Open AccessPlanktonic bacteria and fungi are selectively eliminated by exposure to marine macroalgae in close proximity
Author(s) -
Lam Cindy,
Stang Andre,
Harder Tilmann
Publication year - 2008
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 - 10.1111/j.1574-6941.2007.00426.x
Subject(s) - biology , roseobacter , alphaproteobacteria , laminaria digitata , algae , microorganism , flavobacterium , bacteria , botany , cytophaga , plankton , bacterioplankton , microbial population biology , microbiology and biotechnology , gammaproteobacteria , ecology , phytoplankton , pseudomonas , 16s ribosomal rna , phylogenetics , nutrient , clade , biochemistry , genetics , gene
To test whether macroalgae affect microbial colonizers in close proximity in a phylum‐specific fashion, the community richness of planktonic bacteria and fungi was analyzed with selective oligonucleotide probes targeting the Cytophaga / Flavobacterium / Bacteroides (CFB), Alphaproteobacteria and Roseobacter group and the ITS1 region of marine fungi. Naturally occuring planktonic microorganisms were incubated in the presence of macroalgae or in seawater previously conditioned with macroalgal metabolites. The red algae Ceramium rubrum and Mastocarpus stellatus as well as seawater conditioned with these algae reduced the community composition of bacteria to a greater extent than the brown alga Laminaria digitata , indicating that metabolites differed among macroalgae or that the susceptibility of planktonic bacteria towards alga‐derived antimicrobials correlated with their phylogenetic affiliation. The most affected phylotypes belonged to the CFB and the Roseobacter clade. The planktonic fungal community was only affected in the presence of macroalgae and not in algal‐conditioned water, but with a specificity different from that observed for bacteria. The macroalgae L. digitata and M. stellatus exhibited more pronounced antifungal effects than C. rubrum . This study demonstrates macroalgal defenses against epiphytic microorganisms based on natural delivery mechanisms of allelochemicals utilizing a culture‐independent approach, thus minimizing the ecological bias inherent to culture‐dependent studies based on few microbial isolates.