Yamada K, Mukai K, Doi Y
Polymer Chemistry Laboratory, Institute of Physical and Chemical Research (RIKEN), Saitama, Japan.
Int J Biol Macromol. 1993 Aug;15(4):215-20. doi: 10.1016/0141-8130(93)90040-s.
A bacterium capable of degrading poly(3-hydroxybutyrate) [P(3HB)] was isolated from laboratory media and identified as Pseudomonas pickettii. The strain P. pickettii excreted an extracellular poly(hydroxyalkanoate) (PHA) depolymerase and grew on P(3HB) as the sole carbon source. P. pickettii also grew on 3-hydroxybutyrate, glucose, fructose, citrate or succinate. However, only 3-hydroxybutyrate apart from P(3HB) induced the secretion of PHA depolymerase. The PHA depolymerase was purified from the culture medium containing 3-hydroxybutyrate at the sole carbon source by hydrophobic column chromatography and gel filtration, and its molecular weight was determined as about 40,000 by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate. The optimum activity of degrading P(3HB) by the depolymerase was observed at pH 5.5 and 40 degrees C. The enzymatic degradation of microbial copolyesters was studied by the weight loss (erosion) of solution-cast films of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and poly(3-hydroxybutyrate-co-4-hydroxybutyrate). 1H-n.m.r. analysis of the water-soluble products after the hydrolysis of P(3HB) film by PHA depolymerase revealed that the main product was the monomer 3-hydroxybutyric acid.
从实验室培养基中分离出一种能够降解聚（3-羟基丁酸酯）[P(3HB)]的细菌，鉴定为皮氏假单胞菌。皮氏假单胞菌菌株分泌一种细胞外聚羟基脂肪酸酯（PHA）解聚酶，并以P(3HB)作为唯一碳源生长。皮氏假单胞菌也能在3-羟基丁酸、葡萄糖、果糖、柠檬酸盐或琥珀酸盐上生长。然而，除了P(3HB)之外，只有3-羟基丁酸能诱导PHA解聚酶的分泌。通过疏水柱色谱和凝胶过滤从以3-羟基丁酸为唯一碳源的培养基中纯化PHA解聚酶，在十二烷基硫酸钠存在下通过聚丙烯酰胺凝胶电泳测定其分子量约为40,000。在pH 5.5和40℃下观察到解聚酶降解P(3HB)的最佳活性。通过聚（3-羟基丁酸酯-co-3-羟基戊酸酯）和聚（3-羟基丁酸酯-co-4-羟基丁酸酯）溶液浇铸膜的重量损失（侵蚀）研究了微生物共聚酯的酶促降解。PHA解聚酶水解P(3HB)膜后水溶性产物的1H-n.m.r.分析表明，主要产物是单体3-羟基丁酸。
