两种蓝藻种群间的相互作用

INTERACTION OF TWO POPULATIONS OF THE BLUEGREEN ALGAE IN CO-CULTURE

两种作为生物肥源的固氮蓝藻——多变鱼腥藻“1058”(Anabaena variabilis 1058)和小单歧藻(Tolypothrix tenuis),在实验室中混和培养出现相互作用。隔滤培养试验及加滤液培养试验表明,这两种群的相互作用是通过胞外活性物质而发生直接竞争抑制。竞争抑制的结果与两种藻各自所处的生理状态有关,并有最终达到动态平衡的趋势。在实验室培养条件下,多变鱼腥藻“1058”和小单歧藻均能向培养基中分泌出胞外的致死或抑制生长的活性物质。此类物质的活性类型与培养物的生理状态有关。具致死作用的活性物质产生于种群增长的指数期。多变鱼腥藻“1058”和小单歧藻产生的胞外的具致死作用的活性物质,在物理、化学性质上有一定差异。

Interaction of the populations of two species of blue-green algae Tolypothrix tenuis and Anabaena uariabilis “1058”,in mixed culture,was observed in three different ways:(1) The growth competition was studied in mixed-culture,where the two species grew in one batch of culture.(2) The effect of the filtrate,the extracellular products,from the culture of one sp- ecies on the growth of the other species was studied.(3) In fitrated culture,two algal species were cultivated separately in either side a U-form container partitioned by a micro-pore me- mbrane in the middle.The extracellular products were permeable through the membrane from one side to the other side.The influonce of the biologically active substances prosduced by the algae at different growth stages can be observed and estimated.The growth was me- asured by dry weight of biomass andchlorophyll-a content.The proportion of components of phycobiliprotein (e.g.ratio of phycocyanin to phycoerythrin) was estimated as the specific growth rate of two blue-greens in the mixed cultures. 1.The results obtained are summarized as follows: There were three types of the bioactivity of the extracellular products:(1) The lethal effects on each other caused the by the lethal agents of these two blue-greens were different. (2)The suppressive effects on growth by each other in one community were also found.(3) Effect on growth promotion exhibited only in the extracellular products of A.variabilis “1058”. 2.The results indicate that there occur a direct competitive interaction of two popuIa- tions.This competition was controlled by the bio-active substances of the extracellular produ- cts which might regulate the structural composition and inturn,the succession of the comu- nity.