Bacterial-protozoal interactions in a microbial community of rumen ciliate Entodinium caudatum culture under mercury stress.
We examined the role of rumen ciliates, using Entodinium caudatum as a model organism, in the detoxification of soluble mercury(II) in vitro under conditions with enhanced or reduced diversity of a co-culture bacterial population as well as the effects of long-term mercury(II) stress on in vitro fermentation parameters and major mercury detoxification products. The E. caudatum growth depended on the capability of the co-culture bacterial population to develop resistance to mercury(II) chloride and on culture conditions. The production of fermentation gas was reduced (P < 0.01) in contrast to methane production. Proportions of volatile fatty acids were affected; however, the total concentration of volatile fatty acids was not influenced. No organic mercury species were detected after long-term application (>1 month) of mercury(II) chloride. The major mercury species was inorganic mercury(II) with substantial accumulation in the bacterial fraction (70%) and less in black sediment (21%) and ciliate fraction (9%) at the 25 micromol/L mercury(II) dose. The data indicate that free-living bacteria protect the ciliate cells by transforming mercury(II) into its insoluble forms.
Kisidayová
S
S
Institute of Animal Physiology, Slovak Academy of Sciences, Kosice, Slovak Republic. kisiday@saske.sk
Houserová
P
P
Váradyová
Z
Z
Mihaliková
K
K
Pristas
P
P
Javorský
P
P
D000818:Animals; D001419:Bacteria / Q000187:drug effects* / Q000378:metabolism*; D016798:Ciliophora / Q000187:drug effects* / Q000254:growth & development; D018920:Coculture Techniques; D004785:Environmental Pollutants / Q000378:metabolism / Q000494:pharmacology*; D005232:Fatty Acids, Volatile / Q000378:metabolism / Q000494:pharmacology; D005285:Fermentation / Q000187:drug effects; D008628:Mercury / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D008697:Methane / Q000378:metabolism / Q000494:pharmacology; D012417:Rumen / Q000382:microbiology / Q000469:parasitology; D012756:Sheep / Q000382:microbiology / Q000469:parasitology; D013312:Stress, Physiological / Q000187:drug effects; D013997:Time Factors
D004785:Environmental Pollutants; D005232:Fatty Acids, Volatile; D008628:Mercury; D008697:Methane