Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, Academia Sinica and National Chung Hsing University, Taipei, Taiwan.
Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan.
PLoS One. 2021 Mar 4;16(3):e0247135. doi: 10.1371/journal.pone.0247135. eCollection 2021.
Ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) genes play important roles in CO2 fixation and redox balancing in photosynthetic bacteria. In the present study, the kefir yeast Kluyveromyces marxianus 4G5 was used as host for the transformation of form I and form II RubisCO genes derived from the nonsulfur purple bacterium Rhodopseudomonas palustris using the Promoter-based Gene Assembly and Simultaneous Overexpression (PGASO) method. Hungateiclostridium thermocellum ATCC 27405, a well-known bacterium for its efficient solubilization of recalcitrant lignocellulosic biomass, was used to degrade Napier grass and rice straw to generate soluble fermentable sugars. The resultant Napier grass and rice straw broths were used as growth media for the engineered K. marxianus. In the dual microbial system, H. thermocellum degraded the biomass feedstock to produce both C5 and C6 sugars. As the bacterium only used hexose sugars, the remaining pentose sugars could be metabolized by K. marxianus to produce ethanol. The transformant RubisCO K. marxianus strains grew well in hydrolyzed Napier grass and rice straw broths and produced bioethanol more efficiently than the wild type. Therefore, these engineered K. marxianus strains could be used with H. thermocellum in a bacterium-yeast coculture system for ethanol production directly from biomass feedstocks.
核酮糖-1,5-二磷酸羧化酶/加氧酶（RubisCO）基因在光合细菌的 CO2 固定和氧化还原平衡中发挥重要作用。在本研究中，使用开菲尔酵母 Kluyveromyces marxianus 4G5 作为宿主，通过基于启动子的基因组装和同时过表达（PGASO）方法转化源自非硫紫色细菌 Rhodopseudomonas palustris 的 I 型和 II 型 RubisCO 基因。Hungateiclostridium thermocellum ATCC 27405 是一种众所周知的细菌，能够有效溶解木质纤维素生物质中的顽固性物质，用于降解象草和水稻秸秆，以产生可溶的发酵糖。所得的象草和水稻秸秆培养基用于工程化 K. marxianus 的生长。在双微生物系统中，H. thermocellum 降解生物质原料，产生 C5 和 C6 糖。由于细菌仅使用己糖，其余的戊糖可以被 K. marxianus 代谢产生乙醇。转化的 RubisCO K. marxianus 菌株在水解的象草和水稻秸秆培养基中生长良好，比野生型更有效地生产生物乙醇。因此，这些工程化的 K. marxianus 菌株可以与 H. thermocellum 在细菌-酵母共培养系统中直接从生物质原料生产乙醇。
