High diversity of cultivable heterotrophic bacteria in association with cyanobacterial water blooms

Abstract

Cyanobacterial mass occurrences (water blooms) cause ecological, economic and health problems worldwide. Still, little is known about heterotrophic bacteria associated with cyanobacteria and the interactions between those organisms. We isolated 460 bacterial strains from more than 40 lakes and rivers (151 samples), Baltic Sea (32 samples) and treated drinking water of seven treatment plants (29 samples). The water bodies and the raw water of the treatment plants were frequently dominated by high numbers of cyanobacteria. Various growth media were used to isolate the strains. Analysis of partial 16S rRNA gene fragments (701-905 bp for 358 strains and 413-497 bp for 102 strains) classified the isolated bacteria as Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes and Deinococcus-Thermus. Some of these isolates represented possible new bacterial orders, families, genera or species. We isolated various potentially pathogenic bacteria, such as Aeromonas, Vibrio, Acinetobacter and Pseudomonas, that may cause adverse health effects in humans and animals and should be taken into consideration when assessing the risks caused by cyanobacterial blooms. Several strains also inhibited or enhanced the growth of cyanobacteria. Most of such strains had an enhancing effect on the cyanobacterial growth. Other isolates were affiliated with genera such as Sphingomonas or Flavobacterium, which include strains that are capable of degrading cyanobacterial toxins or other recalcitrant and problematic organic compounds. The isolated strains provide a large group of bacteria that could be used in assessing and controlling the harmful effects of cyanobacteria.

Changes in abundance and community structure of bacteria associated with buoyantMicrocystiscolonies during the decline of cyanobacterial bloom (autumn–winter transition)

“…Some bacterial strains of these species are cold-adapted (Singh et al, 2000). In addition, the Aeromonas genera, which may cause adverse effects to the health of humans and animals, were found to be associated with cyanobacterial blooms (Berg et al, 2009;Kormas et al, 2010). Evidence for Aeromonas chemotaxis to cyanobacteria (Aphanizomenon flos-aquae) was found by Kangatharalingam et al (1991).…”

“…during the vigorous period of bloom (Shi et al, 2010). Bacteria related to Sphingomonas or Flavobacterium are capable of degrading cyanobacterial toxins or other problematic organic complex compounds (Valeria et al, 2006;Berg et al, 2009).…”

Pyrosequencing reveals contrasting seasonal dynamics of taxa within Baltic Sea bacterioplankton communities

“…This is not surprising, as phytoplankton blooms may represent a significant input of biologically labile organic compounds available to the bacterioplankton community. A recent study covering a wide range of aquatic systems (lakes, the Baltic Sea and treated drinking water) suggest that there may be more intricate linkages between heterotrophic bacteria and bloom-forming Cyanobacteria, as many isolated bacterial strains were capable of either enhancing, or occasionally inhibiting, the growth of bloom-forming Cyanobacteria (Berg et al, 2009). The strong positive correlations observed between a few individual OTUs and bloom-forming Cyanobacteria in this study indicate functional couplings and motivate directed studies on their potential interactions.…”

Morphological and physiological changes in Microcystis aeruginosa as a result of interactions with heterotrophic bacteria

“…Bands MC7, MC11 and MC12 are seen as bright bands prior to the cell aggregation and probably represent specialist heterotrophic bacteria responsible for the aggregation of M. aeruginosa. Porphyrobacter species (band MC11) (Berg et al, 2009;Hube, Heyduck-Sö ller & Fische, 2009;Shi et al, 2009) and Flavobacteriaceae species (band MC12) (Eiler & Bertilsson, 2004;Mueller-Spitz, Goetz & McLellan, 2009) have previously been detected in association with Microcystis or other cyanobacterial blooms, but the uncultured bacterium S1-mc07 (band MC7) had never been reported in cyanobacterial blooms. Band MC12 disappeared and band MC5 increased in brightness after colonial M. aeruginosa formation, indicating that pronounced competition among these dominating heterotrophic bacteria and uncultured bacterium S1-mc05 (band MC5) perhaps related to maintenance of colonies of M. aeruginosa with other dominant heterotrophic bacteria (bacterium S1-mc07 and S1-mc11).…”