Surface Associated Bacteria from Three Florida Algae Inhibit Human Pathogens
Faculty Mentor Name
Skylar Carlson
Research or Creativity Area
Natural Sciences
Abstract
Marine algal surface-associated bacteria (SAB) live in highly competitive environments where environmental stressors select for bacteria that produce secondary metabolites that function as chemical defenses, including compounds antibiotic bioactivity. We surveyed three algal species from Fort Pierce, FL: Padina sp. a brown algae, Ulva lactuca, a green algae, and Centroceras clavulatum, a red algae. In this study, SAB were isolated and purified through streak plating to obtain pure, isolated cultures. Isolates from these three algae were grown in a large-scale cultivation to generate sufficient material for isolation of bioactive molecules. Large-scale growth of 500 mL was performed in A1 media composed of starch, yeast extract, peptone, and Instant Ocean (salt used in sea water aquaria to create synthetic ocean water) in Milli-Q water. Cultures were incubated at 25°C while shaking at 150 rpm for 48 h. Following incubation, cultures were extracted using liquid-liquid partitioning with ethyl acetate (EtOAc) to extract secondary metabolites from the aqueous culture medium. The EtOAc layer was separated from culture media via a separatory funnel, concentrated, and analyzed by high-performance liquid chromatography (HPLC) at 1 mg/mL in MeOH to assess the metabolite complexity. These partitions were also prepared at 0.5 mg/mL in dimethyl sulfoxide (DMSO) and evaluated for antibiotic biological activity against four human pathogens: Escherichia coli, Staphylococcus aureus, Staphylococcus epidermis, and Bacillus subtilis. This workflow demonstrates an effective pipeline for the discovery of bioactive compounds from marine algal SAB, integrating isolation of microbes, large-scale cultivation, solvent extraction, analytical chemistry, and antimicrobial screening. The biological activity and UV-vis chromatograms of biologically active extracts will be presented.
Surface Associated Bacteria from Three Florida Algae Inhibit Human Pathogens
Marine algal surface-associated bacteria (SAB) live in highly competitive environments where environmental stressors select for bacteria that produce secondary metabolites that function as chemical defenses, including compounds antibiotic bioactivity. We surveyed three algal species from Fort Pierce, FL: Padina sp. a brown algae, Ulva lactuca, a green algae, and Centroceras clavulatum, a red algae. In this study, SAB were isolated and purified through streak plating to obtain pure, isolated cultures. Isolates from these three algae were grown in a large-scale cultivation to generate sufficient material for isolation of bioactive molecules. Large-scale growth of 500 mL was performed in A1 media composed of starch, yeast extract, peptone, and Instant Ocean (salt used in sea water aquaria to create synthetic ocean water) in Milli-Q water. Cultures were incubated at 25°C while shaking at 150 rpm for 48 h. Following incubation, cultures were extracted using liquid-liquid partitioning with ethyl acetate (EtOAc) to extract secondary metabolites from the aqueous culture medium. The EtOAc layer was separated from culture media via a separatory funnel, concentrated, and analyzed by high-performance liquid chromatography (HPLC) at 1 mg/mL in MeOH to assess the metabolite complexity. These partitions were also prepared at 0.5 mg/mL in dimethyl sulfoxide (DMSO) and evaluated for antibiotic biological activity against four human pathogens: Escherichia coli, Staphylococcus aureus, Staphylococcus epidermis, and Bacillus subtilis. This workflow demonstrates an effective pipeline for the discovery of bioactive compounds from marine algal SAB, integrating isolation of microbes, large-scale cultivation, solvent extraction, analytical chemistry, and antimicrobial screening. The biological activity and UV-vis chromatograms of biologically active extracts will be presented.
