不动杆菌Acinetobacter sp. TAC-1利用聚(3-羟基丁酸酯-co-3-羟基戊酸酯)的碳代谢机理

An examination of the carbon metabolic pathways in Acinetobacter sp. TAC-1 in the context of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) utilization

摘要:

为阐明异养硝化-好氧反硝化(heterotrophic nitrification-aerobic denitrification, HN-AD)菌株不动杆菌(Acinetobacter sp.) TAC-1利用聚(3-羟基丁酸酯-co-3-羟基戊酸酯) [poly (3-hydroxybutyrate-co-3-hydroxyvalerate), PHBV]的碳代谢途径，以乙酸钠(sodium acetate, SOA)为对照，考察TAC-1菌株基因水平上存在的碳水化合物代谢通路。全基因组测序结果表明，TAC-1菌株中存在gltA、icd、sucAB、acs和pckA等碳水化合物代谢酶编码基因；KEGG通路数据库注释进一步证实TAC-1菌株存在糖酵解途径(glycolytic pathway, EMP)、磷酸戊糖途径(pentose phosphate pathway, PPP)、乙醛酸循环(glyoxylate cycle, GAC)和三羧酸循环(tricarboxylic acid cycle, TCA cycle)等碳水化合物代谢通路；不同碳源的代谢物差异表达，进一步证实TAC-1菌利用PHBV的碳代谢途径为：PHBV (通过磷酸戊糖途径)→葡萄糖酸盐(通过糖酵解途径)→乙酰辅酶A (进入三羧酸循环)→CO₂+H₂O (产生电子供体并释放能量)。本研究有望为基于HN-AD和固体碳源的脱氮新工艺的开发和应用提供理论依据。

Abstract:

The present study aimed to unravel the carbon metabolism pathway of Acinetobacter sp. TAC-1, a heterotrophic nitrification-aerobic denitrification (HN-AD) strain that utilizes poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) as a carbon source. Sodium acetate was employed as a control to assess the gene expression of carbon metabolic pathways in the TAC-1 strain. The results of genome sequencing demonstrated that the TAC-1 strain possessed various genes encoding carbon metabolic enzymes, such as gltA, icd, sucAB, acs, and pckA. KEGG pathway database analysis further verified the presence of carbon metabolism pathways, including the glycolytic pathway (EMP), pentose phosphate pathway (PPP), glyoxylate cycle (GAC), and tricarboxylic acid (TCA) cycle in the TAC-1 strain. The differential expression of metabolites derived from distinct carbon sources provided further evidence that the carbon metabolism pathway of TAC-1 utilizing PHBV follows the sequential process of PHBV (via the PPP pathway)→gluconate (via the EMP pathway)→acetyl-CoA (entering the TCA cycle)→CO₂+H₂O (generating electron donors and releasing energy). This study is expected to furnish a theoretical foundation for the advancement and implementation of novel denitrification processes based on HN-AD and solid carbon sources.