Microbial interactions associated with biofilms attached to Trichodesmium spp. and detrital particles in the ocean
Hmelo, Laura R.
MetadataShow full item record
Quorum sensing (QS) via acylated homoserine lactones (AHLs) was discovered in the ocean, yet little is known about its role in the ocean beyond its involvement in certain symbiotic interactions. The objectives of this thesis were to constrain the chemical stability of AHLs in seawater, explore the production of AHLs in marine particulate environments, and probe selected behaviors which might be controlled by AHL-QS. I established that AHLs are more stable in seawater than previously expected and are likely to accumulate within biofilms. Based on this result, I chose to study AHL-QS in the bacterial communities inhabiting biofilms attached to Trichodesmium spp. and detrital (photosynthetically-derived sinking particulate organic carbon, POC) particles. These hot spots of microbial activity are primary sites of interaction between marine primary producers and heterotrophs and crucial components of the biological pump. Biofilm communities associated with Trichodesmium thiebautii colonies in the Sargasso Sea differed considerably from seawater microbial communities. In addition, there was no overlap between the communities associated with tuft and puff colonies. These results suggest that bacterial communities associated with Trichodesmium are not random; rather, Trichodesmium selects for specific microbial flora. Novel 16S rRNA gene sequences are present both in clone libraries constructed from DNA extracted from colonies of Trichodesmium spp. and in culture collections derived from wild and laboratory cultivated Trichodesmium spp., supporting the idea that the phycosphere of Trichodesmium is a unique microenvironment. Using high performance liquid chromatography-mass spectrometry, I demonstrated that bacteria isolated from Trichodesmium synthesize AHLs. In addition, I detected AHLs in sinking particles collected from a site off of Vancouver Island, Canada. AHLs were subsequently added to laboratory cultures of non-axenic Trichodesmium colonies and sinking POC samples. This is the first time AHLs have been detected in POC and indicates that AHL-QS was occurring in POC. Further, I showed that AHLs enhanced certain organic-matter degrading hydrolytic enzyme activities. My results suggest that AHL-QS is a factor regulating biogeochemically relevant enzyme activities on sinking POC and within the biofilms attached to Trichodesmium colonies and thereby may impact the timing and magnitude of biogeochemical fluxes in the ocean.
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2010
Suggested CitationThesis: Hmelo, Laura R., "Microbial interactions associated with biofilms attached to Trichodesmium spp. and detrital particles in the ocean", 2010-06, DOI:10.1575/1912/3856, https://hdl.handle.net/1912/3856
Showing items related by title, author, creator and subject.
Prokaryotic community structure in algal photosynthetic biofilms from extreme acidic streams in Rio Tinto (Huelva, Spain) Souza-Egipsy, Virginia; Gonzalez-Toril, Elena; Zettler, Erik R.; Amaral-Zettler, Linda A.; Aguilera, Angeles; Amils, Ricardo (Spanish Society for Microbiology (SEM), 2008-12)Four algal photosynthetic biofilms were collected from the Rio Tinto (SW Spain) at four localities: AG, Euglena and Pinnularia biofilms; ANG, Chlorella and Pinnularia biofilms; RI, Cyanidium and Dunaliella biofilms; and ...
Leaf litter nutrient uptake in an intermittent blackwater river : influence of tree species and associated biotic and abiotic drivers Mehring, Andrew S.; Kuehn, Kevin A.; Thompson, Aaron; Pringle, Catherine M.; Rosemond, Amy D.; First, Matthew R.; Lowrance, R. Richard; Vellidis, George (2014-12)Organic matter may sequester nutrients as it decomposes, increasing in total N and P mass via multiple uptake pathways. During leaf litter decomposition, microbial biomass and accumulated inorganic materials immobilize and ...
Signature lipids and stable carbon isotope analyses of Octopus Spring hyperthermophilic communities compared with those of aquificales representatives Jahnke, Linda L.; Eder, Wolfgang; Huber, Robert; Hope, Janet M.; Hinrichs, Kai-Uwe; Hayes, John M.; Des Marais, David J.; Cady, Sherry L.; Summons, Roger E. (American Society for Microbiology, 2001-11)The molecular and isotopic compositions of lipid biomarkers of cultured Aquificales genera have been used to study the community and trophic structure of the hyperthermophilic pink streamers and vent biofilm from Octopus ...