Recent research has provided mechanistic insight into the important contributions of the gut microbiota to vertebrate biology, but questions remain about the evolutionary processes that have shaped ...this symbiosis. In the present study, we showed in experiments with gnotobiotic mice that the evolution of Lactobacillus reuteri with rodents resulted in the emergence of host specialization. To identify genomic events marking adaptations to the murine host, we compared the genome of the rodent isolate L. reuteri 100-23 with that of the human isolate L. reuteri F275, and we identified hundreds of genes that were specific to each strain. In order to differentiate true host-specific genome content from strain-level differences, comparative genome hybridizations were performed to query 57 L. reuteri strains originating from six different vertebrate hosts in combination with genome sequence comparisons of nine strains encompassing five phylogenetic lineages of the species. This approach revealed that rodent strains, although showing a high degree of genomic plasticity, possessed a specific genome inventory that was rare or absent in strains from other vertebrate hosts. The distinct genome content of L. reuteri lineages reflected the niche characteristics in the gastrointestinal tracts of their respective hosts, and inactivation of seven out of eight representative rodent-specific genes in L. reuteri 100-23 resulted in impaired ecological performance in the gut of mice. The comparative genomic analyses suggested fundamentally different trends of genome evolution in rodent and human L. reuteri populations, with the former possessing a large and adaptable pan-genome while the latter being subjected to a process of reductive evolution. In conclusion, this study provided experimental evidence and a molecular basis for the evolution of host specificity in a vertebrate gut symbiont, and it identified genomic events that have shaped this process.
The development of antibiotic resistance amongst bacterial pathogens and a population explosion, e.g. in countries such as Indonesia, are two issues the world is facing today. These issues have ...stimulated interest in the development of new antimicrobial therapeutic agents and contraceptive strategies, such as novel spermicides. Bacteriocins, which are bacterially-derived antimicrobial peptides, may fulfill some of the criteria for these new agents.
Weissella confusa MBF8-1, originally isolated from a homemade soy product, exhibits antibacterial activity that was subsequently found to be plasmid-encoded, presumably by three peptides Bac1, Bac2 and Bac3. In the present study, we tested cell-free MBF8-1 bacteriocin preparations and chemically-synthesized versions of Bac1, Bac2 and Bac3 peptides for (i) its antibacterial activity against the indicator bacterium Leuconostoc mesenteroides and (ii) its ability to affect the motility of spermatozoa. Nisin, a known lantibiotic bacteriocin, was used as the control.
Here, we demonstrate that synthetic Bac1, in combination with synthetic Bac2, was sufficient to inhibit the growth of L. mesenteroides and affect sperm motility. However, the presence of all three synthetic peptides, s-Bac1, s-Bac2 and s-Bac3, was required for full potency.
In summary, the bacteriocin-like peptides of W. confusa MBF8-1 have the potential to be developed as a narrow-spectrum antimicrobial agent and a novel spermicidal agent.
Members of the Gram-positive lactic acid bacteria (LAB) are well-known for their beneficial properties as starter cultures and probiotics. Many LAB species produce ribosomally synthesized ...proteinaceous antibiotics (bacteriocins). Weissella confusa MBF8-1 is a strain isolated from a fermented soybean product that not only produces useful exopolysaccharides but also exhibits bacteriocin activity, which we call weissellicin MBF. Here, we show that bacteriocin production by W. confusa MBF8-1 is specified by a large plasmid, pWcMBF8-1. Plasmid pWcMBF8-1 (GenBank accession number KR350502), which was identified from the W. confusa MBF8-1 draft genome sequence, is 17 643 bp in length with a G + C content of 34.8% and contains 25 open reading frames (ORFs). Six ORFs constitute the weissellicin MBF locus, encoding three putative double-glycine-motif peptides (Bac1, Bac2, Bac3), an ABC transporter complex (BacTE) and a putative immunity protein (BacI). Two ORFs encode plasmid partitioning and mobilization proteins, suggesting that pWcMBF8-1 is transferable to other hosts. To the best of our knowledge, plasmid pWcMBF8-1 not only represents the first large Weissella plasmid to be sequenced but also the first to be associated with bacteriocin production in W. confusa.
This paper not only describes the first large plasmid, pWcMBF8-1, to be sequenced from the lactic acid bacterial genus Weissella, but also the first to be associated with bacteriocin (antibacterial) production in the species, Weissella confusa.
