Influence of Algal Photosynthesis on Biofilm Bacterial Production and Associated Glucosidase and Xylosidase Activities

Abstract

Natural photosynthetic biofilms were incubated under light (100 mmol 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 a- and b-glucosidase and b-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 mmol m-2 s-1).

Extracellular enzyme activities in benthic cyanobacterial mats: comparison between nutrient- enriched and control sites in marshes ofnorthern Belize

“…In biofilms, bacteria are in a close relationship with algae and rapidly utilize extracellular organic carbon (EOC) released from algal and cyanobacterial cells during active cell metabolism or following cell senescence (Espeland et al 2001). It has been shown that increased light intensities, to which cyanobacterial mats studied are exposed, stimulate extracellular enzyme activity (Espeland & Wetzel 2001a).…”

“…Mats are an important component of northern Belizean marshes, constituting a major part of biomass and primary production coupled with both nitrogen fixation and production of large amounts of polysaccharide-rich extracellular polymeric substances (EPS). The production of EPS may be an important direct source of carbon for associated communities of heterotrophic bacteria (Bell et al 1983, Espeland et al 2001, while the nitrogen fixed in mats is utilized by non nitrogen-fixing bacteria and macrophytes (Rejmánková & Komárková 2000). Cyanobacterial mats also influence sediment formation in these systems in that large amounts of calcium carbonate are precipitated during photosynthesis forming marl deposits.…”

“…Results of the Generalised Linear Model test comparing the effect of salinity, layer, N and P on the activity of the 4 enzymes at the 9 locations and 4 plots (mean + SE) in dry, damp and wet samples, from the control and the plot cyanobacterial mat (CBM), first (S1) and second (S2) sediment layer for low, medium and high salinity locations Sirová et al: Extracellular enzyme activities in cyanobacterial mats ably the diversion of resources from the synthesis of extracellular enzymes to microbial growth and this in turn may contribute to the high metabolic rates observed for attached microbiota. The disadvantage is a slower response of microbial community to changes in carbon resources (Sinsabaugh et al 1991).In biofilms, bacteria are in a close relationship with algae and rapidly utilize extracellular organic carbon (EOC) released from algal and cyanobacterial cells during active cell metabolism or following cell senescence (Espeland et al 2001). It has been shown that increased light intensities, to which cyanobacterial mats studied are exposed, stimulate extracellular enzyme activity (Espeland & Wetzel 2001a).…”

“…However, our results show no difference in bacterial counts between the upper sediment layers and the mat. This may be caused by the bacteria responding to increased photosynthesis with an increase in biomass rather than an increase in overall numbers (Espeland et al 2001). Some studies have demonstrated increases in cell volumes relative to abundance in bacterial populations grown on UVexposed DOC (Lindell et al 1995(Lindell et al , 1996, and it is possible that bacterial cells in the mat sequester available carbon, thus generating greater individual mass (Espeland et al 2001).…”

Organic matter availability structures of microbial biomass and their activity in Pachamalai Forested stream in Tamilnadu.

“…Peptidase activity was highest during periods of greatest algal biomass development in coarse substrata. This relationship may indicate the use of algal exudates (mainly peptidic molecules) by bacteria (Romaní et al, 2004), since bacterial enzyme production (especially peptidases) can be stimulated by active algal photosynthesis (Espeland et al, 2001). During this period, heterotrophic microbial activity may depend largely on the use of autochthonous sources.…”