假单胞菌属LFM046中丙酸的氧化：与含奇数链长单体和2-甲基异柠檬酸的聚羟基脂肪酸酯合成的相关性。

Oxidation of propionate in Pseudomonas sp. LFM046: Relevance to the synthesis of polyhydroxyalkanoates containing odd-chain length monomers and 2-methylisocitrate.

作者信息

Santos-Oliveira Pedro Henrique, Machado Nathália Fernandes Gonçalves, de Oliveira Rafael David, Velasco-Yépez Eric André, da Silva Sonia Regina, Santos Rocha Rafael Costa, Blank Lars Mathias, da Silva Luiziana Ferreira, Le Roux Galo Antonio Carrillo, Gomez José Gregório Cabrera

机构信息

Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil; iAMB - Institute of Applied Microbiology, ABBt - Aachen Biology and Biotechnology,RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany.

Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil.

出版信息

Bioresour Technol. 2023 Oct 28:129944. doi: 10.1016/j.biortech.2023.129944.

DOI:10.1016/j.biortech.2023.129944

PMID:39492536

Abstract

Pseudomonas sp. LFM046 produces polyhydroxyalkanoates of medium-chain length. When carbohydrates are used, only monomers of even-length chains (3HA) are generated. Propionate, when used as a co-substrate, enabled the synthesis of odd-chain length monomers, albeit with poor yields (Y) of approx. 10 % A mini-Tn5 mutant (LFM693) was generated by interrupting the prpB gene, which encodes the 2-methylisocitrate lyase responsible for one step in propionate oxidation via 2-methylcitrate cycle. At low propionate concentrations of 0.1-0.3 g.L, LFM693 showed higher Y. In contrast, the propionyl incorporation into the polymer was less efficient at high propionate concentrations. The excretion of 2-methylisocitrate partially explained this reduced efficiency. However, mass balances and C isotopomer analysis revealed significant propionate oxidation in LFM693 of 21 % and 46 % for propionate concentrations of 0.5 and 1.0 g.L, respectively. Experiments using C1-labeled (C) propionate revealed an alternative propionate oxidation pathway (α-oxidation, β-oxidation, or 3-methylmalate) whose genes are yet to be revealed.

摘要

假单胞菌属LFM046可产生中链长度的聚羟基脂肪酸酯。当使用碳水化合物时，仅生成偶数链长度的单体（3HA）。当丙酸盐用作共底物时，能够合成奇数链长度的单体，尽管产率（Y）较低，约为10%。通过中断prpB基因产生了一个mini-Tn5突变体（LFM693），该基因编码负责通过2-甲基柠檬酸循环进行丙酸盐氧化的一步反应的2-甲基异柠檬酸裂解酶。在0.1 - 0.3 g.L的低丙酸盐浓度下，LFM693表现出更高的Y。相比之下，在高丙酸盐浓度下，丙酰基掺入聚合物的效率较低。2-甲基异柠檬酸的排泄部分解释了这种效率降低的现象。然而，质量平衡和C同位素异构体分析表明，对于0.5和1.0 g.L的丙酸盐浓度，LFM693中丙酸盐的氧化率分别为21%和46%。使用C1标记（C）丙酸盐的实验揭示了一条替代的丙酸盐氧化途径（α-氧化、β-氧化或3-甲基苹果酸途径），其相关基因尚未被揭示。