Comparison of planktonic and reed biofilm bacteria in different riverine water bodies of river Danube

Abstract

As the submerged shoot parts of common reed (Phragmites australis) can provide large surfaces for biofilm‐forming bacteria, extensive reed stands can effectively contribute to the self‐purification in the littoral zones of freshwaters. However, bacterial biofilm developed on reed surfaces have been studied only in still waters. In the present study, comparative examinations were performed on the planktonic and reed biofilm bacterial communities from two different riverine water bodies. Water and reed biofilm samples were taken at the beginning and end of the vegetation period from (a) a regulated side arm and (b) a separated oxbow of River Danube. Besides measuring physical and chemical environmental variables, planktonic bacterial cell numbers were detected by 4′,6‐diamidino‐2‐phenylindole staining method, and the bacterial communities were compared by denaturing gradient gel electrophoresis. Our results demonstrated that the structure and composition of bacterial communities correlated with different environmental variables and were different regarding both the habitats (planktonic vs. reed biofilm) and the types of riverine water bodies. The seasonal differences in the bacterial community structures were smaller in the river side arm than in the separated oxbow. In the water column, representatives of widespread and typical freshwater planktonic bacteria (“Candidatus Planktophila,” Limnohabitans, and Polynucleobacter), whereas, in the reed biofilm samples, phototrophic and plant associated bacteria were identified.

Planktonic and epilithic prokaryota community compositions in a large temperate river reflect climate change related seasonal shifts

“…Many taxa identified in this study have also been found in other rivers, and their role in the ecosystems and potential effects on human health are also known in some cases. Limnohabitans, Polynucleobacter, hgcI_clade and Sediminibacterium were recorded in rivers worldwide [16,18,[60][61][62][63][64][65]. The genus Limnohabitans includes morphologically diverse, metabolically versatile, fast-growing bacteria which play an important role in channelling carbon from primary producers to higher trophic levels [66].…”