SOD activity was seen in <i>Aureobasidium pullulans </i>both extra-cellularly (93.83 ng ml^-1) and

intra-cellularly (57.14 ng ml^-1) . All the test fungi examined, produced intra-cellular alkaline phosphatase. There was no extracellular alkaline phosphatase. Among the three fungi,

<i>Aureobasidium pullulans </i>showed highest alkaline phosphatise activity (129.9 μ<i>M </i>min^-1) and <i>Aspergillus </i>sp. ABp4 the least (76.4 μ<i>M </i>min^-1).