MELiSSA Pilot Plant - Claude Chipaux Laboratory, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain.
CERES, Instituts d'Estudis Espacials de Catalunya, Campus UAB, Barcelona, Spain.
Microb Biotechnol. 2022 Mar;15(3):931-948. doi: 10.1111/1751-7915.13882. Epub 2021 Aug 2.
MELiSSA (Microecological Life Support System Alternative) is a developing technology for regenerative life support to enable long-term human missions in Space and has developed a demonstration Pilot Plant. One of the components of the MELiSSA Pilot Plant system is an 83L external loop air-lift photobioreactor (PBR) where Limnospira indica (previously named Arthrospira sp. PC8005) is axenically cultivated in a continuous operation mode for long-periods. Its mission is to provide O and consume CO while producing edible material. Biological and process characterization of this PBR is performed by analysing the effect of two main variables, dilution rate (D) and PFD (Photon Flux Density) illumination. A maximum oxygen productivity ( ) of 1.35 mmol l h is obtained at a D of 0.025 h and PFD of 930 µmol m s . Photoinhibition can occur when a 1 g l cell density culture is exposed to PFD higher than 1700 µmol m s . This process is reversible if the illumination is returned to dim light (150 µmol m s ), proving the cell adaptability and capacity to respond at different illumination conditions. Influence of light intensity in cell composition is also described. Specific photon flux density (qPFD) has a direct effect on phycobiliproteins and chlorophyll content causing a decrease of 62.5% and 47.8%, respectively, when qPFD increases from 6.1 to 19.2 µmol g s . The same trend is observed for proteins and the opposite for carbohydrate content. Morphological and spiral structural features of L. indica are studied by confocal microscopy, and size distribution parameters are quantified. A direct effect between trichome width and CDW/OD ratio is observed. Changes in size distribution are not correlated with environmental factors, further confirms the adaptation capacity of the cells. The systematic analysis performed provides valuable insights to understand the key performance criteria of continuous culture in air-lift PBRs.
MELiSSA（微生物生态生命支持系统替代方案）是一种用于再生生命支持的发展技术，可实现人类在太空的长期任务，并已经开发出一个示范试验工厂。MELiSSA 试验工厂系统的一个组成部分是一个 83L 外部循环气升式光生物反应器（PBR），在该 PBR 中，无菌培养 Limnospira indica（以前称为 Arthrospira sp. PC8005），以连续操作模式进行长时间培养。它的任务是提供 O 和消耗 CO，同时生产可食用的物质。通过分析两个主要变量（稀释率（D）和 PFD（光通量密度）照明）的影响来对该 PBR 进行生物和过程特性分析。在 D 为 0.025 h 和 PFD 为 930 μmol m s 时，获得最大氧气生产率（ ）为 1.35 mmol l h 。当细胞密度为 1 g l 的培养物暴露于高于 1700 μmol m s 的 PFD 时，可能会发生光抑制。如果将光照返回至弱光（150 μmol m s ），则该过程是可逆的，证明了细胞在不同光照条件下的适应性和响应能力。还描述了光强度对细胞成分的影响。特定的光通量密度（qPFD）对藻胆蛋白和叶绿素含量有直接影响，当 qPFD 从 6.1 增加到 19.2 μmol g s 时，分别降低 62.5%和 47.8%。对于蛋白质，观察到相同的趋势，而对于碳水化合物含量则相反。通过共聚焦显微镜研究了 L. indica 的形态和螺旋结构特征，并量化了尺寸分布参数。观察到藻丝宽度与 CDW/OD 比值之间存在直接关系。尺寸分布的变化与环境因素无关，进一步证实了细胞的适应能力。进行的系统分析提供了有价值的见解，有助于了解气升式 PBR 中连续培养的关键性能标准。
