Salinity matters the most: How environmental factors shape the diversity and structure of cyanobacterial mat communities in high altitude arid ecosystems

IntroductionMicrobial mats are complex communities of benthic microorganisms that occur at the soil-water interphase in lakes’ shores, streams, and ponds. In the cold, mountainous desert of Eastern Pamir (Tajikistan), where scarce water bodies are influenced by extreme environmental conditions, photosynthetic cyanobacteria form diverse mats. The mats are characterized by different morphology and thickness. Their habitats exhibit a wide range of conditions; from oligosaline to hypersaline, oligotrophic to hypertrophic, and from cold ponds to hot springs. The aim of the present study was to reveal the taxonomic composition and structure of these mats and to examine which environmental factors influence them.MethodsFifty-one mats were collected from small water bodies around Bulunkul, Karakul, and Rangkul Lakes in 2015 and 2017. The physical and chemical properties of the water were measured in situ, while the concentration of nutrients was analyzed ex-situ. To reveal the taxonomic composition of the mats, the hypervariable V3-V4 region of the 16S rRNA gene was examined using NGS technology.ResultsThe results of bioinformatic analyses were compared with microscopic observations. They showed that Cyanobacteria was the dominant phylum, constituting on average 35% of bacterial ASVs, followed by Proteobacteria (28%), Bacteroidota (11%), and Firmicutes (9%). Synechococcales, Oscillatoriales, and Nostocales orders prevailed in Oxyphotobacteria, with a low contribution of Chroococcales, Gloeobacterales, and Chroococcidiopsidales. Occasionally the non-photosynthetic Vampirivibrionia (Melainabacteria) and Sericytochromatia from sister clades to Oxyphotobacteria were noted in the samples. Moreover, there was a high percentage of unidentified cyanobacterial sequences, as well as the recently described Hillbrichtia pamiria gen. et sp. nov., present in one of the samples. Salinity, followed by Na and K concentrations, correlated positively with the composition and structure of Oxyphotobacteria on different taxonomic levels and the abundance of all bacterial ASVs.DiscussionThe study suggests that the investigated communities possibly host more novel and endemic species. Among the environmental factors, salinity influenced the Oxyphotobacteria communities the most. Overall, the microenvironmental factors, i.e. the conditions in each of the reservoirs seemed to have a larger impact on the diversity of microbial mats in Pamir than the “subregional” factors, related to altitude, mean annual air temperature and distance between these subregions

Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains.Peer reviewe

Diversity and Colonization Strategies of Endolithic Cyanobacteria in the Cold Mountain Desert of Pamir

© 2020 by the authors.Microorganisms can survive in extreme environments and oligotrophic habitats thanks to their specific adaptive capacity. Due to its severe and contrasting climate conditions, the cold mountain desert in Eastern Pamir provides a unique environment for analyzing microbial adaptation mechanisms occurring within colonization of endolithic habitats. This study aims to investigate the composition and structure of endolithic microbial communities and analyze the interactions between microorganisms and colonized lithic substrates. Endolithic biofilms were examined using scanning electron microscopy in backscattered electron mode (SEM-BSE) and next-generation sequencing (NGS) applying amplicon sequence variants (ASVs) approach. The investigation of the V3–V4 region of 16S rRNA gene revealed that endolithic communities are dominated by Actinobacteria (26%), Proteobacteria (23%), and Cyanobacteria (11.4%). Cyanobacteria were represented by Oxyphotobacteria with a predominance of subclasses of Oscillatoriophycidae, Synechococcophycideae, and Nostocophycidae as well as the rarely occurring Sericytochromatia. The positive correlation between the contribution of the orders Synechococcales and Rhizobiales to community structure suggests that some functionally closed taxa of Cyanobacteria and Proteobacteria can complement each other, for example, in nitrogen fixation in endolithic communities. The endolithic communities occurring in Eastern Pamir were identified as complex systems whose composition and structure seem to be influenced by the architecture of microhabitats and related microenvironmental conditions.This research was funded by the National Science Centre, grant number 2015/19/B/NZ9/00473 (IJ), the Ministry of Science and Higher Education through the Faculty of Biology, University of Warsaw intramural grant number DSM501-D114-86-0117600-16 (NK), the grant PID2019-105469RBC22 (AR) and Integrated Development Programme (ZIP) of the University of Warsaw (NK).Peer reviewe

