Marine Actinomycetes: History
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Subjects: Marine & Freshwater Biology
Contributor:
William Soto

Actinomycetales is an order of Gram-positive bacteria consisting of both benign and pathogenic bacteria belonging to the phylum Actinobacteria.

  • microbial experimental evolution
  • industrial microbiology
  • actinomycetes

1. Introduction

Actinomycetales is an order of Gram-positive bacteria consisting of both benign and pathogenic bacteria belonging to the phylum Actinobacteria [1]. Actinobacteria have historically been characterized by high GC content in their DNA [2], though some members, particularly freshwater-dwelling ones, have been found in recent years to have relatively low GC content [3]. Members of this order are often distinguished by their mycelial morphology with branched hyphae and the ability to form spores, although not all actinomycetes are sporulating [4]. They exhibit great diversity in a variety of characteristics including moisture tolerance [5], habitat, optimal pH, and thermophilicity [4]. Actinomycetes are often found at moderate pH levels [6][7], though some acidophilic and alkaliphilic species are known [5][8][9][10]. While some thermophilic actinomycetes have been recorded [11], most species appear to prefer moderate temperatures [12][13]. This diversity is also reflected in the near ubiquity of actinomycetes in the environment [14][15][16][17], with samples having been discovered in remote locations such as the Mariana Trench [18] and Antarctica [19]. Actinomycetales diversity may even be greater than previously estimated, as flaws in traditional methods of bacterial classification such as 16S rRNA comparison may have led to errors in Actinomycetal identification [20][21][22]. Actinomycete species are primarily found in soils [2] and were originally thought to be solely terrestrial. This belief was supported by the observation that some terrestrial actinomycete spores wash into the sea, which was thought to explain their presence in water samples [23]. In fact, the first discovery of a marine actinomycete was not until 1984 [24]. Since then, many marine species have been discovered in aquatic systems worldwide [25][26][27][28][29] and even single species have been shown to have widespread distribution in the world’s oceans [27][30].
Marine actinomycetes associate with a variety of aquatic organisms, including invertebrates such as sponges [27][31], corals [32][33], and echinoderms [7], as well as vertebrates such as pufferfish [34]. These interactions may encourage unique chemical ecologies that might influence the evolution of secondary metabolic pathways. In addition to associating with other organisms, marine actinomycetes can exist in both planktonic and biofilm niches, although the majority of strains have been isolated from sediments [35]. The characteristics that promote and result from these different life strategies are not yet well understood. General studies of planktonic and biofilm-forming bacteria indicate that these communities differ in species composition [36][37]. Population sizes of actinomycetes in ocean sediment have been shown to vary with physico-chemical parameters including temperature, pH, pressure, total organic carbon, and salinity, the preferred levels of these parameters varying with location. Strains including Streptomyces, Micromonospora, and Actinomyces have been found at depths as great as 500m [26]. Micromonospora in particular may have greater relative abundance at 450 m than at shallower depths [38]. In addition, studies have shown greater heat resistance of actinomycete samples collected from marine sediment than from seawater, leading to the hypothesis that the more heat-resistant spore form of actinomycetes predominates in sediment compared to the vegetative form [39]. Comparatively little research has been conducted on planktonic actinomycetes in comparison to those in sediments. Early evidence suggests that some planktonic strains are non-sporulating [29] and vary in their temperature optima [40], indicating that they fill a diversity of ecological niches. The relative dearth of discovered planktonic varieties may in part reflect problems with sampling, as bacterial abundance is affected by temporal variations in nutrient availability that are caused by geological activity [41]. Free-floating bacteria may also be more vulnerable to predation by grazers [42] and infection by marine viruses, which are widespread in ocean waters. Populations of rare bacteria may be especially depressed by the presence of viruses, hindering detection efforts [43]. In contrast, bacterial communities in sediment may gain some protection against infection as viral adsorption to sediment may reduce phage replication rates [44].
