Table 1.

Examples of taxonomic classification for some of the major bacterial groups identified as members of the human microbiome, including the respiratory tract. Given the diversity of human microbiota, the table is not intended to be comprehensive. Listed bacterial phyla, classes, orders, families and genera include organisms that have been identified in lung microbiome studies.

Phylum	ACTINOBACTERIA	BACTEROIDETES	FIRMICUTES	PROTEOBACTERIA
Classes	Actinobacteria	Bacteroidia Cytophagia Flavobacteria Sphingobacteria	Bacilli Clostridia Erysipelotrichia	Alphaproteobacteria Betaproteobacteria Deltaproteobacteria Epsilonproteobacteria Gammaproteobacteria
Orders	Acidimicrobiales Actinomycetales Bifidobacteriales Rubrobacterales	Bacteroidales Flavobacteriales Sphingobacteriales	Bacillales Clostridiales Lactobacillales	Burkholderiales Campylobacterales Enterobacteriales Moraxellaceae Neisseriales Pasteurellales Pseudomonadales Sphingomonadales
Families	Actinomycetaceae Bifidobacteriaceae Corynebacteriaceae Mycobacteriaceae Nocardiaceae Streptomycetaceae	Bacteroidaceae Flavobacteriaceae Porphyromonadaceae Prevotellaceae Sphingobacteriaceae	Bacillaceae Clostridiaceae Enterococcaceae Lachnospiraceae Lactobacillaceae Ruminococcaeae Streptoccocaceae Veillonellaceae	Bartonellaceae Burkholderiaceae Enterobacteriaceae Helicobacteraceae Neisseriaceae Pasteurellaceae Pseudomonadaceae Sphingomonadaceae
Genera	Actinomyces Bifidobacterium Corynebacterium Mycobacterium Nocardia Streptomyces	Bacteroides Capnocytophaga Porphyromonas Prevotella Sphingobacterium	Clostridium Faecalibacterium Lachnospira Ruminococcus Streptococcus Veillonella	Acinetobacter Escherichia Enterobacter Haemophilus Moraxella Pseudomonas Sphingomonas