Fang Zemin, Liu Xiaoman, Chen Liyuan, Shen Yu, Zhang Xuecheng, Fang Wei, Wang Xiaotang, Bao Xiaoming, Xiao Yazhong
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.
The State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, 27 Shanda Nanlu, Jinan, Shandong 250100 China.
Biotechnol Biofuels. 2015 Mar 31;8:54. doi: 10.1186/s13068-015-0235-x. eCollection 2015.
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.
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.
The G. lucidum laccase Glac15 has potentials in bioethanol production industry.
漆酶在热化学预处理后木质纤维素生物质的解毒以及从可再生生物质生产增值产品或生物燃料方面具有潜在应用。然而，商业漆酶的高成本严重阻碍了其在大规模工业和环境过程中的应用。因此，有必要鉴定出成本更低但活性更高的新型漆酶，以解毒木质纤维素水解产物，并提高生产生物乙醇等生物燃料的效率。来自灵芝的漆酶是处理木质纤维素生物质的合适候选者。
灵芝77002在液体培养基中以麦麸和花生粉作为能源时，6天内产生三种漆酶同工酶，总漆酶活性为141.1 U/mL。一种名为Glac15的新同工酶被鉴定、纯化并表征。对于所测试的底物，Glac15的最适pH为4.5至5.0，温度范围为45°C至55°C。它在pH值5.0至7.0以及温度低于55°C时稳定，孵育2小时后活性保留超过80%。当用于生物乙醇生产过程时，0.05 U/mL的Glac15去除了预水解物中84%的酚类化合物，酵母生物量达到11.81（600nm处的最佳密度（OD600）），而未处理的样品中酵母无生长。在纤维素酶水解之前添加Glac15对葡萄糖回收率没有显著影响。然而，与对照样品相比，用漆酶处理的样品中乙醇产量有所提高。仅含固体成分、经Glac15处理的固体成分、含50%预水解物的固体成分以及经Glac15处理的含50%预水解物的固体成分的样品，最终乙醇浓度分别为9.74、10.05、10.11和10.81 g/L。
灵芝漆酶Glac15在生物乙醇生产行业具有潜力。
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