STM Article Repository

The production of polyhydroxyalkanoates (PHAs) using raw sewage has been previously attempted to derive value from waste; however, the yields of PHAs were low. Therefore, we attempted to increase the yield by applying different strategies, such as supplementation of sewage with additional carbon sources, dilution of high-carbon-containing wastewater (cheese whey) with low-carbon-containing wastewater (sewage), and concentration of sewage to improve the available carbon source. After applying these strategies, the PHA production capacity of the bacterium Bacillus sp. CYR1 is enhanced 22-fold. CYR1 incubated using cheese whey (CW) diluted with sewage showed higher PHA production than those incubated using CW diluted with distilled water. The PHA produced in this study was identified as poly-
-polyhydroxybutyrate (PHB), and the characteristics of the produced PHB were comparable to those of standard PHB. We believe that our study makes a significant contribution to the literature because we show the potential of CYR1 strain in PHB production using low- or high-carbon-containing wastewater. The reuse of sewage will help to reduce the ecological burden and energy consumption on a global scale.

The increasing burden placed by plastic waste on the environment has necessitated the protection of our planet from environmental disasters. Thus, switching from limited natural and fossil resources to PHAs for plastic production matches today's concrete initiatives to reach the global Climate and Sustainable Development Goals. On a related note, the constant generation of sewage in our daily activities accounts for a high proportion of the environmental load, and the energy and cost required for sewage treatment are extensive. Thus, the reuse of sewage is essential for reducing the ecological burden and energy consumption on a global scale. Consequently, painstaking efforts have been taken to transform waste management into resource management. Our group has been working on the production of bioplastics using rejected materials. Therefore, in this study, we aimed to enhance PHA production from sewage by applying different strategies using Bacillus sp. CYR1. A high rate of glucose consumption (83.6%) was also observed. Higher phaC gene expression levels were observed in high-carbon-containing sewage but at lower nitrogen concentrations. Based on these analyses, it was confirmed that the CYR1 strain can be useful for producing PHA using low- or high-carbon-containing wastewater.