Ali Nadia Sufdar, Huang Fang, Qin Wensheng, Yang Trent Chunzhong
Department of Biology, Lakehead University, Thunder Bay, ON, Canada.
Aquatic and Crop Resource Development Research Centre, National Research Council, Ottawa, ON, Canada.
Front Microbiol. 2022 Jul 18;13:878360. doi: 10.3389/fmicb.2022.878360. eCollection 2022.
Natural biodegradation processes hold promises for the conversion of agro-industrial lignocellulosic biomaterials into biofuels and fine chemicals through lignin-degrading enzymes. The high cost and low stability of these enzymes remain a significant challenge to economic lignocellulosic biomass conversion. Wood-degrading microorganisms are a great source for novel enzyme discoveries. In this study, the decomposed wood samples were screened, and a promising γ-proteobacterial strain that naturally secreted a significant amount of laccase enzyme was isolated and identified as AORB19 based on its phenotypic and genotypic characteristics. The laccase activities in culture medium of strain AORB19 were confirmed both qualitatively and quantitatively. Significant cultural parameters for laccase production under submerged conditions were identified following a one-factor-at-a-time (OFAT) methodology: temperature 30°C, pH 9, yeast extract (2 g/l), Li, Cu, Ca, and Mn (0.5 mM), and acetone (5%). Under the selected conditions, a 6-fold increase (73.3 U/L) in laccase production was achieved when compared with the initial culturing conditions (12.18 U/L). Furthermore, laccase production was enhanced under alkaline and mesophilic growth conditions in the presence of metal ions and organic solvents. The results of the study suggest the promising potential of the identified strain and its enzymes in the valorization of lignocellulosic wastes. Further optimization of culturing conditions to enhance the AORB19 strain laccase secretion, identification and characterization of the purified enzyme, and heterologous expression of the specific enzyme may lead to practical industrial and environmental applications.
自然生物降解过程有望通过木质素降解酶将农业工业木质纤维素生物材料转化为生物燃料和精细化学品。这些酶的高成本和低稳定性仍然是木质纤维素生物质经济转化的重大挑战。木材降解微生物是新型酶发现的重要来源。在本研究中，对分解的木材样本进行了筛选，分离出一种有前景的γ-变形菌菌株，该菌株自然分泌大量漆酶，并根据其表型和基因型特征鉴定为AORB19。对菌株AORB19培养基中的漆酶活性进行了定性和定量确认。采用一次单因素（OFAT）方法确定了在深层培养条件下漆酶产生的重要培养参数：温度30°C、pH 9、酵母提取物（2 g/l）、Li、Cu、Ca和Mn（0.5 mM）以及丙酮（5%）。在选定条件下，与初始培养条件（12.18 U/L）相比，漆酶产量提高了6倍（73.3 U/L）。此外，在金属离子和有机溶剂存在的情况下，在碱性和中温生长条件下漆酶产量得到提高。研究结果表明，所鉴定的菌株及其酶在木质纤维素废物增值方面具有广阔的潜力。进一步优化培养条件以提高AORB19菌株漆酶分泌、纯化酶的鉴定和表征以及特定酶的异源表达可能会带来实际的工业和环境应用。
