Biology subjects

Ganzert, L.

Publications and source records attributed to Ganzert, L..

5 recordsLinked to original sources

bioRxiv2020

Urbanization promotes specific bacteria in freshwater microbiomes including potential pathogens

Freshwater ecosystems are characterized by complex and highly dynamic microbial communities that are strongly structured by their local environment and biota. Growing city populations and the process of urbanization substantially alter freshwater environments. To determine the changes in freshwater microbial communities associated with urbanization, full-length 16S rRNA gene PacBio sequencing was performed from surface water and sediments from a wastewater treatment plant, urban and rural lakes in the Berlin-Brandenburg region, Northeast Germany. Water samples exhibited highly habitat specific bacterial communities with multiple genera showing clear urban signatures. We identified potentially harmful bacterial groups associated with environmental parameters specific to urban habitats such as Alistipes, Escherichia/Shigella, Rickettsia and Streptococcus. We demonstrate that urbanization alters natural microbial communities in lakes and, via simultaneous eutrophication, creates favorable conditions that promote specific bacterial genera including potential pathogens. Our findings are of global relevance highlighting a long-term health risk in urbanized waterbodies, at a time of accelerated global urbanization. The results demonstrate the urgency for undertaking mitigation measures such as targeted lake restoration projects and sustainable water management efforts.

microbiology↗

bioRxiv2019

Variation of bacterial communities along the vertical gradient in Lake Issyk Kul, Kyrgyzstan

In this study, we explored the diversity and community composition of bacteria along a vertical gradient in Lake Issyk Kul, Kyrgyzstan, one of the largest and deepest brackish lakes in in the world. We identified 4904 bacterial ASVs based on analysis of 16S rRNA gene sequences and determined significant changes in the composition responding mainly to the variables depth and salinity. A higher abundance of Proteobacteria and Bacteroidetes was observed in the surface waters and the lake tributaries. Cyanobacteria were more abundant in the deep chlorophyll maximum (28.5 to 128 m), while Planctomycetes and Chloroflexi were dominant at depths between 128 to 600 m. According to our machine learning analysis used for identifying the most critical environmental factors, depth and temperature revealed the strongest effect on members of Proteobacteria, Planctomycetes, and Chloroflexi, while oxygen is associated with the variations in Cyanobacteria. Also, a notable increase in alpha diversity estimations was observed with increasing water depth. This work evidences significant differences in the structure of bacterial communities along the depth gradient in deep, transparent lake ecosystems. Notably, there is a dominance of Planctomycetes and Chloroflexi in the deepest layers, which can only be seen in a few other lakes with similar characteristics as Lake Issyk Kul and raises questions about their ecological role.

ecology↗

bioRxiv2019

Highly diverse fungal communities in carbon-rich aquifers of two contrasting lakes in Northeast Germany

Fungi are an important component of microbial communities and are well known for their ability to degrade refractory, highly polymeric organic matter. In soils and aquatic systems, fungi play an important role in carbon processing, however, their diversity, community structure and function as well as ecological role, particularly in groundwater, are poorly studied. The aim of this study was to examine the fungal community composition, diversity and function of 16 groundwater boreholes located in the vicinity of two lakes in NE Germany that are characterized by contrasting trophic status. The analysis of 28S rRNA gene sequences amplified from the groundwater revealed high fungal diversity and clear differences in community structure between both aquifers. Most sequences were assigned to Ascomycota and Basidiomycota, but members of Chytridiomycota, Cryptomycota, Zygomycota, Blastocladiomycota, Glomeromycota and Neocallmastigomycota were also detected. In addition, 27 species of fungi were successfully isolated from the groundwater wells and tested for their ability to degrade complex organic polymers - the predominant carbon source in the wells. Most isolates showed positive activities for at least one of the tested polymer types, with three strains, belonging to the genera Gibberella, Isaria and Cadophora, being able to degrade all tested substrates. Our results highlight the high diversity of fungi in groundwater, and point to their important ecological role in breaking down highly polymeric organic matter in these isolated microbial habitats.

microbiology↗

bioRxiv2018

Effects of zooplankton carcasses degradation on freshwater bacterial community composition and implications for carbon cycling

Non-predatory mortality of zooplankton provides an abundant, yet, little studied source of high quality labile organic matter (LOM) in aquatic ecosystems. Using laboratory microcosms, we followed the decomposition of organic carbon of fresh 13C-labelled Daphnia carcasses by natural bacterioplankton. The experimental setup comprised blank microcosms i.e. artificial lake water without any organic matter additions (B), and microcosms either amended with natural humic matter (H), fresh Daphnia carcasses (D) or both, i.e. humic matter and Daphnia carcasses (HD). Most of the carcass carbon was consumed and respired by the bacterial community within 15 days of incubation. A shift in the bacterial community composition shaped by labile carcass carbon and by humic matter was observed. Nevertheless, we did not observe a quantitative change in humic matter degradation by heterotrophic bacteria in the presence of LOM derived from carcasses. However, carcasses were the main factor driving the bacterial community composition suggesting that the presence of large quantities of dead zooplankton might affect the carbon cycling in aquatic ecosystems. Our results imply that organic matter derived from zooplankton carcasses is efficiently remineralized by a highly specific bacterial community, but doesnt interfere with the bacterial turnover of more refractory humic matter.

ecology↗

bioRxiv2018

The role of land use types and water chemical properties in structuring the microbiome of a connected lakes system

Lakes and other freshwater bodies are intimately connected to the surrounding land, yet to what extent land-use affects the quality of freshwater and the microbial communities living in various freshwater environments is largely unknown. We address this question through an analysis of the land use surrounding 46 inter-connected lakes located within 7 different drainage basins in northern Germany, and the microbiomes of these lakes during early summer. Lake microbiome structure was not determined by the specific drainage basin or by basin size, and bacterial distribution did not seem to be limited by distance. Instead, land use within the drainage basin could predict, to some extent, NO2+NO3 concentrations in the water, which (together with temperature, chlorophyll a and total phosphorus) affected water microbiome structure. Land use directly surrounding the water bodies, however, had little observable effects on water quality or the microbiome. Several microbial lineages, including environmentally important Cyanobacteria and Verrucomicrobia, were differentially partitioned between the lakes. As the amount of available data on land use (e.g. from remote sensing) increases, identifying relationships between land use, aquatic microbial communities and their effect on water quality will be important to better manage freshwater resources worldwide, e.g. by systemically identifying water bodies prone to ecological changes or the presence of harmful organisms.

microbiology↗