Characterization of a Lactiplantibacillus plantarum R23 Isolated from Arugula by Whole-Genome Sequencing and Its Bacteriocin Production Ability.

Joana Barbosa,Maria Helena Almeida,Paula Teixeira,Helena Albano,Beatriz Silva,Teresa Nogueira

doi:10.3390/ijerph18115515

Abstract

Lactiplantibacillus plantarum is one of the lactic acid bacteria species most used as probiotics and starter cultures in food production. Bacteriocin-producers Lpb. plantarum are also promising natural food preservatives. This study aimed to characterize Lpb. plantarum R23 and its bacteriocins (R23 bacteriocins). The genome sequence of Lpb. plantarum R23 was obtained by whole-genome sequencing (WGS) in an Illumina NovaSeq platform. The activity of Lpb. plantarum R23-produced bacteriocin against two Listeria monocytogenes strains (L7946 and L7947) was evaluated, and its molecular size was determined by tricine-SDS-PAGE. No virulence or antibiotic resistance genes were detected. Four 100% identical proteins to the class II bacteriocins (Plantaricin E, Plantaricin F, Pediocin PA-1 (Pediocin AcH), and Coagulin A) were found by WGS analysis. The small (<6.5 kDa) R23 bacteriocins were stable at different pH values (ranging from 2 to 8), temperatures (between 4 and 100 °C), detergents (all, except Triton X-100 and Triton X-114 at 0.01 g/mL), and enzymes (catalase and α-amylase), did not adsorb to the producer cells, had a bacteriostatic mode of action and their maximum activity (AU/mL = 12,800) against two L. monocytogenes strains occurred between 15 and 21 h of Lpb. plantarum R23 growth. Lactiplantibacillus plantarum R23 showed to be a promising bio-preservative culture because, besides being safe, it produces a stable bacteriocin or bacteriocins (harbors genes encoding for the production of four) inhibiting pathogens as L. monocytogenes. Further studies in different food matrices are required to confirm this hypothesis and its suitability as a future starter culture.

Highlights

IntroductionAdequate amounts of ready-to-eat vegetables should be consumed daily as part of a diversified and healthy diet because they are an essential source of vitamins, minerals, dietary fiber, and phytonutrients [1]
Lactiplantibacillus plantarum R23 was isolated from pre-washed bagged arugula, screened for antimicrobial activity and bacteriocin production, and identified by whole-genome sequencing in our previous publication [15]
The BAGEL4 software showed that a contig of the assembled bacterial genome encodes two proteins that are 100% identical to the class II bacteriocins, Plantaricin E and Plantaricin

Summary

Introduction

Adequate amounts of ready-to-eat vegetables should be consumed daily as part of a diversified and healthy diet because they are an essential source of vitamins, minerals, dietary fiber, and phytonutrients [1]. Fresh vegetable consumption improves gut bacteria diversity, contributing to improved metabolisms [1]. Despite the constant considerable contamination of ready-to-eat vegetables with important foodborne pathogens [2,3,4], bacteria with benefits for the food industry, such as lactic acid bacteria (LAB), have been found in these products [5,6]. Lactiplantibacillus plantarum (previously Lactobacillus plantarum) [7] is one of the main promising species of LAB widely used in food production as a probiotic and starter culture [8,9].

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