Bacillaceae Within Galium aparine L.: A Plant-Associated Treasure of Biosynthetic Diversity and Growth-Promoting Potential.

Endophytic bacteria are key components of plant microbiomes, enhancing host growth, stress tolerance, and defence mechanisms. Ten cultivable strains affiliated with Bacillaceae, including putative novel Priestia and Bacillus species, were previously isolated from Galium aparine L.'s tissues. All tolerated diverse levels of abiotic stresses, produced ammonia and auxins, as well as all exhibited strong hydrolytic enzyme activities (amylase, protease, xylanase, and pectinase), indicating robust metabolic versatility. These bacteria stand out as prolific producers of industrially relevant compounds. Priestia megaterium GR4 demonstrated high production of hydrolytic enzymes and biosurfactants, and most strains synthesized and accumulated polyhydroxyalkanoates (PHA), highlighting their potential as sustainable bioplastic producers. UPLC-MS/MS confirmed koranimine production by Peribacillus frigoritolerans GR2. Previous genome mining studies revealed diverse biosynthetic gene clusters, including those for surfactin and fengycin. Overall, G. aparine endophytes represent powerful biological factories capable of producing a wide range of valuable compounds, including enzymes, biosurfactants and biopolymers, with strong potential for applications in industrial biotechnology, sustainable agriculture, and biocontrol.