School of Life Sciences, Tsinghua University, Beijing, 100084, China.
School of Life Sciences, Tsinghua University, Beijing, 100084, China; Center for Synthetic and Systems Biology, Tsinghua University, Beijing, 100084, China; Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, 100084, China; MOE Key Lab of Industrial Biocatalysis, Dept Chemical Engineering, Tsinghua University, Beijing, 100084, China.
Metab Eng. 2021 Sep;67:53-66. doi: 10.1016/j.ymben.2021.05.010. Epub 2021 Jun 5.
Bacterial outer membrane (OM), an asymmetric lipid bilayer functioning as a self-protective barrier with reduced permeability for Gram-negative bacteria, yet wasting nutrients and energy to synthesize, has not been studied for its effect on bioproduction. Here we construct several OM-defected halophile Halomonas bluephagenesis strains to investigate the effects of OM on bioproduction. We achieve enhanced chassis properties of H. bluephagenesis based on positive cellular properties among several OM-defected strains. The OM-defected H. bluephagenesis WZY09 demonstrates better adaptation to lower salinity, increasing 28%, 30% and 12% on dry cell mass (DCM), poly(3-hydroxybutyrate) (PHB) accumulation and glucose to PHB conversion rate, respectively, including enlarged cell sizes and 21-folds reduced endotoxin. Interestingly, a poly(3-hydroxybutyrate-co-21mol%4-hydroxybutyrate) (P(3HB-co-21mol%4HB)) is produced by H. bluephagenesis WZY09 derivate WZY249, increasing 60% and 260% on polyhydroxyalkanoate (PHA) production and 4HB content, respectively. Furthermore, increased electroporation efficiency, more sensitive isopropyl β-D-1-thio-galactopyranoside (IPTG) induction, better oxygen uptake, enhanced antibiotics sensitivity and ectoine secretion due to better membrane permeability are observed if OM defected, demonstrating significant OM defection impacts for further metabolic engineering, synthetic biology studies and industrial applications.
细菌外膜（OM）是一种不对称的脂质双层，作为革兰氏阴性细菌的自我保护屏障，具有较低的通透性，但为了合成它，却浪费了营养物质和能量。目前尚未研究其对生物生产的影响。在这里，我们构建了几种 OM 缺陷的嗜盐菌 Halomonas bluephagenesis 菌株，以研究 OM 对生物生产的影响。我们通过几种 OM 缺陷菌株中的阳性细胞特性，实现了 H. bluephagenesis 的底盘特性的增强。OM 缺陷的 H. bluephagenesis WZY09 对低盐度具有更好的适应性，在干细胞质量（DCM）、聚（3-羟基丁酸酯）（PHB）积累和葡萄糖到 PHB 转化率方面分别提高了 28%、30%和 12%，包括细胞尺寸增大和内毒素降低 21 倍。有趣的是，H. bluephagenesis WZY09 衍生的 WZY249 产生了一种聚（3-羟基丁酸酯-co-21mol%4-羟基丁酸酯）（P(3HB-co-21mol%4HB)），在聚羟基烷酸酯（PHA）生产和 4HB 含量方面分别提高了 60%和 260%。此外，如果 OM 缺陷，还观察到电穿孔效率增加、异丙基 β-D-1-硫代半乳糖吡喃糖苷（IPTG）诱导更敏感、更好的氧气摄取、增强抗生素敏感性和由于更好的膜通透性而增强的章鱼胺分泌，这表明 OM 缺陷对进一步的代谢工程、合成生物学研究和工业应用具有重要的影响。
