Surfactin Like Broad Spectrum Antimicrobial Lipopeptide Co-produced With Sublancin From Bacillus subtilis Strain A52: Dual Reservoir of Bioactives.

Deepika Sharma,Neeraj Khatri,Shelley Sardul Singh,Suresh Korpole,Shikha Sharma,Vishakha Grover,Prabhu B Patil,Piyush Baindara

doi:10.3389/fmicb.2020.01167

Abstract

An antimicrobial substance producing strain designated as A52 was isolated from a marine sediment sample and identified as Bacillus sp., based on 16S rRNA gene sequence analysis. The ANI and dDDH analysis of the genome sequence displayed high identity with two strains of B. subtilis sub sp. subtilis. Strain A52 yielded two antimicrobial peptides (AMPs) that differed in activity spectrum. MALDI mass spectrometry analysis of HPLC purified fractions revealed mass of peptides as 3881.6 and 1061.9 Da. The antiSMASH analysis of genome sequence unraveled presence of identical biosynthetic cluster involved in production of sublancin from B. subtilis sub sp. subtilis strain 168, which yielded peptide with identical mass. The low molecular weight peptide is found to be a cyclic lipopeptide containing C16 β-hydroxy fatty acid that resembled surfactin-like group of biosurfactants. However, it differed in fatty acid composition and antimicrobial spectrum in comparison to other surfactins produced by strains of B. subtilis. It exhibited broad spectrum antibacterial activity, inhibited growth of pathogenic strains of Candida and filamentous fungi. Further, it exhibited hemolytic activity, but did not show phytotoxic effect in seed germination experiment. The emulgel formulation of surfactin-like lipopeptide showed antimicrobial activity in vitro and did not show any irritation effects in animal studies using BALB/c mice. Moreover, surfactin-like lipopeptide displayed synergistic activity with fluconazole against Candida, indicating its potential for external therapeutic applications.

Highlights

Development of drug resistance is a great threat to the effective treatment of infections caused by opportunistic or nosocomial pathogens (Davies and Davies, 2010; Prestinaci et al, 2015; Li and Webster, 2018; Laws et al, 2019)
In the quest to develop novel antimicrobial agents, the marine ecosystem is favored environmental niche owing to the presence of diverse antimicrobial substances (Desjardine et al, 2007; Baindara et al, 2013; Ponnappan et al, 2015; Agrawal et al, 2017; Gupta et al, 2019)
Strain A52 was identified as a member of the genus Bacillus, taxonomically related to species B. subtilis (Tareq et al, 2014) and B. tequilensis (Rani et al, 2016)

Summary

Introduction

Development of drug resistance is a great threat to the effective treatment of infections caused by opportunistic or nosocomial pathogens (Davies and Davies, 2010; Prestinaci et al, 2015; Li and Webster, 2018; Laws et al, 2019). In an attempt to combat such resistant pathogens, there is an urgent and compelling need to develop novel antimicrobials. To this effect, antimicrobial peptides (AMPs) including bacteriocins and lipopeptides with broad-spectrum antimicrobial activities have been found to be promising alternative candidates (Singh et al, 2014; Sharma et al, 2014; Lum et al, 2015; Raman et al, 2015; Lyu et al, 2016; Gwynne and Gallagher, 2018)

Methods

Results

Conclusion