1. IDENTIFYING CHARACTERISTICS
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).
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.
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
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