PDF(Pubmed)
Abstract：
BACKGROUND: Propionate is a food preservative and platform chemical, but no biological process competes with current petrochemical production routes yet. Although propionate production has been described for gut bacteria of the class Bacteroidia, which also carry great capacity for the degradation of plant polymers, knowledge on propionate yields and productivities across species is scarce. This study aims to compare propionate production from glucose within Bacteroidia and characterize good propionate producers among this group.
RESULTS: We collected published information on propionate producing Bacteroidia, and selected ten species to be further examined. These species were grown under defined conditions to compare their product formation. While propionate, acetate, succinate, lactate and formate were produced, the product ratios varied greatly among the species. The two species with highest propionate yield, B. propionicifaciens (0.39 gpro/ggluc) and B. graminisolvens (0.25 gpro/ggluc), were further examined. Product formation and growth behavior differed significantly during CO2-limited growth and in resting cells experiments, as only B. graminisolvens depended on external-added NaHCO3, while their genome sequences only revealed few differences in the major catabolic pathways. Carbon mass and electron balances in experiments with resting cells were closed under the assumption that the oxidative pentose pathway was utilized for glucose oxidation next to glycolysis in B. graminisolvens. Finally, during pH-controlled fed-batch cultivation B. propionicifaciens and B. graminisolvens grew up to cell densities (OD600) of 8.1 and 9.8, and produced 119 mM and 33 mM of propionate from 130 and 105 mM glucose, respectively. A significant production of other acids, particularly lactate (25 mM), was observed in B. graminisolvens only.
CONCLUSIONS: We obtained the first broad overview and comparison of propionate production in Bacteroidia strains. A closer look at two species with comparably high propionate yields, showed significant differences in their physiology. Further studies may reveal the molecular basis for high propionate yields in Bacteroidia, paving the road towards their biotechnological application for conversion of biomass-derived sugars to propionate.
RESULTS: We collected published information on propionate producing Bacteroidia, and selected ten species to be further examined. These species were grown under defined conditions to compare their product formation. While propionate, acetate, succinate, lactate and formate were produced, the product ratios varied greatly among the species. The two species with highest propionate yield, B. propionicifaciens (0.39 gpro/ggluc) and B. graminisolvens (0.25 gpro/ggluc), were further examined. Product formation and growth behavior differed significantly during CO2-limited growth and in resting cells experiments, as only B. graminisolvens depended on external-added NaHCO3, while their genome sequences only revealed few differences in the major catabolic pathways. Carbon mass and electron balances in experiments with resting cells were closed under the assumption that the oxidative pentose pathway was utilized for glucose oxidation next to glycolysis in B. graminisolvens. Finally, during pH-controlled fed-batch cultivation B. propionicifaciens and B. graminisolvens grew up to cell densities (OD600) of 8.1 and 9.8, and produced 119 mM and 33 mM of propionate from 130 and 105 mM glucose, respectively. A significant production of other acids, particularly lactate (25 mM), was observed in B. graminisolvens only.
CONCLUSIONS: We obtained the first broad overview and comparison of propionate production in Bacteroidia strains. A closer look at two species with comparably high propionate yields, showed significant differences in their physiology. Further studies may reveal the molecular basis for high propionate yields in Bacteroidia, paving the road towards their biotechnological application for conversion of biomass-derived sugars to propionate.
摘要：
背景：丙酸酯是一种食品防腐剂和平台化学品，但是还没有生物工艺与当前的石化生产路线竞争。尽管已经描述了拟杆菌类肠道细菌的丙酸生产，它还具有很大的降解植物聚合物的能力，关于跨物种的丙酸盐产量和生产率的知识很少。这项研究旨在比较Bacteroidia中葡萄糖的丙酸生产，并表征该组中良好的丙酸生产者。
结果：我们收集了有关生产丙酸杆菌的公开信息，并选择了十个物种进行进一步检查。这些物种在限定的条件下生长以比较它们的产物形成。虽然丙酸，醋酸盐,琥珀酸盐,产生了乳酸和甲酸，产品比例在物种之间差异很大。丙酸产量最高的两个物种，B.propinicfaciens(0.39gpro/ggluc)andB.graminisolvens(0.25gpro/ggluc),进一步检查。在CO2限制的生长和静息细胞实验中，产物形成和生长行为显着不同，因为只有B.graminisolvens依赖于外部添加的NaHCO3，而它们的基因组序列仅显示主要分解代谢途径的差异很少。在假设氧化戊糖途径用于葡萄糖氧化旁边的糖酵解的假设下，关闭了静息细胞实验中的碳质量和电子平衡。最后,在pH控制的补料分批培养过程中，丙酸芽孢杆菌和graminisolvens的细胞密度（OD600）达到8.1和9.8，并从130和105mM葡萄糖中产生119mM和33mM的丙酸盐，分别。大量生产其他酸，特别是乳酸（25mM），仅在B.graminisolvens中观察到。
结论：我们获得了拟杆菌菌株中丙酸盐生产的第一个广泛概述和比较。仔细观察两个丙酸产量相当高的物种，在生理上表现出显著差异。进一步的研究可能揭示了杆菌属中高丙酸产量的分子基础，为将生物质衍生糖转化为丙酸盐的生物技术应用铺平了道路。
结果：我们收集了有关生产丙酸杆菌的公开信息，并选择了十个物种进行进一步检查。这些物种在限定的条件下生长以比较它们的产物形成。虽然丙酸，醋酸盐,琥珀酸盐,产生了乳酸和甲酸，产品比例在物种之间差异很大。丙酸产量最高的两个物种，B.propinicfaciens(0.39gpro/ggluc)andB.graminisolvens(0.25gpro/ggluc),进一步检查。在CO2限制的生长和静息细胞实验中，产物形成和生长行为显着不同，因为只有B.graminisolvens依赖于外部添加的NaHCO3，而它们的基因组序列仅显示主要分解代谢途径的差异很少。在假设氧化戊糖途径用于葡萄糖氧化旁边的糖酵解的假设下，关闭了静息细胞实验中的碳质量和电子平衡。最后,在pH控制的补料分批培养过程中，丙酸芽孢杆菌和graminisolvens的细胞密度（OD600）达到8.1和9.8，并从130和105mM葡萄糖中产生119mM和33mM的丙酸盐，分别。大量生产其他酸，特别是乳酸（25mM），仅在B.graminisolvens中观察到。
结论：我们获得了拟杆菌菌株中丙酸盐生产的第一个广泛概述和比较。仔细观察两个丙酸产量相当高的物种，在生理上表现出显著差异。进一步的研究可能揭示了杆菌属中高丙酸产量的分子基础，为将生物质衍生糖转化为丙酸盐的生物技术应用铺平了道路。