Although the ocean presents a vast and varied environment for bacterial populations, most microbiological research has focused on samples from terrestrial environments [45]. This trend may in part be due to greater difficulties in sampling and culturing microbes from seawater and ocean sediment [46]. However, marine and terrestrial environments differ substantially. Marine microbes develop adaptations not present in their land-based counterparts [38][47]. The need for novel adaptations suggests that marine actinomycetes possess unique metabolic and genetic characteristics that are a promising subject for future research. This biological potential is especially important given that actinomycetes have been exploited for decades as a source of bioactive compounds, especially antibiotics. Streptomyces species alone produce over 7600 bioactive microbial metabolites [48], with an increasing proportion of new metabolites being discovered from rare actinomycetes. As much initial research focused on soil-derived species, these have mostly been exhausted as a source of easily detectable compounds. In contrast, marine actinomycetes are only beginning to be characterized and exploited for bioactive compounds [49], and much of their species diversity remains unexplored. Even closely related strains possess unique biosynthetic gene clusters (BGCs) [50][51], groups of genes in proximity to each other on the chromosome that encode secondary metabolites [52]. The existence of these BGCs in close marine relatives suggests the continued investigation of metabolic potential will lead to the discovery of additional natural products that are important, useful, and valuable.
Despite the plethora of BGCs harbored by marine actinomycetes, the genetic diversity discovered by genome sequencing is not fully reflected in laboratory attempts to elicit secondary metabolite production. This relative sparsity of obtained secondary metabolites is due in part to cryptic gene clusters that are only activated under certain conditions [53]. For example, because marine actinomycetes often live in close proximity to other microorganisms, they may possess secondary metabolites for purposes of chemical defense that are only expressed in the presence of competing microbial strains [54]. In addition, the production of some antimicrobial compounds is enhanced by the presence of seawater [39][55][56], implying the existence of unique secondary metabolic pathways not present in terrestrial actinomycetes. To fully exploit the metabolic capacities of marine actinomycetes, new technologies and techniques to increase BGC expression must be utilized [57]. Strategies include the optimization of fermentation conditions [10], as well as advanced techniques such as pathway engineering [58] and gene cloning [59]. Despite the technological demands of natural product discovery, this method continues to promote significant development of novel drugs [60]. In contrast, synthetic approaches have yielded few approved compounds [61]. A final challenge lies in the selective isolation of rare actinomycete strains for further investigation and characterization [62]. Other potential targets for the sustained search of secondary metabolites are plasmids, which are well-documented in marine environments [63]. As in many bacteria, plasmids are common in actinomycete species, with some strains possessing a multitude [64]. Although actinomycetes may possess either linear or circular chromosomes [65][66], their plasmids are usually linear [64]. These extrachromosomal DNA elements can harbor genes encoding secondary metabolites similarly to BGCs [67][68], helping the host better adapt to its environment.
Some of the most extensively researched Actinomycetales are members of the genus Streptomyces. Streptomyces spp. are saprophytic bacteria found in soil as well as aquatic environments, which possess a variety of morphological forms that often resemble fungi [69]. Under unfavorable conditions, aerial hyphae extend away from the mycelium to release spores for dispersal [70]. Most importantly, Streptomyces spp. are the source for the majority of antibiotics discovered from Actinomycetales [48] and possess significant potential for new natural product discovery. It has been predicted that Streptomyces’ capacity for antibiotic production is on the order of 105 and that increasing screening efforts would lead to an improved rate of antimicrobial discovery [71]. Whole-genome sequencing has revealed that individual Streptomyces strains can contain as many as 34 BGCs with secondary metabolite potential, many of which are yet to be explored as sources of antibiotics [72][73]. Due to their ubiquity and reliable history of secondary metabolite discovery, much actinomycete research has focused on members of Streptomyces. However, the study of rare actinomycetes is gaining popularity in an attempt to address the problem of natural product rediscovery [74]. As researchers exhaust the readily isolable products of common species, rare strains provide an alternative resource for the identification of novel secondary metabolites.
While marine actinomycetes are renowned as sources for the acquisition of antibiotics, they are also responsible for the production of other medically important compounds. The gene clusters responsible for these drugs are thought to partially originate from lateral gene transfer [72][75]. Some of these drugs have anticancer effects [76][77]. Coral-associated actinomycetes have shown the ability to inhibit the formation of biofilms [32][78], including those formed by antibiotic-resistant Staphylococcus aureus [79][80], which cause infection via medical devices. Some actinomycetes can also form biofilms that allow them to degrade complex polymers in the environment [81][82][83][84], indicating their value in composting or bioremediation efforts, especially toxic pesticides [85][86]. Actinomycetes are also being investigated for their ability to improve agricultural productivity [87][88]. The myriad functional capacities of actinomycetes may reflect their vast repertoire of secondary metabolic pathways, a survival advantage that granted them significant importance in the search for novel bioactive compounds.

