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Transcriptional responses of Streptococcus gordonii and Fusobacterium nucleatum to coaggregation

Mutha NVR, Mohammed WK, Krasnogor N, Tan GYA, Choo SW, Jakubovics NS

Mol Oral Microbiol, 2018 12;33(6):450-464.
PMID: 30329223 DOI: 10.1111/omi.12248

Cell-cell interactions between genetically distinct bacteria, known as coaggregation, are important for the formation of mixed-species biofilms such as dental plaque. Interactions lead to gene regulation in the partner organisms that may be critical for adaptation and survival in mixed-species biofilms. Here, gene regulation responses to coaggregation between Streptococcus gordonii and Fusobacterium nucleatum were studied using dual RNA-Seq. Initially, S. gordonii was shown to coaggregate strongly with F. nucleatum in buffer or human saliva. Using confocal laser scanning microscopy and transmission electron microscopy, cells of different species were shown to be evenly distributed throughout the coaggregate and were closely associated with one another. This distribution was confirmed by serial block face sectioning scanning electron microscopy, which provided high resolution three-dimensional images of coaggregates. Cell-cell sensing responses were analysed 30 minutes after inducing coaggregation in human saliva. By comparison with monocultures, 16 genes were regulated following coaggregation in F. nucleatum whereas 119 genes were regulated in S. gordonii. In both species, genes involved in amino acid and carbohydrate metabolism were strongly affected by coaggregation. In particular, one 8-gene operon in F. nucleatum encoding sialic acid uptake and catabolism was up-regulated 2- to 5-fold following coaggregation. In S. gordonii, a gene cluster encoding functions for phosphotransferase system-mediated uptake of lactose and galactose was down-regulated up to 3-fold in response to coaggregation. The genes identified in this study may play key roles in the development of mixed-species communities and represent potential targets for approaches to control dental plaque accumulation.

Matched MeSH terms: Adhesins, Bacterial/genetics
Fulltext Evolutionary study of Yersinia genomes deciphers emergence of human pathogenic species

Tan SY, Tan IK, Tan MF, Dutta A, Choo SW

Sci Rep, 2016 10 31;6:36116.
PMID: 27796355 DOI: 10.1038/srep36116

On record, there are 17 species in the Yersinia genus, of which three are known to be pathogenic to human. While the chromosomal and pYV (or pCD1) plasmid-borne virulence genes as well as pathogenesis of these three species are well studied, their genomic evolution is poorly understood. Our study aims to predict the key evolutionary events that led to the emergence of pathogenic Yersinia species by analyzing gene gain-and-loss, virulence genes, and "Clustered regularly-interspaced short palindromic repeats". Our results suggest that the most recent ancestor shared by the human pathogenic Yersinia was most probably an environmental species that had adapted to the human body. This might have led to ecological specialization that diverged Yersinia into ecotypes and distinct lineages based on differential gene gain-and-loss in different niches. Our data also suggest that Y. pseudotuberculosis group might be the donor of the ail virulence gene to Y. enterocolitica. Hence, we postulate that evolution of human pathogenic Yersinia might not be totally in parallel, but instead, there were lateral gene transfer events. Furthermore, the presence of virulence genes seems to be important for the positive selection of virulence plasmid. Our studies provide better insights into the evolutionary biology of these bacteria.

Matched MeSH terms: Adhesins, Bacterial/genetics
Multiplex PCR for detection of Helicobacter pylori infection in gastric biopsies with lower inflammatory score

Fadilah N, Hanafiah A, Razlan H, Wong ZQ, Mohamed Rose I, Rahman MM

Br J Biomed Sci, 2016 Oct;73(4):180-187.
PMID: 27922429

BACKGROUND: No gold standard has yet been established for the diagnosis of H. pylori infection. A multiplex polymerase chain reaction (mPCR) was developed in this study for rapid, sensitive and specific detection of H. pylori from gastric biopsies.
METHODS: H. pylori infections were determined by in-house rapid urease test (iRUT), culture, histology and multiplex PCR.
RESULTS: A total of 140 (60.9%) from 230 patients were positive for H. pylori infection. H. pylori were detected in 9.6% (22/230), 17% (39/230), 12.6% (29/230) and 60% (138/230) of biopsy specimens by culture, iRUT, histology and mPCR, respectively. mPCR identified H. pylori infection in 100% of biopsies with positive histology and culture. All biopsies with positive iRUT yielded positive PCR except two cases. mPCR also detected H. pylori in additional 116, 101 and 109 biopsies that were negative by culture, iRUT and histology, respectively. Positive samples by mPCR showed lower average in H. pylori density, activity and inflammation scores. The Indians showed the highest prevalence of H. pylori infection compared to the Chinese and the Malays. In addition, Chinese patients with older age were significantly infected compared to other ethnicities.
CONCLUSION: PCR was able to detect the highest numbers of positive cases although the lowest average scores were recorded in the activity, inflammatory and H. pylori density.

Matched MeSH terms: Adhesins, Bacterial/genetics

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