| 초록 |
Alcaligenes latus has been known to produce poly(3-hydroxybutyrate), PHB, in a growth-associated manner even under nutrient-sufficient condition. However, the PHB content was always low at ca. 50%, which makes recovery process inefficient. In this study the effect of applying nitrogen limitation on the production of PHB by A. latus was examined. In flask and batch cultures, PHB synthesis rate, defined as gram PHB synthesized per gram residual cell per hour, could be considerably increased by applying nitrogen limitation. PHB content could be increased to 87% by applying nitrogen limitation in batch culture, which was considerably higher than that typically obtainable (50%) in nitrogen sufficient condition. In fed-batch culture, cells were first cultured by DO-stat feeding strategy without applying nitrogen limitation. Nitrogen limitation was applied at cell concentration of 76 g DCW/L, and sucrose concentration was maintained within 5-20 g/L. In 8 hours after nitrogen limitation, cell concentration, PHB concentration, and PHB content reached were 111.7 g DCW/L, 98.7g/L, and 88%, respectively, resulting in the productivity of 4.94 g PHB/L-h. The highest productivity of 5.13 g PHB/L-h was obtained in 16 h.
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