突变工程菌pCBH4高产PHAs分子机制的初步研究(英文)

A Preliminary Study on the Molecular Mechanism of High Yield Polyhydroxyalkanoates Mutation Strain pCBH4 Screened by Ion Beams

聚羟基烷酸酯(PHAs)是一类以胞内颗粒形式存在的能被完全生物降解的贮能物质。本研究利用生物信息学的方法初步分析了离子束诱变选育出的突变工程菌pCBH4高产PHAs分子机制。为了分析高产PHAs特性,实验首先提取pCBH4突变菌株含有合成PHAs基因的质粒并转化受体菌DH5α,然后根据原始序列设计引物,从突变株pCBH4中扩增出phaA、phaB和phaC基因并对其进行了序列分析。结果表明:转化菌表现出高产PHAs特性;phaA基因在序列末端有7处碱基发生改变,这一变化导致5个氨基酸发生了改变;phaC基因也发生了类似的变化。从这些结果可以推断pCBH4突变株高产PHAs不是由于工程菌基因组遗传变异所致,可能是phaA和phaC基因突变的结果。

Polyhydroxyalkanoates （PHAs） are the reserve polyesters accumulated as intracellular granules in many microorganisms which are completely biodegradable. The molecular mechanism of the high yield PHAs strain pCBH4 screened by ion beams was analyzed by bioinformatics method. The plasmid extracted from pCBH4 with the relation genes （phaA, phaB and phaC） for synthesizing PHAs was transformed to Escherichia coli strain DH5α firstly to analyze the characteristics of high yield PHAs. Then, phaA, phaB and phaC were amplified using the pCBH4 as the template and sequenced. The results indicated that the transformed strain from the plasmid DNA of pCBH4 had the characteristic of high yield PHAs. There were seven nucleotide alteration at the terminal ofphaA and thus caused the change of five amino acid residue of PhaA. The similar mutations were also found in phaC. It can be inferred from these results that high yield PHAs may be caused by the mutation of phaA and phaC, not the aberrance of genome in the strain pCBH4.