Effects And Mechanism Of The Synergistic Effects Of Algae Group On Microalgae Oil Production

Microalgae biomass energy is considered as a renewable resource that can replace oil resources.In the natural ecosystem,biodiversity controls the stable growth and protection mechanism of the whole ecosystem.The multi-algae co-culture method can improve the biomass and the lipid yield of the microalgae.At present,most of the research on microalgae biomass energy is based on pure culture microalgae.In the natural environment,microalgae is a kind of population growing microorganism,and the role and mechanism of interspecific synergy in the transformation of microalgae oil is still blank.Firstly,the effect and mechanism of growth of Chlorella regularis and Scenedesmus obliquus in co-culture and individual culture system were investigated.The results showed that the growth of Chlorella regularis and Scenedesmus obliquus were accelerated under co-culture.in the co-culture system,microalgae produced a certain synergistic effect.The main performance is: co-culture growth in advance of 1 day into a stable period.the biomass yield reached 0.967 g/l/d,which was 20.17% and 48.77% higher than the biomass yield of pure cultured coccidia and chlamydomonas,respectively.In the stable period,the COD degradation rate of the co-culture system reached 94.7%,which was 20.3% and 14.2% higher than that of the pure cultured Chlorella regularis and Scenedesmus obliquus,respectively,and the utilization rate of TN reached 93.81%,which was one day earlier than that of the pure culture system.At this time,there were still 26.49% and 12.06% residual nitrogen in the pure culture system of Chlorella regularis and Scenedesmus obliquus.compared with the control group,the mitochondrial activity of the co-culture system was increased by 21.6% and 22.3%,respectively.The results of antioxidant enzyme analysis showed that there was no significant change in the content of antioxidant enzyme in the co-culture system,and it was slightly lower than that in the single culture system,which indicated that the co-culture system had better resistance to the stimulation of the external environment.Secondly,the effect and mechanism of oil accumulation in co-culture and monoculture were investigated.The results showed that on the 8th day,the oil content and yield of the co-culture system were significantly higher than that of the pure culture system.In the oil content,the growth of Chlorella regularis and Scenedesmus obliquus in the co-culture system was 19.65% and 10.32% higher than which in the pure culture system,while the oil yield of Chlorella regularis and Scenedesmus obliquus in the co-culture system was 25% and 11.7% higher than which in the pure culture system,The growth conditions of free fatty acid and nutrient deficiency,especially nitrogen stress,resulted from the combination of factors,may be important factors for the increase of oil yield in co-culture system.The co-culture system improved the composition of fatty acids,significantly increased the content of C16 and C18 fatty acids,and improved the quality of oil.