title: 2,6-Dichlorobenzamide (BAM) herbicide mineralisation by Aminobacter sp. MSH1 during starvation depends on a subpopulation of intact cells maintaining vital membrane functions.
abstract: Mineralisation capability was studied in the 2,6-dichlorobenzamide (BAM)-degrading Aminobacter sp. MSH1 under growth-arrested conditions. Cells were starved in mineral salts (MS) solution or groundwater before (14)C-labelled BAM (0.1mM) was added. Cell physiology was monitored with a panel of vitality stains combined with flow cytometry to differentiate intact, depolarised and dead cells. Cells starved for up to 3 weeks in MS solution showed immediate growth-linked mineralisation after BAM amendment while a lag-phase was seen after 8 weeks of starvation. In contrast, cells amended with BAM in natural groundwater showed BAM mineralisation but no growth. The cell-specific mineralisation rate was always comparable (10(-16)molCintact cell(-1)day(-1)) independent of media, growth, or starvation period after BAM amendment; lower rates were only observed as BAM concentration decreased. MSH1 seems useful for bioremediation and should be optimised to maintain an intact cell subpopulation as this seems to be the key parameter for successful mineralisation.
authors.affiliation: Department of Agriculture and Ecology, Section of Genetics and Microbiology, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark.
authors.forename: Ole R
authors.initials: OR
authors.lastname: Sjøholm
authors.forename: Ole
authors.initials: O
authors.lastname: Nybroe
authors.forename: Jens
authors.initials: J
authors.lastname: Aamand
authors.forename: Jan
authors.initials: J
authors.lastname: Sørensen
mesh_terms: D020561:Alphaproteobacteria / Q000378:metabolism*; D001549:Benzamides / Q000378:metabolism*; D001673:Biodegradation, Environmental; D003470:Culture Media / Q000737:chemistry*; D006540:Herbicides / Q000378:metabolism*; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000378:metabolism
chemical_list: D001549:Benzamides; D003470:Culture Media; D006540:Herbicides; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D014867:Water; C057454:2,6-dichlorobenzamide