Wei Lanzhen, Fan Baoqiang, Yi Jing, Xie Tianqun, Liu Kun, Ma Weimin
Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Guilin Road 100, Shanghai, 200234 China.
Biotechnol Biofuels. 2020 Apr 6;13:64. doi: 10.1186/s13068-020-01704-0. eCollection 2020.
Bisulfite addition is an important H photoproduction strategy that removes O and activates hydrogenase. The pH values of cell cultures can change the ratio of bisulfite to sulfite, which may affect H photoproduction. However, little is known regarding the pH effect of bisulfite addition on H photoproduction and relevant underlying mechanism.
Here, changes in H photoproduction with different initial extracellular pH values showed a parabolic distribution and a pH of 8.0 is an optimal value for H photoproduction in cells treated with bisulfite. Compared to the growth pH (pH 7.3), increased photoproduction of H at this optimal pH was primarily caused by a relatively high residual activity of photosystem II (PSII), which provides a relatively plentiful source of electrons for H photoproduction. Such increased H photoproduction was most likely a result of decreased the ratio of bisulfite to sulfite, consistent with the result that the toxicity of bisulfite on PSII was much more than that of sulfite. This possibility was corroborated by the result that treatment with a combination of 7 mM bisulfite and 6 mM sulfite further enhanced H photoproduction compared with 13 mM bisulfite alone.
Collectively, our findings provide novel mechanistic insights into pH-dependent H photoproduction in cells treated with bisulfite, and demonstrate that sulfite addition is another important strategy for H photoproduction, just like bisulfite addition.
添加亚硫酸氢盐是一种重要的产氢光合成策略，它能去除氧并激活氢化酶。细胞培养的pH值会改变亚硫酸氢盐与亚硫酸盐的比例，这可能会影响产氢光合成。然而，关于添加亚硫酸氢盐对产氢光合成的pH效应及其相关潜在机制知之甚少。
在此，不同初始细胞外pH值下产氢光合成的变化呈抛物线分布，对于用亚硫酸氢盐处理的细胞，pH 8.0是产氢光合成的最佳值。与生长pH值（pH 7.3）相比，在这个最佳pH值下产氢量增加主要是由于光系统II（PSII）的相对较高的残余活性，这为产氢光合成提供了相对充足的电子来源。这种产氢量的增加很可能是亚硫酸氢盐与亚硫酸盐比例降低的结果，这与亚硫酸氢盐对PSII的毒性远大于亚硫酸盐的结果一致。7 mM亚硫酸氢盐和6 mM亚硫酸盐组合处理与单独使用13 mM亚硫酸氢盐相比进一步提高了产氢量，这一结果证实了这种可能性。
总体而言，我们的研究结果为用亚硫酸氢盐处理的细胞中依赖pH的产氢光合成提供了新的机制见解，并证明添加亚硫酸盐是产氢光合成的另一种重要策略，就像添加亚硫酸氢盐一样。
