Actinomycetes
Actinomycetes are a group of bacteria known for their filamentous growth and ability to produce a wide range of bioactive compounds, including antibiotics. They play a crucial role in the decomposition of organic matter in soil and are important for nutrient cycling. Actinomycetes have significant biotechnological and pharmaceutical potential due to their ability to produce diverse secondary metabolites.
6 Key excerpts on "Actinomycetes"
eBook - ePubHandbook of Microbiology
Condensed Edition
- Allen I Laskin(Author)
- 2019(Publication Date)
- CRC Press(Publisher)
...The Actinomycetales Introduction Dr. Hubert A. Lechevalier and Dr. Leo Pine Actinomycetes are filamentous, branching bacteria that are widely distributed in nature. They are mainly found in soil, where they play a major role in the decomposition of organic matter. Some species cause diseases of animals or plants; a few species are parasitic and have been isolated only from their animal hosts. Some Actinomycetes are of medical and industrial importance as producers of antibiotics, and others are used industrially as agents of chemical transformations. For general reviews on Actinomycetes see References 1 to 6. Although branched filaments may also be observed in some budding bacteria, mycoplasmata, and highly pleomorphic organisms found in the genera Actinobacillus and Streptobacillus, 7 these are not classified in the Actinomycetales. Basically, members of the Actinomycetales may be considered to be those bacteria that form a well-defined coherent mycelium. But this structure may be so rudimentary and transient in the genera Actinomyces and Mycobacterium that it may go unnoticed or be essentially nonexistent. Indeed, in the genus Bifidobacterium no mycelium has been described. Thus, no unambiguous morphological feature serves to unite all the members of this widely diversified group. Actinomycetales may form a substrate mycelium only, or both aerial and substrate mycelia, or an aerial mycelium only (Sporichthya). While some species are holocarpic, eucarpic members may show higMy complex mycelial structures with conidia and sporangia. 8 Motility, when observed, is due to flagella...
eBook - ePubMicrobiomes and Plant Health
Panoply and Their Applications
- Manoj Kumar Solanki, Prem Lal Kashyap, Rizwan Ali Ansari, Baby Kumari, Manoj Kumar Solanki, Prem Lal Kashyap, Rizwan Ali Ansari, Baby Kumari(Authors)
- 2020(Publication Date)
- Academic Press(Publisher)
...In their natural habitat such as forests, the Actinomycetes interact in various ways with the higher plants (Muthu et al., 2013). The Actinomycetes are numerous and widely distributed group of soil microorganisms, composing of 10%–50% of the soil microflora community over a broad range of soil conditions, with Streptomyces as the numerically dominant genus (Sharma et al., 2014). Actinomycetes are less abundant in water-logged and acidic soils and may be present in higher than usual numbers in drier, alkaline soils(Solanki et al., 2016). Although they are classified as bacteria, they are fungus-like in appearance and growth (Wang et al., 2018). 14.1.3 Nutrition mode The adaptability of Actinomycetes and their ability to use a varied food source results from their elaborate metabolic capabilities (Yandigeri et al., 2012). Where most bacteria grow by asexual fission of individual cells, the vegetative cells of most Actinomycetes produce slender, branched filaments, or hyphae that are collectively termed mycelia (Rathore et al., 2012). These structures are smaller and of different morphology and composition than their fungal counterparts (Yandigeri et al., 2012). Within these hyphae forms, asexual spores called conidia; the spores are formed when conditions are no longer optimal for vegetative growth and germinate when conditions are again favorable (Solanki et al., 2016). Actinomycetes are heterotrophic and are valuable decomposers of organic matter in soil communities (Gil et al., 2004 ; Malviya et al., 2014). Members of the Streptomycetes family of Actinomycetes, which includes Streptomyces, are responsible for the production of the compound causing the musty odor prominent in freshly turned soils; many also produce antibiotics that inhibit the growth of bacteria and fungi (Hasani et al., 2014 ; Procópio et al., 2012). These organisms produce extensively primary or substrate mycelium as well as more or less abundant secondary or aerial mycelium(Hug et al., 2018)...
