DOI: 10.4103/jhcr.jhcr_3_26 ISSN: 3050-5941
Antibacterial Activity of Nonproteinaceous Compound Isolated from Environmental Bacillus amyloliquefaciens R2 against Methicillin-resistant Staphylococcus aureus and its Preliminary Characterization
Nithin K. Ajith, Anjali Anne Jacob, Giriprasad Venugopal, Mehara Nijamudeen, Anand Lal, Christeena Babu, Ashin P. Mathew, Revathy Jayan, K.R Anugraha, P.M Nishanamol
Background:
Bacillus
spp. have shown potential to produce proteinaceous and nonproteinaceous small molecules such as surfactin, iturin A, bacillaene, bacillibactin, and bacilysin with inhibitory effects on drug-resistant microbes. This study aims to preliminarily characterize the antibacterial activity of
Bacillus amyloliquefaciens
R2 against clinical isolates of methicillin-resistant
Staphylococcus aureus
(MRSA).
Materials and Methods:
The environmental isolate of
Bacillus
spp. was identified by Sanger sequencing. Spore-free cell-free supernatant (CFS) of the test strain
B. amyloliquefaciens
R2 was tested for its antibacterial activity against MRSA by agar well diffusion assay. The functional characterization of this antibacterial activity was done by precipitation with ammonium sulfate, trichloroacetic acid (TCA), as well as treatment with proteinase K. Further characterization was done by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) analysis.
Results:
The CFS of the test strain
B. amyloliquefaciens
R2 at neutral pH inhibited the growth of MRSA by the agar well diffusion method. The antibacterial activity was stable at neutral pH. The antibacterial activity was not observed after precipitation of the CFS with 60% and 80% saturated ammonium sulfate, as well as with 20% TCA. The absence of proteinaceous property of the CFS was further supported by the protease sensitivity test using proteinase K (10 mg/mL). Furthermore, the ATR-FTIR results supported the likelihood that the antibacterial effect was due to a lipopeptide rather than a proteinaceous compound.
Conclusion:
The results highlighted
B. amyloliquefaciens
R2 in the study as a promising source of stable, nonproteinaceous antibacterial compounds effective against MRSA.