Melo-Nascimento Amanda O Dos S, Treumann Claudia, Neves Camila, Andrade Edmilson, Andrade Ana Camila, Edwards Robert, Dinsdale Elizabeth, Bruce Thiago
Department of Bioenergy, Faculdade de Tecnologia e Ciências, Laboratory of Environmental Biotechnology, Salvador, BA, Brazil.
Department of Microbiology, Universidade Federal da Bahia, Salvador, BA, Brazil.
Arch Microbiol. 2018 Oct;200(8):1267-1278. doi: 10.1007/s00203-018-1532-0. Epub 2018 Jun 11.
Overcoming recalcitrance of lignin has motivated bioprospecting of high-yielding enzymes from environmental ligninolytic microorganisms associated with lignocellulose degrading-systems. Here, we performed isolation of 21 ligninolytic strains belonging to the genus Klebsiella spp., driven by the presence of lignin in the media. The fastest-growing strains (FP10-5.23, FP10-5.22 and P3TM1) reached the stationary phase in approximately 24 h, in the media containing lignin as the main carbon source. The strains showed biochemical evidence of ligninolytic potential in liquid- and solid media-converting dyes, which the molecular structures are similar to lignin fragments. In liquid medium, higher levels of dye decolorization was observed for P3TM.1 in the presence of methylene blue, reaching 98% decolorization in 48 h. The highest index values (1.25) were found for isolates P3TM.1 and FP10-5.23, in the presence of toluidine blue. The genomic analysis revealed the presence of more than 20 genes associated with known prokaryotic lignin-degrading systems. Identification of peroxidases (lignin peroxidase-LiP, dye-decolorizing peroxidase-DyP, manganese peroxidase-MnP) and auxiliary activities (AA2, AA3, AA6 and AA10 families) among the genetic repertoire suggest the ability to produce extracellular enzymes able to attack phenolic and non-phenolic lignin structures. Our results suggest that the Klebsiella spp. associated with fresh water and soil may play important role in the cycling of recalcitrant molecules in the Caatinga (desert-like Brazilian biome), and represent a potential source of lignin-degrading enzymes with biotechnological applications.
克服木质素的顽固性推动了对与木质纤维素降解系统相关的环境木质素分解微生物中高产酶的生物勘探。在此，我们在培养基中木质素的驱动下，分离出了21株属于克雷伯氏菌属的木质素分解菌株。生长最快的菌株（FP10 - 5.23、FP10 - 5.22和P3TM1）在以木质素为主要碳源的培养基中约24小时达到稳定期。这些菌株在液体和固体培养基中转化染料时显示出木质素分解潜力的生化证据，这些染料的分子结构与木质素片段相似。在液体培养基中，P3TM.1在亚甲基蓝存在下表现出更高水平的染料脱色，48小时内脱色率达到98%。在甲苯胺蓝存在下，分离株P3TM.1和FP10 - 5.23的指数值最高（1.25）。基因组分析揭示了存在20多个与已知原核生物木质素降解系统相关的基因。在基因库中鉴定出过氧化物酶（木质素过氧化物酶 - LiP、染料脱色过氧化物酶 - DyP、锰过氧化物酶 - MnP）和辅助活性（AA2、AA3、AA6和AA10家族），表明其有能力产生能够攻击酚类和非酚类木质素结构的细胞外酶。我们的结果表明，与淡水和土壤相关的克雷伯氏菌属可能在卡廷加（类似沙漠的巴西生物群落）中顽固性分子的循环中发挥重要作用，并代表了具有生物技术应用潜力的木质素降解酶来源。
