Si Wei, Wu ZhaoWei, Wang LiangLiang, Yang MingMing, Zhao Xin
College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi Province, People's Republic of China.
College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi Province, People's Republic of China; Department of Animal Science, McGill University, Quebec, Canada.
PLoS One. 2015 May 26;10(5):e0128204. doi: 10.1371/journal.pone.0128204. eCollection 2015.
Laccase is an enzyme that catalyzes oxidation of phenolic compounds, diamines and aromatic amines. In this study, a novel laccase-like gene (atm) in a ligninolyitic isolate Agrobacterium sp. S5-1 from soil humus was identified and heterologously expressed in Escherichia coli. Atm exhibited its maximal activity at pH 4.5 and at 50°C. This enzyme was tolerant to high temperature, a broad range of pH, heavy metal ions (Co3+, Mn2+, Cu2+ and Ni2+, 20 mM) and all tested organic solvents. Furthermore, Atm significantly (p<0.05) increased dry matter digestibility of maize straw from 23.44% to 27.96% and from 29.53% to 37.10% after 8 or 24 h of digestion and improved acid detergent fiber digestibility from 5.81% to 10.33% and from 12.80% to 19.07% after 8 or 24 h of digestion, respectively. The combination of Atm and fibrolytic enzymes significantly (p<0.05) enhanced neutral detergent fiber digestibility from 19.02% to 24.55% after 24 h of digestion respectively. Results showed treatment with Atm effectively improved in vitro digestibility of maize straw, thus suggesting that Atm has an application potential for bioconversion of lignin rich agricultural byproducts into animal feed and cellulosic ethanol.
漆酶是一种催化酚类化合物、二胺和芳香胺氧化的酶。在本研究中，从土壤腐殖质中分离得到的木质素降解菌农杆菌属菌株S5-1中的一个新型漆酶样基因（atm）被鉴定出来，并在大肠杆菌中进行了异源表达。Atm在pH 4.5和50°C时表现出最大活性。该酶耐高温、耐广泛的pH范围、耐重金属离子（Co3+、Mn2+、Cu2+和Ni2+，20 mM）以及所有测试的有机溶剂。此外，Atm在消化8小时或24小时后，显著（p<0.05）提高了玉米秸秆的干物质消化率，从23.44%提高到27.96%，从29.53%提高到37.10%；在消化8小时或24小时后，分别将酸性洗涤纤维消化率从5.81%提高到10.33%，从12.80%提高到19.07%。Atm与纤维分解酶的组合在消化24小时后，显著（p<0.05）提高了中性洗涤纤维消化率，从19.02%提高到24.55%。结果表明，Atm处理有效地提高了玉米秸秆的体外消化率，因此表明Atm在将富含木质素的农业副产品生物转化为动物饲料和纤维素乙醇方面具有应用潜力。
