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Published on: September 30, 2014
Semi-purified Antimicrobial Proteins from Oyster Hemolymph Inhibit Pneumococcal Infection
Kate Summer1, Lei Liu2, Qi Guo2
1Faculty of Science and Engineering, Southern Cross University, Military Road, Lismore, NSW, 2480, Australia. k.summer@outlook.com.au.
Abstract:
Pneumococcal infections caused by Streptococcus pneumoniae are a leading cause of morbidity and mortality globally, particularly among children. The ability of S. pneumoniae to form enduring biofilms makes treatment inherently difficult, and options are further limited by emerging antibiotic resistance. The discovery of new antibiotics, particularly those with antibiofilm activity, is therefore increasingly important. Antimicrobial proteins and peptides (AMPs) from marine invertebrates are recognised as promising pharmacological leads. This study determined the in vitro antibacterial activity of hemolymph and unique protein fractions from an Australian oyster (Saccostrea glomerata) against multi-drug-resistant S. pneumoniae. We developed a successful method for hemolymph extraction and separation into 16 fractions by preparative HPLC. The strongest activity was observed in fraction 7: at 42 µg/mL protein, this fraction was bactericidal to S. pneumoniae and inhibited biofilm formation. Proteomic analysis showed that fraction 7 contained relatively high abundance of carbonic anhydrase, cofilin, cystatin B-like, and gelsolin-like proteins, while surrounding fractions, which showed lower or no antibacterial activity, contained these proteins in lower abundance or not at all. This work supports traditional medicinal uses of oysters and contributes to further research and development of novel hemolymph/AMP-based treatments for pneumococcal infections.
Insights
Australian oyster hemolymph shows promise against drug-resistant Streptococcus pneumoniae. A specific protein fraction demonstrated potent antibacterial and antibiofilm activity, offering new hope for treating pneumococcal infections.
Area of Science:
- Marine biology
- Microbiology
- Pharmacology
Background:
- Pneumococcal infections are a major global health concern, causing significant morbidity and mortality.
- Streptococcus pneumoniae's biofilm formation and antibiotic resistance complicate treatment.
- Marine invertebrates, like oysters, are sources of novel antimicrobial compounds.
Purpose of the Study:
- To investigate the antibacterial and antibiofilm potential of Australian oyster (Saccostrea glomerata) hemolymph against multi-drug-resistant S. pneumoniae.
- To identify specific protein fractions with antimicrobial activity.
Main Methods:
- Hemolymph extraction and separation into 16 fractions using preparative HPLC.
- In vitro testing of fractions for bactericidal activity against S. pneumoniae.
- Biofilm inhibition assays.
- Proteomic analysis of active fractions.
Main Results:
- Fraction 7 exhibited the strongest activity, being bactericidal to S. pneumoniae at 42 µg/mL.
- Fraction 7 also effectively inhibited S. pneumoniae biofilm formation.
- Proteomic analysis identified carbonic anhydrase, cofilin, cystatin B-like, and gelsolin-like proteins in fraction 7.
Conclusions:
- Saccostrea glomerata hemolymph contains potent antimicrobial compounds effective against drug-resistant S. pneumoniae.
- Specific protein fractions, notably fraction 7, show significant potential for developing new treatments for pneumococcal infections.
- This research supports traditional uses of oysters and opens avenues for novel antimicrobial peptide (AMP) based therapies.
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