A New Broad-Spectrum Peptide Antibiotic Produced by Bacillus brevis Strain MH9 Isolated from Margalla Hills of Islamabad, Pakistan Syed Aun Muhammad 1 • Amjad Ali 2 • Anam Naz 2 • Afreenish Hassan 2 • Naeem Riaz 3 • Syed Saeed-ul-Hassan 4 • Saadia Andleeb 2 • Debmalya Barh 5 Accepted: 23 December 2015 Ó Springer Science+Business Media New York 2016 Abstract The antimicrobial peptide from a bacterial strain is isolated from soil sample of Margalla Hills of Islamabad, Pakistan. The peptide is found to significantly inhibit the growth of both Gram-positive (Staphylococcus aureus ATCC 6538 and Micrococcus luteus ATCC 10240) and Gram-negative (Escherichia coli ATCC 25922 and Salmonella typhi ATCC 14028) bacteria as compared to gramicidin as standard. The bacterium is identified as Bacillus brevis strain MH9 based on phenotype and phy- logenetic analysis. The antibacterial polypeptide was pro- duced optimally at 35 °C after 48 h of growth, precipitated by 50 % ammonium sulphate, and further purified using HPLC. The sequential steps of purification decrease the peptide contents with prominent antibacterial activity. The peptide composed of 11 amino acid was further charac- terized by FT-IR and NMR. Results suggested that the peptide molecule is a novel antibacterial agent that is effective against both Gram-positive and Gram-negative bacteria. This study may have important implications for new peptide antibiotic that could be a new addition to treat infections. Keywords Antibiotic characterization Á Bacillus brevis MH9 Á Bacterial peptide antibiotic Á Peptide purification Introduction The bacterial infections and resistance to broad-spectrum antibiotics are progressively increasing, demanding iden- tification and development of new bioactive compounds against these pathogens. Since the microorganisms are reservoir of various pharmacological active compounds (Smith et al. 1997; Spellberg et al. 2008) development of antibacterial drugs from natural sources form such microbes are emerging as new trends (Jacob and Zasloff 1994). The genus Bacillus has been extensively used in microbial and pharmaceutical biotechnology for produc- tion of antibiotics and several other important secondary metabolites (Stachelhaus et al. 1995). Several strains of Bacillus reported to produce polypeptide antibiotics including bacitracin, polymyxin, gramicidin, and colistin (Berdy 2005) under various environmental stresses (Kleerebezem and Quadri 2001). These polypeptide antibiotics are usually closely related to each other (Stachelhaus et al. 1995) and differ from each other by one or a few amino acid residues (Katz and Demain 1977). Reported antibacterial polypeptides produced by the genus Bacilli are found effective mostly against Gram- positive bacteria (Anderson et al. 2001; Muhammad et al. 2014). However, polymyxin, colistin, and circulin show actions against Gram-negative species while bacillomycin, mycobacillin, and fungistatin are active against molds and & Amjad Ali amjaduni@gmail.com 1 Institute of Molecular Biology and Biotechnology, Bahauddin Zakariya University, Multan 60000, Pakistan 2 Atta-ur-Rahman School of Applied Biosciences (ASAB), National University of Sciences and Technology (NUST), Islamabad 44000, Pakistan 3 Department of Pharmacy, COMSATS Institute of Information Technology, Abbottabad, Pakistan 4 University College of Pharmacy, University of the Punjab, Lahore, Pakistan 5 Centre for Genomics and Applied Gene Technology, Institute of Integrative Omics and Applied Biotechnology (IIOAB), Nonakuri, Purba Medinipur, West Bengal, India 123 Int J Pept Res Ther DOI 10.1007/s10989-015-9508-2