The Effects of Sodium Percarbonate Generated Free Oxygen on Daphnia—Implications for the Management of Harmful Algal Blooms

Increasing frequencies and durations of harmful algal blooms are a nuisance in many aquatic ecosystems. This has led to the use of a variety of control methods to prevent their appearance or to disperse them following their establishment. Most of these methods are not selective; consequently, research into alternative selective methods has been ongoing. Reactive oxygen species generated following the addition of hydrogen peroxide have been shown to selectively target the cyanobacterial component of harmful algal blooms in experimental and field settings. This study assesses the effects of increasing concentrations of reactive oxygen species from the addition of sodium percarbonate on zooplankton in a small experimental setting using a natural plankton sample. It was found that the genus Daphnia showed moderate sensitivity to sodium percarbonate. Preliminary evidence suggests that the size of an individual may affect the probability of survival, with larger individuals having a lower likelihood of survival. Lower survival rates of large Daphnia were hypothesized to have been caused by higher relative filtration rates of larger individuals. From the zooplankton data obtained, we suggest that a safe concentration of sodium percarbonate for Daphnia individuals would be below 10.0 mg·L−1 sodium percarbonate (2.8 mg·L−1 hydrogen peroxide)

Connectivity of edaphic and endolithic microbial niches in cold mountain desert of eastern pamir (Tajikistan)

Microbial communities found in arid environments are commonly represented by biologicalsoil crusts (BSCs) and endolithic assemblages. There is still limited knowledge concerning endolithsand BSCs occurring in the cold mountain desert of Pamir. The aim of the study was to investigate thecomposition and structure of endolithic bacterial communities in comparison to surrounding BSCs inthree subregions of the Eastern Pamir (Tajikistan). The endolithic and BSC communities were studiedusing culture-independent and culture dependent techniques. The structure of the endolithic bacte-rial communities can be characterized as Actinobacteria–Proteobacteria–Bacteroidetes–Chloroflexi–Cyanobacteria, while the BSCs’ can be described as Proteobacteria–Actinobacteria–Bacteroidetes–Cyanobacteria assemblages with low representation of other bacteria. The endolithic cyanobacterialcommunities were characterized by the high percentage of Chroococcidiopsaceae, Nodosilineaceae,Nostocaceae and Thermosynechococcaceae, while in the BSCs were dominated by Nodosilineaceae,Phormidiaceae and Nostocaceae. The analysis of 16S rRNA genes of the cyanobacterial culturesrevealed the presence of possibly novel species of Chroococcidiopsis,Gloeocapsopsis and Wilmottia.Despite the niches’ specificity, which is related to the influence of microenvironment factors onthe composition and structure of endolithic communities, our results illustrate the interrelationbetween the endoliths and the surrounding BSCs in some regions. The structure of cyanobacterialcommunities from BSC was the only one to demonstrate some subregional differences.This research was funded by the National Science Centre, grant number 2015/19/B/NZ9/00473 (I.J.), the Ministry of Science and Higher Education through the Faculty of Biology, University of Warsaw intramural grant number DSM501-D114-86-0117600-16 (N.K.), by the grant PID2019-105469RB-C22, AEI, MICINN (A.d.l.R.), and Integrated Development Programme (ZIP) of the University of Warsaw (N.K.).Peer reviewe

