Microbial and viral pathogens in freshwater: Current research aspects studied in Germany.

Continuous research in the field of water and health is important to ensure high standards of hygiene and to improve microbial risk assessment and water management. Various waterborne outbreaks induced by pathogenic bacteria, viruses and protozoa have been reported in recent decades. Pathogens derived from human and animal feces have been played frequently a key role in contaminations of freshwater. Reasons for the presence of pathogens in drinking water systems are insufficient wastewater treatment, contaminated raw water or damaged water supply systems. Numerous routes of transmission and the distribution of individual pathogens by raw water and drinking water constitute potential hazards to public health. Recently, different research activities have been initiated in Germany, which focus on the examination of pathogens in water to establish a modern microbial risk assessment according to the high-tech strategy employed by the federal government. This review article provides a compilation of the pathogens that are important in German water bodies (wastewater, surface water, groundwater, and drinking water) and includes coverage of German research on pathogens and technologies for reducing these pathogens in water, challenges to research, and recent developments in concentration and detection methods for pathogens. Finally, current knowledge gaps and ongoing research questions are highlighted

Traditional cattle manure application determines abundance, diversity and activity of methanogenic Archaea in arable European soil.

Based on lipid analyses, 16S rRNA/rRNA gene single-strand conformation polymorphism fingerprints and methane flux measurements, influences of the fertilization regime on abundance and diversity of archaeal communities were investigated in soil samples from the long-term (103 years) field trial in Bad Lauchstädt, Germany. The investigated plots followed a gradient of increasing fertilization beginning at no fertilization and ending at the 'cattle manure' itself. The archaeal phospholipid etherlipid (PLEL) concentration was used as an indicator for archaeal biomass and increased with the gradient of increasing fertilization, whereby the concentrations determined for organically fertilized soils were well above previously reported values. Methane emission, although at a low level, were occasionally only observed in organically fertilized soils, whereas the other treatments showed significant methane uptake. Euryarchaeotal organisms were abundant in all investigated samples but 16S rRNA analysis also demonstrated the presence of Crenarchaeota in fertilized soils. Lowest molecular archaeal diversity was found in highest fertilized treatments. Archaea phylogenetically most closely related to cultured methanogens were abundant in these fertilized soils, whereas Archaea with low relatedness to cultured microorganisms dominated in non-fertilized soils. Relatives of Methanoculleus spp. were found almost exclusively in organically fertilized soils or cattle manure. Methanosarcina-related microorganisms were detected in all soils as well as in the cattle manure, but soils with highest organic application rate were specifically dominated by a close phylogenetic relative of Methanosarcina thermophila. Our findings suggest that regular application of cattle manure increased archaeal biomass, but reduced archaeal diversity and selected for methanogenic Methanoculleus and Methanosarcina strains, leading to the circumstance that high organic fertilized soils did not function as a methane sink at the investigated site anymore

Biogeography of bacterioplankton in inland waters

Bacteria are among the most abundant groups of organisms. They mediate key ecological processes. Recent molecular advances have provided greater insight into bacterial diversity as well as allowing a more thorough examination of patterns in the spatial and temporal distribution of bacteria. Thus, the study of bacterial biodiversity and biogeographical distribution has stimulated considerable interest and dispute over the last decade. This review summarises the findings obtained from studies on the biogeography of bacterioplankton in inland waters. We examine factors and processes that may determine and maintain bacterial diversity and biogeography, and relate these to the theoretical metacommunity framework. We conclude that the importance of local environmental factors (such as lake character) for local bacterioplankton community compositions (BCC) is much more intensively studied than the importance of regional factors, such as dispersal. Further, few attempts have been made to evaluate simultaneously the relative importance of the two types of factors for BCC. Finally, we summarise gaps in knowledge, delineate challenges and put forward possible future research directions