Isolation and Structural Elucidation of Brevibacillin, an Antimicrobial Lipopeptide from Brevibacillus laterosporus That Combats Drug-Resistant Gram-Positive Bacteria

Abstract

A new environmental bacterial strain exhibited strong antimicrobial characteristics against methicillin-resistant Staphylococcus aureus, vancomycin-resistant strains of Enterococcus faecalis and Lactobacillus plantarum, and other Gram-positive bacteria. The producer strain, designated OSY-I 1 , was determined to be Brevibacillus laterosporus via morphological, biochemical, and genetic analyses. The antimicrobial agent was extracted from cells of OSY-I 1 with isopropanol, purified by high-performance liquid chromatography, and structurally analyzed using mass spectrometry (MS) and nuclear magnetic resonance (NMR). The MS and NMR results, taken together, uncovered a linear lipopeptide consisting of 13 amino acids and an N-terminal C 6 fatty acid (FA) chain, 2-hydroxy-3-methylpentanoic acid. The lipopeptide (FA-Dhb-Leu-Orn-Ile-Ile-Val-Lys-Val-Val-Lys-Tyr-Leu-valinol, where Dhb is ␣,␤-didehydrobutyric acid and valinol is 2-amino-3-methyl-1-butanol) has a molecular mass of 1,583.0794 Da and contains three modified amino acid residues: ␣,␤-didehydrobutyric acid, ornithine, and valinol. The compound, designated brevibacillin, was determined to be a member of a cationic lipopeptide antibiotic family. In addition to its potency against drugresistant bacteria, brevibacillin also exhibited low MICs (1 to 8 g/ml) against selected foodborne pathogenic and spoilage bacteria, such as Listeria monocytogenes, Bacillus cereus, and Alicyclobacillus acidoterrestris. Purified brevibacillin showed no sign of degradation when it was held at 80°C for 60 min, and it retained at least 50% of its antimicrobial activity when it was held for 22 h under acidic or alkaline conditions. On the basis of these findings, brevibacillin is a potent antimicrobial lipopeptide which is potentially useful to combat drug-resistant bacterial pathogens and foodborne pathogenic and spoilage bacteria. U nregulated access to antibiotics is one of the main reasons for the spread of antibiotic-resistant pathogens and their resistance genes through migration, travel, and trade (1). It was reported that in Europe alone, 25,000 patients die annually because of bacterial infections which cannot be treated with common antibiotics (2). Examples of antibiotic-resistant bacteria are methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus spp., carbapenem-resistant Mycobacterium tuberculosis, and highly virulent multidrug-resistant Clostridium difficile strains (2-5). Therefore, the discovery and development of new antimicrobial agents are of paramount importance. Despite their natural scarcity, new antimicrobial agents can be discovered by subjecting microorganisms that potentially produce such agents to screening and isolation processes (6, 7).The current study led to the discovery of a new strain of Brevibacillus sp. with promising antimicrobial activity. The genus Brevibacillus was established in 1996 on the basis of a genetic reclassification of strains previously recognized to be Bacillus brevis (8). Many bioactive compounds have been...

Genome-Guided Mass Spectrometry Expedited the Discovery of Paraplantaricin TC318, a Lantibiotic Produced by Lactobacillus paraplantarum Strain Isolated From Cheese

“…The discovery of a new beneficial antimicrobial agent is a tedious and time-consuming task, a fact consistent with the experience of the investigators of the current study (He et al, 2007;Guo et al, 2012;Yang et al, 2016). The urgency to speed up the discovery of new antimicrobials prompted these investigators to benefit from the advances in genomic and mass spectrometric analyses to accomplish this goal.…”

“…The 16S ribosomal RNA (rRNA) gene (16S rDNA) was sequenced to identify the producer isolate, OSY-TC318, as previously described (Weisburg et al, 1991;Yang et al, 2016), with modifications. A single colony of strain OSY-TC318 was cultured in MRS broth at 30 • C for 18 h. Aliquot (1 ml) of the broth culture was centrifuged at 16,000 × g for 2 min.…”

Diversity, Chemical Constituents and Biological Activities of Endophytic Fungi Isolated from Schinus terebinthifolius Raddi

“…Among the volatile compounds identified in the fungal extract of O. elatum, 1-dodecanol was the major compound, followed by 3-methylbutyric acid, 2-phenylethanol, acetic acid and 2-phenylethyl acetate. The antibacterial activity of 1-dodecanol and 3-methylbutyric acid against resistant bacteria has been attributed to their aliphatic carbon chains, which act on the integrity of the plasma membrane [52,53,55]. The aromatic alcohol 2-phenylethanol [54], acetic acid [51] and 2-phenylethyl acetate [50] also have antibacterial activity against different Gram-positive and Gram-negative bacteria.…”

Bacteriocin-like protein produced Brevibacillus laterosporus that can inhibit the growth of drug resistant bacteria

“…It is short-sequence peptides that categorized into different classes based on structural and functional characteristics as [25,28,[30][31]. The mode of action of bacteriocins is most likely based on its amphiphilic nature and the ability of the cationic amino acids to interact with the negatively charged phospholipids of the cell membrane, causing the disruption and depolarization of the membrane [23].…”