Isolation and partial characterization of cyclic lipopeptide antibiotics produced by Paenibacillus ehimensis B7

Linfei Shou,Zhaohui Huang,Mingxu Song,Yu Hu

doi:10.1186/1471-2180-13-87

Linfei Shou, Zhaohui Huang + Show 2 more

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https://doi.org/10.1186/1471-2180-13-87

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Abstract

BackgroundThe prevalence of drug-resistant bacteria has encouraged the search for novel antimicrobial compounds. Food-associated microorganisms, as a source of new antibiotics, have recently received considerable attention. The objective of this study was to find novel antimicrobial agents produced by food microorganisms.ResultsA bacterial strain B7, which has potent antimicrobial activity, was isolated from a sample of dairy waste. This strain was identified as Paenibacillus ehimensis based on the 16S rRNA gene sequence analysis, physiological and biochemical characterization. Two active compounds (PE1 and PE2) were obtained from P. ehimensis B7. Mass spectrometry (MS) analysis showed that the molecular masses of PE1 and PE2 were 1,114 and 1,100 Da, respectively. The tandem MS and amino acid analysis indicated that PE1 and PE2 were analogs of polypeptin, and PE2 was characterized as a new member of this family. Both compounds were active against all tested bacterial pathogens, including methicillin resistant Staphylococcus aureus, Escherichia coli, and pan-drug resistant Pseudomonas aeruginosa clinical isolate. Time-kill assays demonstrated that at 4 × MIC (minimum inhibitory concentration), PE1 and PE2 rapidly reduced the number of viable cells by at least 3-orders of magnitude, indicating that they were bactericidal antibiotics.ConclusionsIn the present work, two cationic lipopeptide antibiotics (PE1 and PE2) were isolated from P. ehimensis B7 and characterized. These two peptides showed broad antimicrobial activity against all tested human pathogens and are worthy of further study.

Highlights

The prevalence of drug-resistant bacteria has encouraged the search for novel antimicrobial compounds
Identification of strain B7 The bacteria strain B7 that is active against methicillin-resistant Staphylococcus aureus (MRSA) American Type Culture Collection (ATCC) 43300 and P. aeruginosa ATCC 27853 was selected for further investigation
The DNA-DNA re-association between strain B7 and P. ehimensis IFO 15659T was 96.3%. All of these characteristics supported the identification of the isolate as a member of P. ehimensis

Summary

Introduction

The prevalence of drug-resistant bacteria has encouraged the search for novel antimicrobial compounds. Food-associated microorganisms, as a source of new antibiotics, have recently received considerable attention. The objective of this study was to find novel antimicrobial agents produced by food microorganisms. As a source of new antibiotics, food-associated microorganisms have recently received increased attention. The well-known active compounds produced by these strains are peptide antibiotics, such as lantibiotics and lipopeptides [11,12,13]. To obtain antimicrobial agents that are novel safe and potent, a lot of food bacteria were isolated and screened for their antimicrobial activity. Strain B7, a new bacterial isolate from a sample of dairy waste, was found to produce antibiotics against both Gram-positive and Gram-negative human pathogens. After isolation and purification of the fermentation products, the chemical structure and biological characteristics of the active compounds produced by P. ehimensis B7 were determined

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