Plaque and Dental Caries Risk in Midlife Benn, Angela M L; Heng, Nicholas C K; Thomson, W Murray ...
Caries research,
02/2023, Letnik:
56, Številka:
5-6
Journal Article
Recenzirano
Dental caries is an endogenous microbial community-based disease resulting from an ecological shift from dynamic stability to metabolic imbalance in a consortium of acidogenic and aciduric bacteria ...comprising the dental plaque biofilm. Participants were members of the Dunedin Multidisciplinary Health and Development Study, a longitudinal investigation of health and behaviour in a cohort born in Dunedin, New Zealand. Oral biofilm samples (collected at age 32 years) from anterior labial supragingival, posterior lingual supragingival, posterior subgingival, and the dorsum of the tongue habitats for 841 participants were analysed using checkerboard DNA-DNA hybridisation (CKB), focussing on 30 ecologically significant bacteria. Associations of CKB data with dental caries at ages 32 and 45 years were assessed using regression modelling, adjusting for potential confounders including sex, xerostomia, and oral hygiene. The putative periodontitis pathobiont Tannerella forsythia (in the anterior supragingival biofilm) was associated with untreated caries at age 32 years. The percentage of total summed cell number counts for two putative periodontitis-associated species (T. forsythia and Micromonas micros) was associated with greater caries experience at age 32 years and the development of new caries between age 32 and 45 years. Additionally, severe caries (3 + cavities) was associated with putative caries pathobionts (Lactobacillus fermentum, Lactobacillus plantarum), periodontitis-associated species, and commensals (M. micros, Campylobacter rectus, Streptococcus mitis biovar I, Streptococcus mitis biovar II) in the subgingival biofilm. Participants with sustained poor oral hygiene through age 32 years not only had greater experience of caries by that age than those with good oral hygiene (fully adjusted incidence risk ratio = 5.10, 95% CI: 3.30, 7.89) but also experienced greater incidence of new caries from age 32 to 45 years (incidence risk ratio = 3.69, 95% CI: 2.62, 5.20). These findings provide evidence in support of the extended caries ecological plaque hypotheses, the polymicrobial aetiology of caries, and the integrated aetiology of dental caries and periodontal diseases. They also underscore the roles of poor oral self-care (particularly over the life course) and xerostomia in the occurrence and progression of caries.
Members of the Gram-positive bacterial genus Streptococcus are a diverse collection of species inhabiting many body sites and range from benign, nonpathogenic species to those causing ...life-threatening infections. The streptococci are also prolific producers of bacteriocins, which are ribosomally synthesized proteinaceous antibiotics that kill or inhibit species closely related to the producer bacterium. With the emergence of bacterial resistance to conventional antibiotics, there is an impetus to discover, and implement, new and preferably 'natural' antibiotics to treat or prevent bacterial infections, a niche that bacterial interference therapy mediated by bacteriocins could easily fill. This review focuses on describing the diversity of bacteriocins produced by streptococci and also puts forth a case for Streptococcus salivarius, a nonpathogenic and numerically predominant oral species, as an ideal candidate for development as the model probiotic for the oral cavity. S. salivarius is a safe species that not only produces broad-spectrum bacteriocins but harbors bacteriocin-encoding (and bacteriocin-inducing) transmissible DNA entities (megaplasmids).
The oral microbiome is ecologically diverse, complex, dynamic, and little understood. We describe the microbiota of four oral habitats in a birth cohort at age 32 and examine differences by sex, oral ...hygiene, and current smoking status, dental caries, and periodontal health. Oral biofilm samples collected from anterior labial supragingival, posterior lingual supragingival, subgingival, and tongue sites of 841 Dunedin Multidisciplinary Health and Development Study members were analysed using checkerboard DNA‐DNA hybridization; focusing on 30 ecologically important bacterial species. The four habitats exhibited distinct microbial profiles that differed by sex. Streptococcus gordonii was more dominant in supragingival and tongue biofilms of males; Porphyromonas gingivalis exhibited higher relative abundance in subgingival biofilm of females. Males had higher scores than females for periodontal pathogens at supragingival sites. The relative abundance of several putative caries and periodontal pathogens differed in smokers and non‐smokers. With poor oral hygiene significantly higher proportions of Gram‐negative facultative anaerobes were present in subgingival biofilm and there were higher scores for the principal components characterised by putative cariogenic and periodontal pathogens at each site. Distinctive microenvironments shape oral biofilms and systematic differences exist by sex, oral hygiene, and smoking status.
