The key difference between actinomyces and actinomycetes is that actinomyces is a genus of actinomycetes, which are anaerobic and not acid-fast, while actinomycetes are a group of filamentous and higher bacteria that are gram-positive.
Actinomycetes are a group of bacteria that are gram-positive and behave much like fungi. They are beneficial for agriculture and soil systems. Actinomycetes grow as colonies that resemble mycelia of fungi. Actinomyces, Nocardia, and Streptomyces are three main genera of Actinomycetes. Among these three genera, Actinomyces are anaerobic while the other two genera are aerobic. Moreover, Actinomyces and Streptomyces are not acid-fast, unlike Nocardia species, which are partially acid-fast.
CONTENTS
1. Overview and Key Difference
2. What are Actinomyces
3. What are Actinomycetes
4. Similarities Between Actinomyces and Actinomycetes
5. Side by Side Comparison – Actinomyces vs. Actinomycetes in Tabular Form
6. Summary
What are Actinomyces?
Actinomyces is a genus of actinomycetes. They are gram-positive bacteria and form branching filaments about 0.5 μm in width. Actinomyces are ubiquitous bacteria present everywhere, including soil and animal and human microbiota. Moreover, most of them are facultative anaerobes, while few species such as A. meyeri and A. israelii are obligate anaerobes. Hence, they grow best under anaerobic conditions. Most Actinomyces are not acid-fast, and they are catalase-negative. They always produce granules. Actinomyces cause actinomycosis, which is a chronic suppurative and granulomatous disease. Actinomyces israelii is the most common causative agent of actinomycosis.
Figure 01: Actinomyces
Furthermore, actinomyces are important microbes in soil ecology because they synthesize a variety of enzymes, which degrade organic plant material, lignin, and chitin. Hence, Actinomyces are an important part of the formation of compost.
What are Actinomycetes?
Actinomycetes are a phylum of gram-positive bacteria. They are prokaryotic organisms with a primitive unicellular organization. Actinomycetes are anaerobic or aerobic microorganisms. They show filamentous and branching growth pattern on solid substrates resembling fungal mycelia. Their colonies are extensive colonies similar to the mycelium. Aerial hyphae are found in many genera of actinomycetes. Some actinomycetes genera are motile and have flagella. Actinomycetes are responsible for the musty odour (smell of freshly ploughed soils), which comes after a rain.
Figure 02: Actinomycetes
Actinomycetes are found in terrestrial and aquatic environments. The common genera of actinomycetes are Streptomyces, Nocardia, and Actinomyces. Many actinomycetes species occur in the soil. Soil bacteria are harmless to animals and plants. They act as good decomposers. Hence, they are important in increasing the availability of nutrients for plant acquisition. Actinomycetes produce a wide variety of useful secondary metabolites that have potent biological activities, including commercially important antibiotics and immunosuppressive compounds, etc. Some of them are used for the manufacturing of commodity chemical, health products, and agrochemicals.
In addition to positive impacts, actinomycetes cause several types of diseases or infections to animals, including humans. Nocardiosis, Actinomycosis, and Streptomycosis are three such diseases.
What are the Similarities Between Actinomyces and Actinomycetes?
- Actinomyces are a genus of Actinomycetes.
- They are gram-positive bacteria.
- They produce colonies resembling the fungus-like branched networks of hyphae.
- Moreover, they are mainly rod-shaped bacteria.
- They cause diseases to animals and humans.
- Both actinomyces and actinomycetes bacteria work as decomposers in soil.
What is the Difference Between Actinomyces and Actinomycetes?
Actinomyces is a genus of actinomycetes, which are gram-positive non-acid-fast bacteria, while actinomycetes are a group of gram-positive bacteria that produce filament like colonies on solid substrates. So, this is the key difference between actinomyces and actinomycetes. Actinomyces mainly cause actinomycosis, while actinomycetes cause actinomycosis, nocardiosis, and streptomycosis.
Another difference between actinomyces and actinomycetes is that actinomyces are mostly anaerobes, while actinomycetes can be aerobic or anaerobic. Moreover, most actinomyces are non-acid-fast, while actinomycetes can be acid-fast or non-acid-fast.
Summary – Actinomyces vs. Actinomycetes
Actinomycetes are a phylum of gram-positive higher bacteria. They produce filamentous and branching colonies on solid substrates resembling fungi. Actinomyces are a genus of actinomycetes that are non-acid-fast and anaerobic. Actinomycetes include both aerobic and anaerobic bacteria, while actinomyces are mostly anaerobic. So, this is the summary of the difference between actinomyces and actinomycetes.
Reference:
1. “ACTINOMYCETES”, Microbiologybook, Available here. Available here.
2. “Actinomyces.” Wikipedia, Wikimedia Foundation, 14 Jan. 2020, Available here.
Image Courtesy:
1. “Actinomyces israelii” By GrahamColm at English Wikipedia (CC BY 3.0) via Commons Wikimedia
2. “Actinomycetes bacteria (10332880924)” By Oregon Caves from Cave Junction, USA – Actinomycetes bacteria (CC BY 2.0) via Commons Wikimedia