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Open Access Research article

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

Zhaohui Huang12*, Yu Hu12, Linfei Shou3 and Mingxu Song12

Author affiliations

1 Clinical laboratory, the Fourth Affiliated Hospital of Soochow University, 200 Huihe Road, Wuxi, 214062, China

2 Clinical laboratory, the Fourth People’s Hospital of Wuxi, 200 Huihe Road, Wuxi, 214062, China

3 Institute for the Control of Agro-chemicals of Zhejiang Province, 29 East Fengqi Road, Hangzhou, 310020, China

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Citation and License

BMC Microbiology 2013, 13:87  doi:10.1186/1471-2180-13-87

Published: 17 April 2013

Abstract

Background

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.

Results

A 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.

Conclusions

In 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.

Keywords:
Paenibacillus ehimensis; Lipopeptide antibiotics; Drug-resistant bacteria