Aim
To determine the relationship between periodontal pathogen load and anti‐human heat shock protein 60 (hHSP60) antibodies in patients with established cardiovascular disease (CVD).
Materials and ...Methods
Participants were cardiovascular patients (n = 74) with a previous hospital admission for myocardial infarction. Concurrent periodontal pathogen load of Porphyromonas gingivalis, Fusobacterium nucleatum, Tannerella forsythia and Aggregatibacter actinomycetemcomitans was determined using quantitative real‐time PCR. Serum antibodies to these pathogens, GroEL and hHSP60 were determined using an ELISA.
Results
There was a trend for increasing anti‐hHSP60 antibody as the number of bacterial species increased. The strongest positive correlations were found between anti‐hHSP60 levels and numbers of T. forsythia (r = 0.43; p < 0.001) and between anti‐hHSP60 and anti‐GroEL levels (r = 0.39; p = 0.001). Patients with extensive periodontal pocketing (≥4 mm) had higher numbers of P. gingivalis and T. forsythia (p < 0.05) and a higher subgingival pathogen load (p < 0.05) than patients with minimal pocketing (≤1 site ≥ 4 mm). They also had significantly elevated anti‐hHSP60 levels (p < 0.05). Overall, the highest anti‐hHSP60 levels were seen in patients with extensive periodontal pocketing and all four bacterial species.
Conclusions
In cardiovascular patients, a greater burden of subgingival infection with increased levels of P. gingivalis and T. forsythia is associated with modestly higher anti‐hHSP60 levels.
The human oral cavity is home to one of the most diverse, dynamic and complex collections of microbes (the 'oral microbiota') with an estimated 700-1,000 different microbial species inhabiting a ...variety of ecological niches, such as the teeth, tongue, gums and saliva. Despite decades of research, much is still unknown of the functions and activities of the oral microbiota as many species, particularly those discovered by culture-independent (molecular) techniques, are yet to be cultivated. The past decade has seen the introduction of so-called next-generation DNA sequencing (NGS) technologies which can generate unprecedented amounts of DNA sequence data quickly and reliably. NGS has revolutionised the study of oral microbiota by allowing microbial community profiling in health and disease. Furthermore, NGS facilitates the cost-effective sequencing of individual microbial genomes. Over the past 10 years, our research groups have collaborated on a variety of NGS projects involving whole-genome sequencing of a variety of oral and non-oral bacteria, and oral microbiota profiling in health and disease (severe dental caries and periodontal disease). This paper aims to provide an overview of the NGS technologies we have used and the bioinformatic tools available to analyse NGS-scale datasets, and to highlight some of our NGS achievements.
Dental caries is an infectious disease that is continuing to increase in prevalence, reducing the quality of life for millions worldwide as well as causing considerable expense, with an estimated ...US$108 billion spent on dental care in the USA each year. Oral probiotics are now being investigated to determine whether they could play a role in the prevention and treatment of this disease. Streptococcus salivarius strain JH is a potential probiotic candidate that produces multiple proteinaceous antimicrobials (bacteriocins), the inhibitory spectrum of which includes Streptococcus mutans, one of the principal causative agents of dental caries. The genome of strain JH has previously been shown to contain the biosynthetic loci for the bacteriocins salivaricin A3, streptin and streptococcin SA-FF22. Here we show that strain JH also produces salivaricin E, a 32 aa lantibiotic with a mass of 3565.9 Da, which is responsible for the inhibition of S. mutans growth. In addition, strain JH was shown to produce dextranase, an enzyme that hydrolyses (1 → 6)-α-D-glucosidic linkages, at levels higher than any other S. salivarius tested. In vitro testing showed that partial hydrolysis of the exopolymeric substances of S. mutans, using strain JH dextranase, improved the anti-S. mutans inhibitory activity of the lytic bacteriocin, zoocin A. The multiple bacteriocin and dextranase activities of strain JH support its candidature for development as an oral probiotic.
In order to assess the colonization efficacy of the oral probiotic Streptococcus salivarius K12, a rapid method for specific detection and enumeration of the strain was developed. Here, we describe a ...two-step TaqMan™ quantitative PCR assay using primer-probe combinations targeting genes of the locus encoding the lantibiotic bacteriocin salivaricin B.
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