Tri H. Nguyen * , Phong V. Nguyen , Kha M. Tran , Van T. T. Le , Duy D. Ngo , & Khanh Q. Hoang

* Correspondence: Nguyen Huu Tri (email: nhtri@hcmuaf.edu.vn)

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Abstract

The aim of this study was to isolate and optimize the growth conditions of thermophilic microorganism from hot springs. The isolation was conducted by using the mineral salt basal medium supplemented with 0.6% yeast extract at 500C. Totally, 33 isolates of thermophilic microorganism were isolated from hot springs at Truong Xuan (Khanh Hoa province) and Binh Chau (Ba Ria - Vung Tau province). The effects of temperature (45 - 800C), pH (pH 6 - 9) and carbon sources (malate, pyruvate, acetate, glucose, fructose, or carbon dioxide) on the growth of isolates were examined. In addition, the isolate morphology was also investigated by Gram and spore staining. The isolated thermophilic microorganism showed the diversity in colony morphology and color appearance. Most of them were rod shaped, spore-forming and most grew well at 500C and pH 7. The highest growth of all isolates was observed under malate, glucose, or fructose, as an organic carbon source and unable to use carbon dioxide. Six out of 33 thermophilic microorganism isolates (namely BM7, BS5, NS1, NS3, NS4, and NW6) grew rapidly under high temperatures from 50 - 550C and their morphology characteristics showed high similarity to Bacillus sp. The study evidenced the polymorphic diversity of thermophiles in the geothermal hot spring ecosystems.

Keywords: Bacillus sp., Hot spring, Isolation, Spore staining, Thermophilic microorganism

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References

Cao, T. D., Do, T. H., Nguyen, K. N., Chau, V. Q., & Vu, N. T. (1998). Geographic Atlas of Vietnamese. Ha Noi, Vietnam: Education Publishing House.

Claus, D., & Berkeley, R. C. W. (1986). The genus Bacillus. In Sneath, P. H. A. (Ed.). Bergey’s manual of systematic bacteriology (1105-1139). Baltimore, USA:

Williams and Wilkins. Gaughran, E. R. (1947). The thermophilic microorganisms. Bacteriological reviews 11(3), 189.

Goto, E., Kodama, T., & Minoda, Y. (1977). Isolation and culture conditions of thermophilic hydrogen bacteria. Agricultural and Biological Chemistry 41(4), 685- 690.

Hildur V., Dagn ́y B. R., & J ́ohann O. (2011). Hydrogenophilus islandicus sp. nov., a thermophilic hydrogen-oxidizing bacterium isolated from an Icelandic hot spring. International Journal of Systematic and Evolutionary Microbiology 61, 290-294.

Kim, B. H., & Gadd, G. M. (2008). Bacterial physiology and metabolism. Cambridge, England: Cambridge University Press.

Nguyen, T. K., Tran, T. T., Tran, H. T., & Tran M. D. (2015). Potential of thermostable enzymes production from bacterial strains isolated in Binh Chau hot spring. The 6th Scientific Conference on Biological Resources. Ha Noi, Vietnam.

Rastogi, G., Bhalla, A., Adhikari, A., Bischoff, K. M., Hughes, S. R., Christopher, L. P., & Sani, R. K. (2010). Characterization of thermostable cellulases produced by Bacillus and Geobacillus strains. Bioresource Technology 101(22), 8798-8806.

Tran, M. D., Nguyen, T. K., Nguyen, D. T., & Nguyen, V. Q. (2012). Biological characteristics and classification of the thermophilic bacteria BML07 strain producing both thermostable amylase and cellulase isolated from My Lam hot spring. Journal of Science and Technology 50(1), 29-38.

Tulasi, S., Jennifer, L., & Yutaka, K. (2013). Thermophilic Microbes in Environmental and Industrial Biotechnology. In Biotechnology of Thermophiles (2nd ed.). New York, USA: Springer.