eBook - ePubMarine Microbiology
Bioactive Compounds and Biotechnological Applications
- Se-Kwon Kim, Se-Kwon Kim(Authors)
- 2013(Publication Date)
- Wiley-VCH(Publisher)
...They have the ability to produce a range of secondary metabolites having potential therapeutic values. Marine Actinomycetes are Gram-positive bacteria that are filamentous in nature, and produce diverse biologically active metabolic compounds that can serve as enzymes, or for treating cancer, malaria, fungal, and bacterial diseases. 10.3 Marine Actinomycete Compounds as Antibacterials Products derived from natural resources have a number of advantages over manmade synthetic compounds. Novel antibacterial compounds derived from various marine Actinomycetes can be utilized for treating drug-resistant strains or multidrug-resistant bacteria in humans. Streptomyces species are the largest group known to produce secondary metabolites of immense importance. Different classes of compounds have been isolated from Streptomyces species. Bonactin was isolated from Streptomyces species BD21-2 that has shown action against both Gram-positive and Gram-negative bacteria. This strain was isolated from the Kailua beach in Hawaii [1]. Essramycin, a triazolopyrimidine antibiotic isolated from the Streptomyces species Merv8102, has shown antibiotic action against both Gram-positive and Gram-negative bacteria at minimum inhibitory concentration of 2–8 μg/mL [2]. Lajollamycin is a yellow compound derived from Streptomyces nodosus (NPS007994) that has shown a broad range of antibiotic activity against both drug-sensitive and drug-resistant Gram-positive and Gram-negative bacteria. S. nodosus was collected from Scripps Canyon, La Jolla, California [3]. Streptomyces strain CNQ-525 produces napyradiomycin and its derivatives. A80915A and A80915B have shown potent antibacterial action against methicillin-resistant Staphylococcus aureus (MRSA)...
eBook - ePubBiodiversity and Conservation
Characterization and Utilization of Plants, Microbes and Natural Resources for Sustainable Development and Ecosystem Management
- Jeyabalan Sangeetha, Devarajan Thangadurai, Goh Hong Ching, Saher Islam, Jeyabalan Sangeetha, Devarajan Thangadurai, Goh Hong Ching, Saher Islam(Authors)
- 2019(Publication Date)
- Apple Academic Press(Publisher)
...CHAPTER 7 DIVERSITY AND METABOLITES OF Actinomycetes FROM PEAT SWAMP FOREST SOILS WONGSAKORN PHONGSOPITANUN and SOMBOON TANASUPAWAT Department of Biochemistry and Microbiology, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand 7.1 INTRODUCTION Actinomycetes, belonging to phylum Actinobacteria, class Actinobacteria, are Gram-stain-positive filamentous bacteria with high guanine and cytosine contents of their genomic DNA. According to the Bergey’s Manual of Systematic Bacteriology (Volume 5), the Actinobacteria can be classified into six classes as Actinobacteria, Acidimicrobiia, Coriobacteriia, Nitriliruptoria, Rubrobacteria, and Thermoleophilia. Among them, the Streptomyces belongs to the family Streptomycetaceae, the largest genus of phylum Actinobacteria are well known for the bioactive compound producers (antibiotics, antiviral, antitumor, immune suppressant agents, herbicide, insecticide, phytotoxins, plant growth regulator and antiparasitic agents) (Berdy, 2005). Many compounds produced from Actinomycetes are clinically useful antibiotics including actinomycin D (Waksman and Woodruff, 1940), amphotericin B (Steinberg et al., 1956), neomycin (Lechevalier, 1975), avermectin (Burg et al., 1979), vancomycin (Levine, 2006) and platensimycin (Wang et al., 2006). Actinomycetes are widely distributed in environments especially in terrestrial soils. However, in the last decade, many of actinomycete species are discovered from others habitats, including insects (Currie et al., 1999), plant materials (Qin et al., 2012); deep marine sediment (Pathom-aree et al., 2006), marine sponges as well as animals such as pufferfish (Wu et al., 2005). Although terrestrial soils are the major habitat of Actinomycetes, peat swamp forest soils show the unique habitat and the actinomycete biodiversity remains poorly understood...
