Development of antibacterial hydrogel using endophytic <i>Alternaria</i> fungus extract isolated from Australian native plant

To address the problems associated with pathogenic bacteria in healthcare settings, the development of novel antibacterial materials is of high priority. For such purposes, endophytic fungi - symbiotic microorganisms residing within healthy plant tissues - represent a promising yet largely unexplored source of antibacterial compounds. In this study, an antibacterial extract derived from an endophytic <i>Alternaria</i> fungus previously isolated from <i>Eremophila longifolia</i> was incorporated within gelatin methacryloyl (GelMA) to produce a novel antibacterial hydrogel. Whilst rheological and compression testing revealed the addition of the extract resulted in reduction in the crosslink density of the hydrogel, all GelMA-extract formulations produced a solid mechanical stable hydrogel. The GelMA hydrogel containing a range of extract concentrations demonstrated variable inhibition of bacterial (<i>Staphylococcus aureus</i>) growth, with a concentration of 10 mg mL^-1 extract demonstrating complete inhibition over 24 h, while showing no toxicity toward brine shrimp nauplii, indicating good biocompatibility. The GelMA-extract demonstrated minimal rapid release from the hydrogel, followed by a slower release at longer times. As such, the developed hydrogel composite is promising for antibacterial applications in biomedical settings, while the results also highlight the potential for utilising endophytic extracts in the development of novel antibacterial materials.