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Available guidance to mitigate health risks from exposure to freshwater harmful algal blooms (HABs) is largely derived from temperate ecosystems. Yet in tropical ecosystems, HABs can occur year-round, and resource-dependent populations face multiple routes of exposure to toxic components. Along Winam Gulf, Lake Victoria, Kenya, fisher communities rely on lake water contaminated with microcystins (MCs) from HABs. In these peri-urban communities near Kisumu, we tested hypotheses that MCs exceed exposure guidelines across seasons, and persistent HABs present a chronic risk to fisher communities through ingestion with minimal water treatment and frequent, direct contact. We tested source waters at eleven communities across dry and rainy seasons from September 2015 through May 2016. We measured MCs, other metabolites, physicochemical parameters, chlorophyll a, phytoplankton abundance and diversity, and fecal indicators. We then selected four communities for interviews about water sources, usage, and treatment. Greater than 30% of source water samples exceeded WHO drinking water guidelines for MCs (1μg/L), and over 60% of source water samples exceeded USEPA guidelines for children and immunocompromised individuals. 50% of households reported sole use of raw lake water for drinking and household use, with alternate sources including rain and boreholes. Household chlorination was the most widespread treatment utilized. At this tropical, eutrophic lake, HABs pose a year-round health risk for fisher communities in resource -limited settings. Community-based solutions and site-specific guidance for Kisumu Bay and similarly impacted regions is needed to address a chronic health exposure likely to increase in severity and duration with global climate change.

Cyanobacterial bioactive metabolites (cyanotoxins/cyanopeptides) inhibit enzymes such as proteases, carboxypeptidases, and phosphatases that disrupt metabolic processes relevant to human and ecosystem health. From surface water samples collected in 2017 (n = 44), 2018 (n = 100), and 2019 (n = 171), we report concentrations of more than 20 biologically active cyanobacterial compounds in the western basin of Lake Erie, one of the five Laurentian Great Lakes with multinational jurisdiction. Toxic microcystins LA and LR as well as anabaenopeptin B and F were most frequently detected at >90%. Microcystins RR and YR and anabaenopeptin A were detected at relatively high frequency at >80% in 2019. There was strong correlation among arginine-containing microcystin variants (RR, YR, HtyR, LR, HilR, WR, D-Asp3-LR, Spearman's Rho >0.80) but not with arginine-lacking LY, LW, LF. Anabaenopeptin F, with the arginine sidechain, also correlated with these same arginine-containing microcystin variants (Spearman's Rho >0.70). In 2019, only 4% of lake water samples exceeded the recreational water guideline for total microcystins (10 µg l-1) set by Health Canada with the maximum concentration ∼26 µg l-1. The drinking water guideline (1.5 µg l-1) was exceeded in 34% of lake water samples but treated water was not tested. Although maximum total anabaenopeptins concentration was almost four times higher (almost 100 µg l-1) than microcystins, no anabaenopeptin guideline values have been derived as their impact is currently considered to be ecological rather than toxic to humans/animals. These results can be used to evaluate risk from cyanobacterial bioactive metabolites, including toxins, in Lake Erie and aid binational lake management and policy development in the Great Lakes basin. [ABSTRACT FROM AUTHOR]

Author(s): Mary Ann Moran (corresponding author) [1]; Alison Buchan [3]; José M. González [4]; John F. Heidelberg [5]; William B. Whitman [2]; Ronald P. Kiene [6]; James R. Henriksen [2]; [...]

The implication of Silicibacter sp. strain TM1040 in establishing and maintaining its interaction with Pfiesteria piscicida is discussed. The test results show that TM1040 is a very good model for studying bacterium-dinoflagellate interactions.

A test is conducted on the hypothesis that a relationship is struck between the Roseobacter species and Dimethylsulfoniopropionate producing dinoflagellates. The methods and results are discussed.

Pollutants such as polychlorinated biphenyls and dioxins pose a serious threat to human and environmental health. Natural attenuation of these compounds by microorganisms provides one promising avenue for their removal from contaminated areas. Over the past 2 decades, studies of the bacterium Sphingomonas wittichii RW1 have provided a wealth of knowledge about how bacteria metabolize chlorinated aromatic hydrocarbons. Here we describe the finished genome sequence of S. wittichii RW1 and major findings from its annotation. doi: 10.1128/JB.01030-10