title: Toxic effects of Streptomyces griseus spores and exudate on gill pathology of freshwater fish.
abstract: Many unexplained fish-kills in British waters are considered microbial in origin and a large proportion of field sites contains elevated concentrations of filamentous actinobacteria. The present study has shown that a strain of Streptomyces griseus, isolated from field sites, elicits pathological changes to the gills of fish under laboratory conditions which mirror those found in situ. These changes include hyperplasia leading to fusion of the secondary lamellae and loss of microridging on the filamental epithelium of the primary lamellae. Juveniles of up to six fish species were exposed to spore suspensions or exudate of S. griseus in the range of 1 x 10(2)-1 x 10(6)spores ml(-1) for up to 96 h. The exudate was more potent than the spores and there was a positive correlation between exudate concentration and the rate and extent of fish gill pathology with bream and rainbow trout being more sensitive than carp, tench and roach. The results are discussed in the context of recognising and managing potential fish mortalities caused by microbial toxins.
authors.affiliation: School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 OEX, UK.
authors.forename: J W
authors.initials: JW
authors.lastname: Lewis
authors.affiliation: School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 OEX, UK. Electronic address: n.morley@rhul.ac.uk.
authors.forename: N J
authors.initials: NJ
authors.lastname: Morley
authors.affiliation: Division of Biomedical and Life Sciences, School of Health and Medicine, Lancaster University, Lancaster LA1 4YQ, UK.
authors.forename: J
authors.initials: J
authors.lastname: Drinkall
authors.affiliation: Ecology and Soils, Science, Environment Agency, Howbery Park, Wallingford OX10 8BD, UK.
authors.forename: B J
authors.initials: BJ
authors.lastname: Jamieson
authors.affiliation: Environment Agency, Rivers House, Inworth Road, Feering, Essex CO5 1UD, UK.
authors.forename: R
authors.initials: R
authors.lastname: Wright
authors.affiliation: Division of Biomedical and Life Sciences, School of Health and Medicine, Lancaster University, Lancaster LA1 4YQ, UK.
authors.forename: J D
authors.initials: JD
authors.lastname: Parry