2. Medical Applications

Over 80% of all antibiotics used in the medical field originate from Actinobacteria [89], with 50% of clinically relevant antibiotics originating from the Streptomyces [90]. Each actinobacterial strain has the potential to produce 10 to 20 secondary metabolites [91], reaffirming the phylum’s profound capacity to produce antibiotics. The primary drug classes for clinical antibiotics are aminoglycosides, β-lactams, glycopeptides, macrolides, and tetracyclines [92]. Specific antibiotics derived from actinomycetes that are used in clinics today include neomycin, streptomycin, kanamycin, cephamycin, vancomycin, erythromycin, and tylosin [2]. Here, we present a limited representation of actinomycete clinical applications.

3. Environmental Applications

In addition to their utility in medical contexts, actinomycetes are being evaluated for a variety of environmental applications, including anti-biofouling and the bioremediation of inorganic and organic wastes, metals, and radioactive wastes. Aquatic actinomycetes may be especially useful for these purposes as they preclude the need to adapt terrestrial bacteria to survive in marine or freshwater conditions.

4. Industrial Applications

Members of the Actinomycetales order are also highly regarded in various industrial applications. They are being evaluated for probiotic use in aquaculture, biofuel production, and the production of compounds used in the development of plastics, detergents, and other products. While these applications are still in the research and development phase, it is likely that the use of Actinomycetales in these industrial contexts will become more prevalent in the coming years.

5. Areas of Further Exploration

To aid in the isolation and development of actinomycete products, several actinomycete characteristics should be explored in further detail. Some of these characteristics, discussed here, include their ability to perform quorum sensing, transfer and receive genes through plasmids, form symbiotic relationships, and interact with phages. In combination with genetic engineering and other development techniques, the investigation of these characteristics should provide stronger foundational knowledge of actinomycete function, as well as more efficient product development methodologies.