eBook - ePubAtlas of Oral Microbiology
From Healthy Microflora to Disease
- Xuedong Zhou, Yuqing Li, Xuedong Zhou, Yuqing Li(Authors)
- 2015(Publication Date)
- Academic Press(Publisher)
...Chapter 3 Supragingival Microbes Abstract This chapter describes the cell and colony morphology, cultural and biochemical characteristics of oral microbes that are mainly isolated from supragingival plaques, including gram-positive bacteria of the genera Actinomyces, Bifidobacterium, Lactobacillus, Rothia, Staphylococcus, and Streptococcus, as well as gram-negative bacteria of the genera Leptotrichia and Veillonella. Keywords Actinomyces ; Bifidobacterium ; Lactobacillus ; Leptotrichia ; Rothia ; Staphylococcus ; Streptococcus ; Supragingival; Veillonella 3.1. Gram-positive bacteria 3.1.1. Actinomyces Actinomyces are irregular gram-positive bacilli and are also commonly found anaerobic bacteria in oral samples. When they were first discovered, Actinomycetes were believed to be fungi or were grouped as “other microorganism.” Recently, numerous studies have shown that Actinomycetes have general characteristics common to bacteria and were classified as prokaryotic organisms. In the 1984 edition of Bergey’s Manual of Determinative Bacteriology, Actinomyces were included in the group of gram-positive irregular bacilli. Common members of the Actinomyces genus in oral microbiology are Actinomyces israelii, Actinomyces naeslundii, Actinomyces odontolyticus, and Actinomyces viscosus. They are characterized by a relatively high GC content in their DNA, ranging from 57% to 69% (Tm method). The type species of this genus is Actinomyces bovis. The shape and size of bacterial cells can vary greatly but are often found to be irregular branched bacilli with a diameter of 0.2–1.0 μm and a length of about 5.0–10.0 μm. The cells are usually rod-shaped, but can occasionally be club-shaped with irregular arrangements including single, paired, chain, clusters, and fence-shaped. The cells produce no spores, show no motility, and also do not produce conidia...
- Grace R. Carter, John R. Cole Jr., Grace R. Carter, John R. Cole, Jr.(Authors)
- 2012(Publication Date)
- Academic Press(Publisher)
...22 Actinomyces, Nocardia, Streptomyces, Dermatophilus, and Rhodococcus J.F. Prescott Publisher Summary This chapter describes some irregular and nonsporeforming gram-positive rods that are commonly encountered in diagnostic laboratories, either as aerobic or as facultatively anaerobic isolates. The chapter focuses on Actinomyces, Nocardia, Streptomyces, Dermatophilus, and Rhodococcus. Nocardia and Rhodococcus are closely related to the genera Mycobacterium and Corynebacterium but differ distinctly from Actinomyces in cell-wall chemical characteristics and percentages of guanine and cytosine. Actinomyces are gram-positive, diphtheroidal, or branching filamentous rods. Actinomyces pyogenes are commonly coccobacillary in an aerobic atmosphere. Actinomyces are facultatively anaerobic, with most species being preferentially anaerobic although some species grow well in air. Actinomyces are fermentative in metabolism whereas Nocardia are oxidative. Actinomyces cause chronic infections of soft and hard tissue, often with the formation of sulfur granules. Actinomyces infections are often associated with the presence of foreign bodies, whereas Nocardia infections are seen in immunocompromised hosts or as iatrogenic infections. Nocardia, Actinomadura, and Streptomyces are obligate aerobic saprophytes and are found in soil. Of these three genera, Nocardia are most commonly encountered, but Actinomadura and Streptomyces are cultured from mycetomas in animals in tropical areas. The only pathogenic species of Dermatophilus is Dermatophilus congolensis...
