Abstract: To obtain a strain which can use inexpensive carbon source to synthesize poly-β- hydroxybutyrate(PHB) in a short time，a bacterium CCZU-6X with high production of poly-β-hydroxybutyrate (PHB) was isolated and purified from soil，which was identified as Rhodococcus sp. according to its morphological，physiological properties and 16S rDNA sequence analysis. The optimum fermentation conditions were found as follows：the most suitable carbon source was 10 g/L lactose，and nitrogen source was 2 g/L ammonium sulfate，initial pH 7.5，250 mL flask containing 30 mL medium，30 ℃，shaking at 160 r/min for 18 h. Under the optimum conditions，the production of PHB was 4.54 g/L，as high as 79.52 % of dried cell weight.

Key words: poly-&beta, -hydroxybutyrate；Rhodococcus sp.；fermentation；optimization

摘要： 为了获得利用廉价碳源在细菌胞内快速大量合成聚-β-羟基丁酸酯（poly-β-hydroxybutyrate，PHB）的菌株，通过苏丹黑染色法，从土壤中分离筛选得到一株聚-β-羟基丁酸酯（PHB）高产菌株CCZU-6X，经形态观察、生理生化实验和16S rDNA序列分析，鉴定该菌为红球菌属（Rhodococcus sp.）。该菌株的最佳发酵条件为10 g/L乳糖、2 g/L硫酸铵、起始pH值7.5、装液量30 mL/250 mL、转速160 r/min、温度30 ℃、发酵时间18 h，在此优化条件下PHB的积累量达到细胞干重的79.52%，产量为4.54 g/L。

关键词: 聚-&beta, -羟基丁酸酯；红球菌属；发酵；优化