1. Overview
Streptomyces was discovered from soil in 1916 by Waksman and Henrici, and the Streptomyces family was proposed in 1943. With the development of molecular biology tools, Stackebrandt et al. constructed a phylogenetic tree of Streptomyces in 1997 based on the results of 16S rRNA similarity and DNA DNA hybridization, which marked the beginning of the molecular taxonomy period of Streptomyces, and suggested that Streptomyces should be promoted to a suborder in Actinomycetes and named Streptomyces suborder. In the Bergey's manual of systematic bacteriology published in 2012, K mpfer et al. officially classified the suborder Streptomyces as Streptomycetes.
Streptomyces has characteristic morphological characteristics, it is a gram-positive aerobic bacteria, can produce a variety of water-soluble or fat-soluble pigments, has well-developed branched hyphae, the hyphae are slender, the transverse septum is sparse, and it differentiates into vegetative hyphae (also known as intrabasal hyphae) and aerial hyphae. After the aerial hyphae mature, they develop into spore filaments, which can be erect, spiral, and whorl, and can split a large number of conidia for dissemination.
The nearly 30 years between 1940 and 1970 are known as the "** era of antibiotic discovery", during which researchers found a large number of antibiotics from soil Streptomyces, such as streptomycin, erythromycin, tetracycline, kanamycin, oxytetracycline, etc. Interestingly, about two-thirds of natural antibiotics are produced by actinomycetes, and about 75% of these antibiotics are produced by Streptomyces spp., which make a huge contribution to human medicine.
Patterns of Streptomyces morphological structure.
2. Culture characteristics of Streptomyces gray
The main representative of the Streptomyces genus is Streptomyces gray, which produces streptomycin, which in specimens presents Gram-positive, elongated, irregularly branched filaments.
Morphology of Streptomyces in specimens.
Streptomyces gray grows slowly and can grow slowly on blood plates37. Streptomyces gray colonies are not easy to disperse, and gram-positive bacilli can be seen on Gram staining, with elongated irregular branched hyphae. The results of acid-fast staining and weak acid-fast staining were negative.
Streptomyces gray culture characteristics.
Note: A: blood plate, 37, 3d, the colony is yellow, chrysanthemum-like, radial, slightly "phagocytosis"; B: blood plate, 37, 5d, colony produces pigment C: blood plate, 37, 7d, colony begins to appear transparent hemolysis; d: blood plate, 37, 7d, obvious transparent hemolytic ring; E: blood plate, 37, 5 days, colony yellow; f: Gram stain of colonies (100); g: weak acid-fast staining (100); h: Acid-fast staining (100).