Effect Of Marine Microalgae In Mix-culture Of Different Species

Platymonus subcordiformis,Isochrysis galbana,and Pseudo-nitzschia pungens are three of common marine microalgae.Platymonus subcordiformis is rich in various nutrients such as unsaturated fatty acids.Besides,Platymonus subcordiformis grows rapidly.Therefore it has been regarded as one of the important economic marine microalgae.Isochrysis galbana is small and rich in lots of nutrients.It is one of the common bait microalgae.Pseudo-nitzschia pungens belongs to Nitzschiaceae,which has widely distributed in polar,temperate,subtropical and tropical area.In the study,we use Platymonus subcordiformis,Isochrysis galbana and Pseudo-nitzschia pungens as experimental materials;experiments were carried out by coculturing Platymonus subcordiformis-Isochrysis galbana and Platymonus subcordiformis-Pseudo-nitzschia pungens,discussing the growth of each component and the interaction.The results are as follows.(1)Coculture of Platymonus subcordiformis and Isochrysis galbana at suitable proportion under proper condition increases the cell density of Platymonus subcordiformis,but the growth of Isochrysis galbana is inhibited.The content of chlorophyll-a and biomass are also improved in the mix culture.(2)There is allelopathic effect between Platymonus subcordiformis and Isochrysis galbana.The cell filtrate or cell lysis solution of Isochrysis galbana has a promoting effect on the growth of Platymonus subcordiformis,with the cell density increasing by 2.5%-19.0% and 8.1%-23.2%.While the cell filtrate of Platymonus subcordiformis and cell lysis solution of Platymonus subcordiformis had no obvious effect on the growth of Isochrysis galbana.(3)Coculture of Platymonus subcordiformis and Pseudo-nitzschia pungens at suitable proportion under proper condition can increase the cell density of Platymonus subcordiformis to some degree,and its cell density is increased by 8.3%-15.6%.However,the growth of Pseudo-nitzschia pungens is inhibited.(4)The cell filtrate of Pseudo-nitzschia pungens and cell lysis solution of Pseudo-nitzschia pungens have no promotion effect on the growth of Platymonus subcordiformis,but the cell filtrate of Platymonus subcordiformis and cell lysis solution of Platymonus subcordiformis have inhibited the growth of Pseudo-nitzschia pungens.