Abstract

SARMIENTO RANGEL, Yvonne; HAZEL VERGEL, Ariadna  and  CARDENAS CARO, Diana María. Evaluation of the stability of Trichoderma sp. and Azotobacter sp. preserved by different methods. Rev. colomb. biotecnol [online]. 2013, vol.15, n.1, pp.150-158. ISSN 0123-3475.

In the Laboratory of Applied Microbiology of the University Francisco de Paula Santander (Cúcuta, Colombia), strains of microbial cultures of biotechnological interest are constantly entering, particularly from the agricultural sector, which are used for teaching and research activities. There is an interest in keeping them viable over time, which was the main reason of this research: To evaluate the stability of the isolates of Trichoderma sp. and Azotobacter sp., using different conservation techniques: vials with saline solution (0,85% NaCl) in two temperature conditions: refrigeration (4°C) and room temperature (30°C), sterile soil under refrigeration (4°C), and successive peals methodology as the control treatment. Results showed no significant differences according to Duncan test (P d" 0.05) in the microbial survival ratio between preservation methods. However, a greater stability in cell concentration was observed with the techniques of vials with sterile saline solution and sterile soil -both under refrigeration-, during the four-month evaluation, with no register of contamination on cultures. Also, there was an optimum growth of microbial cultures macroscopically and the microscopic characteristics were stable in these two methods of preservation for both strains. For this reason, we suggest these conservation techniques for the two microorganisms, considering further advantages such as ease of technology, availability of equipment, materials and personnel available in the laboratory.

Keywords : bank of strains; conservation of microorganisms; cell viability; Trichoderma sp.; Azotobacter sp.

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