School of Agricultural Technology, Walailak University, Nakhon Si Thammarat 80160, Thailand.
J Biosci Bioeng. 2011 Jun;111(6):658-64. doi: 10.1016/j.jbiosc.2011.01.014. Epub 2011 Feb 24.
Kinetic parameters for growth and extracellular 5-aminolevulinic acid (ALA) production of Rhodopseudomonas palustris KG31 under light and dark conditions in a medium containing volatile fatty acids (VFA) as the carbon sources were estimated using a Gompertz model. The lag phase for growth and the maximum specific growth rate under microaerobic-light cultivations were 7.29-12.49 h and 0.038-0.094 h(-1), respectively, whereas under aerobic-dark cultivations, they were 2.03-14.25 h and 0.016-0.022 h(-1), respectively. The lag phase for extracellular ALA production and the maximum specific extracellular ALA production rate under microaerobic-light cultivations (15.72-24.74 h and 0.222-0.299 h(-1), respectively) were better than those obtained under aerobic-dark cultivations (24.57-44.84 h and 0.103-0.215 h(-1), respectively). The biomass and the extracellular ALA yields of 39.66-56.25 gDCW/l/mol C, and 148.47-245.75 μM/mol C, respectively, under microaerobic-light cultivations were higher than of those obtained under aerobic-dark conditions. An enhancement of extracellular ALA production under aerobic-dark conditions revealed that the ALA yield was markedly increased 8-fold (48.36 μM) by the addition of 10mM succinate, 4.5mM glycine, and 15 mM levulinic acid (LA). By controlling dissolved oxygen (DO) and pH values, a maximum extracellular ALA yield of 66.38 μM was found. The degradation rate of ALA in the culture broth was closely related to the pH value.
在含有挥发性脂肪酸（VFA）作为碳源的培养基中，使用 Gompertz 模型估算了在光和暗条件下 Rhodopseudomonas palustris KG31 的生长和胞外 5-氨基乙酰丙酸（ALA）生产的动力学参数。在微需氧-光照培养下，生长的迟滞期和最大比生长速率分别为 7.29-12.49 h 和 0.038-0.094 h(-1)，而在需氧-暗培养下，分别为 2.03-14.25 h 和 0.016-0.022 h(-1)。在微需氧-光照培养下，胞外 ALA 生产的迟滞期和最大比胞外 ALA 生产速率分别为 15.72-24.74 h 和 0.222-0.299 h(-1)，优于需氧-暗培养下的迟滞期和最大比胞外 ALA 生产速率（分别为 24.57-44.84 h 和 0.103-0.215 h(-1)）。在微需氧-光照培养下，生物量和胞外 ALA 得率分别为 39.66-56.25 gDCW/l/mol C 和 148.47-245.75 μM/mol C，高于需氧-暗条件下的生物量和胞外 ALA 得率。在需氧-暗条件下，通过添加 10mM 琥珀酸、4.5mM 甘氨酸和 15mM 乙酰丙酸（LA），胞外 ALA 产量显著提高 8 倍（48.36 μM），揭示了胞外 ALA 产量的提高。通过控制溶解氧（DO）和 pH 值，发现胞外 ALA 的最大产量为 66.38 μM。培养物中 ALA 的降解速率与 pH 值密切相关。
