Streptomyces sp. NELs-40 extract potently inhibits MRSA growth and biofilm formation in vitro, revealing 30 antimicrobial BGCs.
Background
The escalating prevalence of multidrug-resistant Staphylococcus aureus (MRSA) presents a critical therapeutic challenge, demanding novel strategies beyond conventional single-target antibiotics. Current treatments often fall short due to widespread resistance mechanisms, necessitating the discovery of new antimicrobial agents. Streptomyces species are well-recognized as prolific producers of diverse bioactive secondary metabolites, making them promising sources for the discovery of novel antimicrobials to combat resistant pathogens like MRSA.
Study Design
Researchers characterized Streptomyces sp. NELs-40 genomically and optimized its antimicrobial production. Genomic DNA was sequenced (Illumina HiSeq X10) and analyzed for 16S rRNA, ANI, AAI, dDDH, and antiSMASH for biosynthetic gene clusters (BGCs). Antimicrobial production was optimized using a Plackett-Burman design. Antibacterial activity of the ethyl acetate extract was assessed against MRSA ATCC 43300 via well diffusion, MIC determination, and anti-biofilm assays. Bioactive metabolites were identified using GC-MS and tested for stability.
Results
Genomic analysis of Streptomyces sp. NELs-40 revealed a complete genome of 7,973,786 bp with 71.76% GC content, harboring 6,872 protein-coding genes and 49 biosynthetic gene clusters (BGCs). Notably, 30 of these BGCs were associated with antimicrobial compound biosynthesis, representing diverse classes including polyketides and nonribosomal peptides. Taxonomic classification was confirmed with high similarity to S. parvus (ANI 99.6%, AAI 98.31%, dDDH 88.70%). Statistical optimization identified pH as the primary factor significantly affecting antimicrobial production (p < 0.05).
Key Findings
- Streptomyces sp. NELs-40 genome contains 49 biosynthetic gene clusters (BGCs), 30 linked to antimicrobial production.
- Optimization showed pH significantly impacts antimicrobial production (p < 0.05).
The ethyl acetate extract of Streptomyces sp. NELs-40 demonstrated potent activity against MRSA ATCC 43300, yielding inhibition zones of 37 mm, an MIC of 125 μg/mL, and 32.25% biofilm inhibition.
- The extract exhibited an MIC of 125 μg/mL against MRSA, demonstrating potent antibacterial activity.
- NELs-40 extract inhibited MRSA biofilm formation by 32.25%.
Why It Matters
Streptomyces sp. NELs-40 represents a promising source for novel antimicrobial compounds, offering a potential solution to the growing crisis of multidrug-resistant Staphylococcus aureus. This research provides a strong foundation for isolating and characterizing specific bioactive molecules from this strain, which could lead to new therapeutic agents beyond conventional antibiotics. The identified compounds and their stability profile suggest potential for drug development. Further isolation, structural elucidation, and in vivo testing are crucial to translate these in vitro findings into clinical applications and develop usable protocols.
streptomyces
mrsa
antibacterial
biofilm-inhibition
antimicrobial-discovery
natural-products