Wu Hong, Fan Zhongyun, Jiang Xiaoran, Chen Jinchun, Chen Guo-Qiang
School of Life Sciences, Tsinghua University, Beijing, 100084, China.
Center for Synthetic and Systems Biology, Tsinghua University, Beijing, 100084, China.
Microb Cell Fact. 2016 Jul 27;15(1):128. doi: 10.1186/s12934-016-0531-6.
Most bacteria are grown in a binary fission way meaning a bacterial cell is equally divided into two. Polyhydroxyalkanoates (PHA) can be accumulated as inclusion bodies by bacteria. The cell division way and morphology have been shown to play an important role in regulating the bacterial growth and PHA storages.
The common growth pattern of Escherichia coli was changed to multiple fission patterns by deleting fission related genes minC and minD together, allowing the formation of multiple fission rings (Z-rings) in several positions of an elongated cell, thus a bacterial cell was observed to be divided into more than two daughter cells at same time. To further improve cell growth and PHA production, some genes related with division process including ftsQ, ftsL, ftsW, ftsN and ftsZ, together with the cell shape control gene mreB, were all overexpressed in E. coli JM109 ∆minCD. The changing pattern of E. coli cell growth and morphology resulted in more cell dry weights (CDW) and more than 80 % polyhydroxybutyrate (PHB) accumulation increases compared to its binary fission control grown under the same conditions.
This study clearly demonstrated that combined over-expression genes ftsQ, ftsW, ftsN, ftsL and ftsZ together with shape control gene mreB in multiple division bacterial E. coli JM109 ∆minCD benefited PHA accumulation. Our study provides useful information on increasing the yield of PHA by changing the cell division pattern and cell morphology of E. coli.
大多数细菌以二分裂方式生长，即一个细菌细胞平均分为两个。聚羟基脂肪酸酯（PHA）可作为包涵体被细菌积累。细胞分裂方式和形态已被证明在调节细菌生长和PHA积累中起重要作用。
通过共同缺失与分裂相关的基因minC和minD，将大肠杆菌常见的生长模式转变为多分裂模式，使得在伸长细胞的几个位置形成多个分裂环（Z环），从而观察到一个细菌细胞同时被分为两个以上的子细胞。为进一步提高细胞生长和PHA产量，将包括ftsQ、ftsL、ftsW、ftsN和ftsZ在内的一些与分裂过程相关的基因，以及细胞形状控制基因mreB，在大肠杆菌JM109 ∆minCD中进行过表达。与在相同条件下生长的二分裂对照相比，大肠杆菌细胞生长和形态的变化模式导致更多的细胞干重（CDW）以及聚羟基丁酸酯（PHB）积累增加80%以上。
本研究清楚地表明，在多分裂细菌大肠杆菌JM109 ∆minCD中，ftsQ、ftsW、ftsN、ftsL和ftsZ基因与形状控制基因mreB的联合过表达有利于PHA积累。我们的研究为通过改变大肠杆菌的细胞分裂模式和细胞形态提高PHA产量提供了有用信息。
