This book describes the present state of knowledge regarding the impact of cyanobacteria on health through the use of water. It considers aspects of risk management and details the information needed for protecting drinking water sources and recreational water bodies from the health hazards caused by cyanobacteria and their toxins. It also outlines the state of knowledge regarding the principal considerations in the design of programmes and studies for monitoring water resources and supplies and describes the approaches and procedures used.
The development of this publication was guided by the recommendations of several expert meetings concerning drinking water (Geneva, December 1995; Bad Elster, June
1996) and recreational water (Bad Elster, June 1996; St Helier, May 1997). An expert meeting in Bad Elster, April 1997, critically reviewed the literature concerning the toxicity of cyanotoxins and developed the scope and content of this book. A draft manuscript was reviewed at an editorial meeting in November 1997, and a further draft was
reviewed by the working group responsible for updating the Guidelines for Drinkingwater Quality in March 1998.

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Toxic cyanobacteria in water: a guide to their public health consequences, monitoring and management.

The rise of harmful cyanobacteria blooms: The potential roles of eutrophication and climate change

Cyanobacteria are the Earth's oldest known oxygen-evolving photosynthetic microorganisms, and they have had major impacts on shaping our current atmosphere and biosphere. Their long evolutionary history has enabled cyanobacteria to develop survival strategies and persist as important primary producers during numerous geochemical and climatic changes that have taken place on Earth during the past 3.5 billion years. Today, some cyanobacterial species form massive surface growths or 'blooms' that produce toxins, cause oxygen depletion and alter food webs, posing a major threat to drinking and irrigation water supplies, fishing and recreational use of surface waters worldwide. These harmful cyanobacteria can take advantage of anthropogenically induced nutrient over-enrichment (eutrophication), and hydrologic modifications (water withdrawal, reservoir construction). Here, we review recent studies revealing that regional and global climatic change may benefit various species of harmful cyanobacteria by increasing their growth rates, dominance, persistence, geographic distributions and activity. Future climatic change scenarios predict rising temperatures, enhanced vertical stratification of aquatic ecosystems, and alterations in seasonal and interannual weather patterns (including droughts, storms, floods); these changes all favour harmful cyanobacterial blooms in eutrophic waters. Therefore, current mitigation and water management strategies, which are largely based on nutrient input and hydrologic controls, must also accommodate the environmental effects of global warming.

Climate change: A catalyst for global expansion of harmful cyanobacterial blooms

Cyanobacteria are the Earth’s oldest oxygenic photoautotrophs and have had major impacts on shaping its biosphere. Their long evolutionary history (∼3.5 by) has enabled them to adapt to geochemical and climatic changes, and more recently anthropogenic modifications of aquatic environments, including nutrient over-enrichment (eutrophication), water diversions, withdrawals, and salinization. Many cyanobacterial genera exhibit optimal growth rates and bloom potentials at relatively high water temperatures; hence global warming plays a key role in their expansion and persistence. Bloom-forming cyanobacterial taxa can be harmful from environmental, organismal, and human health perspectives by outcompeting beneficial phytoplankton, depleting oxygen upon bloom senescence, and producing a variety of toxic secondary metabolites (e.g., cyanotoxins). How environmental factors impact cyanotoxin production is the subject of ongoing research, but nutrient (N, P and trace metals) supply rates, light, temperature, oxidative stressors, interactions with other biota (bacteria, viruses and animal grazers), and most likely, the combined effects of these factors are all involved. Accordingly, strategies aimed at controlling and mitigating harmful blooms have focused on manipulating these dynamic factors. The applicability and feasibility of various controls and management approaches is discussed for natural waters and drinking water supplies. Strategies based on physical, chemical, and biological manipulations of specific factors show promise; however, a key underlying approach that should be considered in almost all instances is nutrient (both N and P) input reductions; which have been shown to effectively reduce cyanobacterial biomass, and therefore limit health risks and frequencies of hypoxic events.

Harmful cyanobacterial blooms: causes, consequences, and controls.

Medical device-associated infections account for a large proportion of hospital-acquired infections. A variety of opportunistic pathogens can cause implant infections, depending on the type of the implant and on the anatomical site of implantation. The success of these versatile pathogens depends on rapid adhesion to virtually all biomaterial surfaces and survival in the hostile host environment. Biofilm formation on implant surfaces shelters the bacteria and encourages persistence of infection. Furthermore, implant-infecting bacteria can elude innate and adaptive host defences as well as biocides and antibiotic chemotherapies. In this Review, we explore the fundamental pathogenic mechanisms underlying implant infections, highlighting orthopaedic implants and Staphylococcus aureus as a prime example, and discuss innovative targets for preventive and therapeutic strategies.

