Presentation Title

The Effects of Oxidative Stress on the Manganese Oxidizing Protein

Start Date

November 2016

End Date

November 2016

Location

HUB 302-123

Type of Presentation

Poster

Abstract

Manganese (Mn) oxidizing microorganisms catalyze the oxidation of soluble Mn(II) into insoluble Mn(III/IV) oxides. Mn(III/IV) oxides have a variety of environmental applications such as soil remediation, filtration of wastewater, and the removal of harmful metals (e.g. lead and arsenic). A truncated version of the manganese oxidizing protein (MopA-hp) discovered in Erythrobacter sp. SD-21 was purified and expressed to determine enzymatic activity. Anaerobic assays indicated that MopA-hp is dependent on oxygen for the oxidation of Mn(II). Pyrroloquinoline quinone (PQQ), is a known antioxidant and also promotes the catalytic reaction of MopA-hp. Under aerobic conditions, there was a significant decrease in Mn(II) oxidation without PQQ. Oxygen and PQQ may play a role in superoxide (O2-) formation, which can lead to hydrogen peroxide (H2O2) production. Superoxide dismutase (SOD), an O2- scavenger was tested to determine whether or not O2- or H2O2 contributed to Mn oxidation. The addition of SOD decreased enzymatic activity. We hypothesized that the decrease activity could be due to the formation of H2O2 by SOD, and not due to the loss of O2-. To test this hypothesis, catalase, an enzyme that degrades H2O2 into oxygen and water was added to the assay along with SOD; enzymatic activity was restored by the addition of catalase. This suggests that there is H2O2 formation in the presence of SOD. H2O2 is known to reduce the concentration of Mn oxides. By degrading the H2O2 into oxygen and water, catalase prevents H2O2 from reducing Mn oxides back into Mn(II).

Key words: Bioremediation, Manganese, Protein purification, reactive oxygen species, Environmental microbiology

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Nov 12th, 1:00 PM Nov 12th, 2:00 PM

The Effects of Oxidative Stress on the Manganese Oxidizing Protein

HUB 302-123

Manganese (Mn) oxidizing microorganisms catalyze the oxidation of soluble Mn(II) into insoluble Mn(III/IV) oxides. Mn(III/IV) oxides have a variety of environmental applications such as soil remediation, filtration of wastewater, and the removal of harmful metals (e.g. lead and arsenic). A truncated version of the manganese oxidizing protein (MopA-hp) discovered in Erythrobacter sp. SD-21 was purified and expressed to determine enzymatic activity. Anaerobic assays indicated that MopA-hp is dependent on oxygen for the oxidation of Mn(II). Pyrroloquinoline quinone (PQQ), is a known antioxidant and also promotes the catalytic reaction of MopA-hp. Under aerobic conditions, there was a significant decrease in Mn(II) oxidation without PQQ. Oxygen and PQQ may play a role in superoxide (O2-) formation, which can lead to hydrogen peroxide (H2O2) production. Superoxide dismutase (SOD), an O2- scavenger was tested to determine whether or not O2- or H2O2 contributed to Mn oxidation. The addition of SOD decreased enzymatic activity. We hypothesized that the decrease activity could be due to the formation of H2O2 by SOD, and not due to the loss of O2-. To test this hypothesis, catalase, an enzyme that degrades H2O2 into oxygen and water was added to the assay along with SOD; enzymatic activity was restored by the addition of catalase. This suggests that there is H2O2 formation in the presence of SOD. H2O2 is known to reduce the concentration of Mn oxides. By degrading the H2O2 into oxygen and water, catalase prevents H2O2 from reducing Mn oxides back into Mn(II).

Key words: Bioremediation, Manganese, Protein purification, reactive oxygen species, Environmental microbiology