Project leader: Professor LIISA LEPISTÖ,
Finnish Environment Institute, P.O. Box 140, FIN-00251 Helsinki, Finland, tel. +358 9 40300 312, e-mail: liisa.lepisto@ymparisto.fi
Researcher: Katri Berg, Finnish Environment Institute, karti.berg@ymparisto.fi
Other researchers of the project:
Dr. Christina Lyra, Finnish Environment Institute
Doc, M.D. Kalle Hoppu, Helsinki University Central Hospital, Poison Information Centre
M.Sc. Marjut Räsänen, City of Helsinki Environment Center
Doc, Dr. Maarit Niemi, Finnish Environment Institute
Dr. Kirsti Lahti, Water Protection Association of the River Vantaa and Helsinki Region
Dr. Jarkko Rapala, National Product Control Agency for Welfare and Health
Ms Kirsti Erkomaa, Finnish Environment Institute
Dr. Andrew Negri, Australian Institute of Marine Science
Dr. Alison Robertson, Australian Institute of Marine Science
Key words: cyanobacteria, toxication, pathogenic bacteria, bacterial diversity
Results
The study combined medical, environmental, microbiological, taxonomical and biochemical expertise in order to study acute intoxications associated with cyanobacteria, identify the causative agents and describe heterotrophic bacterial diversity in association of cyanobacteria.
Over five hundred cyanobacterial water blooms were studied for species composition and the presence of toxins. Approximately 130 samples were associated with adverse human health effects (headache, skin and eye irritations, fever, vomiting, diarrhea, and more severe symptoms such as visual disturbances, seizure and musculoskeletal symptoms). Over 150 patients were interviewed, and their symptoms were linked to the results of the water analyses. Such a wide research on acute human illness caused by cynobacteria has not been conducted previously anywhere.
The highly neurotoxic saxitoxin was found for the first time in Finland, and in high concentrations. The occurrence of the toxin correlated strongly with the presence of the cyanobacterium Anabaena lemmerannii and with high N/P ratio of the lakes. Neurotoxins of cyanobacteria were associated with oligo-humic lakes, and hepatotoxins in moderately humic lakes. The emerging cytotoxin cylindrospermopsin was detected for the first time from boreal aquatic environment. The study increased significantly knowledge on the occurrence of neurotoxic and hepatotoxic cyanobacteria in different types of boreal waters.
The heterotrophic microbial diversity in association of cyanobacteria was shown to be extremely diverse. We isolated approximately 1500 heterotrophic bacterial strains from the water samples. Approximately 350 of them have thus far been preliminary identified. Several of the identified strains were previously unidentified or uncultured bacteria that exist only as gene sequences in genetic data banks. One new bacterial genus, Paucibacter toxinivorans that degrades cyanobacterial hepatotoxins was described.
Several potential human and animal pathogens were detected and isolated from the water samples. Presumptive Vibrio cholerae, V. vulnificus and V. parahaemolyticus were detected in high numbers in bathing waters along the Baltic Sea coast. A collection of approximately 100 Vibrio strains was isolated. Only few V. cholerae strains could be clinically studied with the provided funding. They were all non-O1, non-O139 serotypes (NCV), not causative agents of cholera epidemics but classified as emerging pathogens that may cause e.g. severe infections. The potential fish pathogen Aeromonas salmonicida was identified from several cyanobacterial water blooms. The virulence of the strains could not be studied with the provided funding. Also other potential human or animal pathogens such as Aeromonas spp. (360 strains), Pseudomonas spp. (230 strains) and haemolytic bacteria (300 strains) were isolated. Thus far, approximately 50 of them have been preliminary identified. According to the preliminary results the set of the strains consisted also of other emerging pathogens. Potentially pathogenic bacteria among cyanobacteria have not been studied previously. In addition, several bacterial strains (Proteobacteria and Actinomycetales) were preliminary shown either to enhance or inhibit the growth of cyanobacteria.
Selected publications:
Kolmonen, E., K. Sivonen, J. Rapala and K. Haukka. 2004. Diversity of cyanobacteria and heterotrophic bacteria in cyanobacterial blooms in Lake Joutikas, Finland. Aquatic Microbial Ecology 36:201-211.
Lepistö, L., J. Rapala, C. Lyra, K. A. Berg, K. Erkomaa and J. Issakainen. 2005. Occurrence and toxicity of cyanobacterial blooms dominated by Anabaena lemmermannii P. RICHTER and Aphanizomenon spp. in boreal lakes in 2003. Algological Studies 117 (Cyanobacterial Research 6):315–328.
Lepistö, L., K. Lahti, J. Rapala, L. Villa and I. Sammalkorpi. 2005. Effects of fish removal on cyanobacteria and their toxicity in Lake Tuusulanjärvi, Southern Finland. Verh. Internat. Verein. Limnol. 29:473–477.
Rapala, J., K. A. Berg, C. Lyra, R. M. Niemi, W. Manz, S. Suomalainen, L. Paulin and K. Lahti. 2005. Paucibacter toxinivorans gen. nov. sp. nov., a bacterium degrading cyclic cyanobacterial hepatotoxins microcystins and nodularin. International Journal of Systematic and Evolutionary Microbiology 55:1563–1568.
Rapala, J., A. Robertson, A. P. Negri, K. A. Berg, P. Tuomi, C. Lyra, K. Erkomaa, K. Lahti, K. Hoppu and L. Lepistö. 2005. First report of saxitoxin in Finnish lakes and possible associated effects on human health. Environmental Toxicology 20:331–340.
Spoof, L., K. A. Berg, J. Rapala, J. S. Metcalf, K. Lahti, L. Lepistö, G. A. Codd and J. Meriluoto. First observation of cylindrospermopsin in the boreal environment (Finland). Environmental Toxicology (in press).
Lepistö, L., P. Kauppila, J. Rapala, M. Pekkarinen and L. Villa. Estimation of reference conditions for phytoplankton in a naturally eutrophic shallow lake. Hydrobiologia (in press).
An abstract of the research plan (January 2003)