Influence of algal photosynthesis on biofilm bacterial production and associated glucosidase and xylosidase activities

Natural photosynthetic biofilms were incubated under light (100 mu mol m(-2) s(-1)) and dark conditions to elucidate the impact of photosynthesis on bacterial production, abundance, biovolume, biomass, and enzyme activities over 24 h. Use of organic carbon-free media limited carbon sources to algal photosynthesis and possibly the polysaccharides of the biofilm matrix. Bacterial production of biofilm communities was significantly higher in light incubations (p < 0.001). The greatest differences in production rates between light and dark incubations occurred between 8 and 24 h. Biomass-specific - and beta -glucosidase and beta -xylosidase activities were stimulated by photosynthesis, with significantly greater activities occurring at hours 16 and 24 in the light treatment (P < 0.01). The results indicate that algal photosynthesis can have a significant impact on bacterial productivity biomass, biovolume, and enzyme production over longer time periods at low photon flux densities (100 mu mol m(-2) s(-1)).