Human microbiome digest, August 19, 2014

Lots of oral and gut microbiome papers today – Alzheimer’s, probiotics, chemotherapy and radiation.

Oral microbiome

Review: The Microbiome and Disease: Reviewing the Links between the Oral Microbiome, Aging, and Alzheimer’s Disease – Deborah K. Shoemark – Journal of Alzheimer’s Disease

“Evidence linking oral bacteria to Alzheimer’s disease (AD) is discussed in the context of aging, drawing together data from epidemiological, experimental, genetic, and environmental studies. “

* Human oral viruses are personal, persistent and gender-consistent – Shira R Abeles – ISME Journal

“To improve our understanding of the DNA viruses that inhabit the human oral cavity, we examined saliva from a cohort of eight unrelated subjects over a 60-day period. “

* Predictive modeling of gingivitis severity and susceptibility via oral microbiota – Shi Huang – ISME Journal

“In diseased plaque microbiota, 27 bacterial genera changed in relative abundance and functional genes including 33 flagellar biosynthesis-related groups were enriched.”

Phylogenetic and functional gene structure shifts of the oral microbiomes in periodontitis patients – Yan Li – ISME Journal

“Here, we examined the phylogenetic and functional gene differences between periodontal and healthy individuals using MiSeq sequencing of 16S rRNA gene amplicons and a specific functional gene array”

Perspective: Fungal-bacterial interactions and their relevance to oral health: linking the clinic and the bench – Patricia I. Diaz – Frontiers in Cellular and Infection Microbiology

“We highlight the need to conduct longitudinal clinical studies to simultaneously characterize the bacterial and fungal components of the human oral microbiome in health and during disease progression.”

Effect of an oxygenating agent on oral bacteria in vitro and on dental plaque composition in healthy young adults – Mercedes Fernandez y Mostajo – Frontiers in Cellular and Infection Microbiology

“During the experiment individuals used AX mouthwash twice daily in absence of other oral hygiene measures. The microbiological composition of plaque was assessed by 16S rRNA gene amplicon sequencing.”

* Review: Advancements toward a systems level understanding of the human oral microbiome
Jeffrey S. McLean – Frontiers in Cellular and Infection Microbiology

“This review will discuss some of the recent insights into the oral microbiome at a fundamental level, existing knowledge gaps, as well as challenges that have surfaced and the approaches to address them.”

Gut microbiome

* Xylan utilization in human gut commensal bacteria is orchestrated by unique modular organization of polysaccharide-degrading enzymes – Meiling Zhang – PNAS USA

“Here we demonstrate that two human gut commensal Bacteroides are equipped with unique enzymes that allow degradation of xylan, a common hemicellulose in human diets.”

Evaluation of bifidobacterial community composition in the human gut by means of a targeted amplicon sequencing (ITS) protocol – Christian Milani – FEMS Microbiology Ecology

“Here, we define the internal transcribed spacer (ITS) sequences of all currently known Bifidobacterium taxa, providing a Bifidobacterium-specific primer pair that targets a hyper-variable region within the ITS suitable for precise taxonomic identification of all 48 so far recognized members of the Bifidobacterium genus.”

* Multi-omics analysis of Inflammatory Bowel Diseases – Hu Huang – Immunology Letters

“There is strong evidence of interactions between host genotype, environment, and gut microbiome profile in IBD.”

The methylome of the gut microbiome: disparate Dam methylation patterns in intestinal Bacteroides dorei – Michael T. Leonard – Frontiers in Microbiology

“Here metagenomic sequencing using the Pacific Biosciences platform allowed for rapid identification of bacterial GATC methylation status of a bacterial species in human stool samples. “

Perspective: Imposition of encapsulated non-indigenous probiotics into intestine may disturb human core microbiome – Abolfazl Barzegari – Frontiers in Microbiology

“..we envision that multi-probiotic therapy and holistic personalized microbiome supplements may be scientifically justified and valued in individualized probiotic designs and even targeted therapy of life-threatening diseases such as cancers in the future. “

Editorial: gut microbiota and chemotherapy- or radiation-induced gastrointestinal mucositis – M. R. Ferreira and H. J. N. Andreyev – Alimentary Pharmacology & Therapeutics

“Studies in those undergoing cancer therapy will lead to a new era in the treatment and prevention of the currently dreadful GI toxicity suffered by so many patients, and what we learn will almost certainly bring important insights to many other GI disorders.”

Respiratory microbiome

Cell-associated bacteria in the human lung microbiome – Robert P Dickson – Microbiome

“We present a novel methodological and analytical approach to the localization of lung microbiota and show that the prominent members of the lung microbiome are cell-associated, potentially via biofilms, cell adhesion, or intracellularity.”

