title: Effects of symbiotic bacteria on chemical sensitivity of Daphnia magna.
abstract: The crustacean zooplankton Daphnia magna has been widely used for chemical toxicity tests. Although abiotic factors have been well documented in ecotoxicological test protocols, biotic factors that may affect the sensitivity to chemical compounds remain limited. Recently, we identified symbiotic bacteria that are critical for the growth and reproduction of D. magna. The presence of symbiotic bacteria on Daphnia raised the question as to whether these bacteria have a positive or negative effect on toxicity tests. In order to evaluate the effects of symbiotic bacteria on toxicity tests, bacteria-free Daphnia were prepared, and their chemical sensitivities were compared with that of Daphnia with symbiotic bacteria based on an acute immobilization test. The Daphnia with symbiotic bacteria showed higher chemical resistance to nonylphenol, fenoxycarb, and pentachlorophenol than bacteria-free Daphnia. These results suggested potential roles of symbiotic bacteria in the chemical resistance of its host Daphnia.
authors.affiliation: Department of Biotechnology, Graduate School of Engineering, Osaka University, Osaka, Japan.
authors.forename: Patcharaporn
authors.initials: P
authors.lastname: Manakul
authors.affiliation: Department of Biotechnology, Graduate School of Engineering, Osaka University, Osaka, Japan.
authors.forename: Saranya
authors.initials: S
authors.lastname: Peerakietkhajorn
authors.affiliation: Department of Biotechnology, Graduate School of Engineering, Osaka University, Osaka, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Matsuura
authors.affiliation: Department of Biotechnology, Graduate School of Engineering, Osaka University, Osaka, Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kato
authors.affiliation: Department of Biotechnology, Graduate School of Engineering, Osaka University, Osaka, Japan. Electronic address: watanabe@bio.eng.osaka-u.ac.jp.
authors.forename: Hajime
authors.initials: H
authors.lastname: Watanabe
mesh_terms: D000818:Animals; D001419:Bacteria; D003621:Daphnia; D054750:Ecotoxicology; D013559:Symbiosis; D018675:Toxicity Tests / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical
keywords: Bacteria; Daphnia; Ecotoxicology; Fenoxycarb; Nonylphenol; Pentachlorophenol; Symbiotic bacteria; Toxicity; Triclosan