This entry is adapted from the peer-reviewed paper 10.3390/md19070365

References

  1. McGuire, A.; Weiner, B.; Park, S.; Wapinski, I.; Raman, S.; Dolganov, G.; Peterson, M.; Riley, R.; Zucker, J.; Abeel, T.; et al. Comparative analysis of Mycobacterium and related actinomycetes yields insight into the evolution of Mycobacterium tuberculosis pathogenesis. BMC Genom. 2012, 13, 120.
  2. Barka, E.A.; Vatsa, P.; Sanchez, L.; Gaveau-Vaillant, N.; Jacquard, C.; Meier-Kolthoff, J.P.; Klenk, H.-P.; Clément, C.; Ouhdouch, Y.; van Wezel, G.P. Taxonomy, physiology, and natural products of actinobacteria. Microbiol. Mol. Biol. Rev. 2015, 80, 1–43.
  3. Kavagutti, V.S.; Andrei, A.-Ş.; Mehrshad, M.; Salcher, M.M.; Ghai, R. Phage-centric ecological interactions in aquatic ecosystems revealed through ultra-deep metagenomics. Microbiome 2019, 7, 135.
  4. Embley, T.M.; Stackebrandt, E. The molecular phylogeny and systematics of the actinomycetes. Annu. Rev. Microbiol. 1994, 48, 257–289.
  5. Zenova, G.M.; Manucharova, N.A.; Zvyagintsev, D.G. Extremophilic and extremotolerant actinomycetes in different soil types. Eurasian Soil Sci. 2011, 44, 417–436.
  6. Basavaraj, K.N.; Chandrashekhara, S.; Shamarez, A.M.; Goudanavar, P.S.; Manvi, F.V. Isolation and morphological characterization of antibiotic producing actinomycetes. Trop. J. Pharm. Res. 2010, 9, 231–236.
  7. Ramesh, S.; Mathivanan, N. Screening of marine actinomycetes isolated from the Bay of Bengal, India for antimicrobial activity and industrial enzymes. World J. Microbiol. Biotechnol. 2009, 25, 2103–2111.
  8. Gohel, S.D.; Singh, S.P. Cloning and expression of alkaline protease genes from two salt-tolerant alkaliphilic actinomycetes in E. coli. Int. J. Biol. Macromol. 2012, 50, 664–671.
  9. Poomthongdee, N.; Duangmal, K.; Pathom-aree, W. Acidophilic actinomycetes from rhizosphere soil: Diversity and properties beneficial to plants. J. Antibiot. 2015, 68, 106–114.
  10. Vasavada, S.H.; Thumar, J.T.; Singh, S.P. Secretion of a potent antibiotic by salt-tolerant and alkaliphilic actinomycete Streptomyces sannanensis strain RJT-1. Curr. Sci. 2006, 91, 1393–1397.
  11. Kurapova, A.I.; Zenova, G.M.; Sudnitsyn, I.I.; Kizilova, A.K.; Manucharova, N.A.; Norovsuren, Z.; Zvyagintsev, D.G. Thermotolerant and thermophilic actinomycetes from soils of Mongolia desert steppe zone. Microbiology 2012, 81, 98–108.
  12. Saito, S.; Kato, W.; Ikeda, H.; Katsuyama, Y.; Ohnishi, Y.; Imoto, M. Discovery of “heat shock metabolites” produced by thermotolerant actinomycetes in high-temperature culture. J. Antibiot. 2020, 73, 203–210.
  13. Song, Q.; Huang, Y.; Yang, H. Optimization of fermentation conditions for antibiotic production by actinomycetes yj1 strain against Sclerotinia sclerotiorum. J. Agric. Sci. 2012, 4, 95–102.
  14. George, M.; Anjumol, A.; George, G.; Abdulla, M.H. Distribution and bioactive potential of soil actinomycetes from different ecological habitats. Afr. J. Microbiol. Res. 2012, 6, 2265–2271.
  15. Oskay, A.M.; Üsame, T.; Cem, A. Antibacterial activity of some actinomycetes isolated from farming soils of Turkey. Afr. J. Biotechnol. 2004, 3, 441–446.
  16. Peela, S.; Kurada, V.B.; Terli, R. Studies on antagonistic marine actinomycetes from the Bay of Bengal. World J. Microbiol. Biotechnol. 2005, 21, 583–585.
  17. Takahashi, Y.; Omura, S. Isolation of new actinomycete strains for the screening of new bioactive compounds. J. Gen. Appl. Microbiol. 2003, 49, 141–154.
  18. Pathom-Aree, W.; Stach, J.E.M.; Ward, A.C.; Horikoshi, K.; Bull, A.T.; Goodfellow, M. Diversity of actinomycetes isolated from Challenger Deep sediment. Extrem. Life Under Extrem. Cond. 2006, 10, 181–189.
