氮磷胁迫下藻-菌群落的变化研究

Variation of Algal-bacterial Community under Nitrogen-Phosphorus Stress

近年来,由于水体富营养化而导致的蓝藻水华在我国太湖与滇池等淡水湖泊频繁爆发,已成为严重的环境问题,而氮、磷则是引起水体富营养化的重要营养因子。文章通过藻细胞计数、细菌群落的DGGE监测,以及典型对应CCA分析,系统研究了不同的氮磷浓度、N/P比对藻-菌群落结构的影响及其相互关系。结果表明,氮磷浓度和N/P比均会影响藻类生长,其中,氮磷浓度较N/P比对藻类生物量的影响更大;N/P=12为藻类生长的最适条件,氮限制(N/P=3)和磷限制(N/P=48)均会抑制藻类生长;添加外源氮磷可促进细菌的生长,提高其多样性,但随着N/P比的提高,其种群多样性呈逐渐下降趋势;细菌群落主要由β-proteobacteria类细菌组成,其次是α-proteobacteria,然后是Bacteroidetes和γ-proteobacteria。与氮、磷营养盐相比,藻类群落对细菌群落的影响更大。

An experiment with water samples from Taihu Lake was conducted to investigate the algal-bacterial community affected by the factors such as concentrations of nitrogen and phosphorus and N/P ratio by means of algal--cell-counting, EGGE of bacterial community and canonical correspondence analysis（CCA）. The experimental result showed the major factor affecting algal-bacterial community was concentrations of N and P, while algal growth was influenced by ratio of N/P：N/P 3 was nitrogen limitation; N/P--48 phosphorus limitation; and N/P=12 was the optimum condition for algal growth. Besides, diversity of bacteria was improved with the increases of exogenous N and P, but declined with the increase of N/P; bacterial community was composed of mainly β-proteobacteria, followed by α-proteobacteria, Bacteroidetes and then γ- proteobacteria. Compared with nutrient salts of N and P, it seemed that algal community exerted more impact on bacterial community.