Resumen en inglés

Under normal conditions the microalgae are subject to periods of light / dark, and this alternation is generally also used in their cultivation. In this work, the effect of the photoperiod influence on the production of carotenoids and on the morphology of the microalgae Tetraselmis gracilis was evaluated, based on the biological method to determine population growth, the chemical method by spectrophotometry to estimate the concentration of carotenes and photographic record of cells for morphological measurements. The evaluation of population growth consisted of an experimental procedure, bioassay type, in which there were 3 experimental units each with 150 mL of F / 2 Guillard medium with 25% salinity, subjected to a photoperiod of 24: 0 and another 6 units which were maintained with a type of photoperiod 8:16 and 12:12, each with three replicates for a total of 9 units of each of the treatments, cell counts were performed each 48 hours in Neubauer chamber and variables of cell density, growth rate and doubling time were estimated, the determination of morphological changes was made by calculating cell volume. The photoperiod 24: 0 presented the highest cell density in growth with a value of 597958 cel / mL-1, the results of specific growth rate evidenced significant differences between treatments at 432 and 480 hours of culture, doubling times daily were on average very similar between treatments. The highest production of total carotenoids occurred when the microalgae was exposed to 8:16 photoperiod conditions in the exponential phase of growth, the 24: 0 treatment presented the highest values of cell volume as the phases of the experiment passed, in comparison to the other 2 photoperiods. The results showed that the photoperiod has a significant effect on the specific growth rate of Tetraselmis gracilis, as well as having a significant effect on the production of carotenoids. This study showed that T. gracilis, when exposed to variations in light intensity, that is, photoperiods, presents variations in growth, carotene content and cell volume, which serves as a basis for future research that has the object of study. massify its cultivation under controlled conditions for subsequent applications in various sectors of the industry.