Actinobacteria

Bacteria belonging to the Actinobacteria phylum can be found naturally in the human body on sites ranging from the skin to mucosal surfaces within the gastrointestinal tract. These bacteria are considered important members of a normal microbiota and scientists have found that their presence and abundance in specific sites correlates with the individual’s health status. Knowledge of these species is clinically important.

Actinobacteria have assumed highly variable lifestyles, including pathogens (e.g., Corynebacterium, Tropheryma, Mycobacterium, Propionibacterium, and Nocardia), soil dwellers (Streptomyces), plant commensals (Leifsonia), and even gastrointestinal commensals and symbionts (Bifidobacterium). Actinobacteria has long deviated from other bacteria, which makes it nearly impossible to identify any bacterial group phylogenetically close to this phylum. However, state-of-the-art sequencing technology has recently transformed bacterial biology by enhancing our understanding of genetics, physiology, and evolutionary development of bacteria. Various Actinobacteria genomes have been sequenced, revealing a wide genomic heterogeneity, which reflect their vast biodiversity.

Actinobacteria in the Human Microbiome

Bacteria belonging to the Actinobacteria phylum can be found naturally in the human body on sites ranging from the skin to mucosal surfaces within the gastrointestinal tract. These bacteria are considered important members of a normal microbiota and scientists have found that their presence and abundance in specific sites correlates with the individual’s health status. Knowledge of these species is clinically important.

Some of the commensals, symbionts, and opportunistic pathogens found in the human microbiome are bacteria found within the phylum Actinobacteria, which includes 219 genera in 48 families and five orders. The majority of these bacteria live in the soil, but a few groups inhabit the healthy human microbiota. These are predominantly members in the genera Corynebacterium, Propionibacterium, Rothia, Actinomyces, and Bifidobacterium. The presence and abundance of these specific bacteria on certain sites of the human body accurately reflects the individuals’ health status. In terms of clinical significance, the genome sequences for certain strains of each genus were recently decoded and have given insight into how Actinobacteria adapt within the human body.

Actinobacteria in Medicine & Agriculture

Actinobacteria, especially the most commonly found Actonobacteria genus, Streptomyces spp., produce many bioactive metabolites that are critical to modern-day medicine, such as antibacterials, antifungals, antivirals, immunomodifiers, antithrombotics, anti-tumor drugs, and enzyme inhibitors. Specific Actinobacteria-derived antibiotics commonly used in medicine include aminoglycosides, anthracyclines, chloramphenicol, macrolide, and tetracyclines.

In agriculture, Actinobacteria bacteria is used for insecticides, herbicides, fungicides, and growth promoting substances for plants and animals.

References Bressan, W. Biological control of maize seed pathogenic fungi by use of actinomycetes. Biocontrol. 2003. 48 (2): 233–240. doi:10.1023/a:1022673226324.