Rhodovulum sulfidophilum DSM-1374 is a potential producer of polyester when growing in phototrophic conditions. The present study investigated on a polyester product (P3HB) by culturing Rhodovulum sulfidophilum DSM-1374 in two different photobioreactors (PBR-1 and PBR-2) both with 4-L working volumes. PBR-1 is equipped with an internal rotor having 4 paddles to mix the bacterial culture while PBR-2 has an internal coil-shaped rotor. After selecting PBR-1, which best performed in the preliminary experiment, the effect of different stressing growth conditions as pH (7.0, 8.0, and 9.0), temperature (25, 30, and 35 °C), and medium salinity (1.5, 2.5, 3.5, and 4.5%) were tested. When the pH of the culture was set to 8.0, the capability of the bacterium to synthetize the polyester increased significantly reaching a concentration of 412 mg (P3HB)/L; the increase of the pH at 9.0 caused a reduction of the P3HB concentration in the culture. The medium salinity of 4.5% was the best stress-growth condition to reach the highest concentration of polyester in the culture (820 ± 50 mg (P3HB)/L) with a P3HB mass fraction in the dry biomass of 33 ± 1.5%. Stresses caused by culture temperature are another potential parameter that could increase the synthesis of P3HB.

中文翻译：

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pH，温度和盐分对培养海洋红景天DSM-1374的P3HB合成的影响。

当在光养条件下生长时，嗜硫杜鹃DSM-1374是聚酯的潜在生产者。本研究通过在两个具有4升工作体积的不同光生物反应器（PBR-1和PBR-2）中培养硫丹红球菌DSM-1374来研究聚酯产品（P3HB）。PBR-1配备了一个内部转子，该转子具有4个桨叶以混合细菌培养物，而PBR-2具有一个内部线圈形转子。选择在初步实验中效果最好的PBR-1后，不同的胁迫生长条件如pH（7.0、8.0和9.0），温度（25、30和35°C）和中等盐度（1.5， 2.5％，3.5％和4.5％）进行了测试。当培养物的pH设置为8.0时，细菌合成聚酯的能力显着提高，达到412 mg（P3HB）/ L的浓度。pH值在9.0时升高，导致培养物中P3HB浓度降低。中等盐度为4.5％是达到培养物中聚酯最高浓度（820±50 mg（P3HB）/ L）的最佳应力增长条件，干生物质中P3HB的质量分数为33±1.5％。培养温度引起的应激是另一个可能增加P3HB合成的潜在参数。