Two Microbial Stories: Temporal and Spatial Dynamics of the Microbiome in Aquaculture and the Evolution of Host Specificity in Aeromonas  

Aquaculture is an important tool for solving the growing worldwide food demand, but infectious diseases of farmed animals represent a serious roadblock to industry growth. Therefore, it is essential to understand the microbial communities that reside within aquaculture facilities to identify reservoirs of bacterial pathogens and potential endogenous antagonists of disease-causing bacteria. We performed a multi-year survey at a large trout farm and detected the trout pathogen Flavobacterium columnare at low concentrations in water entering the farm. F. columnare was present in biofilms lining the raceways and likely seeded the water leaving in the raceways with this pathogen. From these biofilms, we cultured bacteria and identified 33 strains that inhibited the growth of pathogens. A genomic and pharmacological network analysis revealed that one Pseudomonas apudapuas strain produced a novel antimicrobial compound. We plan to apply similar approaches in studies of Hawaiian streams and fishponds to support locally grown food production. Aeromonas species are beneficial symbionts of medicinal leeches but are also pathogens of animals, including humans, and present in the aquatic environment. We identified a region on the chromosome that confers the ability to metabolize sialic acid and is predicted to protect against antimicrobial peptides. This locus was always present in Aeromonas strains isolated from leeches and absent in isolates from other sources, suggesting that this is a host-specificity conferring region. This 42-kb genomic island is likely horizontally transferred between strains. We postulate that this genomic island can extend the host range in recipient strains. These findings provide important insights into strain-specific differences in bacteria and the evolution of host specificity.

Learning objectives::

1.  Describe how bacterial biofilms change in composition over time and increase in species diversity.

2.  Discuss the role of aquatic biofilms as a source of bacteria that produce novel antibiotics.

3.  Identify genes that enable beneficial bacteria to colonize a specific host and be transferred horizontally to other bacteria.

Agenda

7:30 Breakfast

8:30 PhD. oral presentations

10:30 Keynote speaker presentation

11:30 Lunch

12:30 Posters

2:00 Masters Oral Presentations

4:00 Break

4:30 Awards ceremony

5:00 Business meeting

5:30 Meeting end