  19. Mevs, U.; Stackebrandt, E.; Schumann, P.; Gallikowski, C.A.; Hirsch, P. Modestobacter multiseptatus gen. Nov., sp. Nov., a budding actinomycete from soils of the Asgard Range (Transantarctic Mountains). Int. J. Syst. Evol. Microbiol. 2000, 50, 337–346.
  20. Bull, A.T.; Ward, A.C.; Goodfellow, M. Search and discovery strategies for biotechnology: The paradigm shift. Microbiol. Mol. Biol. Rev. 2000, 64, 573–606.
  21. Girard, G.; Traag, B.A.; Sangal, V.; Mascini, N.; Hoskisson, P.A.; Goodfellow, M.; van Wezel, G.P. A novel taxonomic marker that discriminates between morphologically complex actinomycetes. Open Biol. 2013, 3, 130073.
  22. Stach, E.M.; Bull, A.T. Estimating and comparing the diversity of marine actinobacteria. Antonie Van Leeuwenhoek 2005, 87, 3–9.
  23. Cross, T. Aquatic actinomycetes: A critical survey of the occurrence, growth and role of actinomycetes in aquatic habitats. J. Appl. Bacteriol. 1981, 50, 397–423.
  24. Helmke, E.; Weyland, H. Rhodococcus marinonascens sp. nov., an actinomycete from the sea. Int. J. Syst. Bacteriol. 1984, 34, 127–138.
  25. Colquhoun, J.A.; Mexson, J.; Goodfellow, M.; Ward, A.C.; Horikoshi, K.; Bull, A.T. Novel rhodococci and other mycolate actinomycetes from the deep sea. Antonie Van Leeuwenhoek 1998, 74, 27–40.
  26. Das, S.; Lyla, P.S.; Ajmal Khan, S. Distribution and generic composition of culturable marine actinomycetes from the sediments of Indian continental slope of Bay of Bengal. Chin. J. Oceanol. Limnol. 2008, 26, 166–177.
  27. Freel, K.C.; Edlund, A.; Jensen, P.R. Microdiversity and evidence for high dispersal rates in the marine actinomycete ‘Salinispora pacifica’. Environ. Microbiol. 2012, 14, 480–493.
  28. Mincer, T.J.; Jensen, P.R.; Kauffman, C.A.; Fenical, W. Widespread and Persistent populations of a major new marine actinomycete taxon in ocean sediments. Appl. Environ. Microbiol. 2002, 68, 5005–5011.
  29. Yi, H.; Schumann, P.; Sohn, K.; Chun, J. Serinicoccus marinus gen. nov., sp. nov., a novel actinomycete with l-ornithine and l-serine in the peptidoglycan. Int. J. Syst. Evol. Microbiol. 2004, 54, 1585–1589.
  30. Jensen, P.R.; Mafnas, C. Biogeography of the marine actinomycete Salinispora. Environ. Microbiol. 2006, 8, 1881–1888.
  31. Jensen, P.R.; Gontang, E.; Mafnas, C.; Mincer, T.J.; Fenical, W. Culturable marine actinomycete diversity from tropical Pacific Ocean sediments. Environ. Microbiol. 2005, 7, 1039–1048.
  32. Nithyanand, P.; Thenmozhi, R.; Rathna, J.; Pandian, S.K. Inhibition of Streptococcus pyogenes biofilm formation by coral-associated actinomycetes. Curr. Microbiol. 2010, 60, 454–460.
  33. Waturangi, D.E.; Hariyanto, J.P.; Lois, W.; Hutagalung, R.A.; Hwang, J.K. Inhibition of marine biofouling by aquatic actinobacteria and coral-associated marine bacteria. Malays. J. Microbiol. 2017, 13, 92–99.
  34. Wu, Z.; Xie, L.; Xia, G.; Zhang, J.; Nie, Y.; Hu, J.; Wang, S.; Zhang, R. A new tetrodotoxin-producing actinomycete, Nocardiopsis dassonvillei, isolated from the ovaries of puffer fish Fugu rubripes. Toxicon 2005, 45, 851–859.
  35. Ghanem, N.B.; Sabry, S.A.; El-Sherif, Z.M.; El-Ela, G.A.A. Isolation and enumeration of marine actinomycetes from seawater and sediments in Alexandria. J. Gen. Appl. Microbiol. 2000, 46, 105–111.
  36. Bystrianský, L.; Hujslová, M.; Hršelová, H.; Řezáčová, V.; Němcová, L.; Šimsová, J.; Gryndlerová, H.; Kofroňová, O.; Benada, O.; Gryndler, M. Observations on two microbial life strategies in soil: Planktonic and biofilm-forming microorganisms are separable. Soil Biol. Biochem. 2019, 136, 107535.
