ABSTRACT

The green alga Chlorella sp. and the filamentous cyanobacterium Leptolyngbya sp., regularly cope with various stressors including frequent hydration–desiccation cycles. When grown in axenic cultures, Chlorella sp. is unable to resurrect even after very slow desiccation unless desiccation takes place in the presence of Leptolyngbya sp. or a lysate thereof. When Chlorella sp. was provided with extracellular polysaccharides from Leptolyngbya sp., or its main sugar constituents, it was able to be resurrected after mild desiccation. These findings suggest that desiccation tolerance of Chlorella sp. in the field depends on the presence of Leptolyngbya sp. or components thereof. Chlorella sp. was originally isolated as a contaminant in a decaying stationary culture of Leptolyngbya sp. that was established by the addition of a cyanobacterial growth media to biological soil crusts. Co-incubation with a dialysis tube containing Leptolyngbya sp. severely inhibited growth of Chlorella sp. These data suggest that secondary metabolites excreted by Leptolyngbya sp., the nature of which is yet unknown, inhibit growth of Chlorella sp. Thus, though Leptolyngbya sp. enables the survival of Chlorella sp. in a desert habitat, it simultaneously inhibits growth of this potential competitor. The combination of positive and negative effects of Leptolyngbya sp. on fitness of Chlorella sp. creates a scenario in which the former tightly controls the abundance of the latter.

摘要

绿藻小球藻属。和丝状蓝细菌Leptolyngbya sp。定期应对各种压力源，包括频繁的水合-干燥循环。当生长在无菌培养，小球藻属。除非干燥非常缓慢，否则即使在Leptolyngbya sp。存在的情况下也无法进行干燥，它也无法复活。或其裂解物。当小球藻藻。向其提供了来自Leptolyngbya sp。的细胞外多糖或其主要糖成分，经过温和的干燥后，它可以复活。这些发现表明小球藻的干燥耐受性。在现场取决于存在Leptolyngbya SP。或其组件。小球藻藻。最初是在Leptolyngbya sp。这是通过向生物土壤结皮中添加蓝细菌生长培养基而建立的。与含有Leptolyngbya sp。的透析管共同孵育。严重抑制了小球藻的生长。这些数据表明，Leptolyngbya sp。分泌的次生代谢产物抑制了小球藻sp。的生长。因此，尽管Leptolyngbya sp。使小球藻得以生存sp。在沙漠栖息地中，它同时抑制了这一潜在竞争者的生长。Leptolyngbya sp。的正面和负面影响相结合。对小球藻的适应性。创建一个方案，其中前者严格控制后者的数量。