Comparison of plasmids from clinical Lactobacillus strains
Loading...
Date
2018
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Western Cape
Abstract
The vaginal mucosa is dominated by Gram positive, rod shaped lactobacilli which serve as a
natural barrier against infection. In both healthy and BV infected women Lactobacillus
crispatus and Lactobacillus jensennii has been found to be the predominant Lactobacillus
species. Many studies have been conducted to assess factors influencing lactobacilli dominance
in the vaginal microbiome. However, no study has evaluated the impact of plasmids on the
vaginal lactobacilli. In the present study two plasmids, pLc17 and pLc4, isolated from vaginal
Lactobacillus species of both healthy and BV infected women were characterized. pLc4 was
present in both Lactobacillus crispatus and Lactobacillus jensennii while pLc17 was only
present in Lactobacillus crispatus. pLc17 (16663 bp in size) encoded a ribonucleotide
diphosphate reductase (RNR), a filamentation induced by cAMP-like (FIC-like) protein and
numerous mobile elements. The FIC-like protein may assist pLc17 to persist within the
bacterial population, while RNR is commonly associated with phages and may indicate phage
infection. pLc4 (4224 bp in size) encodes for a replication initiator protein and a plasmid
partitioning protein. The replication protein on pLc4 shows 44% identity with the replication
initiation protein of pSMQ173b_03. On further phylogenetic and sequence analysis with other
Rolling Circle Replication (RCR) plasmids, pLc4 appears to be novel as the plasmid shows a
low degree of similarity to these RCR plasmids. pLc17 appears to carry both a RCR replicon as
well as a theta replicon, similar to pIP501, the broad-host-range plasmid from Bacillus subtilis.
The relative Plasmid Copy Number (PCN) for pLc4 and pLc17 was analysed using quantitative
polymerase chain reaction (qPCR) for the healthy state relative to the disease state from twentyeight
vaginal swab samples obtained from the National Institute for Communicable Diseases
(NICD). The relative PCN for pLc4 and pLc17 had a fold increase of ~2.803 and ~1.693,
respectively in the healthy patient samples relative to BV infected patient samples. However,
there were not found to be significant differences when taking the standard error into account
Due to the novelty of these plasmids further analysis and characterisation is required for both
plasmids, to establish what role they may play in the health of the vaginal milieu.
Description
Magister Scientiae - MSc (Biotechnology)
Keywords
Lactobacillus crispatus, Lactobacillus jensennii, pLc17, pLc4, Ribonucleosidediphosphate
reductase, Rolling Circle Replication (RCR), Quantitative polymerase chain
reaction (qPCR), Plasmid copy number (PCN), Theta replication, National Institute for Communicable Diseases, Communicable Diseases