  37. Zwart, G.; Crump, B.C.; Agterveld, M.P.K.; Hagen, F.; Han, S.-K. Typical freshwater bacteria: An analysis of available 16s rrna gene sequences from plankton of lakes and rivers. Aquat. Microb. Ecol. 2002, 28, 141–155.
  38. Bredholt, H.; Fjærvik, E.; Johnsen, G.; Zotchev, S.B. Actinomycetes from sediments in the Trondheim Fjord, Norway: Diversity and biological activity. Mar. Drugs 2008, 6, 12–24.
  39. Barcina, I.; Iriberri, J.; Egea, L. Enumeration, isolation and some physiological properties of actinomycetes from sea water and sediment. Syst. Appl. Microbiol. 1987, 10, 85–91.
  40. Hahn, M.W.; Pöckl, M. Ecotypes of planktonic actinobacteria with identical 16s rrna genes adapted to thermal niches in temperate, subtropical, and tropical freshwater habitats. Appl. Environ. Microbiol. 2005, 71, 766–773.
  41. Morris, R.M.; Vergin, K.L.; Cho, J.-C.; Rappé, M.S.; Carlson, C.A.; Giovannoni, S.J. Temporal and spatial response of bacterioplankton lineages to annual convective overturn at the Bermuda Atlantic time-series study site. Limnol. Oceanogr. 2005, 50, 1687–1696.
  42. Jürgens, K.; Matz, C. Predation as a shaping force for the phenotypic and genotypic composition of planktonic bacteria. Antonie Van Leeuwenhoek 2002, 81, 413–434.
  43. Bouvier, T.; Giorgio, P.A.D. Key role of selective viral-induced mortality in determining marine bacterial community composition. Environ. Microbiol. 2007, 9, 287–297.
  44. Maat, D.S.; Prins, M.A.; Brussaard, C.P.D. Sediments from arctic tide-water glaciers remove coastal marine viruses and delay host infection. Viruses 2019, 11, 123.
  45. Fenical, W.; Jensen, P.R. Developing a new resource for drug discovery: Marine actinomycete bacteria. Nat. Chem. Biol. 2006, 2, 666–673.
  46. Amann, R.I.; Ludwig, W.; Schleifer, K.-H. Phylogenetic identification and in situ detection of individual microbial cells without cultivation. Microbiol. Mol. Biol. Rev. 1995, 59, 143–169.
  47. Lam, K.S. Discovery of novel metabolites from marine actinomycetes. Curr. Opin. Microbiol. 2006, 9, 245–251.
  48. Bérdy, J. Bioactive microbial metabolites: A personal view. J. Antibiot. 2005, 58, 1–26.
  49. Baltz, R.H. Renaissance in antibacterial discovery from actinomycetes. Curr. Opin. Pharmacol. 2008, 8, 557–563.
  50. Letzel, A.-C.; Li, J.; Amos, G.C.A.; Millán-Aguiñaga, N.; Ginigini, J.; Abdelmohsen, U.R.; Gaudêncio, S.P.; Ziemert, N.; Moore, B.S.; Jensen, P.R. Genomic insights into specialized metabolism in the marine actinomycete Salinispora. Environ. Microbiol. 2017, 19, 3660–3673.
  51. Seipke, R.F. Strain-level diversity of secondary metabolism in Streptomyces albus. PLoS ONE 2015, 10, e0116457.
  52. Jensen, P.R. Natural products and the gene cluster revolution. Trends Microbiol. 2016, 24, 968–977.
  53. Winter, J.M.; Behnken, S.; Hertweck, C. Genomics-inspired discovery of natural products. Curr. Opin. Chem. Biol. 2011, 15, 22–31.
  54. Abdelmohsen, U.R.; Grkovic, T.; Balasubramanian, S.; Kamel, M.S.; Quinn, R.J.; Hentschel, U. Elicitation of secondary metabolism in actinomycetes. Biotechnol. Adv. 2015, 33, 798–811.
  55. Imada, C. Enzyme inhibitors and other bioactive compounds from marine actinomycetes. Antonie Van Leeuwenhoek 2005, 87, 59–63.
  56. Imada, C.; Koseki, N.; Kamata, M.; Kobayashi, T.; Hamada-Sato, N. Isolation and characterization of antibacterial substances produced by marine actinomycetes in the presence of seawater. Actinomycetologica 2007, 21, 27–31.
