Yamada Ryosuke, Yokota Moe, Matsumoto Takuya, Hankamer Ben, Ogino Hiroyasu
Department of Chemical Engineering, Osaka Prefecture University, Sakai, Osaka, Japan.
Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.
Biotechnol J. 2023 Feb;18(2):e2200099. doi: 10.1002/biot.202200099. Epub 2022 Dec 13.
By co-culturing selected microalgae and heterotrophic microorganisms, the growth rate of microalgae can be improved even under atmospheric conditions with a low CO concentration. However, the detailed mechanism of improvement of proliferative capacity by co-culture has not been elucidated. In this study, we investigated changes in the proliferative capacity of the green alga Chlamydomonas reinhardtii by co-culturing with Escherichia coli.
In the co-culture, the number of C. reinhardtii cells reached 2.22 × 10 cell/L on day 14 of culture. This was about 1.9 times the number of cells (1.16 × 10 cell/L) on day 14 compared to C. reinhardtii cells in monoculture. The starch content per cell in the co-culture of C. reinhardtii and E. coli on the 14th day (2.09 × 10 g/cell) was 1.3 times higher than that in the C. reinhardtii monoculture (1.59 × 10 g/cell), and the starch content per culture medium improved 2.5 times with co-cultivation. By analyzing the gene transcription profiles and key media components, we clarified that E. coli produced CO from the organic carbon in the medium and the organic carbon produced by photosynthesis of C. reinhardtii, and this CO likely enhanced the growth of C. reinhardtii.
Consequently, E. coli plays a key role in promoting the growth of C. reinhardtii as well as the accumulation of starch which is a valuable intermediate for the production of a range of useful chemicals from CO .
通过将选定的微藻与异养微生物共同培养，即使在低二氧化碳浓度的大气条件下，微藻的生长速率也能得到提高。然而，共培养提高增殖能力的详细机制尚未阐明。在本研究中，我们通过与大肠杆菌共同培养，研究了莱茵衣藻增殖能力的变化。
在共培养中，莱茵衣藻细胞数量在培养第14天达到2.22×10⁶细胞/升。这大约是单培养中莱茵衣藻细胞在第14天细胞数量（1.16×10⁶细胞/升）的1.9倍。在第14天，莱茵衣藻与大肠杆菌共培养时每个细胞的淀粉含量（2.09×10⁻¹²克/细胞）比莱茵衣藻单培养时（1.59×10⁻¹²克/细胞）高1.3倍，并且通过共培养每个培养基中的淀粉含量提高了2.5倍。通过分析基因转录谱和关键培养基成分，我们阐明大肠杆菌从培养基中的有机碳以及莱茵衣藻光合作用产生的有机碳中产生二氧化碳，并且这种二氧化碳可能促进了莱茵衣藻的生长。
因此，大肠杆菌在促进莱茵衣藻生长以及淀粉积累方面起着关键作用，淀粉是由二氧化碳生产一系列有用化学品的宝贵中间体。
