Preserving boiled eggs with a sterilization system employing microbial laccase and wood vinegar

A combination of a microbial laccase and wood vinegar was used to treat the shell surface of boiled eggs. The laccase enhanced the sterilization effect of phenolic compounds contained in the wood vinegar and resulted in prevention of microbial infection of the boiled eggs after storage for 21 days at 40°C and 75% relative humidity. Significant phenoxy radicals, formed by the catalytic reaction of the laccase, could be detected in the shell of the boiled eggs.     

Laccase Gene LAC1 of Colletotrichum lagenarium Is Not Essential for Melanin Biosynthesis and Pathogenicity

Laccase has been shown to oxidize 1,8-dihydroxynaphthalene (1,8-DHN) in the final step of melanin biosynthesis in several fungi. In this study, a laccase gene (LAC1) was cloned from Colletotrichum lagenarium that synthesizes 1,8-DHN melanin, and characterized. To clone the LAC1 sequences, genomic DNA was subject to polymerase chain reactions (PCR) with degenerate oligonucleotide primers that were designed on the basis of amino acid sequences conserved among characterized laccases from other ascomycetes Botrytis cinerea, Neurospora crassa, Aspergillus nidulans, and Cryphonectria parasiticus. The LAC1 gene contained an open reading frame composed of 589 codons and three introns of 51, 49, and 57 nucleotides. The deduced amino acid sequence of Lac1p had high similarity to that of laccase from N. crassa and significant homology with those of multicopper blue proteins. Under melanin-induced culture of this fungus, laccase activity significantly increased and LAC1 expression was also detected. However, the lac1Δ mutants retained laccase activity and had no significant phenotypic differences in melanin production or pathogenicity from the wild-type strain. Received 23 February 2001/ Accepted in revised form 29 March 2001     

一株产漆酶细菌的分离、鉴定及对造纸黑液处理的初步研究

利用铜离子作为筛选剂,从凉水国家级自然保护区的土样中分离纯化出一株具有高漆酶活性的细菌.通过形态学观察、生理生化特性测定及16S rDNA序列分析,鉴定其为枯草芽孢杆菌(Bacillus subtilis),命名为B.subtilis WD23.根据GenBank上公布的Baccillus subtilis cotA ...     

12个金针菇菌株菌丝的生长速度及胞外酶活力比较

主要比较了生产上常用的12个金针菇[Flammulina velutiper(Fr.)Sing.]菌株菌丝的生长速度及菌落特征,同时,对12个菌株的胞外酶,如羧甲基纤维素酶、木聚糖酶、漆酶的活力进行了测定,以期找出菌丝生长速度与胞外酶活力的相关性,为正确评价菌种质量提供科学依据。结果表明,12个菌株间菌丝生长速度存在差异,在PDA加富培养基上生长较快的菌株是9号和12号;在模拟出菇培养基上生长较快的菌株是7号、8号和12号。羧甲基纤维素酶活力最高的菌株是5号,木聚糖酶和漆酶活力最高的菌株是1号。胞外酶活力大小表现的顺序与生长速度偶联性较差。     

纳米纤维制备过程中酶处理对分散性能的影响

植物纤维原料中少量的纤维素、半纤维素及木质素之间存在着醚键、酯键和苯基糖苷键等化学键联结,形成木质素碳水化合物复合体(LCCs),而这种共价键联接可能使微纤丝难以彻底解离成纳米纤维,由此影响到纳米纤维的分散及稳定性能.试验以漂白硫酸盐云杉木浆为原料,经打浆、磨浆及高压均质处理的常规制备纳米纤维流程,在高压均质前增加木聚糖酶/漆酶体系处理环节,研究探讨其对纳米纤维分散及稳定性能的影响.结果表明,经木聚糖酶和漆酶处理后,红外吸收光谱分析发现在811 cm-1处的半乳葡甘聚糖、896 cm-1处异头碳(C1)伸缩振动、1 056 cm-1处苯环伸展振动(木素)、1 161 cm-1处C-O-C不对称伸展振动、1 460 cm-1处-CH2变形振动(木质素苯环间侧链)等特征吸收峰强度均明显减弱或消失,表明存在于微纤丝之间的半纤维素和木质素发生降解,LC键发生断裂.同时,经过木聚糖酶和漆酶处理后,SEM显示纤维结构变得疏松、表面裂纹及孔隙变大;经高压均质处理后制得的纳米纤维,其水相分散及稳定性能得到明显提高.     

美味牛肝菌合成漆酶的发酵条件研究

[目的]研究美味牛肝菌合成漆酶的最适发酵条件。[方法]采用液体深层培养法研究不同碳源、氮源、pH、温度等因素对美味牛肝菌产酶量的影响。[结果]美味牛肝菌合成漆酶的最适发酵条件为：葡萄糖2.0%,牛肉膏0.5%,KH2PO4 0.4%,MgSO4.7H2O 0.3%,微量元素溶液8.0%,维生素B1 0.003%,pH 4.5,温度28℃,培养时间为8 d。[结论]在此条件下,漆酶产量最高,为71.27 U/ml,该研究为美味牛肝菌漆酶的开发应用提供了科学依据。     

漆树酶催化氧化甲苯-3,4-二硫酚

以漆树酶催化氧化甲苯－３,４－二硫酚并在产品分离纯化和光谱分析,确定产物结构。     

红平菇木质素降解酶系统漆酶、锰过氧化物酶及木质素过氧化物酶的检测

木材白腐菌在分解木质素的过程中会产生非特异性的分解木质素结构的酶系统,这些酶系统主要包括细胞外过氧化物酶[锰过氧化物酶(manganese peroxidase,MnP)、木质素过氧化物酶(lignin peroxidase,LiP)]和细胞外酚氧化酶[漆酶(laccase)].因此,在生物修复方面,白腐菌能够有效地降解废水和土壤中难被降解的多氯联苯、多环芳烃、DDT、染料、炸药和其他氯化物、叠氮化合物等.     

烟草木质素降解菌的筛选及在烟草中的应用

 采用木质素含量较高的烟梗为筛选材料,分离筛选到一株具有降烟草木质素功能的真菌,并测定了该菌的产酶活性、代谢物中挥发性成分及粗酶液在烟草快速陈化中的作用。结果表明：（1）该菌在15 d可产生最高酶活 1 920 U/L;（2）发酵液中挥发性成分主要为倍半萜烯醇、萜烯醇类烟草本香成分;（3）经膜过滤后的粗酶液在烟草快速陈化过程中降低烟草木质素含量达8%以上,可降低烟叶呛咳和刺激性,提高抽吸品质。     

基因工程菌漆酶降解2-氯苯酚的研究

利用基因工程菌甲醇毕赤酵母(PMAD16/pMET(A-Lcc1)培养产生的重组漆酶,研究了重组漆酶对降解2-氯苯酚的影响。结果表明:重组漆酶对2-氯苯酚降解的最佳pH值为6.0,温度为50℃,当溶液中漆酶活力为1.2 U/mL时,在最适脱色条件下作用6 h,粗漆酶和纯化漆酶对2-氯苯酚(250 mg/L)的降解率分别为91.3%和88.2%,重组漆酶可有效地降解2-氯苯酚。