Identification of novel bacteriocin against Staphylococcus and Bacillus species

Due to the continues emergence of antimicrobial resistance, discovery of novel compounds are urgently required. Thus, this study is focused to identify a novel antimicrobial peptide (bacteriocin) targeting multidrug-resistant pathogenic bacteria.

About 80 environmental isolates were recovered and screened for anti-bacterial activity using simultaneous antagonism assays. Produced peptide (AB3) was purified using Strata-XL-C and Sep-Pack columns. Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) analysis and MIC were conducted on the AB3 peptide to determine its molecular weight and spectrum of activity. Extraction and amplification for the 16S rRNA gene of the producing strain was accomplished using QIAamp DNA Mini Kit and GeneAmp PCR system thermocycler, respectively. Novelty of the compound was assessed based on all obtained genomic and proteomic data using Basic Local Alignment Search Tool search and Unni-Prot and Bactibase, respectively.

About 5% of screened isolates showed antagonistic activity toward tested indicators. Obtained compound showed narrow spectrum of activity toward certain Gram-positive species including, methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA) and Bacillus species. MALDI-TOF analysis revealed the flowing molecular masses: 1288.207 Da, 1304.536 Da, 1326.529 Da, 1403.591 Da, and 1472.792 Da. The extensive genomic and proteomic analysis have indicated the discovery of novel bacteriocin produced by Bacillus malacitensis.

A novel bacteriocin (AB3) was identified from B. malacitensis, which has showed promising in vitro bactericidal activity toward MSSA, MRSA, and Bacillus subtilis. This compound holds great potential to replace or used in combination with currently used antibiotics to treat serious untreatable bacterial infections. However, further investigations to determine its suitability for therapeutic use in human health are needed.