Bacterial production and enzyme activity within attached microbial communities

Laboratory studies were conducted to examine the punitive effects of different spectral wavelengths, humic substances, and photosynthetically induced pH changes on bacterial cell-free and surface-bound enzymes of biofilm communities. Results indicated that the formation of humic-enzyme complexes produce three primary interactions: inhibition, stabilization, and photochemical protection. Photochemical degradation in the absence of humic substances occurred over a broad range of spectral wavelengths, including PAR (400–700nm). Finally, pH changes will likely produce significant alteration of enzyme activities within biofilm communities.; Studies of biofilm communities were designed to evaluate the potential influence of attached algal photosynthesis on bacterial production and enzyme activities. Results demonstrated that bacterial production, biomass, biovolume, and enzyme activity of biofilms can be enhanced by active photosynthesis at low photon flux densities over 24 h. Evaluations of bacteria with phosphatase activity within biofilms determined that the proportion of cells with phosphatase activity is indirectly influenced by algal photosynthesis.; Bacterial phosphatase of natural photosynthetic biofilms was examined to elucidate the relationship between community phosphatase activity and individual cell activity under phosphorus deficiency. Experiments indicated that the proportion of bacteria displaying surface-bound phosphatase activity is not correlated with whole-community phosphatase activity. Methods for determining cell specific activities are strongly influenced by the fraction of the community used in calculations. Results suggest that surface-bound phosphatase remain hydrolytically active after cell membranes are compromised.