营养盐胁迫对球形棕囊藻不同形态细胞多糖与TEP产量的影响

Effects on polysaccharide and transparent exopolymer particles (TEP) production in different morphologic cells of Phaeocystis globosa under nutrient-limitation

关键词:  有害藻华  球形棕囊藻  营养盐胁迫  透明胞外聚合颗粒物  多糖

Key words:  harmful algal bloom  Phaeocystis globosa  nutrient stress  transparent exopolymer particles  nutrient stress  polysaccharide

摘要:

为了探究营养盐胁迫对广西北部湾不同株系球形棕囊藻藻细胞多糖产量和TEP释放的影响。本文采用单因子控制实验，设置4：1、24.5:1和64:1三个氮磷限制比例，对单倍体和二倍体细胞进行人工海水培养，比较不同株系球形棕囊藻生长变化及各生长期内藻多糖含量和TEP释放差异。结果表明，二倍体细胞对营养盐的吸收利用速度比单倍体细胞更快，氮、磷限制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生长率（P<0.05）。球形棕囊藻细胞分泌的多糖主要以sEPS为主，其次是IPS，bEPS占总糖比例最低。氮、磷限制促进球形棕囊藻sEPS分泌，对IPS有抑制作用；单倍体细胞和二倍体细胞的bEPS分泌趋势相反。氮、磷限制组对单倍体株单细胞EPS、IPS和TEP产量均无显著差异（P>0.05）。磷限制组的二倍体株单细胞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。

Abstract:

To investigate the effects of nutrient stress on polysaccharide production and TEP release in algal cells of Phaeocystis globosa from different strains in Beibu Gulf of Guangxi. In this study, a single factor control experiment was used to set the nitrogen and phosphorus limiting ratios of 4:1, 24.5:1 and 64:1. The haploid and diploid cells were cultured in artificial seawater to compare the growth changes of Phaeocystis globosa from different strains and the differences of polysaccharide content and TEP release in each growth period. The results showed that diploid cells absorbed and used nutrients faster than haploid cells, and nitrogen and phosphorus restriction promoted the growth of diploid cells more than haploid cells. The growth rate of diploid cells was significantly higher than that of haploid cells (P<0.05). The sEPS were main polysaccharides secreted by Phaeocystis globosa cells, followed by IPS, and bEPS accounted for the lowest proportion of total sugars. Nitrogen and phosphorus restriction promoted sEPS secretion of Phaeocystis globosa and inhibited IPS. The secretion trend of bEPS in haploid and diploid cells was opposite. There were no significant differences in EPS, IPS and TEP yields of haploid single cells in nitrogen and phosphorus restriction groups (P>0.05). EPS, IPS and TEP yields of diploid strains in phosphorus restricted group were significantly higher than those in control group and nitrogen restricted group (P<0.05). In conclusion, nutrient stress stimulated EPS and TEP production in Phaeocystis globosa, and TEP production in Phaeocystis globosa was affected by nutrient relative stock. Polysaccharide and TEP in diploid cells were more sensitive to phosphorus restriction than in haploid cells.