  57. Wilkinson, B.; Micklefield, J. Mining and engineering natural-product biosynthetic pathways. Nat. Chem. Biol. 2007, 3, 379–386.
  58. Baltz, R.H. Strain improvement in actinomycetes in the postgenomic era. J. Ind. Microbiol. Biotechnol. 2011, 38, 657–666.
  59. Schmidt, E.W. From chemical structure to environmental biosynthetic pathways: Navigating marine invertebrate–bacteria associations. Trends Biotechnol. 2005, 23, 437–440.
  60. Bull, A.T.; Stach, J.E.M. Marine actinobacteria: New opportunities for natural product search and discovery. Trends Microbiol. 2007, 15, 491–499.
  61. Newman, D.J.; Cragg, G.M. Natural products as sources of new drugs over the 30 years from 1981 to 2010. J. Nat. Prod. 2012, 75, 311–335.
  62. Tiwari, K.; Gupta, R. Diversity and isolation of rare actinomycetes: An overview. Crit. Rev. Microbiol. 2013, 39, 256–294.
  63. Sobecky, P.A. Plasmid ecology of marine sediment microbial communities. Hydrobiologia 1999, 401, 9–18.
  64. Cornell, C.R.; Marasini, D.; Fakhr, M.K. Molecular characterization of plasmids harbored by actinomycetes isolated from the great salt plains of oklahoma using pfge and next generation whole genome sequencing. Front. Microbiol. 2018, 9, 2282.
  65. Hopwood, D.A. Soil to genomics: The Streptomyces chromosome. Annu. Rev. Genet. 2006, 40, 1–23.
  66. Kirby, R. Chromosome diversity and similarity within the Actinomycetales. FEMS Microbiol. Lett. 2011, 319, 1–10.
  67. Kinashi, H.; Mori, E.; Hatani, A.; Nimi, O. Isolation and characterization of linear plasmids from lankacidin-producing Streptomyces species. J. Antibiot. 1994, 47, 1447–1455.
  68. Suwa, M.; Sugino, H.; Sasaoka, A.; Mori, E.; Fujii, S.; Shinkawa, H.; Nimi, O.; Kinashi, H. Identification of two polyketide synthase gene clusters on the linear plasmid pSLA2-L in Streptomyces rochei. Gene 2000, 246, 123–131.
  69. Hodgson, D.A. Primary metabolism and its control in Streptomycetes: A most unusual group of bacteria. Adv. Microb. Physiol. 2000, 42, 47–238.
  70. Flärdh, K.; Buttner, M.J. Streptomyces morphogenetics: Dissecting differentiation in a filamentous bacterium. Nat. Rev. Microbiol. 2009, 7, 36–49.
  71. Watve, M.G.; Tickoo, R.; Jog, M.M.; Bhole, B.D. How many antibiotics are produced by the genus Streptomyces? Arch. Microbiol. 2001, 176, 386–390.
  72. Bentley, S.D.; Chater, K.F.; Cerdeño-Tárraga, A.-M.; Challis, G.L.; Thomson, N.R.; James, K.D.; Harris, D.E.; Quail, M.A.; Kieser, H.; Harper, D.; et al. Complete genome sequence of the model actinomycete Streptomyces coelicolor A3(2). Nature 2002, 417, 141–147.
  73. Ohnishi, Y.; Ishikawa, J.; Hara, H.; Suzuki, H.; Ikenoya, M.; Ikeda, H.; Yamashita, A.; Hattori, M.; Horinouchi, S. Genome sequence of the streptomycin-producing microorganism Streptomyces griseus IFO 13350. J. Bacteriol. 2008, 190, 4050–4060.
  74. Tiwari, K.; Gupta, R.K. Rare actinomycetes: A potential storehouse for novel antibiotics. Crit. Rev. Biotechnol. 2012, 32, 108–132.
  75. Jensen, P.R.; Williams, P.G.; Oh, D.-C.; Zeigler, L.; Fenical, W. Species-specific secondary metabolite production in marine actinomycetes of the genus Salinispora. Appl. Environ. Microbiol. 2007, 73, 1146–1152.
  76. Fiedler, H.-P.; Bruntner, C.; Riedlinger, J.; Bull, A.T.; Knutsen, G.; Goodfellow, M.; Jones, A.; Maldonado, L.; Pathom-aree, W.; Beil, W.; et al. Proximicin a, b and c, novel aminofuran antibiotic and anticancer compounds isolated from marine strains of the actinomycete Verrucosispora. J. Antibiot. 2008, 61, 158–163.
