Complexation,Stabilization, and UV Photolysis of Extracellular and Surface-Bound Glucosidase and Alkaline Phosphatase: Implications for Biofilm Microbiota |
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Authors: | Espeland EM Wetzel RG |
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Institution: | (1) Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama 35487-0206, USA, US;(2) Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599-7431, USA, US |
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Abstract: | Biofilm-produced and commercially-purified a- and b-glucosidase and alkaline phosphatase were subjected to different spectral
portions of natural and artificial light and exposed to various humic substances to elucidate their impact on enzyme activities.
Photochemical degradation of all enzymes occurred under different portions of the light spectrum. UVB irradiance produced
the greatest overall photochemical degradation of enzymes, with significant rates occurring with UVA and PAR irradiance. The
complexation of enzymes with humic substances resulted in inhibition, stabilization, and photochemical protection of the enzyme.
Inhibition of enzyme activity occurred via reductions in overall enzyme activity in the presence of humic substances. However,
humic-enzyme complexation also resulted in stabilization by restricting enzyme degradation while retaining high activities.
Enzymes exposed to natural and artificial light sources had significantly lower reductions in enzyme activities in the presence
of humic substances, which indicates that humic-enzyme complexes may protect enzymes from light-induced photochemical degradation.
Bacterial surface-bound a- and b-glucosidase activities were significantly reduced in the presence of humic substances. Photosynthetically
induced pH changes within biofilm communities can cause large reductions in a- and b-glucosidase activities while enhancing
the hydrolytic activity of alkaline phosphatase. |
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