Department of Biology, Faculty of Science, Mahidol University, Thung Phaya Thai, Ratchathewi, Bangkok, 10400, Thailand.
Department of Biochemistry, Faculty of Science, Mahidol University, Thung Phaya Thai, Ratchathewi, Bangkok, 10400, Thailand.
Sci Rep. 2024 Jun 10;14(1):13350. doi: 10.1038/s41598-024-64237-8.
Lignin, a heterogeneous aromatic polymer present in plant biomass, is intertwined with cellulose and hemicellulose fibrils, posing challenges to its effective utilization due to its phenolic nature and recalcitrance to degradation. In this study, three lignin utilizing bacteria, Klebsiella sp. LEA1, Pseudomonas sp. LEA2, and Burkholderia sp. LEA3, were isolated from deciduous forest soil samples in Nan province, Thailand. These isolates were capable of growing on alkali lignin and various lignin-associated monomers at 40 °C under microaerobic conditions. The presence of Cu significantly enhanced guaiacol oxidation in Klebsiella sp. LEA1 and Pseudomonas sp. LEA2. Lignin-related monomers and intermediates such as 2,6-dimethoxyphenol, 4-vinyl guaiacol, 4-hydroxybenzoic acid, benzoic acid, catechol, and succinic acid were detected mostly during the late stage of incubation of Klebsiella sp. LEA1 and Pseudomonas sp. LEA2 in lignin minimal salt media via GC-MS analysis. The intermediates identified from Klebsiella sp. LEA1 degradation suggested that conversion and utilization occurred through the β-ketoadipate (ortho-cleavage) pathway under limited oxygen conditions. The ability of these bacteria to thrive on alkaline lignin and produce various lignin-related intermediates under limited oxygen conditions suggests their potential utility in oxygen-limited processes and the production of renewable chemicals from plant biomass.
木质素是一种存在于植物生物质中的杂芳族聚合物，与纤维素和半纤维素纤维交织在一起，由于其酚类性质和对降解的抗性，使其难以有效利用。在这项研究中，从泰国那空叻差是玛府的落叶林土壤样本中分离出了三种木质素利用细菌，分别是克雷伯氏菌（Klebsiella） LEA1、假单胞菌（Pseudomonas） LEA2 和伯克霍尔德氏菌（Burkholderia） LEA3。这些分离株能够在 40°C 下微氧条件下在堿木质素和各种木质素相关单体上生长。Cu 的存在显著增强了 Klebsiella sp. LEA1 和 Pseudomonas sp. LEA2 对愈创木酚的氧化作用。木质素相关单体和中间体，如 2,6-二甲氧基苯酚、4-乙烯基愈创木酚、4-羟基苯甲酸、苯甲酸、儿茶酚和琥珀酸，主要在 Klebsiella sp. LEA1 和 Pseudomonas sp. LEA2 用木质素最小盐培养基进行培养的后期通过 GC-MS 分析检测到。从 Klebsiella sp. LEA1 降解中鉴定出的中间体表明，在有限氧气条件下，通过β-酮己二酸（邻位裂解）途径发生了转化和利用。这些细菌在堿性木质素上生长并在有限氧气条件下产生各种木质素相关中间体的能力表明它们在缺氧过程和从植物生物质生产可再生化学品方面具有潜在的应用价值。