  77. Williams, P.G.; Buchanan, G.O.; Feling, R.H.; Kauffman, C.A.; Jensen, P.R.; Fenical, W. New cytotoxic salinosporamides from the marine actinomycete Salinispora tropica. J. Org. Chem. 2005, 70, 6196–6203.
  78. You, J.; Xue, X.; Cao, L.; Lu, X.; Wang, J.; Zhang, L.; Zhou, S. Inhibition of Vibrio biofilm formation by a marine actinomycete strain A66. Appl. Microbiol. Biotechnol. 2007, 76, 1137–1144.
  79. Bakkiyaraj, D.; Pandian, S.T.K. In vitro and in vivo antibiofilm activity of a coral associated actinomycete against drug resistant Staphylococcus aureus biofilms. Biofouling 2010, 26, 711–717.
  80. Park, J.-H.; Lee, J.-H.; Kim, C.-J.; Lee, J.-C.; Cho, M.H.; Lee, J. Extracellular protease in actinomycetes culture supernatants inhibits and detaches Staphylococcus aureus biofilm formation. Biotechnol. Lett. 2012, 34, 655–661.
  81. Mor, R.; Sivan, A. Biofilm formation and partial biodegradation of polystyrene by the actinomycete Rhodococcus ruber: Biodegradation of polystyrene. Biodegradation 2008, 19, 851–858.
  82. Tseng, M.; Hoang, K.-C.; Yang, M.-K.; Yang, S.-F.; Chu, W.S. Polyester-degrading thermophilic actinomycetes isolated from different environment in Taiwan. Biodegradation 2007, 18, 579–583.
  83. Wei, Y.; Wu, D.; Wei, D.; Zhao, Y.; Wu, J.; Xie, X.; Zhang, R.; Wei, Z. Improved lignocellulose-degrading performance during straw composting from diverse sources with actinomycetes inoculation by regulating the key enzyme activities. Bioresour. Technol. 2019, 271, 66–74.
  84. Zhao, Y.; Zhao, Y.; Zhang, Z.; Wei, Y.; Wang, H.; Lu, Q.; Li, Y.; Wei, Z. Effect of thermo-tolerant actinomycetes inoculation on cellulose degradation and the formation of humic substances during composting. Waste Manag. 2017, 68, 64–73.
  85. Dai, Z.-L.; Yang, W.-L.; Fan, Z.-X.; Guo, L.; Liu, Z.-H.; Dai, Y.-J. Actinomycetes Rhodococcus ruber CGMCC 17550 degrades neonicotinoid insecticide nitenpyram via a novel hydroxylation pathway and remediates nitenpyram in surface water. Chemosphere 2021, 270, 128670.
  86. Fuentes, M.; Benimeli, C.; Cuozzo, S.; Amoroso, M. Isolation of pesticide-degrading actinomycetes from a contaminated site: Bacterial growth, removal and dechlorination of organochlorine pesticides. Int. Biodeterior. Biodegrad. 2010, 64, 434–441.
  87. AbdElgawad, H.; Abuelsoud, W.; Madany, M.M.Y.; Selim, S.; Zinta, G.; Mousa, A.S.M.; Hozzein, W.N. Actinomycetes enrich soil rhizosphere and improve seed quality as well as productivity of legumes by boosting nitrogen availability and metabolism. Biomolecules 2020, 10, 1675.
  88. Hozzein, W.N.; Abuelsoud, W.; Wadaan, M.A.M.; Shuikan, A.M.; Selim, S.; Al Jaouni, S.; AbdElgawad, H. Exploring the potential of actinomycetes in improving soil fertility and grain quality of economically important cereals. Sci. Total Environ. 2019, 651, 2787–2798.
  89. Ilic, S.B.; Konstantinovic, S.S.; Todorovic, Z.B.; Lazic, M.L.; Veljkovic, V.B.; Jokovic, N.; Radovanovic, B.C. Characterization and antimicrobial activity of the bioactive metabolites in Streptomycete isolates. Microbiology 2007, 76, 421–428.
  90. Van der Heul, H.U.; Bilyk, B.L.; McDowall, K.J.; Seipke, R.F.; Van Wezel, G.P. Regulation of antibiotic production in actinobacteria: New perspectives from the post-genomic era. Nat. Prod. Rep. 2018, 35, 575–604.
  91. Arasu, M.V.; Duraipandiyan, V.; Agastian, P.; Ignacimuthu, S. In vitro antimicrobial activity of Streptomyces spp. ERI-3 isolated from Western Ghats rock soil (India). J. De Mycol. Médicale 2009, 19, 22–28.
  92. Mast, Y.; Stegmann, E. Actinomycetes: The antibiotics producers. Antibiotics 2019, 8, 105.
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