[P003] Poster

12:10 PM - 1:00 PM JST(3:10 AM - 4:00 AM UTC)

[P02-233] Effects of Nitrogen and Temperature Conditions on PHB Production in Cyanobacteria

○sehee Chung¹, donghee Kim¹, young-kee Kim¹ (1. Hankyong National University (Korea))

Keywords:

cyanobacteria,PHB,Synechocystis salina,polyhydroxybutyrate,bioplastic

Approximately 400 million tons of plastic are produced annually worldwide, of which 40–50% are used as disposable products and subsequently landfilled or accumulated in the environment. This results in serious problems such as resource depletion, greenhouse gas emissions, and microplastic pollution. Accordingly, sustainable and biodegradable alternative materials such as polyhydroxybutyrate (PHB) have attracted increasing attention. Conventional PHB production has primarily relied on heterotrophic microorganisms, which presents economic and environmental limitations due to the dependence on external organic carbon sources. In contrast, the photosynthetic cyanobacterium Synechocystis salina can produce PHB using only light and CO_2, making it a promising microorganism for sustainable bioplastic production. Microbial growth requires various nutrients, including nitrogen, which is essential for protein synthesis. Under nitrogen-limited conditions, cell growth is inhibited, and excess energy and carbon are redirected toward PHB accumulation; therefore, nitrogen deprivation serves as an effective trigger for PHB biosynthesis. In addition, temperature is an important environmental factor that influences microbial growth and metabolic activity. In this study, we investigated the effects of nitrogen limitation and temperature conditions on PHB production in S. salina. The results showed that although cell growth decreased under nitrogen-limited conditions, PHB accumulation increased significantly. Temperature conditions also influenced PHB accumulation and growth characteristics. These results indicate that PHB synthesis in S. salina can be regulated through environmental control such as nitrogen availability and temperature. These findings demonstrate the potential of photosynthetic microorganisms as sustainable platforms for PHB production and contribute to the development of eco-friendly bioplastics.