Short chain length polyhydroxyalkanoate (scl-PHA) produced by the marine bacterium Pseudomonas sputi MaRe06 inhibits Staphylococcus aureus biofilm formation.

Staphylococcus aureus is a major biofilm-forming pathogen that is often linked to skin infections and colonization of medical devices. This bacterium poses a significant challenge to infection control efforts. This study isolated and characterized a short chain length polyhydroxyalkanoate (scl-PHA) produced by the marine bacterium Pseudomonas sputi MaRe06 as an antibiofilm agent. Structural characterization using FT-IR, ESI-TOF MS and 1H NMR revealed a copolymer composed of hydroxybutyrate (HB) and hydroxyvalerate (HV) units, corresponding to poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [poly(3HB-co-3 HV)]. ESI+ and ESI- mass spectra showed oligomeric distributions consistent with HB/HV combinations. The PHA exhibited strong antibiofilm activity against S. aureus, reaching 92% inhibition at 300 μg/mL. Using the Galleria mellonella in vivo model, toxicity evaluation showed 83.33% larvae survival at 50 mg/kg, with no significant difference compared to viability controls (two-way ANOVA, Bonferroni test, p < 0.05). To our knowledge, this is the first report of poly(3HB-co-3 HV) production by Pseudomonas sputi and the first evaluation of the antibiofilm potential of scl-co-PHA from this marine species isolated from restinga ecosystems. These findings highlight P. sputi MaRe06 as a promising microbial platform for producing bioactive compounds capable of inhibiting bacterial biofilm formation.