The human microbiome is the aggregate of all microbiota that reside on or within human tissues and biofluids along with the corresponding anatomical sites in which they reside, including the gastrointestinal tract, skin, mammary glands, seminal fluid, uterus, ovarian follicles, lung, saliva, oral mucosa, conjunctiva, and the biliary tract. Types of human microbiota include bacteria, archaea, fungi, protists, and viruses. Though micro-animals can also live on the human body, they are typically excluded from this definition. In the context of genomics, the term human microbiome is sometimes used to refer to the collective genomes of resident microorganisms; however, the term human metagenome has the same meaning.
Lactobacillus acidophilus is a rod-shaped, Gram-positive, homofermentative, anaerobic microbe first isolated from infant feces in the year 1900. The species is commonly found in humans, specifically the gastrointestinal tract and oral cavity as well as some speciality fermented foods such as fermented milk or yogurt, though it is not the most common species for this. The species most readily grows at low pH levels, and has an optimum growth temperature of 37 °C. Certain strains of L. acidophilus show strong probiotic effects, and are commercially used in dairy production. The genome of L. acidophilus has been sequenced.
Gut microbiota, gut microbiome, or gut flora are the microorganisms, including bacteria, archaea, fungi, and viruses, that live in the digestive tracts of animals. The gastrointestinal metagenome is the aggregate of all the genomes of the gut microbiota. The gut is the main location of the human microbiome. The gut microbiota has broad impacts, including effects on colonization, resistance to pathogens, maintaining the intestinal epithelium, metabolizing dietary and pharmaceutical compounds, controlling immune function, and even behavior through the gut–brain axis.
Bacteroides is a genus of Gram-negative, obligate anaerobic bacteria. Bacteroides species are non endospore-forming bacilli, and may be either motile or nonmotile, depending on the species. The DNA base composition is 40–48% GC. Unusual in bacterial organisms, Bacteroides membranes contain sphingolipids. They also contain meso-diaminopimelic acid in their peptidoglycan layer.
Dysbiosis is characterized by a disruption to the microbiome resulting in an imbalance in the microbiota, changes in their functional composition and metabolic activities, or a shift in their local distribution. For example, a part of the human microbiota such as the skin flora, gut flora, or vaginal flora, can become deranged, with normally dominating species underrepresented and normally outcompeted or contained species increasing to fill the void. Similar to the human gut microbiome, diverse microbes colonize the plant rhizosphere, and dysbiosis in the rhizosphere, can negatively impact plant health. Dysbiosis is most commonly reported as a condition in the gastrointestinal tract or plant rhizosphere.
William R. Davis is a Milwaukee-based American cardiologist, low-carbohydrate diet advocate and author of health books known for his stance against "modern wheat", which he labels a "perfect, chronic poison."
The human virome is the total collection of viruses in and on the human body. Viruses in the human body may infect both human cells and other microbes such as bacteria. Some viruses cause disease, while others may be asymptomatic. Certain viruses are also integrated into the human genome as proviruses or endogenous viral elements.
David Perlmutter is an American celebrity doctor, author, low-carbohydrate diet advocate and promoter of functional medicine.
Microbiota-accessible carbohydrates (MACs) are carbohydrates that are resistant to digestion by a host's metabolism, and are made available for gut microbes, as prebiotics, to ferment or metabolize into beneficial compounds, such as short chain fatty acids. The term, ‘‘microbiota-accessible carbohydrate’’ contributes to a conceptual framework for investigating and discussing the amount of metabolic activity that a specific food or carbohydrate can contribute to a host's microbiota.
A microbiome is the community of microorganisms that can usually be found living together in any given habitat. It was defined more precisely in 1988 by Whipps et al. as "a characteristic microbial community occupying a reasonably well-defined habitat which has distinct physio-chemical properties. The term thus not only refers to the microorganisms involved but also encompasses their theatre of activity". In 2020, an international panel of experts published the outcome of their discussions on the definition of the microbiome. They proposed a definition of the microbiome based on a revival of the "compact, clear, and comprehensive description of the term" as originally provided by Whipps et al., but supplemented with two explanatory paragraphs. The first explanatory paragraph pronounces the dynamic character of the microbiome, and the second explanatory paragraph clearly separates the term microbiota from the term microbiome.
Sarkis Mazmanian is an American medical microbiologist who has served as a professor at the California Institute of Technology since 2006. He is currently the Luis & Nelly Soux Professor of Microbiology in the Division of Biology and Biological Engineering, and a board member of Seed. Prior to this, Mazmanian was affiliated with Harvard Medical School and the University of Chicago. In 2012, Mazmanian was awarded a MacArthur Fellowship for his pioneering work on the human microbiome.
B. Brett Finlay, is a Canadian microbiologist well known for his contributions to understanding how microbes cause disease in people and developing new tools for fighting infections, as well as the role the microbiota plays in human health and disease. Science.ca describes him as one of the world's foremost experts on the molecular understanding of the ways bacteria infect their hosts. He also led the SARS Accelerated Vaccine Initiative (SAVI) and developed vaccines to SARS and a bovine vaccine to E. coli O157:H7. His current research interests focus on pathogenic E. coli and Salmonella pathogenicity, and the role of the microbiota in infections, asthma, and malnutrition. He is currently the UBC Peter Wall Distinguished Professor and a Professor in the Michael Smith Laboratories, Microbiology and Immunology, and Biochemistry and Molecular Biology, and Co-director and Senior Fellow for the CIFAR Humans and Microbes program. He is also co-author of the book Let Them Eat Dirt: Saving Your Child from an Oversanitized World and The Whole-Body Microbiome: How to Harness Microbes - Inside and Out - For Lifelong Health. Finlay is the author of over 500 publications in peer-reviewed journals and served as editor of several professional publications for many years.
The Zoe Health Study, formerly the COVID Symptom Study, is a health research project of British company Zoe Limited which uses a mobile app that runs on Android and iOS.
Jennifer Beam Dowd is an American social scientist who is a Professor of Demography and Population Health and deputy director of the Leverhulme Centre for Demographic Science at the University of Oxford. Her research considers the social determinants of health and the relationship between infections and immune function. She is a member of Those Nerdy Girls, an all-woman team of public health researchers who are relaying COVID-19 information as part of Dear Pandemic.
Ruth E. Ley is a British-American microbial ecologist. Ley was an associate professor in the Department of Microbiology and the Department of Molecular Biology and Genetics at Cornell University until 2018. She is currently serving as the director of the Microbiome Science Department at the Max Planck Institute for Biology.
Christopher David Gardner is an American nutrition researcher. He is the director of nutrition studies at the Stanford Prevention Research Center and the Rehnborg Farquhar Professor of Medicine at Stanford University.
Cathryn R. Nagler is an American immunologist. She is the Bunning Family Professor in the Pritzker School of Molecular Engineering, the Department of Pathology, and the college at the University of Chicago. Nagler is also the co-founder and president of the startup company ClostraBio, Inc.
William John Bulsiewicz better known as Dr. B., is an American board-certified gastroenterologist and author known for his exploration of the relationship between the gut microbiome and plant-based nutrition.
Megan Rossi is a dietitian, nutritionist and author specialising in the microbiome. Her PhD in gut health received the Dean's Award top 5% for Outstanding Research Higher Degree.
