title: Enzymological Characterization of Atm, the First Laccase from Agrobacterium sp. S5-1, with the Ability to Enhance In Vitro digestibility of Maize Straw.
abstract: 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.
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi Province, People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Si
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi Province, People's Republic of China.
authors.forename: ZhaoWei
authors.initials: Z
authors.lastname: Wu
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi Province, People's Republic of China.
authors.forename: LiangLiang
authors.initials: L
authors.lastname: Wang
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi Province, People's Republic of China.
authors.forename: MingMing
authors.initials: M
authors.lastname: Yang
authors.affiliation: 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.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhao
mesh_terms: D060054:Agrobacterium / Q000201:enzymology*; D001426:Bacterial Proteins / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D042845:Laccase / Q000737:chemistry*; D008031:Lignin / Q000737:chemistry*; D019216:Metals, Heavy / Q000737:chemistry; D003313:Zea mays / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D019216:Metals, Heavy; C036909:lignocellulose; D008031:Lignin; D042845:Laccase