Nutrient optimization for production of polyhydroxybutyrate from halotolerant photosynthetic bacteria cultivated under aerobic-dark condition
Nutrient optimization for production of polyhydroxybutyrate from halotolerant photosynthetic bacteria cultivated under aerobic-dark condition
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有氧-黑暗条件下耐盐光合细菌生产聚羟基丁酸酯的营养优化
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发表时间：
2008
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影响因子：
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通讯作者：
P. Prasertsan
中科院分区：
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作者：
Kanokphorn Sangkharak;P. Prasertsan
三株耐盐细菌菌株：球形红细菌ES16（野生型）以及球形红细菌ES16的两个突变株，即N20和U7，在谷氨酸 - 苹果酸（GM）培养基中培养，并筛选聚羟基丁酸酯（PHB）的产生情况。发现突变株N20和U7积累的PHB（分别占细胞干重的53.9%和42.0%）比野生型菌株（占细胞干重的19.5%）分别高3.6倍和2.8倍。选择球形红细菌N20来研究营养和环境条件对PHB积累的影响。最佳条件为：4 g/L乙酸盐、0.02 g/L硫酸铵、碳氮比为6∶1、1.0 g/L磷酸氢二钾、1.0 g/L磷酸二氢钾和3%氯化钠，初始pH为7.0。在此最佳条件下，最大PHB积累量从占细胞干重的53.9%增加到88%，在37℃培养60小时后，获得了9.11±0.08 g/L的生物量和8.02±0.10 g/L的PHB浓度。这些结果是迄今为止报道的光合细菌所获得的最高值。
Three halotolerant bacterial strains; Rhodobacter sphaeroides ES16 (the wild type) and the two mutant strains of R. sphaeroides ES16, namely N20 and U7, were cultivated in glutamate-malate (GM) medium and screened for production of polyhydroxybutyrate (PHB). The mutant strains N20 and U7 were found to accumulate PHB (53.9 and 42.0% of DCW, respectively) 3.6 and 2.8 times higher than the wild type strain (19.5% of DCW), respectively. R. sphaeroides N20 were selected for studies on the effects of nutrient and environmental conditions on PHB accumulation. The optimal condition was 4 g/l acetate, 0.02 g/l (NH 4 ) 2 SO 4 , C/N ratio of 6:1, 1.0 g/l K 2 HPO 4 , 1.0 g/l KH 2 PO 4 and 3% NaCl with initial pH at 7.0. Under this optimal condition, the maximum PHB accumulation increased from 53.9% to 88% of DCW and 9.11 ± 0.08 g/l biomass, 8.02 ± 0.10 g/l PHB concentration were achieved after 60 hrs cultivation at 37oC. These results are the highest values ever obtained from photosynthetic bacteria reported so far.