Taxonomic and ecological studies of actinomycetes from Vietnam: isolation and genus-level diversity

Institute of Microbiology and Biotechnology, Vietnam National University, Hanoi, Vietnam.
The Journal of Antibiotics (Impact Factor: 2.19). 05/2011; 64(9):599-606. DOI:10.1038/ja.2011.40

ABSTRACT Actinomycetes were isolated from 109 soil and 93 leaf-litter samples collected at five sites in Vietnam between 2005 and 2008 using the rehydration-centrifugation (RC) method, sodium dodecyl sulfate-yeast extract dilution method, dry-heating method and oil-separation method in conjunction with humic acid-vitamin agar as an isolation medium. A total of 1882 strains were identified as Vietnamese (VN)-actinomycetes including 1080 (57%) streptomycetes (the genus Streptomyces isolates) and 802 (43%) non-streptomycetes. The 16S ribosomal RNA gene sequences of the VN-actinomycetes were analyzed using BLAST searches. The results showed that these isolates belonged to 53 genera distributed among 21 families. Approximately 90% of these strains were members of three families: Streptomycetaceae (1087 strains, 58%); Micromonosporaceae (516 strains, 27%); and Streptosporangiaceae (89 strains, 5%). Motile actinomycetes of the genera Actinoplanes, Kineosporia and Cryptosporangium, which have quite common morphological characteristics, were frequently isolated from leaf-litter samples using the RC method. It is possible that these three genera acquired common properties during a process of convergent evolution. By contrast, strains belonging to the suborder Streptosporangineae were exclusively isolated from soils. A comparison of the sampling sites revealed no significant difference in taxonomic diversity between these sites. Among the non-streptomycetes, 156 strains (19%) were considered as new taxa distributed into 21 genera belonging to 12 families. Interestingly, the isolation of actinomycetes from leaf-litter samples using the RC method proved to be the most efficient way to isolate new actinomycetes in Vietnam, especially the Micromonosporaceae species.Keywords: actinomycete ecology; taxonomic diversity; Vietnamese actinomycetes

0 0
  • [show abstract] [hide abstract]
    ABSTRACT: The recently-developed statistical method known as the "bootstrap" can be used to place confidence intervals on phylogenies. It involves resampling points from one's own data, with replacement, to create a series of bootstrap samples of the same size as the original data. Each of these is analyzed, and the variation among the resulting estimates taken to indicate the size of the error involved in making estimates from the original data, In the case of phylogenies, it is argued that the proper method of resampling is to keep all of the original species while sampling characters with replacement, under the assumption that the characters have been independently drawn by the systematist and have evolved independently. Majority-rule consensus trees can be used to construct a phylogeny showing all of the inferred monophyletic groups that occurred in a majority of the bootstrap samples. If a group shows up 95% of the time or more, the evidence for it is taken to be statistically significant. Existing computer programs can be used to analyze different bootstrap samples by using weights on the characters, the weight of a character being how many times it was drawn in bootstrap sampling. When all characters are perfectly compatible, as envisioned by Hennig, bootstrap sampling becomes unnecessary; the bootstrap method would show significant evidence for a group if it is defined by three or more characters.
    Evolution 01/1985; 39(4):783-791. · 4.86 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Three actinomycetes, designated strains VN05A0342, VN05A0351 and VN05A0415(T), were isolated from plant-litter samples collected in the north of Vietnam and examined in a polyphasic taxonomic study. Phylogenetic analysis based on the 16S rRNA gene sequences showed that these isolates were most closely related to the type strain of Kineosporia mikuniensis (98.5 % sequence similarity). Morphological properties (the formation of spore domes and motile spores) and chemotaxonomic data supported the assignment of the three isolates to the genus Kineosporia. The isolates all contained the following: meso-diaminopimelic acid in the peptidoglycan (with small amounts of the ll isomer); ribose, mannose, galactose and glucose as the whole-cell sugars; MK-9(H(4)) as the predominant isoprenoid quinone; C(18 : 1) and C(16 : 0) as the major cellular fatty acids; and phosphatidylcholine, phosphatidylglycerol, diphosphatidylglycerol and phosphatidylinositol as the phospholipids. The high DNA-DNA relatedness (>71 %) among the three isolates showed that they represented a single species. On the other hand, the DNA-DNA relatedness between the novel isolates and all type strains of Kineosporia species was less than 46 %. The physiological properties of our isolates were distinct from those of all of the Kineosporia species with validly published names, e.g. decomposition of l-tyrosine and aesculin and the utilization of raffinose and d-arabitol. Therefore, strains VN05A0342, VN05A0351 and VN05A0415(T) represent a novel species of the genus Kineosporia, for which the name Kineosporia babensis sp. nov. is proposed. The type strain is VN05A0415(T) (=VTCC-A-0961(T) =NBRC 104154(T)).
    International journal of systematic and evolutionary microbiology 03/2009; 59(Pt 3):550-4. · 2.11 Impact Factor
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: Four strains that form sporangia with motile sporangiospores and mycelia were isolated from soil samples. Their many sporangia were covered by mycelia. They had glutamic acid, glycine, alanine and meso-diaminopimelic acid as cell wall amino acids (wall chemotype II), acofriose (3-O-mythylrhamnose) as a characteristic whole-cell sugar, and menaquinone 9(H6). The taxonomic characteristics of these strains differ from those of the previously described motile actinomycetes. On the basis of the morphological, physiological, chemotaxonomic and phylogenetic analyses, a new genus is proposed, Cryptosporangium, and two new species, Cryptosporangium arvum sp. nov (type strain IFO 15965T) for strain YU 629-21T and Cryptosporangium japonicum sp. nov (type strain IFO 15966T) for strains YU 636-3T, YU 655-31 and YU 656-31.
    International journal of systematic bacteriology 08/1998; 48 Pt 3:995-1005. · 2.27 Impact Factor


Available from