Environmental Microbiology Group, Northwestern Center for Biological Research (CIBNOR), Av. IPN 195, 23096, La Paz, BCS, Mexico.
The Bashan Institute of Science, 1730 Post Oak Court, Auburn, AL, 36830, USA.
Microb Ecol. 2019 May;77(4):980-992. doi: 10.1007/s00248-018-1282-1. Epub 2018 Nov 5.
The effect of three different nutritional conditions during the initial 12 h of interaction between the microalgae Chlorella sorokiniana UTEX 2714 and the plant growth-promoting bacterium Azospirillum brasilense Cd on formation of synthetic mutualism was assessed by changes in population growth, production of signal molecules tryptophan and indole-3-acetic acid, starch accumulation, and patterns of cell aggregation. When the interaction was supported by a nutrient-rich medium, production of both signal molecules was detected, but not when this interaction began with nitrogen-free (N-free) or carbon-free (C-free) media. Overall, populations of bacteria and microalgae were larger when co-immobilized. However, the highest starch production was measured in C. sorokiniana immobilized alone and growing continuously in a C-free mineral medium. In this interaction, the initial nutritional condition influenced the time at which the highest accumulation of starch occurred in Chlorella, where the N-free medium induced faster starch production and the richer medium delayed its accumulation. Formation of aggregates made of microalgae and bacteria occurred in all nutritional conditions, with maximum at 83 h in mineral medium, and coincided with declining starch content. This study demonstrates that synthetic mutualism between C. sorokiniana and A. brasilense can be modulated by the initial nutritional condition, mainly by the presence or absence of nitrogen and carbon in the medium in which they are interacting.
在微藻集胞藻 UTEX 2714 与植物促生菌 Azospirillum brasilense Cd 最初 12 小时的相互作用期间,三种不同营养条件对合成共生形成的影响通过种群生长、信号分子色氨酸和吲哚-3-乙酸的产生、淀粉积累以及细胞聚集模式的变化来评估。当相互作用由富含营养的培养基支持时,检测到两种信号分子的产生,但当这种相互作用开始于无氮(N-free)或无碳(C-free)培养基时则没有。总的来说,当共固定化时,细菌和微藻的种群更大。然而,在单独固定化的 C. sorokiniana 中连续生长在 C-free 矿物培养基中时,测量到的淀粉产量最高。在这种相互作用中,初始营养条件影响了 Chlorella 中淀粉积累量最高的时间,其中无氮培养基诱导更快的淀粉产生,而更丰富的培养基则延迟其积累。在所有营养条件下,微藻和细菌组成的聚集体形成,在矿物培养基中 83 小时达到最大值,与淀粉含量的下降同时发生。本研究表明,C. sorokiniana 和 A. brasilense 之间的合成共生可以通过初始营养条件进行调节,主要是通过培养基中氮和碳的存在或不存在来调节。