In the present study,Phaeodactylum tricornutum was grown in laboratory under darkness condition for 12 days in order to investigate its growth and some chemical compositions in response to the darkness environment and to evaluate the adaptation of this economic microalga to darkness stress.The results indicated that Phaeodactylum tricornutum could still survive in the darkness condition,while darkness stress imposed significantly inhibitory influence on the growth of Phaeodactylum tricornutum during the course of the experiment.Algal cell density and biomass in the darkness treatment were reduced to 2.93×105 cells·ml-1 and 0.011 g·ml-1 on the day of termination of the experiment,only 8.0% and 37.3% of the control.Moreover,some chemical compositions including chlorophyll a,soluble sugar and protein were also apparently limited in the darkness condition,the contents of which were approximately 89%,87% and 85% lower than those in the control on the 12th day.Our results have provided supportive evidence that Phaeodactylum tricornutum tended to exhibit the capacity of sustaining in the darkness stress,which might be due to its pronounced ability in the biosynthesis and metabolism of protein,soluble sugar and chlorophylla,but its growth performance was remarkably restricted over time.The findings presented here suggested that the adaptive ability of Phaeodactylum tricornutum to darkness stress should be considered into the core collection and screening,as well as comprehensive exploiture of microalgal resources.
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