氮、磷限制对球形棕囊藻不同形态细胞生长和多糖产量的影响

Effects on Cell Growth and Polysaccharide Production in Different Morphologic Cells of Phaeocystis globosa Under N or P Limitation

为探究营养盐胁迫对广西北部湾不同倍性球形棕囊藻(Phaeocystis globosa)细胞生长和多糖产量的影响,本研究采用单因子控制试验,设置4.0∶1.0、24.5∶1.0和64.0∶1.03个氮、磷限制比例,对球形棕囊藻的单倍体和二倍体细胞进行人工海水培养,比较二者的生长变化及各生长期内藻多糖含量和透明胞外聚合颗粒物(Transparent Exopolymer Particles,TEP)的释放差异。结果表明,氮、磷营养对二倍体细胞前期生长的促进作用强于单倍体细胞,二倍体细胞生长率显著高于单倍体细胞(P<0.05)。球形棕囊藻细胞分泌的多糖主要以溶解性胞外多糖(Soluble Exopolysaccharide,sEPS)为主,其次是胞内多糖(Intracellular Polysaccharide,IPS),固着性胞外多糖(Bound Exopolysaccharide,bEPS)占总糖比例最低。单倍体细胞和二倍体细胞的bEPS分泌趋势相反。氮、磷限制组的单倍体单细胞胞外多糖(Extracellular Polysaccharide,EPS)、IPS和TEP产量均无显著差异(P>0.05)。磷限制组的二倍体单细胞EPS、IPS和TEP产量显著高于对照组和氮限制组(P<0.05)。总而言之,营养盐胁迫刺激球形棕囊藻EPS和TEP的产生,球形棕囊藻TEP的产生受营养盐相对存量的影响。二倍体细胞多糖与TEP对磷限制的响应比单倍体细胞更敏感。

In order to explore the effects of nutrients stress on cell growth and polysaccharide production of Phaeocystis globosa with different ploidy in Beibu Gulf of Guangxi,a single factor control experiment was used to set 3 nitrogen and phosphorus limitation ratios of 4.0∶1.0,24.5∶1.0 and 64.0∶1.0 in this study.The haploid and diploid cells of P.globosa were cultured in artificial seawater to compare the growth changes of the two cells and the differences of polysaccharides content and Transparent Exopolymer Particles(TEP)release in each growth period.The results showed that the promoting effect of nitrogen and phosphorus nutrition on the early growth of diploid cells was stronger than that of haploid cells,and the growth rate of diploid cells was significantly higher than that of haploid cells(P<0.05).The Soluble Exopolysaccharide(sEPS)were main polysaccharides secreted by P.globosa cells,followed by Intracellular Polysaccharide(IPS),and Bound Exopolysaccharide(bEPS)accounted for the lowest proportion of total sugars.The secretion of bEPS in haploid cells and diploid cells showed the opposite trend.There were no significant differences in Extracellular Polysaccharide(EPS),IPS and TEP yields of haploid single cells in nitrogen and phosphorus limitation groups(P>0.05).The production of EPS,IPS and TEP in diploid single cells of the phosphorus limited group was significantly higher than that of the control group and the nitrogen limited group(P<0.05).In summary,nutrient stress stimulated the production of EPS and TEP in P.globosa,and the production of TEP in P.globosa was affected by the relative stock of nutrients.The response of diploid cell polysaccharides and TEP to phosphorus limitation was more sensitive than that of haploid cells.