Vaginal microbiome

A Systems Biology Approach Investigating the Effect of Probiotics on the Vaginal Microbiome and Host Responses in a Double Blind, Placebo-Controlled Clinical Trial of Post-Menopausal Women – Jordan E. Bisanz – PLOS ONE

“Analysis using 16S rRNA sequencing and metabolomics profiling revealed that the relative abundance of Lactobacillus was increased following probiotic administration as compared to placebo, which was weakly associated with an increase in lactate levels. “

Lactobacillus-dominated cervicovaginal microbiota associated with reduced HIV/STI prevalence and genital HIV viral load in African women – Hanneke Borgdorff – ISME Journal

“In this study, cervical samples of 174 Rwandan female sex workers were analyzed cross-sectionally using a phylogenetic microarray. “

* also tweeted by @MicrobiomDigest (yup, that’s me).

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Human microbiome, July 15

Not-always-rare taxa in a wide range of ecosystems, microbiome in early life, focus on Lactobacillus and Bacteroides and microbiota and inflammation.

General microbiome

Science Webinar: The promise of the microbiome: Function and dysfunction in humans and beyond – David A. Relman, Jack A. Gilbert, Rob Knight

“Microbiomes–the distinct microbial populations that colonize an array of bodily and environmental niches–are rapidly gaining prominence in numerous fields of research. “

Gut microbiome

Screen shot 2014-07-15 at 05.18PM, Jul 15Conditionally Rare Taxa Disproportionately Contribute to Temporal Changes in Microbial Diversity – Ashley Shade – mBio

“Using 16S rRNA amplicon sequencing of 3,237 samples from 42 time series of microbial communities from nine different ecosystems (air; marine; lake; stream; adult human skin, tongue, and gut; infant gut; and brewery wastewater treatment), we introduce a new method to detect typically rare microbial taxa that occasionally become very abundant (conditionally rare taxa [CRT]) and then quantify their contributions to temporal shifts in community structure.”

Screen shot 2014-07-15 at 05.20PM, Jul 15Functional genomics of Lactobacillus casei establishment in the gut – Hélène Licandro-Seraut – PNAS

“By determining the relative quantity of each of the 1,110 mutants before and after the in vivo challenge, we identified a core of 47 L. casei genes necessary for its establishment in the gut. “

Screen shot 2014-07-15 at 05.21PM, Jul 15Tuning transcription of nutrient utilization genes to catabolic rate promotes growth in a gut bacterium – Varsha Raghavan – Molecular Microbiology

“We report that the regulator controlling utilization of chondroitin sulfate (CS) in the mammalian gut symbiont Bacteroides thetaiotaomicron is activated by an intermediate in CS breakdown rather than CS itself.”

Pregnancy and Birth

Screen shot 2014-07-15 at 06.38PM, Jul 15 1Review: The Microbiome in Early Life: Self-Completion and Microbiota Protection as Health Priorities – Rodney R. Dietert – Birth Defects Research Part B: Developmental and Reproductive Toxicology

“This minireview considers the benefits of refocusing attention away from treating the patient as a mammalian human to managing the complete patient: a majority microbial superorganism. “

Screen shot 2014-07-15 at 06.38PM, Jul 15Review: Anaerobes and Bacterial Vaginosis in Pregnancy: Virulence Factors Contributing to Vaginal Colonisation – Charlene W. J. Africa – Int. J. Environ. Res. Public Health

“This paper reviewed new available information regarding possible factors contributing to the establishment of the BV vaginal biofilm, examined the proposed role of anaerobic microbial species recently detected by new culture-independent methods and discusses developments related to the effects of BV on human pregnancy. “

Oral microbiome

Review: Acquisition and maturation of oral microbiome throughout childhood: An update – Benedita Sampaio-Maia – Dental Research Journal

“This revision presents an overview of this renewed knowledge on oral microbial community acquisition in the newborn and on the evolution of this microbiome to adulthood. “

 

Animal models of human microbiome and disease

Screen shot 2014-07-15 at 05.17PM, Jul 15Commensal microbes drive intestinal inflammation by IL-17–producing CD4+ T cells through ICOSL and OX40L costimulation in the absence of B7-1 and B7-2 – Lijun Xin – PNAS

“Here we show that B7 deprivation in mice overrides the necessity for Tregs in averting systemic autoimmunity and inflammation in extraintestinal tissues, whereas peripherally induced Tregs retained in the absence of B7 selectively mitigate intestinal inflammation caused by Th17 effector CD4+ T cells. “

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