不同氮磷比对球形棕囊藻释放含硫化合物及DMSP降解途径的影响

Effects of Different Ratios of Nitrogen and Phosphorus on the Release of Sulfur Compounds and Degradation Pathway of DMSP from Phaeocystis globosa

本文探讨了球形棕囊藻(Phaeocystis globosa)在不同氮磷比条件下各生长时期内释放到培养液中二甲巯基丙酸内盐(DMSP)、二甲基硫(DMS)和丙烯酸(AA)等含硫化合物浓度及DMSP降解途径的影响,所设置氮磷比为4∶1、16∶1、40∶1和80∶1。结果表明,球形棕囊藻的DIC吸收速率在80∶1组出现最大值(147μmol·kg^(-1)·d^(-1)),pH提升量在4∶1组出现最大值(0.13 d^(-1)),而最大藻细胞密度在16∶1和40∶1组出现较高值(285×10^(4)和264×10^(4) cells·mL^(-1))。单位细胞颗粒态DMSP和AA浓度在16∶1组出现最大值(2.741和2.949 fmol·cell-1),而溶解态DMSP在40∶1组出现最大值(0.543 fmol·cell^(-1)),DMS在16∶1和40∶1组均出现最大值(0.038 fmol·cell^(-1))。当氮磷比为4∶1时,DMS/AA出现最大值26.53%,表明DMSP酶裂解途径占比最大;当氮磷比为80∶1时,DMS/(DMSP+AA)出现最大值11.89%,表明DMS生产百分比最大;当氮磷比为40∶1时,AA/(DMSP+AA)出现最大值69.34%,表明总DMSP降解率最大。总而言之,当氮磷比为16∶1时最有利于球形棕囊藻含硫化合物的产生,不同氮磷比会对DMSP的降解途径产生影响。

The concentrations of sulfur-containing compounds(dimethylsulphoniopropionate(DMSP),dimethylsulphide(DMS)and acrylic acid(AA))in the culture medium of Phaeocystis globosa during different growth periods were observed under different nitrogen and phosphorus ratios.The effects of nitrogen-phosphorus ratio on the degradation pathway of DMSP were also discussed.The nitrogen-phosphorus ratio was set to 4∶1,16∶1,40∶1,and 80∶1.The results showed that the largest DIC absorption per day was observed in the 80∶1 group(147μmol·kg^(-1)·d^(-1));the largest pH increase was found in the 4∶1 group(0.13 d^(-1)).The superior algal cell density appeared in the 16∶1 and 40∶1 groups(285×10^(4) and 264×10^(4) cells·mL^(-1)).The maximum values(2.741 and 2.949 fmol·cell^(-1))of particulate DMSP and AA per cell appeared in the 16∶1 group,while the maximum value(0.543 fmol·cell-1)of dissolved DMSP per cell appeared in the 40∶1 group.DMS per cell had the maximum value(0.038 fmol·cell^(-1))in both the 16∶1 and 40∶1 groups.The maximum value of DMS/AA(ratio of the enzymatic cleavage of DMSP)appeared under the condition of N/P ratio 4∶1 with a peak of 26.53%.The maximum value of DMS/(DMSP+AA)(DMS production percentage)appeared under the condition of N/P ratio 80∶1 with a peak of 11.89%.The maximum value of AA/(DMSP+AA)(degradation ratio of the total DMSP)appeared under the condition of N/P ratio 40∶1 with a peak of 69.34%.Therefore,when the N/P ratio was 16∶1,it was most conducive to the production of sulfur-containing compounds in Phaeocystis globose;when the N/P ratio was 4∶1,the enzymatic cleavage pathway of DMSP accounted for the largest proportion.