Insight into the hidden bacterial diversity of Lake Balaton, Hungary

Abstract

In the present study, the prokaryotic community structure of the water of Lake Balaton was investigated at the littoral region of three different points (Tihany, Balatonmáriafürdő and Keszthely) by cultivation independent methods [next-generation sequencing (NGS), specific PCRs and microscopy cell counting] to check the hidden microbial diversity of the lake. The taxon-specific PCRs did not show pathogenic bacteria but at Keszthely and Máriafürdő sites extended spectrum betalactamase-producing microorganisms could be detected. The bacterial as well as archaeal diversity of the water was high even when many taxa are still uncultivable. Based on NGS, the bacterial communities were dominated by Proteobacteria, Bacteroidetes and Actinobacteria, while the most frequent Archaea belonged to Woesearchaeia (Nanoarchaeota). The ratio of the detected taxa differed among the samples. Three different types of phototrophic groups appeared: Cyanobacteria (oxygenic phototrophic organisms), Chloroflexi (anaerobic, organotrophic bacteria) and the aerobic, anoxic photoheterotrophic group (AAPs). Members of Firmicutes appeared only with low abundance, and Enterobacteriales (order within Proteobacteria) were present also only in low numbers in all samples.

Does the Kis-Balaton Water Protection System (KBWPS) Effectively Safeguard Lake Balaton from Toxic Cyanobacterial Blooms?

“…During June 2018, Microcystis aeruginosa and Oscillatoria tenuis were the only two cyanobacterial species detected in the Siófok Basin (Basin 4). This result differs from the observations of Tóth et al [ 53 ] made during August 2018 and Farkas et al [ 40 ] made during June 2017. In the study of Farkas et al [ 40 ], the dominant species in the central and eastern basins (Basins 3 and 4) of Lake Balaton was determined to be the picocyanobacterium Synechococcus sp.…”

“…In the study of Farkas et al [ 40 ], the dominant species in the central and eastern basins (Basins 3 and 4) of Lake Balaton was determined to be the picocyanobacterium Synechococcus sp. The study of Tóth et al [ 53 ] further confirms this finding as samples originating from Tihány were dominated by species originating from the order Synechococcales, while there were far fewer cyanobacteria from the order Nostocales. In addition, the study of Somogyi et al [ 54 ] reviews the decade-long occurrence of picoplankton in Lake Balaton.…”

“…The difference in cyanobacteria community composition between the studies most likely originates from the method of determination. In the present study, we used a traditional microscopy-based species determination method, whereas the studies of Tóth et al [ 53 ] and Farkas et al [ 40 ] solely relied on next-generation sequencing. Picocyanobacteria are very small (up to 2 µm in diameter [ 54 ]) and hardly detectable with light microscopy.…”

Freshwater ecosystems: research, policy and applications

“…The paper by Tóth et al (2020) links the two previous papers in its topic and presents original research on Lake Balaton microbial communities. Using cultivation-independent methods (NGS next-generation sequencing, specific PCRs and microscopic cell counting), they discovered a much higher diversity of microbes than assumed on the basis of previous cultivation-based findings.…”

“…Based on the environmental factors, the suggested method also makes it possible to formulate suggestions towards conservation. For their study, Decsi et al chose the River Zala catchment area, which is the largest tributary of the Lake Balaton and thus is of special importance to the dynamics of several of the groups reviewed in other papers of this issue (see Somogyi et al 2020;Tóth et al 2020).…”