Some preliminary results from a collaboration project with NguyenTatThanh University.
Dinh Thi Lan Linh, Nguyen Thi Ngoc Yen, Nguyen Huynh Kim and Phan Canh Trinh

The Actinobacteria group has well-known for the ability to produce novel antibiotics. Source from agriculture has been studied for many decades, leading to limit the discovery of new species, as well as new secondary metabolites. In this study, we do experiments on samples collected from contaminated areas around the industrial zone as a selective pressure to obtain potential strains.

Materials and methods
The Actinomycetes strains isolated from soil samples from polluted areas of Ho Chi Minh City, and Binh Duong will be screened for antimicrobial activity by agar plug diffusion method. Identification of the morphological, physiological, and biochemical characteristics, and sequencing 16S rDNA (with strains had high antibacterial activity). Investigation of environmental factors, culture conditions, and harvesting time with highly bioactive actinomycetes strains by using agar well diffusion method. Extraction, fractionation of raw extract from potentials by thin-layer chromatographic methods, direct autobiography, classical column chromatography, and HPLC.
The research identified 12 different Actinomycetes strains through morphological, physiological, and biochemical characteristics. After screening antimicrobial activity, CNC05 and ST03 were selected for further identification using 16S rDNA analysis. Determining the optimal medium, fermentation conditions, and harvesting time of CNC05 extracts using agar well diffusion method. Finally, we obtained the one – substance fraction from total ethyl acetate extract via column chromatography, with the purity > 90%.
CNC05 was cultured on ISP2 medium exhibited high antimicrobial property, especially on ethyl acetate extract. The antibacterial fraction may be a mixture of many substances determined by direct autobiography on thin-layer chromatography. The results find a fraction containing one substance with strong antimicrobial activity from ethyl acetate extract, the purity is 90,16%.
Keywords: Actinomycetes, antimicrobial activity, fermentation, ethyl acetate extract, column chromatography.

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