title: Antimicrobial activity of extracts from macroalgae Ulva lactuca against clinically important Staphylococci is impacted by lunar phase of macroalgae harvest.
abstract: Staphylococcus aureus is a common human bacterial pathogen that causes skin and soft tissue infections. Methicillin-resistant Staph. aureus (MRSA) are increasingly drug-resistant, and thus there is great need for new therapeutics to treat Staph. aureus infections. Attention has focused on potential utility of natural products, such as extracts of marine macroalgae, as a source of novel antimicrobial compounds. The green macroalgae Ulva lactuca produces compounds inhibitory to human pathogens, although the effectiveness of U. lactuca extracts against clinically relevant strains of Staph. aureus is poorly understood. In addition, macroalgae produce secondary metabolites that may be influenced by exogenous factors including lunar phase, but whether lunar phase affects U. lactuca antimicrobial capacity is unknown. We sought to evaluate the antibacterial properties of U. lactuca extracts against medically important Staphylococci, and to determine the effect of lunar phase on antimicrobial activity. We report that U. lactuca methanolic extracts inhibit a range of Staphylococci, and that lunar phase of macrolagae harvest significantly impacts antimicrobial activity, suggesting that antimicrobial properties can be maximized by manipulating time of algal harvest. These findings provide useful parameters for future studies aimed at isolating and characterizing U. lactuca anti-Staphylococcal agents.
  
  
  CONCLUSIONS
  The growing prevalence of antibiotic-resistant human pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) has intensified efforts towards discovery and development of novel therapeutics. Marine macroalgae like Ulva lactuca are increasingly recognized as potential sources of antimicrobials, but the efficacy of U. lactuca extracts against common, virulent strains of Staph. aureus is poorly understood. We demonstrate that U. lactuca methanolic extracts inhibit a variety of clinically relevant Staphylococcus strains, and that the antimicrobial activity can be maximized by optimizing time of algal harvest. These findings provide potentially useful parameters for future work of isolating and identifying novel antimicrobial agents from macroalgae.
authors.affiliation: Department of Chemistry and Physics, University of New England, Biddeford, ME, USA.
authors.forename: A M
authors.initials: AM
authors.lastname: Deveau
authors.affiliation: Department of Marine Sciences, University of New England, Biddeford, ME, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Miller-Hope
authors.affiliation: Department of Biology, University of New England, Biddeford, ME, USA.
authors.forename: E
authors.initials: E
authors.lastname: Lloyd
authors.affiliation: Department of Chemistry and Physics, University of New England, Biddeford, ME, USA.|Departments of Biology and Chemistry, Wheaton College, Norton, MA, USA.
authors.forename: B S
authors.initials: BS
authors.lastname: Williams
authors.affiliation: Department of Chemistry and Physics, University of New England, Biddeford, ME, USA.|Department of Biology, University of New England, Biddeford, ME, USA.
authors.forename: C
authors.initials: C
authors.lastname: Bolduc
authors.affiliation: Department of Chemistry and Physics, University of New England, Biddeford, ME, USA.|Department of Biology, University of New England, Biddeford, ME, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Meader
authors.affiliation: Department of Biology, University of New England, Biddeford, ME, USA.
authors.forename: F
authors.initials: F
authors.lastname: Weiss
authors.affiliation: Department of Biology, University of New England, Biddeford, ME, USA.
authors.forename: K M
authors.initials: KM
authors.lastname: Burkholder
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial; D006801:Humans; D016106:Methicillin Resistance / Q000187:drug effects; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D016081:Moon; D010936:Plant Extracts / Q000494:pharmacology*; D012624:Seaweed / Q000378:metabolism*; D013203:Staphylococcal Infections / Q000382:microbiology; D013997:Time Factors; D044445:Ulva / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D010936:Plant Extracts
keywords: Staphylococcus aureus; Ulva lactuca; antimicrobials; macroalgae; natural products