Streptomyces lavendulae

Streptomyces lavendulae
Scientific classification
Domain: Bacteria
Phylum: Actinobacteria
Class: Actinobacteria
Order: Actinomycetales
Family: Streptomycetaceae
Genus: Streptomyces
Species: S. lavendulae
Binomial name
Streptomyces lavendulae
(Waksman et al. 1951)

Streptomyces lavendulae is a species of bacteria from the genus Streptomyces. It is isolated from soils globally and is known for its production of medically useful biologically active metabolites. To see a photo of this organism click here.

Description and significance

Streptomyces lavendulae was first isolated from soil in 1916,[1] and has since been isolated from many soils throughout the world. It is characterized by colorless growth with lavender colored aerial mycelium, though white mutants have been observed . The order Actinomycetales is composed of organisms well known for their ability to make a wide range of biologically active metabolites.[2] S. lavendulae produces many medically useful antibiotics including streptothricin[3] and lavendamycin,[4] although some mutant strains exist without aerial mycelium, which are unable to produce antibiotics.[5]

Cell morphology and physiology

Actinomycetes are Gram-positive bacteria that resemble fungi in structure with a complex branched network of cells called a mycelium. Isolates of Streptomyces lavendulae from different soils around the world vary morphologically and physiologically, with some strains producing straight aerial mycelium, while other isolates form spiral mycelium.[6] The coloration of the mycelia can range from white to lavender to a deep red. These mycelia later give rise to spores that are oval with a smooth surface. All strains of S. lavendulae produce dark pigments on organic media, which can range in color from brown to greenish-black.[7] S. lavendulae growth occurs between 20 °C and 43 °C and its optimum temperature is 37 °C and growth and sporulation occur at pH ranging from 5.0-8.0 and its optimum pH is 7.0.[8]

Metabolism

Streptomyces have the ability to utilize many different compounds as part of their metabolism including sugars, amino acids, and alcohols through the production of extracellular enzymes. Carbon utilization studies on S. lavendulae have shown good or moderate growth with glucose, fructose, and arabinose as the substrate.[9]

Genome structure

While most bacteria have circular chromosomes, all actinomycetes chromosomes are linear and fairly large, 8-9Mb.[10][11] In addition, actinomycete genomes contain extrachromosomal genetic elements such as rolling circle replication plasmids.[12] These extrachromosomal genetic elements have been shown to transport their own genes as well as chromosomal genes to other actinomycete hosts.[13] This provides a pathway for genetic information to be exchanged between cells, and could provide a mechanism for the transfer of antibiotic resistance between organisms. One study found genes for streptothricin resistance, an antibiotic produced by Actinomycete bacteria, on plasmids within gram-negative bacteria.[14]

Pathology

Streptomyces lavendulae has not been identified as a pathogen and is not known to be the cause of any human diseases.

Medical importance

Production of antibiotics

Filamentous soil bacteria from the genus Streptomyces are important sources of biologically active compounds used in pharmaceutical and agrochemical industries. In fact, bacteria from the genus Streptomyces produce 75% of commercially and medically useful antibiotics.[15] In 1942, Streptothricin, an antibiotic made by Actinomycetes, was found to be produced by a strain of S. lavendulae.[16]

Many natural compounds have led to the discovery of drugs used to treat human disease. Out of the 22,500 biologically active compounds that have been extracted from microbes, 45% are from Actinobacteria.[17] In 1956, Streptomyces lavendulae was found to produce an antibiotic called Mitomycin C, which has been studied for its cytotoxic effects on cancer cells.[18]

Antibiotic resistance

It has been observed that cultures of S. lavendulae that produce streptothricin are resistant to the effects of this antibiotic.[19] Many studies show the presence of multiple pathways for resistance toward a single antibiotic with the resistance genes located next to the antibiotic biosynthetic genes.[20] Mytomycin C (MC), an antibiotic produced by S. lavendulae, exhibits cytotoxicity when the activated drug covalently binds complementary strands of DNA.[21] Streptomycetes contain an average G+C content of 70% making them very susceptible to the harmful effects of MC. S. lavendulae has three known genetic loci for resistance to MC. The first genetic locus (mcr) codes for two genes which inactivate MC in vivo through an oxidation process.[22] The second locus (mrd) binds with MC as a complex which prevents drug activation.[23] The third locus (mct) encodes a membrane-associated protein involved in the excretion of MC from the cell.[24] These antibiotic resistance genes are tightly linked within the MC biosynthetic gene cluster. This coordinated gene regulation along with the multiple resistance loci effectively confer MC antibiotic resistance to S. lavendulae.