Implant infections: adhesion, biofilm formation and immune evasion

Cyanobacterial secondary metabolites have attracted increasing scientific interest due to bioactivity of many compounds in various test systems. Among the known structures, oligopeptides are often found with many congeners sharing conserved substructures, while being highly variable in others. A major part of known oligopeptides are of non-ribosomal origin and can be grouped into classes with conserved structural properties. Thus, the overall structural diversity of cyanobacterial oligopeptides only seemingly suggests an equally high diversity of biosynthetic pathways and respective genes. For each class of peptides, some of which have been found in all major branches of the cyanobacterial evolutionary tree, homologous synthetases and genes can be inferred. This implies that non-ribosomal peptide synthetase genes are a very ancient part of the cyanobacterial genome and presumably have evolved by recombination and duplication events to reach the present structural diversity of cyanobacterial oligopeptides. In addition, peptide synthetases would appear to be an essential part of the cyanobacterial evolution and physiology. The present review presents an overview of the biosynthesis of cyanobacterial peptides and corresponding gene clusters, the structural diversity of structural types and structural variations within peptide classes, and implications for the evolution and plasticity of biosynthetic genes and the potential function of cyanobacterial peptides.

Cyanobacterial peptides – Nature's own combinatorial biosynthesis

Applications of whole-cell matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry in systematic microbiology.

The invention of MALDI-TOF-MS enormously contributed to the understanding of protein chemistry and cell biology. Without this technique proteomics would most likely not be the important discipline it is today. Besides 'true' proteomics, MALDI-TOF-MS was applied for the analysis of microorganisms for their taxonomic characterization from its beginning. This approach has since been developed as a diagnostic tool readily available for routine, high-throughput analysis of microbial isolates from clinical specimens by intact-cell mass spectrometry (ICMS), the direct analysis of whole bacterial cell without a preceding fractionation or separation by chromatography or electrophoresis. ICMS exploits the reproducibility of mass fingerprints for individual bacterial and fungal strains as well as the high similarity of mass fingerprints within a species. Comparison of mass spectral data to genomic sequences emphasized the validity of peak patterns as taxonomic markers. Supported by comprehensive databases, MALDI-TOF-MS-based identification has been widely accepted in clinical laboratories within only a few years.

Proteomics for routine identification of microorganisms.

We studied plankton dynamics using a Lagrangian sampling strategy in a 21-km-long reach of the river Spree (Germany), located downstream of a shallow lake. The lake was productive and had a high output of plankton into the river. The zooplankton community was dominated by rotifers whose densities reached 130-4,500 ind liter-l in the lake outlet. The phytoplankton community was dominated by centric diatoms. Downstream, densities of all zooplanktonic taxa decreased exponentially with coefficients of determination of up to R* = 0.99. Relative abundances stayed almost unchanged in dominant species, and coefficients of variation did not exceed 15% despite a total reduction of individuals to 3-30% within the river reach. Chlorophyll a and oxygen contents decreased exponentially, whereas Secchi depths and inorganic nutrient concentrations increased. Population growth rates in zooplankton and phytoplankton were always negative and positively correlated to flow velocity. Ratios of the total number of rotifer eggs to the total number of rotifer females were constant. In Kerutellu cochlearis and Synchuetu oblonga, the dominant rotifer species, birth rates remained high during downstream transport. Therefore, the negative growth rates in the river (= - 1.5 d-l) were caused by an abrupt increase in death rates to levels of about 1.9 d-l at the lake-river transition. This shift was induced by an increase in predation rate caused by the filtration activity of unionid bivalves that were abundant in the river reach.

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1998.43.5.0753

Can mussels control the plankton in rivers?- a planktological approach applying a Lagrangian sampling strategy

Microcystis sp. has been recognized in recent years as a producer of a high number of secondary metabolites. Among these, peptides that are produced by the non-ribosomal peptide synthetase pathway often show bioactivity or are toxic to humans. The production of particular peptides is specific for individual Microcystis clones, allowing their characterization as chemotypes by analysing the peptidome. The authors studied the in situ diversity of peptides and chemotypes in Microcystis communities from lakes in and around Berlin, Germany, by direct analysis of individual colonies by MALDI-TOF mass spectrometry. From 165 colonies analysed a total of 46 individual peptides could be identified, 21 of which have not been described previously. For six of the new peptides the structures could be elucidated from fragment patterns, while for others only a preliminary classification could be achieved. In most colonies, two to ten individual peptides were detected. In 19 colonies, 16 of which were identified as M. wesenbergii, no peptide metabolites could be detected. The peptide data of 146 colonies were subjected to an ordination (principal components analysis). The principal components were clearly formed by the microcystin variants Mcyst-LR, -RR and -YR, anabaenopeptins B and E/F, a putative microviridin, and a new cyanopeptolin. In the resulting ordination plots most colonies were grouped into five distinct groups, while 40 colonies scattered widely outside these groups. In some cases colonies from different lakes clustered closely, indicating the presence of similar chemotypes in the respective samples. With respect to colony morphology no clear correlation between a chemotype and a morphospecies could be established, but M. aeruginosa, for example, was found to produce predominantly microcystins. In contrast, M. ichthyoblabe colonies were mostly negative for microcystins and instead produced anabaenopeptins. The number of peptides detected in a limited number of samples and the various combinations of peptides in individual Microcystis colonies highlights the immense metabolic potential and diversity of this genus.

Martin Welker

Papers

Cyanobacterial peptides – Nature's own combinatorial biosynthesis

Applications of whole-cell matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry in systematic microbiology.

Proteomics for routine identification of microorganisms.

Can mussels control the plankton in rivers?- a planktological approach applying a Lagrangian sampling strategy

Diversity and distribution of Microcystis (Cyanobacteria) oligopeptide chemotypes from natural communities studied by single-colony mass spectrometry.