Thin-layer photosynthetic biocatalysts (PBCs) offer an innovative and promising approach to the solar-powered generation of renewable chemicals and fuels. Thin-layer PBCs incorporate photosynthetic microbes, engineered for the production of targeted chemicals, into specifically tailored bio-based polymeric matrices. This unique integration forms a biocatalytic architecture that allows controlled distribution of light, nutrients, and substrates to the entrapped cells, optimising their performance. The research outlined in this study offers a systematic engineering approach to developing a biocatalytic architecture with improved light utilisation and enhanced photosynthetic conversion of captured light energy to molecular hydrogen (H₂), an important energy carrier and fuel. This was achieved by entrapping wild-type green alga Chlamydomonas reinhardtii and its mutants with truncated light-harvesting chlorophyll antenna (Tla) complexes within thin-layer (up to 330 μm-thick) polymeric matrices under sulphur-deprived conditions. Our step-by-step engineering strategy involved: (i) synchronising culture growth to select cells with the highest photosynthetic capacity for entrapment, (ii) implementing a photosynthetic antenna gradient in the matrix by placing Tla cells atop the wild-type algae for better light distribution, (iii) replacing the conventional alginate formulation with TEMPO-oxidised cellulose nanofibers for improved matrix stability and porosity, and (iv) employing a semi-wet production approach to simplify the removal of produced H₂ from the matrix with entrapped cells, thus preventing H₂ recycling. The engineered PBCs achieved a fourfold increase in H₂ photoproduction yield compared to conventional alginate films under the same irradiance (0.65 vs. 0.16 mol m⁻² under 25 μmol photons m⁻² s⁻¹, respectively) and maintained H₂ photoproduction activity for over 16 days. This resulted in a remarkable 4% light energy to hydrogen energy conversion efficiency at peak production activity and over 2% throughout the entire production period. These significant advancements highlight the potential of engineered thin-layer PBCs for efficient H₂ production. The technology could be adapted for biomanufacturing various renewable chemicals and fuels.

中文翻译：

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工程生物催化结构，可增强藻类 H2 生产中的光利用率


薄层光合生物催化剂 （PBC） 为太阳能发电可再生化学品和燃料提供了一种创新且有前途的方法。薄层 PBC 将专为生产目标化学品而设计的光合微生物整合到专门定制的生物基聚合物基质中。这种独特的整合形成了一种生物催化结构，允许光、营养物质和底物以受控方式分布到被包埋的细胞，从而优化其性能。本研究中概述的研究提供了一种系统的工程方法来开发一种生物催化结构，以提高光利用率并增强捕获的光能向分子氢 （H₂） 的光合作用转化，氢分子是一种重要的能源载体和燃料。这是通过在缺硫条件下将野生型绿藻莱茵衣藻及其突变体与截短的光捕获叶绿素天线 （Tla） 复合物捕获在薄层（高达 330 μm）聚合物基质中来实现的。我们的分步工程策略包括：（i） 同步培养生长以选择具有最高光合包埋能力的细胞，（ii） 通过将 Tla 细胞放置在野生型藻类上以获得更好的光分布，在基质中实施光合天线梯度，（iii） 用 TEMPO 氧化纤维素纳米纤维代替传统的藻酸盐配方，以提高基质稳定性和孔隙率， （iv） 采用半湿法生产方法来简化从具有包埋细胞的基质中去除产生的 H₂，从而防止 H₂ 回收。 在相同辐照度下（在 25 μmol 光子 ^{m-2 s-1} 下分别为 0.65 和 0.16 mol ^m-2）和保持 H₂ 的情况下，与传统藻酸盐薄膜相比，工程 PBC 的 H₂ 光产率提高了四倍照片产生活动超过 16 天。这导致在生产活动高峰期光能到氢能的转换效率显著提高了 4%，在整个生产期间的光能转换效率超过 2%。这些重大进展凸显了工程化薄层 PBC 在高效 H₂ 生产方面的潜力。该技术可适用于生物制造各种可再生化学品和燃料。