The identification of novel bacterial strains with a high production potential of polyhydroxybutyrate (PHB) to substitute the bioplastics with non-biodegradable plastics and reducing environmental pollution is really effective. The present study was done with the purpose of PHB bioplastic production using a novel bacterial strain. Twenty-one different bacterial isolates were obtained from petrochemical wastewater, which among them, 10 isolates were PHB positive. The presence of PHB granules was detected in the isolates using Sudan Black B staining. The most excellent PHB-accumulating bacterium with a maximum yield of PHB (61.53%) was selected and identified as Bacillus cereus saba.zh, based on morphological, biochemical, and molecular techniques. 16S rRNA nucleotide sequence of the bacterium was assigned accession number: MT975245 in the NCBI database. The phylogenetic tree data showed that the closest type strain to the Bacillus cereus saba.zh is the Bacillus cereus SDB4 (91%). The three genes (phaA, phaB, and phaC) responsible for the PHB biosynthesis were amplified using the specific oligonucleotide primers by PCR technique. The highest PHB yield was achieved when the culture medium was supplemented with 3% sugarcane molasses as a carbon source, ammonium sulfate as the nitrogen source, at pH 7, and temperature of 30 °C. The characterization of the extracted polymer by FTIR and ¹H NMR spectroscopy proves the presence of methyl, methylene, methine, hydroxyl, and ester carbonyl groups and confirmed the structure of biopolymer as PHB. The novel strain Bacillus cereus saba.zh has good potential as an appropriate candidate for low-cost industrial production of bioplastic.

鉴定具有高聚羟基丁酸酯（PHB）生产潜力的新型细菌菌株，以用不可生物降解的塑料替代生物塑料并减少环境污染确实有效。本研究的目的是使用一种新型细菌菌株生产 PHB 生物塑料。从石化废水中分离得到21株不同的细菌，其中PHB阳性10株。使用苏丹黑 B 染色在分离物中检测到 PHB 颗粒的存在。筛选出最高PHB产率（61.53%）的最优良的PHB积累菌为蜡状芽孢杆菌（ Bacillus cereus ）saba.zh，基于形态学、生化和分子技术。该细菌的 16S rRNA 核苷酸序列在 NCBI 数据库中被指定登录号：MT975245。系统发育树数据显示，与蜡状芽孢杆菌saba.zh最接近的菌株是蜡状芽孢杆菌SDB4（91%）。三个基因（phaA、phaB和phaC) 负责 PHB 生物合成通过 PCR 技术使用特定的寡核苷酸引物进行扩增。当培养基中添加 3% 的甘蔗糖蜜作为碳源，硫酸铵作为氮源，pH 为 7，温度为 30 °C 时，PHB 产量最高。通过 FTIR 和¹ H NMR 光谱对提取的聚合物进行表征，证明了甲基、亚甲基、次甲基、羟基和酯羰基的存在，并证实了生物聚合物的结构为 PHB。新菌株蜡状芽孢杆菌saba.zh 具有作为低成本工业生产生物塑料的合适候选者的良好潜力。