Open AccessDiversity and vertical distribution of magnetotactic bacteria along chemical gradients in freshwater microcosms
Author(s) -
Flies Christine B.,
Jonkers Henk M.,
Beer Dirk,
Bosselmann Katja,
Böttcher Michael E.,
Schüler Dirk
Publication year - 2005
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1016/j.femsec.2004.11.006
Subject(s) - magnetotactic bacteria , microcosm , biology , temperature gradient gel electrophoresis , bacteria , biogeochemical cycle , sediment , environmental chemistry , ecology , 16s ribosomal rna , chemistry , paleontology
The vertical distribution of magnetotactic bacteria along various physico‐chemical gradients in freshwater microcosms was analyzed by a combined approach of viable cell counts, 16S rRNA gene analysis, microsensor profiling and biogeochemical methods. The occurrence of magnetotactic bacteria was restricted to a narrow sediment layer overlapping or closely below the maximum oxygen and nitrate penetration depth. Different species showed different preferences within vertical gradients, but the largest proportion (63–98%) of magnetotactic bacteria was detected within the suboxic zone. In one microcosm the community of magnetotactic bacteria was dominated by one species of a coccoid “ Alphaproteobacterium ”, as detected by denaturing gradient gel electrophoresis in sediment horizons from 1 to 10 mm depth. Maximum numbers of magnetotactic bacteria were up to 1.5 × 10 7 cells/cm 3 , which corresponded to 1% of the total cell number in the upper sediment layer. The occurrence of magnetotactic bacteria coincided with the availability of significant amounts (6–60 μM) of soluble Fe(II), and in one sample with hydrogen sulfide (up to 40 μM). Although various trends were clearly observed, a strict correlation between the distribution of magnetotactic bacteria and individual geochemical parameters was absent. This is discussed in terms of metabolic adaptation of various strains of magnetotactic bacteria to stratified sediments and diversity of the magnetotactic bacterial communities.