A newly isolated strain for poly(3-hydroxybutyrate) production under anaerobic conditions and the key enzyme analysis.

• Anaerobic environment (DO < 0.2 mg/L) did not inhibit the growth of Pseudomonas sp. • PHB accumulation by Pseudomonas sp. in anaerobic environment is about 1.9 times higher than in aerobic environment. • A significant increase in the activity of key enzyme for PHB synthesis was found in anaerobic environment. Polyhydroxyalkanoates (PHAs) are biodegradable polyesters with great possibility to replace petroleum-based plastics, but the high costs of production associated with energy inputs have been an obstacle to their commercial application. The production of PHAs under anaerobic environments without aeration appears to be more attractive but has not been adequately investigated. A strain capable of accumulating poly(3-hydroxybutyrate) (PHB) under anaerobic conditions was isolated. The strain anaerobically accumulated PHB reached 38.7 % of cell dry weight (CDW), which was 1.9 times higher than under aerobic conditions. It was also found that the concentrations of key enzymes for PHB synthesis were higher under anaerobic conditions than under aerobic conditions. The highest PHB accumulation was 77.9 % obtained at oxygen-limited conditions and the highest PHB yield was 0.13 g PHB/g carbon obtained at anaerobic conditions. It suggests that the conditions should be well controlled according to the purpose of PHB production. This study offers a new alternative of PHAs formation. [ABSTRACT FROM AUTHOR]