Characterization of a Potentially Novel Antibiotic-Producing Strain JPT8 from Urban Worm Farm Soil

Abstract

Antimicrobial resistance (AMR) poses an escalating global health crisis, with few novel structural classes of antibiotics approved in decades. To address this gap, we isolated and characterized a potentially novel antibiotic-producing bacterium, strain JPT8, from urban worm farm soil – an underexplored niche enriched by organic inputs and anthropogenic selective pressures – using a multidisciplinary pipeline combining microbiology, biochemistry, and molecular biology.

Serial dilution and plating yielded over 500 colonies. Four isolates showed reproducible inhibition against Staphylococcus aureus in patch-on-lawn assays, with JPT8 producing the largest zones (up to 23 mm). Scale-up fermentation in minimal media, dichloromethane extraction, and bioactivity-guided fractionation via thin-layer and silica gel column chromatography identified stable bioactive compounds in fractions S7 and S10 (10–20 mm zones in disc diffusion). Morphological (circular, undulate, tan colonies), biochemical (Gram-positive, catalase-positive, endospore-forming), and 16S rRNA gene sequencing (forward read: 1129 bp raw, trimmed to high-confidence 616 bp alignment with 88% identity) revealed only 82% pairwise similarity to the closest match (Bacillus pumilus NJ-M2, NZ_CP012329.1) and 79% to other Bacillus references, falling well below standard species delineation thresholds (~98.7%).

These findings suggest that JPT8 represents a divergent lineage with antimicrobial potential; however, further genomic and chemical characterization is required.