Abstract
A bacteriocinogenic Lactobacillus rhamnosus L156.4 strain isolated from the feces of NIH mice was identified by 16S rRNA gene sequencing and MALDI-TOF mass spectrometry. The entire genome was sequenced using Illumina, annotated in the PGAAP, and RAST servers, and deposited. Conserved genes associated with bacteriocin synthesis were predicted using BAGEL3, leading to the identification of an open reading frame (ORF) that shows homology with the L. rhamnosus GG (ATCC 53103) prebacteriocin gene. The encoded protein contains a conserved protein motif associated a structural gene of the Enterocin A superfamily. We found ORFs related to the prebacteriocin, immunity protein, ABC transporter proteins, and regulatory genes with 100% identity to those of L. rhamnosus HN001. In this study, we provide evidence of a putative bacteriocin produced by L. rhamnosus L156.4 that was further confirmed by in vitro assays. The antibacterial activity of the substances produced by this strain was evaluated using the deferred agar-spot and spot-on-the lawn assays, and a wide antimicrobial activity spectrum against human and foodborne pathogens was observed. The physicochemical characterization of the putative bacteriocin indicated that it was sensitive to proteolytic enzymes, heat stable and maintained its antibacterial activity in a pH ranging from 3 to 9. The activity against Lactobacillus fermentum, which was used as an indicator strain, was detected during bacterial logarithmic growth phase, and a positive correlation was confirmed between bacterial growth and production of the putative bacteriocin. After a partial purification from cell-free supernatant by salt precipitation, the putative bacteriocin migrated as a diffuse band of approximately 1.0–3.0 kDa by SDS-PAGE. Additional studies are being conducted to explore its use in the food industry for controlling bacterial growth and for probiotic applications.
Highlights
Lactobacillus rhamnosus is a facultative heterofermentative lactic acid bacterium (LAB) that is closely related to Lactobacillus casei and Lactobacillus zeae and encompasses a genetically diverse group of strains with a high frequency of discriminative core genome polymorphisms and a remarkable accessory genome, or variome distribution (Ceapa et al, 2015)
The results showed that the related region of the predicted bacteriocin of L. rhamnosus L156.4 is not identical to the one identified in L. rhamnosus GG (ATCC 53103)
We provided evidence of a putative bacteriocin produced by L. rhamnosus L156.4 isolated from the feces of NIH mice, which was further confirmed by in vitro assays
Summary
Lactobacillus rhamnosus is a facultative heterofermentative lactic acid bacterium (LAB) that is closely related to Lactobacillus casei and Lactobacillus zeae and encompasses a genetically diverse group of strains with a high frequency of discriminative core genome polymorphisms and a remarkable accessory genome, or variome distribution (Ceapa et al, 2015). Bacteriocinogenic L. rhamnosus strains have been isolated from human feces (Gorbach, 1996; Gill et al, 2000; Cukrowska et al, 2009; Dimitrijevicet al., 2009; Aguilar-Uscanga et al, 2013), vaginal microbiota (Li et al, 2005), fermented beverages (Todorov and Dicks, 2005), grape peels (Sarika et al, 2010), milk samples (Srinivasan et al, 2013), and cheese (Jeong and Moon, 2015) This species is generally recognized as safe (GRAS) and has been widely explored as a probiotic in animal production (Weese and Anderson, 2002) human health (Gill et al, 2000; Cukrowska et al, 2009; Douillard et al, 2013; Szajewska and Kołodziej, 2015) and as a biopreservative in food systems (Cotter et al, 2005; Douillard et al, 2013). The currently accepted system for classifying bacteriocins is based on whether they are post-translationally modified (class I) or are unmodified/minimally modified (class II) (Cotter et al, 2005, 2013)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
