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Combined artificial high-silicate medium and LED illumination promote carotenoid accumulation in the marine diatom Phaeodactylum tricornutum.
Microbial Cell Factories ( IF 6.4 ) Pub Date : 2019-12-02 , DOI: 10.1186/s12934-019-1263-1
Zhiqian Yi 1, 2, 3 , Yixi Su 1 , Paulina Cherek 3 , David R Nelson 4 , Jianping Lin 5 , Ottar Rolfsson 1 , Hua Wu 2 , Kourosh Salehi-Ashtiani 4 , Sigurdur Brynjolfsson 1 , Weiqi Fu 1, 4
Affiliation  

BACKGROUND Diatoms, which can accumulate large amounts of carotenoids, are a major group of microalgae and the dominant primary producer in marine environments. Phaeodactylum tricornutum, a model diatom species, acquires little silicon for its growth although silicon is known to contribute to gene regulation and play an important role in diatom intracellular metabolism. In this study, we explored the effects of artificial high-silicate medium (i.e. 3.0 mM sodium metasilicate) and LED illumination conditions on the growth rate and pigment accumulation in P. tricornutum, which is the only known species so far that can grow without silicate. It's well known that light-emitting diodes (LEDs) as novel illuminants are emerging to be superior monochromatic light sources for algal cultivation with defined and efficient red and blue lights. RESULTS Firstly, we cultivated P. tricornutum in a synthetic medium supplemented with either 0.3 mM or 3.0 mM silicate. The morphology and size of diatom cells were examined: the proportion of the oval and triradiate cells decreased while the fusiform cells increased with more silicate addition in high-silicate medium; the average length of fusiform cells also slightly changed from 14.33 µm in 0.3 mM silicate medium to 12.20 µm in 3.0 mM silicate medium. Then we cultivated P. tricornutum under various intensities of red light in combination with the two different levels of silicate in the medium. Higher biomass productivity also achieved in 3.0 mM silicate medium than in 0.3 mM silicate medium under red LED light irradiation at 128 μmol/m2/s or higher light intensity. Increasing silicate reversed the down-regulation of fucoxanthin and chlorophyll a under high red-light illumination (i.e. 255 μmol/m2/s). When doubling the light intensity, fucoxanthin content decreased under red light but increased under combined red and blue (50:50) lights while chlorophyll a content reduced under both conditions. Fucoxanthin accumulation and biomass productivity increased with enhanced red and blue (50:50) lights. CONCLUSION High-silicate medium and blue light increased biomass and fucoxanthin production in P. tricornutum under high light conditions and this strategy may be beneficial for large-scale production of fucoxanthin in diatoms.

中文翻译:

人工合成的高硅酸盐介质和LED照明可促进类胡萝卜素在海洋硅藻Phaeodactylum tricornutum中的积累。

背景技术可以积聚大量类胡萝卜素的硅藻是微藻的主要种类,并且是海洋环境中主要的主要生产者。尽管已知硅可促进基因调节并在硅藻细胞内代谢中发挥重要作用,但三角硅藻(Phaeodyylum tricornutum)是一种硅藻的典范,其生长所需的硅很少。在这项研究中,我们探索了人工高硅酸盐介质(即3.0 mM偏硅酸钠)和LED照明条件对三角果假单胞菌的生长速率和色素累积的影响,这是迄今为止唯一已知的无需硅酸盐即可生长的物种。 。众所周知,作为新颖的发光体,发光二极管(LED)逐渐成为具有定义和有效的红,蓝光的藻类培养的优质单色光源。结果首先,我们在补充有0.3 mM或3.0 mM硅酸盐的合成培养基中培养了角果假单胞菌。研究了硅藻细胞的形态和大小:在高硅酸盐介质中,随着硅酸盐添加量的增加,椭圆形细胞和三辐射细胞的比例降低,而梭形细胞的比例增加。梭形细胞的平均长度也略有变化,从0.3 mM硅酸盐介质中的14.33 µm变为3.0 mM硅酸盐介质中的12.20 µm。然后,我们结合培养基中两种不同水平的硅酸盐,在不同强度的红光下培养了角果假单胞菌。在以128μmol/ m2 / s或更高的光强度照射红色LED的情况下,与0.3 mM硅酸盐介质相比,在3.0 mM硅酸盐介质中也实现了更高的生物量生产率。在高红光照明(即255μmol/ m2 / s)下,增加硅酸盐可逆转岩藻黄质和叶绿素a的下调。当光强度增加一倍时,在红色光下岩藻黄质含量降低,而在红色和蓝色(50:50)组合光下,叶绿素含量升高,而在两种条件下叶绿素a含量均降低。岩藻黄质的积累和生物量生产力随着红色和蓝色(50:50)光的增强而增加。结论在高光照条件下,高硅酸盐介质和蓝光增加了三角果假单胞菌中生物量和岩藻黄质的产量,该策略可能有利于硅藻中岩藻黄质的大规模生产。50)在两种情况下均点亮,而叶绿素a含量降低。岩藻黄质的积累和生物量生产力随着红色和蓝色(50:50)光的增强而增加。结论在高光照条件下,高硅酸盐介质和蓝光增加了三角果假单胞菌中生物量和岩藻黄质的产量,该策略可能有利于硅藻中岩藻黄质的大规模生产。50)在两种情况下均点亮,而叶绿素a含量降低。岩藻黄质的积累和生物量生产力随着红色和蓝色(50:50)光的增强而增加。结论在高光照条件下,高硅酸盐介质和蓝光增加了三角果假单胞菌中生物量和岩藻黄质的产量,该策略可能有利于硅藻中岩藻黄质的大规模生产。
更新日期:2019-12-02
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