Isolation, purification et mise en culture des cyanobactéries toxigéniques

This chapter summarizes the most commonly used methods for the isolation, purification, and cultivation of toxic cyanobacteria. The aim is to give general advice on how to isolate and maintain clonal cyanobacterial cultures in order to use them in genetic studies. The traditional methods for the isolation of cyanobacteria into culture are well established and described and there are several excellent reviews with detailed information on culturing techniquesB-BLOOMS, CCAMBIO, CYANOCOS

Environmental factors related to the distribution pattern of Raphidiopsis raciborskii and R. mediterranea in Central East Europe

Raphidiopsis raciborskii originates from tropical and subtropical regions, however its expansion toward temperate zone during last decades has been observed. Phenotypic plasticity, occurrence of ecotypes differing in their environmental adaptations and climate changes are indicated among factors responsible for its successful expansion. Much less is known about distribution pattern of Raphidiopsis mediterranea native for warm areas along Mediterranean cost. Therefore, the aim of the study was to determine the current distribution of these species in Polish and Lithuanian lakes and to detect environmental factors related to their occurrence. The R. raciborskii was much more common and occurred in 31 out of 112 lakes, while R. mediterranea in 7 lakes. The contribution of these species in total phytoplankton biomass ranged from 0.1 to 31% and from 0.1 to 2.6% respectively. Similarly to previous studies R. raciborskii was much more common in Western Poland where it significantly increased its contribution in phytoplankton biomass however it was detected in several new lakes in Eastern Poland. In Lithuania its occurrence is still limited to one lake. R. mediterranea occurred in similar number of lakes in both regions of Poland only. Among environmental factors conductivity and temperature were positively correlated with R. raciborskii biomass

Data_Sheet_1_Salinity matters the most: How environmental factors shape the diversity and structure of cyanobacterial mat communities in high altitude arid ecosystems.docx

IntroductionMicrobial mats are complex communities of benthic microorganisms that occur at the soil-water interphase in lakes’ shores, streams, and ponds. In the cold, mountainous desert of Eastern Pamir (Tajikistan), where scarce water bodies are influenced by extreme environmental conditions, photosynthetic cyanobacteria form diverse mats. The mats are characterized by different morphology and thickness. Their habitats exhibit a wide range of conditions; from oligosaline to hypersaline, oligotrophic to hypertrophic, and from cold ponds to hot springs. The aim of the present study was to reveal the taxonomic composition and structure of these mats and to examine which environmental factors influence them.MethodsFifty-one mats were collected from small water bodies around Bulunkul, Karakul, and Rangkul Lakes in 2015 and 2017. The physical and chemical properties of the water were measured in situ, while the concentration of nutrients was analyzed ex-situ. To reveal the taxonomic composition of the mats, the hypervariable V3-V4 region of the 16S rRNA gene was examined using NGS technology.ResultsThe results of bioinformatic analyses were compared with microscopic observations. They showed that Cyanobacteria was the dominant phylum, constituting on average 35% of bacterial ASVs, followed by Proteobacteria (28%), Bacteroidota (11%), and Firmicutes (9%). Synechococcales, Oscillatoriales, and Nostocales orders prevailed in Oxyphotobacteria, with a low contribution of Chroococcales, Gloeobacterales, and Chroococcidiopsidales. Occasionally the non-photosynthetic Vampirivibrionia (Melainabacteria) and Sericytochromatia from sister clades to Oxyphotobacteria were noted in the samples. Moreover, there was a high percentage of unidentified cyanobacterial sequences, as well as the recently described Hillbrichtia pamiria gen. et sp. nov., present in one of the samples. Salinity, followed by Na and K concentrations, correlated positively with the composition and structure of Oxyphotobacteria on different taxonomic levels and the abundance of all bacterial ASVs.DiscussionThe study suggests that the investigated communities possibly host more novel and endemic species. Among the environmental factors, salinity influenced the Oxyphotobacteria communities the most. Overall, the microenvironmental factors, i.e. the conditions in each of the reservoirs seemed to have a larger impact on the diversity of microbial mats in Pamir than the “subregional” factors, related to altitude, mean annual air temperature and distance between these subregions.</p