PAH biodegradative genotypes in Lake Erie sediments: Evidence for broad geographical distribution of pyrene-degrading Mycobacteria

Despite a long history of anthropogenic contamination of Lake Erie sediments, little work has been done to understand the potential for PAH biodegradation by indigenous microbial communities. Pyrene-degrading Mycobacterium are prevalent in many polycyclic aromatic hydrocarbon (PAH)-contaminated freshwater sediments, and are of interest for their ability to degrade environmentally recalcitrant high molecular weight PAHs. This work tested the hypothesis that pyrene-degrading mycobacteria are prevalent in Lake Erie; an additional aim was to gain a baseline picture of the sediment microbial communities through sequencing a 16S rDNA clone library. Biodegradation potential of Lake Erie Mycobacterium populations was assessed through quantification of pyrene dioxygenase genes (nidA) and mycobacteria 16S rDNA genes using quantitative real time PCR. nidA was detected at all seven sampling sites across Lake Erie, with abundances ranging from 2.09 to 70.4 × 106 copies per gram sediment, with highest abundances at the most PAH-contaminated site (Cleveland Harbor). This is in contrast to naphthalene dioxygenase genes commonly used as biomarkers of PAH degradation: nahAc (from γ-proteobacteria) was not detected anywhere, and nagAc (from β-proteobacteria) was detected only in Cleveland Harbor, despite dominance by proteobacteria in Lake Erie sediment 16S rDNA clone libraries (\u3e50% of clones). The prevalence of Mycobacterium nidA genotypes corroborated previous studies indicating that PAH-degrading mycobacteria have a cosmopolitan distribution and suggests they play an important but overlooked role in natural attenuation and cycling of PAHs in Lake Erie

Lake Erie \u3cem\u3eMicrocystis\u3c/em\u3e: relationship between microcystin production, dynamics of genotypes and environmental parameters in a large lake

Cyanobacteria of genus Microcystis sp. have been commonly found in Lake Erie waters during recent summer seasons. In an effort to elucidate relationships between microcystin production, genotypic composition of Microcystis community and environmental parameters in a large lake ecosystem, we collected DNA samples and environmental data during a three-year (2003–2005) survey within Lake Erie and used the data to perform a series of correlation analyses. Cyanobacteria and Microcystis genotypes were quantified using quantitative real-time PCR (qPCR). Our data show that Microcystis in Lake Erie forms up to 42% of all cyanobacteria, and that Microcystis exists as a mixed population of potentially toxic and (primarily) non-toxic genotypes. In the entire lake, the total abundance of Microcystis as well as the abundance of microcystin-producing Microcystis is strongly correlated with the abundance of cyanobacteria suggesting that Microcystis is a significant component of the cyanobacterial community in Lake Erie during summer seasons. The proportion of total Microcystis of all cyanobacteria was strongly linked to the microcystin concentrations, while the percentage of microcystin-producing genotypes within Microcystis population showed no correlation with microcystin concentrations. Correlation analysis indicated that increasing total phosphorus concentrations correlate strongly with increasing microcystin concentrations as well as with the total abundance of Microcystis and microcystin-producing Microcystis

The diversity and distribution of toxigenic \u3cem\u3eMicrocystis\u3c/em\u3e spp. In present day and archived pelagis and sediment samples from Lake Erie

The reoccurrence of significant cyanobacterial blooms in Lake Erie during the last 13 years has raised questions concerning the long-term persistence of microcystin-producing cyanobacteria and the presence of natural sediment reservoirs for potentially toxic cyanobacteria in this large lake system. To address these questions, we analyzed phytoplankton and sediment samples which were collected and preserved in the 1970s as well as samples collected in 2004 from locations within Lake Erie. The identification of microcystin-producing cyanobacteria in Lake Erie was examined via PCR amplification of the mcyA gene fragment. Based on the high % sequence similarity, the mcyA sequences from all 1970s phytoplankton and sediment samples were determined to belong to Microcystis spp., in spite of reports suggesting that Lake Erie was dominated by filamentous cyanobacteria in the 1970s. In sediment samples from 2004, signature genes for Microcystis were distributed and preserved not only in the surface sediments but also up to 10–12 cm in depth. Based on cell quantities determined by a quantitative polymerase chain reaction (qPCR) method, 0.18% of eubacteria in the sediments were Microcystis cells, of which 4.8% were potential microcystin producers. In combination with experiments showing that Microcystis cells can be cultured from Lake Erie surface sediments, this paper demonstrates the potential for these sediments to act as a reservoir for pelagic Microcystis populations and that the composition of the population of microcystin-producing cyanobacteria in Lake Erie has not changed remarkably since the 1970s

Reconstruction and identification of τ lepton decays to hadrons and ντ at CMS

This paper describes the algorithms used by the CMS experiment to reconstruct and identify τ → hadrons + ντ decays during Run 1 of the LHC. The performance of the algorithms is studied in proton-proton collisions recorded at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb‑1. The algorithms achieve an identification efficiency of 50–60%, with misidentification rates for quark and gluon jets, electrons, and muons between per mille and per cent levels