Yaxin-1161G chlorophyll fluorescence experiment published a research paper in《Nature Communications》
On April 4, 2023, the team led by Huang Xin from Harbin Institute of Technology published a research paper in《Nature Communications》 titled "Aluminum cell biology as a step rewards photosynthesis independent hydrogen production.". This paper reveals the significant role of algal cell biomimetics in non photosynthetic hydrogen production.
The engineering of hydrogen production by algal cells began as early as 1942, based on the use of light energy to capture electrons in the system and drive hydrogenase activity at the reducing end of the photosynthetic electron transfer chain. However, photosynthetic hydrogen production is brief and typically only lasts for a few minutes during the dark light transition period, as the accompanying photosynthetic oxygen strongly inhibits the activity of hydrogenase. Therefore, strategies based on anaerobic fermentation, enhanced respiration, nutrient deprivation, and gene engineering for oxygen tolerant hydrogenases were developed to eliminate the negative effects of oxygen production. In addition, recent studies have shown that inducing algal cell aggregation is a feasible strategy for creating local hypoxia conditions in the air.
In this study, a cell biomimetic method was developed that combines living algae cells with ultra-thin shells of conductive polymers and calcium carbonate exoskeletons to form a discrete cellular microenvironment capable of sustained photosynthesis and non photosynthesis of hydrogen gas. The surface enhanced algal cells cause oxygen consumption and provide structural and chemical stability, jointly generating local hypoxia conditions and accompanying hydrogenase activity, allowing them to function in the air.
Yaxin-1168 algae fluorescence kinetics measurement system
To confirm the photosynthetic reaction of external electrons under reduced oxygen concentration, the authors measured the chlorophyll fluorescence transient curve and fluorescence kinetics parameters to evaluate the absorption and capture of light energy by PSII, as well as the subsequent photosynthetic electron transfer process. Fluorescence experiments showed that for PPy/CaCO3 coated cells with EY and TEOA added to the external medium, the Fm in the chlorophyll fluorescence curve increased, indicating an enhanced activity of D1 protein in PSII, which contributes to higher efficiency of PSII electron acceptors. In addition, an improved electron transfer quantum yield (phi Eo) was observed, indicating that the light energy captured from PSII is more efficiently utilized for subsequent transfer processes. Combined with the enhanced Sm value, it can be inferred that the PQ library has been expanded, and more electrons are transferred through the photosynthetic chain. In addition, the density of PSII reaction centers also increased, as shown by the improvement in the reduced number of PSII centers (RC/CSm) on each CSm. In terms of specific energy flux in the light system, for PPy/CaCO3 coated cells with EY and TEOA, the absorption energy (ABS/CSm) and capture energy (TRo/CSm) per unit excitation cross-section (CSm) were enhanced, indicating that chlorophyll absorbed more light energy and was then used for QA reduction. In addition, the electron transfer energy (ETo/CSm) and reduction endpoint electron acceptor (REo/CSm) per unit of CSm also increased, indicating improved QA reduction and re oxidation of electron transport, with more electrons reaching the end of the electron transfer chain. These observations reveal that external electrons are involved in the photosynthetic pathway of Chlorella vulgaris cells and improve all efficiency of light energy absorption, capture, and transfer. Therefore, the performance indices based on absorption (PIabs), cross section (PIcs), and energy conversion (PItotal), as well as Fv/Fm values, were significantly improved, indicating that PPy/CaCO3 encapsulation of Chlorella vulgaris cells successfully internalized external electrons and enhanced photoactivity.
The instrument used in the fluorescence experiment in this study is the chlorophyll fluorescence (Yaxin-1161G) independently developed by Beijing Yaxin Etiquette Technology Co., Ltd. This instrument is a precision instrument that comprehensively measures the dynamic process of chlorophyll fluorescence. The measurement process is carried out under artificial light sources, minimizing the interference of external stray light. Based on transient fluorescence method, a measurement method for Yaxin-1161G is formed by combining modulation and non modulation functions. It is a probe tool for analyzing the working conditions of PS I and PS II, and can observe both fast and slow phases of fluorescence kinetics. More advanced products have been launched, including the Yaxin-1165 plant fluorescence kinetics measurement system and the Yaxin-1168 algae fluorescence kinetics measurement system.
