Resilience of planktonic bacterial community structure in response to short-term weather deterioration during the growing season in an alpine lake

Abstract

The disturbing effect of a short-term cooling period during summer on planktonic bacterial community structure of an alpine lake was investigated using 16S rDNA pyrosequencing. Proteobacteria, Actinobacteria, and Bacteroidetes constituted the most abundant phyla. During the sampling period (from July to August 2010), a sudden cooling period with high precipitation occurred, as indicated by a decrease in conductivity, calcium, and dissolved organic carbon concentration resulting from increased runoff. The relative abundance of Actinobacteria, Betaproteobacteria, and Cyanobacteria decreased during this short-term cooling period. Instead, a rapid shift from Betaproteobacteria to Gammaproteobacteria occurred, which was mainly caused by an increase of Acinetobacter rhizosphaerae. Soon after the shortterm cooling period, warmer weather conditions got re-established and Betaproteobacteria recovered and became again dominant. Non-metric multi-dimensional scaling analysis and Venn diagrams revealed a planktonic bacterial community composition with high similarity at the beginning and the end of the growing season. Air temperature and precipitation were significantly correlated with the observed variation in operational taxonomic unit (OTU) relative abundance. It is concluded that, in response to the short-term cooling period, a distinct planktonic bacterial OTU community developed. It rapidly diminished, however, as summer conditions became reestablished, implying the recovery of the original bacterial community structure.

Sediment Bacteria in the Alpine Lake Sayram: Vertical Patterns in Community Composition

“…Some Hydrogenophaga species have been found to be important anaerobic DNRA bacteria [43] and potential degraders for petroleum hydrocarbon and polynuclear aromatic hydrocarbons (PAHs) [44]. A previous study has also linked Pseudomonas and Hydrogenophaga to hydrogen autotrophic denitrification [41]. In our investigation, it was clearly observed that the relative abundance of Acinetobacter increased with sediment depth (Figure 2), suggesting that a greater degree of hydrogen autotrophic denitrification occurred in the deeper sediment layers than in the top sediment layers.…”

“…This may explain why Acinetobacter is the most dominant genus in the sediment core of Lake Sayram, which is a cold-water inland lake, with a mean temperature of about 1.1 • C and a maximum temperature of roughly 19 • C [16]. Previous studies have also shown that many Acinetobacter species isolated from oligotrophic habitats have a stronger tolerance to low temperatures and can thrive well in cold environments [40][41][42].…”

Gut microbiome of century-old snail specimens stable across time in preservation

“…Significant variation in community composition is attributed to factors other than preservation period, including geographic location. Other factors not addressed in this study, such as whether the samples were first fixed in formalin and then moved into ethanol preservation, percentage of ethanol used (e.g., 70% versus 95% ethanol), and temperature-controlled storage, as well as fluctuations like freeze–thaw cycles, may have a greater impact on microbiome makeup than storage time [ 6 , 14 , 29 ].…”

Bacterial matrix metalloproteases and serine proteases contribute to the extra-host inactivation of enteroviruses in lake water

“…While all samples were taken during dry and sunny weather, intermittent days with heavy rainfall between sampling events were noted. Weather variations are known to modify the level of nutrients available for microorganisms, naturally reshaping bacterial populations over short periods of time [ 20 , 21 ]. Rainfall may thus contribute to the observed differences in virus decay between samples.…”