References

  1. ↑ Waksman SA, Curtis RE. 1916. The actinomyces of the soil. Soil Sci. 1:99-134.
  2. ↑ Ikea H, Ishikawa J, Hanamoto A, Shinose M, Kikuchi H, Shiba T, Sakaki Y, Hattori M, Omura S. 2003. Complete genome sequence and comparative analysis of the industrial microorganism Streptomyces avermitilis. Nat Biotechnol. 21:526-531.
  3. ↑ Waksman SA, Bugie E, Schatz A. 1944. Isolation of Antibiotic Substances from Soil Micro-Organisms, with special reference to Streptothricin and Streptomycin. Proceedings of Staff Meetings of the Mayo Clinic. 19(23):537-548.
  4. ↑ Balitz DM, Bush JA, Bradner WT, Doyle TW, O'Herron FA, Nettleton DE. 1982. Isolation of lavendamycin, a new antibiotic from Streptomyces lavendulae. J Antibiot (Tokyo). 35(3):259-65.
  5. ↑ Waksman SA, Schatz A. 1945. Strain specificity and production of antibiotic substances. VI Strain variation and production of streptothricin by Actinomyces lavendulae. Proc Natl Acad Sci. 31:208-214.
  6. ↑ Waksman SA, Harris D, Lechevalier M. 1951. Studies on Streptomyces Lavendulae. New Jersey Agricultural Experiment Station. 62:149-161.
  7. ↑ Mencher JR, Heim AH. 1962. Melanin Biosynthesis by Streptomyces lavendulae. Microbiology. 28:665-670.
  8. ↑ Shibata M, Uyeda M, Kido Y, Toya N, Nakashima R, Terazumi R. 1980. A New Antibiotic K-82 A and Minor Components Produced by Streptomyces lavendulae, Strain No. K-82. The Journal of Antibiotics. 33:11 1231-1235.
  9. ↑ Nishimura M, Inouye S. 2000. Inhibitory Effects of Carbohydrates on Cholesterol Esterase Biosynthesis in Streptomyces lavendulae H646-SY2. Journal of Bioscience and Bioengineering. 90:5 564-566.
  10. ↑ Lin YS, Kieser HM, Hopwood DA, Chen CW. 1994. The chromosomal DNA of Streptomyces lividans 66 is linear. Mol Microbial. 14(5):1103.
  11. ↑ Redenbach M, Kieser HM, Denapaite D, Eichner A, Cullum J, Kinashi H, Hogwood DA. 1996. A set of ordered cosmids and a detailed genetic and physical map for the 8 Mb Streptomyces coelicolor A3(2) chromosome. Mol Microbial. 21:77-96.
  12. ↑ Kieser T, Hopwood DA, Wright HM, Thompson CJ. 1982. pIJ101, a multi-copy broad host-range Streptomyces plasmid: functional analysis and development of DNA cloning vectors. Mol Gen Genet. 185(2):223-228.
  13. ↑ Hosted TJ, Wang T, Horan AC. 2004. Characterization of the Streptomyces lavendulae IMRU 3455 linear plasmid pSLV45. Microbiology. 150:1819-1827.
  14. ↑ Tschäpe H, Tietze E, Prager R, Voigt W, Wolter E, Seltmann G. 1984. Plasmid-borne streptothricin resistance in gram-negative bacteria. Plasmid. 12:3 189-196.
  15. ↑ Miyadoh S. 1993. Research on Antibiotic Screening in Japan over the Last Decade: A Producing Microorganisms Approach. Actinomycetologica. 9:100-106.
  16. ↑ Waksman SA, Woodruff HB. 1942. Streptothricin, a new selective bacteriostatic and bactericidal agent, particularly active against gram-negative bacteria. Proc Soc Exptl Biol Med. 49:207-210.
  17. ↑ Demain AL, Sanchez S. 2009. Microbial drug discovery: 80 years of progress. J Antibiot. 62:5-16.
  18. ↑ Lown JW, Begetter A, Johnson D, Morgan AR. 1976. Studies related to antitumor antibiotics. Part V. Reactions of mitomycin C with DNA examined by ethidium fluorescence assay. Canadian Journal of Biochemistry. 54:2 110-119.
  19. ↑ Cundliffe E. 1989. How Antibiotic-Producing Organisms Avoid Suicide. Annual Review of Microbiology. 43:207-233.
  20. ↑ Cundliffe E. 1992. Self-protection mechanisms in antibiotic producers. Ciba Found Symp. 171:199-214.
  21. ↑ Iyer VN, Szybalski W. 1964. Mitomycins and porfiromycin: chemical mechanism of activation and cross-linking of DNA. Science. 145:55-56.
  22. ↑ August PR, Rahn JA, Flickinger MC, Sherman DH. 1996. Inducible synthesis of Mitomycin C resistance gene product (MCRA) from Streptomyces lavendulae. Gene: An International Journal on Genes and Genomes. 175:261-267.
  23. ↑ Sheldon PJ, Johnson DA, August PR, Liu HW, Sherman DH. 1996. Characterization of a Mitomycin-Binding Drug Resistance Mechanism from the Producing Organism, Streptomyces lavendulae. Journal of Bacteriology. 179:5 1796-1804.
  24. ↑ Sheldon PJ, Mao Y, He M, Sherman DH. 1999. Mitomycin Resistance in Streptomyces lavendulae Includes a Novel Drug-Binding-Protein-Dependent Export System. Journal of Bacteriology. 181:8 2507-2512.
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