A non-pediocin low molecular weight antimicrobial peptide produced by Pediococcus pentosaceus strain IE-3 shows increased activity under reducing environment.

Pradip K Singh,Suresh Korpole,Shalley Sharma,Annu Kumari

doi:10.1186/s12866-014-0226-2

Pradip K Singh, Suresh Korpole + Show 2 more

Open Access

https://doi.org/10.1186/s12866-014-0226-2

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Journal: BMC microbiology	Publication Date: Aug 27, 2014
Citations: 57	License type: CC BY 4.0

Affiliation: Institute of Microbial Technology

Abstract

BackgroundSpecies of the genus Pediococcus are known to produce antimicrobial peptides such as pediocin-like bacteriocins that contain YGNGVXC as a conserved motif at their N-terminus. Until now, the molecular weight of various bacteriocins produced by different strains of the genus Pediococcus have been found to vary between 2.7 to 4.6 kD. In the present study, we characterized an antimicrobial peptide produced by P. pentosaceus strain IE-3.ResultsAntimicrobial peptide was isolated and purified from the supernatant of P. pentosaceus strain IE-3 grown for 48 h using cation exchange chromatography and reversed-phase high-performance liquid chromatography (RP-HPLC) techniques. While MALDI-TOF MS experiments determined the precise molecular mass of the peptide to be 1701.00 Da, the de novo sequence (APVPFSCTRGCLTHLV) of the peptide revealed no similarity with reported pediocins and did not contain the YGNGVXC conserved motif. Unlike pediocin-like bacteriocins, the low molecular weight peptide (LMW) showed resistance to different proteases. Moreover, peptide treated with reducing agent like dithiothreitol (DTT) exhibited increased activity against both Gram-positive and Gram-negative test strains in comparison to native peptide. However, peptide treated with oxidizing agent such as hydrogen peroxide (H2O2) did not show any antimicrobial activity.ConclusionTo our knowledge this is the lowest molecular weight peptide produced by members of the genus Pediococcus. The low molecular weight peptide shared amino acid arrangement with N-terminal sequence of Class IIa, pediocin-like bacteriocins and showed increased activity under reducing conditions. Antimicrobial peptides active under reduced conditions are valuable for the preservation of processed foods like meat, dairy and canned foods where low redox potential prevails.

Highlights

Species of the genus Pediococcus are known to produce antimicrobial peptides such as pediocin-like bacteriocins that contain YGNGVXC as a conserved motif at their N-terminus
The 48 h cell free fermented broth (CFB) of P. pentosaceus strain IE-3 grown in anaerobic broth displayed antimicrobial activity against different indicator strains in well diffusion assay (Table 1)
A curve displaying antimicrobial production versus bacterial growth showed that the antimicrobial peptide production was initiated during early log phase (6 h of incubation) which increased to a maximum level by initial stationary phase (14 h) and remained constant thereafter (Figure 1a)

Summary

Introduction

Species of the genus Pediococcus are known to produce antimicrobial peptides such as pediocin-like bacteriocins that contain YGNGVXC as a conserved motif at their N-terminus. Though pediocin producing members of the genus Pediococcus are largely isolated from dairy products, they have been reported from diverse environments including human stool sample [15,16]. Among the known variants of pediocin-like bacteriocins, pediocin PA1 is well-studied 4.6 kDa antimicrobial peptide with thermo-stability and wide pH range activity [17]. It was inactivated by proteases like pepsin, trypsin, chymotrypsin, proteinase K and pronase E [10]. We describe the isolation, purification and characterization of a novel antimicrobial peptide produced by P. pentosaceus strain IE-3 isolated from a dairy effluent sample [21]

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Conclusion