title: Purification and culture characteristics of 36 benthic marine diatoms isolated from the Solthörn tidal flat (Southern North Sea).
abstract: Marine benthic diatoms growing in biofilms on sediment surfaces generally occur associated with heterotrophic bacteria, whereas modern molecular techniques and analyses of species-specific physiology create a demand for axenic cultures. Numerous benthic diatoms were isolated from surface sediments during a monitoring of the Solthörn tidal flat (southern North Sea, Germany) from May 2008 to May 2009. Of these, around 50% could be purified from the accompanying heterotrophic bacteria using different antibiotics combined with physical separation methods (vortexing, ultrasound). Overall, seven different antibiotics were tested at different concentrations, and a best working protocol was developed. The axenic strains were stable on average for only around 15 months, indicating a symbiotic interaction between the benthic diatoms and the associated bacteria. While most short-term effects during the purification process were restricted to differences in growth rates among xenic and axenic diatom strains, long-term cultivation led to distinct changes in cell volumes and growth characteristics of the axenic strains.
authors.affiliation: Institute of Chemistry and Biology of the Marine Environment, University of Oldenburg, Schleusenstrasse 1, 26382, Wilhelmshaven, Germany.
authors.forename: Bettina
authors.initials: B
authors.lastname: Scholz
keywords: antibiotics; axenic cultures; benthic marine diatoms; exopolysaccharides; physical pretreatments; strain stability; xenic cultures