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 VN05A0415T represent a novel species of the genus Kineosporia, for which the name Kineosporia babensis sp. nov. is proposed. The type strain is VN05A0415 T
A novel actinomycete, designated strain VN05A0561T , was isolated from plant litter collected at Ba Be National Park, Vietnam. The substrate mycelia and spore chains fragmented in a manner similar to nocardioform actinomycetes; the spores had smooth surfaces and were rodshaped. Strain VN05A0561 T had the following chemotaxonomic characteristics: mesodiaminopimelic acid in the cell-wall peptidoglycan, arabinose and galactose as characteristic sugars, MK-8(H 4 ) as the major isoprenoid quinone, phosphatidylcholine as the diagnostic phospholipid and iso-C 16 : 0 as the major cellular fatty acid. Strain VN05A0561 T shared low levels of 16S rRNA gene sequence similarity (,97 %) with the type strains of recognized species of the genus Pseudonocardia and could be differentiated from its closest phylogenetic relatives based on phenotypic characteristics. These results suggested that strain VN05A0561 T represents a novel species of the genus Pseudonocardia, for which the name Pseudonocardia babensis sp. nov. is proposed. The type strain is VN05A0561 T (5VTCC-A-The genus Pseudonocardia was established as a nocardioform actinomycete by Henssen (1957), and its description has been emended based on both chemotaxonomic and morphological variations (Reichert et al., 1998;Huang et al., 2002;Park et al., 2008). On the basis of the lack of mycolic acids and the presence of cell-wall type IV, the genera Amycolata (Lechevalier et al., 1986) and Pseudoamycolata were also proposed as nocardioform actinomycetes. However, the latter two genera were found to have chemotaxonomic properties similar to those of the genus Pseudonocardia (Kothe et al., 1989;Takeuchi et al., 1992), and were incorporated in the genus Pseudonocardia on the basis of 16S rRNA gene sequence analysis (Warwick et al., 1994;McVeigh et al., 1994). Subsequently, members of the genus Actinobispora (Jiang et al., 1991) were also transferred to the genus Pseudonocardia based on identification with the use of specific PCR primers, and re-analysis of 16S rRNA gene sequences and menaquinones of the type species (Huang et al., 2002 Reichert et al., 1998;Gu et al., 2006; Chen et al., 2009).In the present study, a Pseudonocardia-like strain isolated from a plant litter sample collected during the course of a study on the diversity of actinomycetes inhabiting Vietnam (Sakiyama et al., 2009) was studied by using a polyphasic taxonomic approach.Plant litter samples were collected at the Ba Be National Park, Bac Kan, in the mountainous area of northern Vietnam. Samples were dried at room temperature for 5-7 days and subsequently used for isolation. Rehydration and centrifugation methods (Hayakawa et al., 2000) were employed for isolation by using humic acid-vitamin agar (Hayakawa & Nonomura, 1987) containing nalidixic acid (20 mg l 21) and kabicidine (0.75 mg l 21). Strain VN05A0561 T was isolated after incubation for more than 10 days at room temperature. Strain VN05A0561T was cultured on yeast extract-soluble starch medium (YS medium; per litre distilled water: 2 g yeast extract...
Fungal diseases are a huge problem in agriculture, causing serious damage to annual crop yields worldwide. In order to control fungal pathogens in plants, using antagonistic microorganisms is a common approach, especially actinomycetes, as biocontrols considered to be very potential and safe for the environment. With the advantage of high levels of biodiversity, Vietnamese actinomycetes are of a valuable resource for finding strains that are capable of biocontrolling fungal pathogens in plants. Thus, in this study, 70 actinomycete strains were isolated from Cuc Phuong and Ba Be National Parks by four different isolation methods including rehydration centrifugation, sodium dodecyl sulfate – yeast extract, dry heating and dilution methods. Of these, 29 strains (41.4%) belong to rare actinomycete genera including Actinoplanes, Acrocarpospora, Dactylosporangium, Kineosporia, Micromonospora, Nocardia, Nocardiopsis and Pseudonocardia, which are rarely studied in Vietnam. Subsequently, 70 actinomycete strains were subjected to antagonistic activity assays against four highly pathogenic fungi in plants including Alternaria sp., Botrytis cinerea, Colletotrichum gloeosporioides and Phytophthora capsici. The results showed that 80.5% of Streptomyces and 31% of rare actinomyces could inhibit the growth of at least one of the four pathogenic fungal strains. Moreover, ten actinmomycete strains were found to be able to inhibit three types of tested fungal pathogens, simutaneously. Especially, four actinomycete strains (VTCC-A-828, VTCC-A-671, VTCC-A-605, and VTCC-A-69), having the highest antagonistic activity against four fungal pathogens Alternaria sp., Botrytis cinerea, Colletotrichum gloeosporioides and Phytophthora capsici, respectively, were selected. The results in this study indicate the great potential application for Vietnam's microorganisms in the field of plant protection.
During surveys conducted on freshwater fungi from Vietnam, a new aquatic anamorphic fungus was isolated from decaying leaves in Vietnam. The fungus produced phialidic, swollen conidiophore and conidiogenous cells with one-celled conidia with four very tiny lobes. Based on its conidial development and other morphological characteristics, we confirmed that this is a novel fungus and described it as P. ambigua sp. nov. Phylogenetic analyses of P. ambigua based on the LSU nrDNA sequences showed that this fungus clusters in a single clade with the two known Polylobatispora spp. with 97% bootstrap value which is sister with Pseudoprobiscisporaceae . The Polylobatispora clade is nested in the Attracrosporales , Sordariomycetes . Furthermore, in this study two known species of Polylobatispora ( P. deltoidea and P. quinquecornuta ) were also isolated and illustrated.
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