Resumen

MORONTA, R; MORA, R  y  MORALES¹, E. Response of the microalga Chlorella sorokiniana to pH, salinity and temperature in axenic and non axenic conditions. Rev. Fac. Agron. [online]. 2006, vol.23, n.1, pp.28-43. ISSN 0378-7818.

Abstract Microalgal culture in non axenic conditions can be used as food source for aquaculture species, wastewater treatment and in axenic conditions for the extraction of valuable chemicals. However, the response of the microalgae in axenics conditions can be modulated with respect to non axenic conditions. The aim of this study was to test the response of the microalga Chlorella sorokiniana in function of pH (5, 6, 7, 8 and 9), temperature (25, 30, 37, 40 and 42°C) and salinity (15, 25 and 35 ppm) in non-axenic and axenic cultures. All bioassays were carried out with photoperiod 12:12h, 98µmol.quanta.m-2.s-1, 28ºC. Non-axenic cultures in ALGAL medium and by triplicate were maintained at volume of 250ml in flasks with 500ml in capacity. Whereas, axenic cultures by fire replicas were carried out in test tubes with volume of 15ml in autotrophic, mixotrophic and heterotrophic conditions with organotrophic and ALGAL medium. In non-axenic cultures, the microalga was more sensible to salinity, temperature and pH below 5, with optimal growth at 30°C and pH 7-8 in non saline medium. Instead, in axenic conditions, the microalga was able to grow up to 42°C, pH above 3 and salinity up to 35 ppm in mixotrophy, reaching the highest growth at pH 7-8, between 0 and 25 ppm and 37°C. Chlorophyll synthesis was older in non axenic cultures. These results suggest that the response of C. sorokiniana, to pH, temperature and salinity can be modulated by associated bacterial flora

Palabras clave : Chlorella sorokiniana,; pH; salinity; temperature; axenic; non-axenic.