11th ICRS Abstract book - Nova Southeastern University

8.210
Quorum Sensing Inhibitory Activities From Coral-Associated Bacteria
Stephanie HALBIG* 1 , Max TEPLITSKI 1 , Kim RITCHIE 2
1 Soil and Water Science, University of Florida, Gainesville, FL, 2 Mote Marine Lab,
Sarasota, FL
Many symbionts and pathogens rely on a cell-to-cell communication mechanism called
“quorum sensing” (QS) to structure multicellular communities and coordinate their
interactions with eukaryotic hosts. Interactions that are influenced by QS between coral
associated commensal bacteria and a coral pathogen were investigated in this study. A
collection of coral-associated bacteria, including those from zooxanthellae cultures, was
screened for the ability to inhibit a model QS reporter, Chromobacterium violaceum to
investigate potential roles for QS in the interactions between normal coral microflora and
opportunistic pathogens. Six isolates showing the greatest degree of inhibition were
chosen and identified by 16S sequencing as Planococcus spp, Photobacterium spp.,
Marinobacter salsuginis, Agrobacterium stellulatum, Vibrio spp., and Caryophanon spp.
The range of QS inhibition was tested with a suite of reporters carrying receptors for
different QS signals. Isolates in co-culture were able to inhibit reporter activity by 75% -
100%. Inhibition of surface spreading in S. marcescens by the isolates was tested.
Marinobacter salsuginis and Agrobacterium spp. from zooxanthellae, and
Photobacterium spp., Planococcus spp., and Caryophanon spp. from coral mucus all
showed inhibition of surface spreading in at least one of the S. marcescens strains tested.
The mechanism by which surface motility is inhibited was confirmed in experiments with
a mutant of S. marcescens that carries a reporter gene insertion in the surfactant gene that
is involved in surface colonization. The role of QS in surface spreading of PDL100 was
investigated using a “quorum-quenching” approach. A plasmid borne QS signal
lactonase aiiA was conjugated into PDL100 to generate a functional QS mutant and
spreading behavior was monitored. Our results indicate that native coral-associated
bacteria are capable of inhibiting QS that may aid in the defense against pathogen
colonization.
8.211
Bacterial Diversity Associated With The Corals Of Gulf Of Mannar
Shunmugiah Thevar Karutha PANDIAN* 1 , Paramasivam NithyANAND 1
1 department Of Biotechnology, Alagappa University, Karaikudi 630 003, India
Coral microbiology is an emerging field, driven largely by a desire to understand, and
ultimately prevent, the worldwide destruction of coral reefs. Coral microbiology is still in
infancy in India and molecular cataloguing of bacterial diversity associated with Indian
corals is not well established. As a preface, we attempted to divulge the bacterial
diversity associated with the coral Acropora digitifera, a predominant coral species of the
Gulf of Mannar region. Samples of coral mucus and coral tissues were collected form
Acropora digitifera from Hare Island. Bacteria were isolated from both coral mucus and
coral tissue by serially diluting the sample and plating them on different media to isolate
total heterotrophic bacteria, Pseudomonas .sp and Vibrio. sp. As expected, the total
bacterial count was highest in coral mucus followed by coral tissue, sediment and
seawater. The isolated bacteria were identified by biochemical tests as well as by
molecular typing. 16S rRNA genes were successfully amplified from the genome of the
isolates using universal eubacterial 16S rRNA primers. The different phylotypes obtained
through ARDRA were selected for 16S rRNA gene sequencing. 16S rRNA gene
sequencing is underway and the same is expected to reveal the different bacteria
associated with the coral Acropora digitifera. Isolation of Enterobacter cloacae, a member
of coliform group indicates that there is evidence of anthropogenic pressure in the coral
reef ecosystem and warrants constant monitoring of total and fecal coliforms in the coral
reef ecosystem. Preliminary knowledge about the number and different types of Vibrio.
sp associated with healthy corals is of utmost importance because it helps in identifying
pathogenic Vibrios. sp which are responsible for mass coral bleaching. The outcome of
this study is very important to evolve appropriate strategies for conservation of coral reef
ecosystem of the Gulf of Mannar.
Poster Mini-Symposium 8: Coral Microbial Interactions
8.212
Are You Interested in The Invisible? Tools For Coral Reef Microbiology
Forest ROHWER* 1 , Mark HATAY 1 , Linda WEGLEY 1 , Neilan KUNTZ 1 , Olga PANTOS 1
1 Biology, San Diego State University, San Diego, CA
In the last decade, there has been an increasing awareness that microbes and viruses are
important components of coral reef ecosystems. Novel tools are needed for coral reef
microbiology, some of which will be highlighted here. SPIDERS is a syringe pump system that
can be used to deliver treatments, such as varying levels of inorganic and organic nutrients,
pesticides, herbicides, etc., both on land and underwater. Using SPIDERS, a researcher can
determine how different stressors change the coral holobiont under field conditions. The
SUPERSUCKERS system can be used by a diver to remove the mucus from the surface of a
coral without introducing contaminants from the surrounding water column. These samples can
then be assayed in FAM, a simple, field deployable system for rapid quantification of microbes.
We have also developed a field kit for collecting and processing water samples for dissolved
organic carbon, nutrient, and isotope measurements. With these tools it is relatively easy for
coral reef scientists to collect and start assaying the invisible, microbial components on coral
reefs.
8.213
Histopathological Analysis Of Hyaline, Fibrillar Lesions in The Caribbean Staghorn
Coral, acropora Cervicornis
Erin HODEL* 1,2 , Esther PETERS 3
1 CSA International, Inc., Stuart, FL, 2 National Coral Reef Institute, Nova Southeastern
University Oceanographic Center, Dania Beach, 3 Tetra Tech, Inc., Fairfax, VA
Tissue and cellular parameters definitive of healthy, stressed, or diseased states are not well
understood for any coral species. The histology of the Caribbean staghorn coral, Acropora
cervicornis, was examined after field collection and after 4 weeks of exposure in laboratory
aquaria to high levels of sedimentation (200 mg cm-2 day) and phosphate (4 µM).
Histopathological analysis revealed small- to large-sized lesions consisting of strands of
proteinaceous, hyaline, fibrillar material surrounded by or underlying gastrovascular canallining
tissue in the skeleton of both experimental and field-collected specimens; however,
lesions were larger in experimental specimens. Staining properties of the strands varied within
each lesion, indicating regions with different biochemistry. With Harris’s hematoxylin and
eosin, lesions were mostly eosinophilic but graded into basophilic portions along the strands.
The strands were mostly positive for the periodic acid-Schiff reaction, indicating neutral or
acidic properties and suggesting a mucopolysaccharide origin. Gomori’s methanamine silver
procedure positively stains fungi black and was used after filaments resembling fungal hyphae
were discovered within the lesions and calicodermis of several specimens. Filaments and
clustered bodies containing black- and blue-staining granules were revealed that might have
been of fungal origin. The lesions were usually bordered by calicodermis and observed in areas
where skeleton had been prior to decalcification. In some cases, the calicodermis was
hypertrophied near the lesions, which is consistent with organic matrix formation and enhanced
skeletal deposition. Therefore, these lesions may have been a result of augmented organic
matrix formation in order to “wall off” invading fungi or other organisms with aragonite. Such
lesions in coral tissues might indicate a defensive or immune response toward potentially
invasive organisms to protect coral tissues; however, more observations are needed to link them
with compromised health status.
316