title: Biological Characteristics and Antimicrobial Activity of EndophyticStreptomycessp. TQR12-4 Isolated from EliteCitrus nobilisCultivar Ham Yen of Vietnam.
abstract: Ham Yen orange (Citrus nobilisLour) is the highly valuable commercial fruit of Vietnam. With the blooming of fruit production and farming area, this specialty crop is facing threats from several serious diseases; therefore the search for new effective biocontrollers is required to prevent the existing excessive use of fertilizers and plant protection chemicals. Endophytic actinomycetes are of great scientific interest due to their high potential of application in agriculture and pharmaceutical research. In this work, endophytic actinomycetes were isolated from a native orange species of Northeast mountainous province Tuyen Quang. Among 49 isolates obtained, the isolate TQR12-4 strongly inhibited test pathogensColletotrichum truncatum,Geotrichum candidum,Fusarium oxysporum, andF. udum. This isolate gave comparatively high biomass yields on different substrates, for example, carboxy methyl cellulose, starch, protein, and chitin, within a wide range of temperature from 15 to 45°C and pH from 4 to 10. Sequence analysis of 16S rDNA gene showed that TQR12-4 shared 99% similarity toStreptomyces prasinopilosus; however, it slightly differed from the latter in spore morphology and hence was named asStreptomycessp. TQR12-4. A thermostable antifungal substance of nonpeptide nature produced byStreptomycessp. TQR12-4 had MIC againstFusarium udumof 100μg/mL and 400μg/mL respective to extract fractionsX4andX5.
authors: Institute of Biotechnology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Street, Cau Giay, Ha Noi, Vietnam.
authors: Phan Thi
authors: 0000-0002-6689-2334
authors: PT
authors: Hong-Thao
authors: Institute of Biotechnology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Street, Cau Giay, Ha Noi, Vietnam.
authors: Nguyen Vu
authors: NV
authors: Mai-Linh
authors: Institute of Biotechnology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Street, Cau Giay, Ha Noi, Vietnam.
authors: Nguyen Thi
authors: NT
authors: Hong-Lien
authors: Institute of Biotechnology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Street, Cau Giay, Ha Noi, Vietnam.
authors: Nguyen
authors: N
authors: Van Hieu