Poster Presentation Australian Society for Microbiology Annual Scientific Meeting 2024

Identification and characterisation of antimicrobial molecules in sydney rock oysters (#24)

Jessica C Gibbs 1 2 , Trong Tran 1 2 , Scott Cummins 1 2 , Conor Fogarty 1 2 , Zubaida P Patwary 1 2 , Dylan W Ebner 1 2 , David J McMillan 1 2
  1. School of Science, Technology and Engineering, University of the Sunshine Coast, Sippy Downs, QLD, Australia
  2. Centre for Bioinnovation, University of the Sunshine Coast, Sippy Downs, QLD, Australia

Introduction

The emergence of antimicrobial resistance (AMR) is a global issue that impacts the healthcare, agricultural and aquaculture industries (1). There is an unmet need to identify new antibacterial molecules with new mechanisms of action that combat specific pathogens, or which harbour broad spectrum activity (1). Marine environments are an ideal source of such molecules (2, 3). Organisms from these environments are rich in unique molecules with unique chemical structures (4, 5). The aim of this research is to identify and characterise antimicrobial and anti-virulence molecules from the Sydney Rock Oyster.

Methods

Two separate extracts of the SRO were prepared. The first peptide-enriched extracts (mantle, haemolymph, gill, and adductor muscle) were derived from individual tissues of the SRO. The second set of small molecule-enriched extracts (Hexane, Methanol, Water and Dichloromethane) were prepared by organic extraction of whole SRO. Both sets of extracts were assessed for the presence of antimicrobial, anti-biofilm and anti-motile properties against a panel of ESKAPE pathogens and Vibrio parahaemolyticus. They were assessed in MIC, anti biofilm and anti-motility bio assays.

Results

None of the peptide-enriched extracts possessed direct antimicrobial or anti-motile activity. However, the mantle extract displayed partial biofilm inhibition of Staphylococcus aureus at 100μg/mL. The small molecule-enriched extracts prepared from whole SRO also showed no antimicrobial or anti-motile activity. The water extract also partially inhibited biofilm formation of S. aureus.

Conclusion

Extracts displaying bio-active properties are being fractionated by LCMS to obtain pure compounds. These compounds will undergo further testing and structural elucidation to identify individual molecules that confer antimicrobial or anti-virulence activity.

 

  1. Ventola CL. The antibiotic resistance crisis: part 1: causes and threats. P T. 2015;40(4):277-83
  2. Jiménez C. Marine Natural Products in Medicinal Chemistry. ACS Medicinal Chemistry Letters. 2018;9(10):959-61.
  3. Harvey AL, Edrada-Ebel R, Quinn RJ. The re-emergence of natural products for drug discovery in the genomics era. Nat Rev Drug Discov. 2015;14(2):111-29.
  4. Rasko DA, Sperandio V. Anti-virulence strategies to combat bacteria-mediated disease. Nat Rev Drug Discov. 2010;9(2):117-28.
  5. Moloney MG. Natural Products as a Source for Novel Antibiotics. Trends Pharmacol Sci. 2016;37(8):689-701.