溶藻细菌L7(Algicidal Bacteria Strain L7)与中肋骨条藻(Skeletonema costatum)的相互作用

Interaction between Algicidal Bacteria Strain L7 and Skeletonema Costatum

将6组不同初始种群密度的溶藻细菌L7（Bacillus cereus）菌悬液和添加了溶藻细菌L7胞内、外代谢产物的2216E培养液加入到中肋骨条藻（Skeletonema costatum）悬浮液中,将5组不同初始种群密度的中肋骨条藻悬浮液和添加了中肋骨条藻胞内外代谢产物的f/2-Si培养液加入到溶藻细菌L7悬浮液中,探讨溶藻细菌L7和中肋骨条藻的相互作用.在第7天时,L7胞外代谢产物使中肋骨条藻细胞数量下降95.42％,表现为间接溶藻,胞内代谢产物使藻细胞数量增长361.47％,表现为加快藻增长.L7初始种群密度为3.89×106cfu/mL和3.89 × 107cfu/mL时,在第7天藻细胞数量均下降80％以上;初始种群密度为3.89×102～3.89×104cfu/mL时,在第7天L7促进藻生长.中肋骨条藻种群密度为3.89×103 cells/L、3.89×104 cells/L及3.89×106 cells/L时,最迟于第7天,L7种群密度开始低于对照组,即中肋骨条藻能够在一段时间后抑制L7生长.从第4天开始,中肋骨条藻胞外代谢产物使L7种群密度低于对照组,即中肋骨条藻对L7产生抑制作用;胞内代谢产物对L7生长的影响不明显.

To study the interaction between algicidal bacteria strain L7 and Skeletonema costatum,6 groups of Bacillus cereus suspension with different initial population densities and 2216E culture medium with the intracellular and extracellular metabolites of Bacillus cereus were co-cultured in Skeletonema costatum medium.In the meanwhile,5 groups of Skeletonema costatum suspension with different initial population densities and f/2-Si culture medium with the intracellular and extracellular metabolites of Skeletonema costatum were co-cultured in Bacillus cereus medium.On the 7th day,the extracellular metabolites of L7 decreased the density of Skeletonema costatum by 95.42％,presenting indirect algicidal,while the intracellular metabolites of L7 increased the density of Skeletonema costatum by 361.47％,presenting algae growth stimulation.When the initial population densities of L7 were 3.89 × 106 and 3.89 × 107 cfu/mL,the densities of algae were decreased by over 80％ on the 7th day.When the initial population densities of L7 were 3.89 × 105～3.89 × 104 cfu/mL,the algae grew faster on the 7th day.When the initial population densities of Skeletonema costatum were 3.89 × 103 cells/L,3.89 × 104 cells/L and 3.89 × 106 cells/L,the population densities of L7 started to get lower than those of the control groups latest from the 7th day.That is,Skeletonema costatum could inhibit the growth of L7 after a short period of time.The extracellular metabolites of Skeletonema costatum decreased the densities of L7 lower than those of the control groups from the 4th day.That is,Skeletonema costatum could inhibit the growth of L7.However,the intracellular metabolites of Skeletonema costatum had no obvious effects on the growth of L7.