Joint BioEnergy Institute, 5885 Hollis St, Emeryville, CA, 94608, USA.
Sandia National Laboratories, 7011 East Ave, Livermore, CA, 94551, USA.
Microb Cell Fact. 2021 Sep 15;20(1):181. doi: 10.1186/s12934-021-01670-8.
Hydroxycinnamic acids such as p-coumaric acid (CA) are chemically linked to lignin in grassy biomass with fairly labile ester bonds and therefore represent a straightforward opportunity to extract and valorize lignin components. In this work, we investigated the enzymatic conversion of CA extracted from lignocellulose to 4-vinylphenol (4VP) by expressing a microbial phenolic acid decarboxylase in Corynebacterium glutamicum, Escherichia coli, and Bacillus subtilis. The performance of the recombinant strains was evaluated in response to the substrate concentration in rich medium or a lignin liquor and the addition of an organic overlay to perform a continuous product extraction in batch cultures. We found that using undecanol as an overlay enhanced the 4VP titers under high substrate concentrations, while extracting > 97% of the product from the aqueous phase. C. glutamicum showed the highest tolerance to CA and resulted in the accumulation of up to 187 g/L of 4VP from pure CA in the overlay with a 90% yield when using rich media, or 17 g/L of 4VP with a 73% yield from CA extracted from lignin. These results indicate that C. glutamicum is a suitable host for the high-level production of 4VP and that further bioprocess engineering strategies should be explored to optimize the production, extraction, and purification of 4VP from lignin with this organism.
羟基肉桂酸（如对香豆酸（CA））与草本生物质中的木质素通过相当不稳定的酯键化学结合，因此代表了提取和利用木质素成分的直接机会。在这项工作中，我们通过在谷氨酸棒杆菌、大肠杆菌和枯草芽孢杆菌中表达微生物酚酸脱羧酶，研究了从木质纤维素中提取的 CA 到 4-乙烯基苯酚（4VP）的酶促转化。根据丰富培养基或木质素液中的底物浓度以及添加有机覆盖层以在分批培养中进行连续产物提取来评估重组菌株的性能。我们发现，使用十一醇作为覆盖层可以在高底物浓度下提高 4VP 的产量，同时将产物从水相提取出>97%。谷氨酸棒杆菌对 CA 的耐受性最高，在使用丰富培养基时，从纯 CA 中积累了高达 187 g/L 的 4VP，产率为 90%，或者从木质素中提取的 CA 中积累了 17 g/L 的 4VP，产率为 73%。这些结果表明，谷氨酸棒杆菌是 4VP 高水平生产的合适宿主，应该探索进一步的生物工艺工程策略，以优化该生物从木质素中生产、提取和纯化 4VP。
