Synthetic plastics have multiple applications in modern world. However, being non-degradable in nature, these have turned into environmental pollutants. Natural ecosystem and global biodiversity are facing serious challenges due to the plastic pollution. Effective degradation and replacement of synthetic plastics with natural and ecofriendly biomaterial is crucial. Polyhydroxyalkanoates (PHAs) are the microbial polyesters and have great potential as biopolymers for the development of bioplastics. PHA produced and accumulated as granules in the cytoplasm of various microbes under limited supply of nutrients can serve the purpose of bioplastic production. Biosynthesis of PHA using bacteria needs well-optimized nutrient and growth conditions for which, studies optimizing the parameters of bacterial growth using various carbon and nitrogen sources are required. Current study optimized the production of PHA by two indigenously isolated strains of Pseudomonas sp. AK-3 and AK-4. The strain AK-3 produced 1.08 g/L of PHA with a yield of 54.82% in the presence of 2% sucrose as carbon source and 1% of (NH₄)₂SO₄ as nitrogen source (C/N ratio of 4:1). The yield, however, reduced to 7.73% when 2% (NH₄)₂SO₄ was added as a nitrogen source in the production medium (C/N ratio of 4:2). Pseudomonas sp. AK-4 produced 0.92 g/L of PHA with a yield of 43.80% for 2% sucrose as carbon source. Addition of 1% (NH₄)₂SO₄ had negligible effect on the yield. Considerable increase in cell dry mass was observed when high concentrations of various carbon sources were used. Biosynthesis of PHA was declined when 1% concentrations of nitrogen sources such as ammonium chloride (NH₄Cl), ammonium nitrate (NH₄NO₃) and ammonium sulphate (NH₄)₂SO₄ were used. The optimum temperature and pH for production of PHA were found to be 38 °C and 8.0 respectively, with an optimum incubation period of 72 h. FTIR results of the extracted polyesters showed transmittance peaks at wavenumbers of 1725 cm⁻¹, 1375 cm⁻¹, 1278 cm⁻¹, 1132 cm⁻¹, 1054 cm⁻¹ and 977 cm⁻¹. Based on FTIR analysis it was concluded that the polyester produced by both Pseudomonas sp. AK-3 and AK-4 was poly-3-hydroxybutyrate P(3HB).

合成塑料在现代世界中有多种应用。然而，由于本质上不可降解，这些已变成环境污染物。由于塑料污染，自然生态系统和全球生物多样性正面临严峻挑战。用天然和环保的生物材料有效降解和替代合成塑料至关重要。聚羟基链烷酸酯 (PHA) 是一种微生物聚酯，作为生物聚合物开发生物塑料具有巨大的潜力。在营养供应有限的情况下，各种微生物的细胞质中以颗粒形式产生和积累的 PHA 可以用于生物塑料生产的目的。使用细菌生物合成 PHA 需要优化的营养和生长条件，需要研究使用各种碳源和氮源优化细菌生长参数。目前的研究通过两种本地分离的菌株优化了 PHA 的生产。假单胞菌属 AK-3 和 AK-4。AK-3菌株在2%蔗糖作为碳源和1% (NH ₄ ) ₂ SO ₄作为氮源（C/N比为4: 1）。然而，当在生产培养基中添加2% (NH ₄ ) ₂ SO ₄作为氮源时（C/N比为4:2），产率降低至7.73%。假单胞菌属 对于 2% 蔗糖作为碳源，AK-4 产生 0.92 g/L PHA，产率为 43.80%。添加1% (NH ₄ ) ₂ SO ₄对产量的影响微乎其微。当使用高浓度的各种碳源时，观察到细胞干质量显着增加。当使用浓度为 1% 的氮源如氯化铵 (NH ₄ Cl)、硝酸铵 (NH ₄ NO ₃ ) 和硫酸铵 (NH ₄ ) ₂ SO ₄时，PHA 的生物合成下降。发现生产PHA的最佳温度和pH分别为38°C和8.0，最佳孵育期为72小时。提取的聚酯的FTIR结果显示在1725 cm ^-1、1375 cm ^-1、1278 cm ^-1、1132 cm ^{-1的波数处有透射峰}, 1054 cm ^-1和 977 cm ^-1。基于 FTIR 分析得出的结论是，由两种假单胞菌生产的聚酯。AK-3 和 AK-4 是聚 3-羟基丁酸酯 P(3HB)。