The term metagenome refers to the genetic material which is present in a sample taken from the environment, and is made up of the genomes (genetic information) of an array of individual microorganisms.

Also known as methanogens, these types of organisms produce methane as a by-product of their metabolism. Among other things, this contributes to flatulence production in humans. They thrive in low oxygen environments such as the human gut.

A microbe is a tiny microscopic organism, such as a bacterium, fungus or virus. There are trillions of microbes in the human microbiome.

A vast army of microbes that protect us against germs, break down foods to release energy, and produce vitamins to keep us healthy. A microbiome encompasses the entirety of microbes in a defined habitat, including all of their genetic make-up and their environmental interactions. For example; a human microbiome (all of the microbes that we share our body with) includes approximately 100 trillion microbes, outnumbering our own cells by 10 to 1.

The gut microbiota is with humans from birth and affects function throughout the body. The human microbiota consists of a wide variety of bacteria, viruses, fungi, and other single-celled animals that live in the body. The microbiome is the name given to all of the genes inside these microbial cells.
Microbiota refers to the microorganisms (both probiotic and pathogenic) residing in the gastrointestinal tract. An imbalance in the microbiota is known as dysbiosis.

Microflora (gastrointestinal) is the collective term given to bacteria and micro-organisms (e.g. algae and fungi) that live in the gut.

A mole is an amount of a substance that contains a large number (6 followed by 23 zeros) of molecules or atoms. A millimole is one-thousandth of a mole. When written as mmol/L it is expressed as the number of millimoles per litre.

Mucosa, also known as the mucous membrane, refers to the moist lining of internal, hollow organs such as the mouth and gastrointestinal tract.

The term mycobiome refers to the fungal populations in a given environment. Studies have demonstrated the existence of diverse fungal colonies throughout the human body, and suggest their importance in both health and disease. There are many different genera of fungi, including Candida, Fusarium, Cladosporium and Aureobasidium.