title: Identification of a laccase Glac15 from Ganoderma lucidum 77002 and its application in bioethanol production.
abstract: BACKGROUND
  Laccases have potential applications in detoxification of lignocellulosic biomass after thermochemical pretreatment and production of value-added products or biofuels from renewable biomass. However, their application in large-scale industrial and environmental processes has been severely thwarted by the high cost of commercial laccases. Therefore, it is necessary to identify new laccases with lower cost but higher activity to detoxify lignocellulosic hydrolysates and better efficiency to produce biofuels such as bioethanol. Laccases from Ganoderma lucidum represent proper candidates in processing of lignocellulosic biomass.
  
  
  RESULTS
  G. lucidum 77002 produces three laccase isoenzymes with a total laccase activity of 141.1 U/mL within 6 days when using wheat bran and peanut powder as energy sources in liquid culture medium. A new isoenzyme named Glac15 was identified, purified, and characterized. Glac15 possesses an optimum pH of 4.5 to 5.0 and a temperature range of 45°C to 55°C for the substrates tested. It was stable at pH values ranging from 5.0 to 7.0 and temperatures lower than 55°C, with more than 80% activity retained after incubation for 2 h. When used in bioethanol production process, 0.05 U/mL Glac15 removed 84% of the phenolic compounds in prehydrolysate, and the yeast biomass reached 11.81 (optimal density at 600 nm (OD600)), compared to no growth in the untreated one. Addition of Glac15 before cellulase hydrolysis had no significant effect on glucose recovery. However, ethanol yield were improved in samples treated with laccases compared to that in control samples. The final ethanol concentration of 9.74, 10.05, 10.11, and 10.81 g/L were obtained from samples containing only solid content, solid content treated with Glac15, solid content containing 50% prehydrolysate, and solid content containing 50% prehydrolysate treated with Glac15, respectively.
  
  
  CONCLUSIONS
  The G. lucidum laccase Glac15 has potentials in bioethanol production industry.
authors.affiliation: School of Life Sciences, Anhui University, 111 Jiulong Road, Hefei, Anhui 230601 China ; Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis, 111 Jiulong Road, Hefei, Anhui 230601 China.
authors.forename: Zemin
authors.initials: Z
authors.lastname: Fang
authors.affiliation: School of Life Sciences, Anhui University, 111 Jiulong Road, Hefei, Anhui 230601 China ; Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis, 111 Jiulong Road, Hefei, Anhui 230601 China.
authors.forename: Xiaoman
authors.initials: X
authors.lastname: Liu
authors.affiliation: The State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, 27 Shanda Nanlu, Jinan, Shandong 250100 China.
authors.forename: Liyuan
authors.initials: L
authors.lastname: Chen
authors.affiliation: The State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, 27 Shanda Nanlu, Jinan, Shandong 250100 China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Shen
authors.affiliation: School of Life Sciences, Anhui University, 111 Jiulong Road, Hefei, Anhui 230601 China ; Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis, 111 Jiulong Road, Hefei, Anhui 230601 China.
authors.forename: Xuecheng
authors.initials: X
authors.lastname: Zhang
authors.affiliation: School of Life Sciences, Anhui University, 111 Jiulong Road, Hefei, Anhui 230601 China ; Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis, 111 Jiulong Road, Hefei, Anhui 230601 China.
authors.forename: Wei
authors.initials: W
authors.lastname: Fang
authors.affiliation: Department of Chemistry & Biochemistry, Florida International University, Miami, FL 33199 USA.
authors.forename: Xiaotang
authors.initials: X
authors.lastname: Wang
authors.affiliation: The State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, 27 Shanda Nanlu, Jinan, Shandong 250100 China.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Bao
authors.affiliation: School of Life Sciences, Anhui University, 111 Jiulong Road, Hefei, Anhui 230601 China ; Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis, 111 Jiulong Road, Hefei, Anhui 230601 China.
authors.forename: Yazhong
authors.initials: Y
authors.lastname: Xiao
keywords: Bioethanol; Characterization; Detoxification; Ganoderma lucidum; Identification; Laccase