Main Article Content
Soybean is a high economic value crop widely grown in Vietnam and many countries in the world. This plant is capable of fixing nitrogen thanks to the activity of diverse symbiotic microorganisms. Of them, rhizobial bacteria inhabiting the roots of the legume plants play an important role in the nodulation and nitrogen fixation. In this paper, ten strains of rhizobial bacteria were isolated from root nodules of soybean grown at farms in Hanoi, and studied with respect to their physiological and biochemical characteristics. The isolate T14 was selected as the most important rhizobial bacteria for rapid in vitro growth. Taxonomic data showed that isolate T14 shared 99% similarity with species Sinorhizobium fredii, hence it was named Sinorhizobium fredii T14. Study on the physiological and cultivation characteristics of this strain revealed that the rapid growth occured within the pH range of 6 ÷ 9 and temperatures of 24 ÷ 42oC. The strain tolerated high salt concentrations up to 2.5%. In shake flask cultures, strain T14 degraded gelatin and converted nitrate to nitrite at high rate. Fluoresence of the cultures was not observed in our study.
 Phạm Văn Thiều, Cây đậu tương - Kỹ thuật trồng và chế biến sản phẩm, NXB Nông Nghiệp, Hà Nội, 2002.
 Nguyễn Lân Dũng, Nguyễn Đình Quyến, and Phạm Văn Ty, Vi sinh vật học, NXB Giáo Dục, 2000.
 N. Teaumroong and N. Boonkerd, Detection of Bradyrhizobium spp. and B. japonicum in Thailand by primer-based technology and direct DNA extraction, in Molecular Microbial Ecology of the Soil, Springer, Dordrecht, 1998.
 M. J. Lorite, S. Muñoz, J. Olivares, M. J. Soto, J. Sanjuán, Characterization of Strains unlike Mesorhizobium loti That Nodulate Lotus spp. in Saline Soils of Granada, Spain, Appl. Environ. Microbiol., 76 (2010) 4019.
 E. M. Elsoni and A. G. Osma, Effects of Biofertilization on Yield, Physical Characteristics and Chemical Composition of Pigeon Pea (Cajanus cajan L.), Pak. J. Nutr., 10 (2011) 978.
 K. Mukherjee and T. R. Bürglin, MEKHLA, a Novel Domain with Similarity to PAS Domains, Is Fused to Plant Homeodomain-Leucine Zipper III Proteins, Plant Physiol., 140 (2006) 1142.
 A. Glazer and H. Nikaido, Microbial biotechnology, Fundamentals of applied Microbiology, 2nd edition, 2007.
 F. J. López-Baena, J. E. Ruiz-Sainz, M. A. Rodríguez-Carvajal, J. M. Vinardell, Bacterial Molecular Signals in the Sinorhizobium fredii - Soybean Symbiosis, Int. J. Mol. Sci., 17, (2016) 1.
 J. M. Vincent, A Manual for the Practical Study of Root-nodule Bacteria, Black well scientifc publications, 1970.
 P. Somasegaran and H. J. Hoben, Handbook for Rhizobia - Methods in Legume-Rhizobium Technoloy, Springer-Verlag, New York, 1994.
 S. Bhatt, Dr.R.V.Vyas, H.N. Shelat, S.J. Mistry, Isolation and Identification of Root Nodule Bacteria of Mung Bean (Vigna radiata L.) for Biofertilizer Production, Int. J. Res. Pure Appl. Microbiol., 3 (2013) 127.
 B. Singh, R. Kaur, and K. Singh, Characterization of Rhizobium strain isolated from the roots of Trigonella foenumgraecum (fenugreek), Afr. J. Biotechnol., 7 (2008).
 F. D. Hashem, D. M. Swelim, L. . Kuykendell, A. . Mohamed, S. . Abdel-Wahab, and N. I. Hegazi, Identifcation and characterization of salt tolerant Leuceana- nodulation Rhizobium strains,”Biol Fertil. Soil, 27 (1998) 35341.
 J. Aurag and A. Laboratoire de M. Sasson, Tolerance of Rhizobium leguminosarum bv phaseoli to acidity and drought, World J. Microbiol. Biotechnol. U. K., 1992.
 J. Sambrook and D.W. Russell , Molecular cloning, 2001.
 N. Malfanova, B. Lugtenberg, G. Berg, Chapter 2, in ‘Molecular microbial ecology of the rhizosphere’, de Bruijn FJ (ed), Wiley-Blackwell, 2013.
 F. M. Hashem, D. M. Swelim, L. D. Kuykendall, A. I. Mohamed, S. M. Abdel-Wahab, and N. I. Hegazi, Identification and characterization of salt- and thermo-tolerant Leucaena-nodulating Rhizobium strains, Biol. Fertil. Soils, 27 (1998) 335.
 C. Kucuk, M. Kivanc, E. Kinaci, Characterization of Rhizobium sp. Isolated from Bean, Turk J Biol, 30 (2006) 127.
 W. J. Hunter, L. D. Kuykendall, and D. K. Manter, Rhizobium selenireducens sp. nov.: a selenite-reducing alpha-Proteobacteria isolated from a bioreactor, Curr. Microbiol., 55 (2007) 455.