BIOL/CSES 4684

STREPTOMYCES

SOIL MICROBIOLOGY

This webpage was created by Sarah Grubbs

1. IDENTIFYING CHARACTERISTICS

Prokaryotic.
Contain peptidoglycan in their cell walls.
Vegetative hypae (0.5-2.0 um in diameter).
A few species bear short chains of spores on the substrate mycelium.
Cells stain Gram positive.
Spores are nonmotile.
Many strains produce one or more antibiotics.
Chemoorganotrophic.
Tough, leathery mycelium characteristics.
Catalase positive.
Optimum temperature 25-35 C.
Optimum pH range is 6.5-8.0.
Colonies are usually white to gray to yellow-pigmented.
Is the name genus of the Streptomycetes in the Actinomycetes.

The above picture shows a culture of Streptomyces on starch-casein agar.

2. TAXONOMIC DESCRIPTION
Gram positive but not acid-alcohol-fast. The cell well peptidoglycan contains major amounts of L-diaminopimelic acid (L-DAP). The streptomyces lack mycolic acids but contain major amounts of saturated, iso-, and anteiso- fatty acids; possess either hexa- or octahydrogented menaquinones with nine isoprene units as the predominant isoprenolog; and have complex polar lipids patterns that typically contain diphosphatidylglycerol.

Members of the genus Streptomyces are aerobes and chemoorganotrophic, having a oxidative type of metabolism. They are catalase positive and generally reduce nitrates to nitrites and degrade adenine, esculin, casein, gelatin, hypoxanthine, starch, and l-tyrosine. Use a wide range of organic compounds as sole sources of carbon for energy and growth. The type species is Streptomyces albus, and differentiation of species in this genus remains difficult. There are over 50 named species, and differentiation is based on a combination of pigmentation, morphology, and physiology.

The above picture shows Streptomycescondia under electron microscopy (11,000X).

3. ISOLATION AND ECOLOGY
On isolation, colonies are small (1-10mm diameter) discrete and lichenoid, leathery or butyrous; initially relatively smooth surfaced but later develop a wide variety of aerial mycelia that may appear granular, powdery, velvety or floccose. There are many types of isolation media available. Streptomyces produce a wide variety of pigments responsible for colors of the vegetative mycelium, aerial mycelium and substrate. Many strains produce one or more anti-bacterial, anti-fungal, anti-algal, anti-viral or anti-tumor compounds. Many strains are sensitive to anti-bacterial agents.

The color of mature sporulated aerial mycelia can be white, gray (gray to brownish), yellow (yellow to greenish yellow), and some other colors that are less common. Streptomyces are slow growing organisms and isolation plates are often incubated for 1 to 2 weeks to allow differentiation and adequate growth of the colonies.

Recent research on Stretomyces indicates that they, along with certain fungi, may play an important role in the degradation of lignin. A few species are pathogenic for animals and humans; others are phytopathogens. They play important roles in degradation in compost piles. Streptomyces are important agents in the degradation of organic matter in soil and contribute to the formation of stable humus. Many actinomycetes are good chitin degraders because actinomycetes are "late colonizers" although this should not detract from the vital roles they play in degradation processes and the formation of humus.

The above picture shows a close-up of Streptomyces colonies on agar.

4. ADDITIONAL SOURCES OF INFORMATION
Alexander, Martin. 1991. Introduction to Soil Microbiology. Krieger Publishing Company. Malabar , Florida. 37-48, 153-169 pp.

Metting, F. Blaine. 1992. Soil Microbiology Ecology. Marcel Dekker, Inc. New York.137-139 pp.

Sylvia, David M. 1998. Principles and Applications of Soil Microbiology. Prentic Hall. New Jersey.7,48, 65-66, 160 pp.

5. LINK TO OTHER SITES ON STREPTOMYCES

The Actinomycete Internet Resource Center

http://bioserver.myongji.ac.kr/bioscience/faculty/strplab.html