摘要
目的:以不同植物中分离到的4株内生球毛壳菌NK102、NK103、NK104和NK105为对象,研究不同生态来源球毛壳菌降解木质素和纤维素的能力。方法:首先采用羧甲基纤维素和纤维素刚果红平板检测各菌株的纤维素降解能力,并利用Bavendamm平板反应检测各菌株的木质素降解能力;将4株菌分别培养在以微晶纤维素、杨树叶和木屑为惟一碳源的液体培养基中,通过检测培养液中纤维素酶和漆酶的酶活力,比较各菌株分解利用天然木质纤维素材料的能力,连续培养12 d后检测培养液中次级代谢产物的合成情况;利用已测序的球毛壳菌CBS148.51的基因组信息,寻找编码木质纤维素降解酶类的基因,为球毛壳菌分解利用木质纤维素提供分子生物学依据。结果:NK102、NK103、NK104和NK105在羧甲基纤维素培养基和纤维素刚果红培养基上都能够生长并形成水解圈;Bavendamm平板反应显示4株菌降解木质素的能力由强到弱依次是NK103、NK102、NK105和NK104。4株菌都能分解利用微晶纤维素、杨树叶和木屑,分泌纤维素酶和漆酶,其中NK102在以木屑为碳源的培养基上纤维素酶活力最强,达到0.76 U/mL发酵液,NK103在以杨树叶为碳源的培养基上漆酶活力最强。与此同时,4株菌在发酵培养过程中都能够稳定地合成球毛壳甲素(ChA),ChA产量受到碳源影响,在以杨树叶为碳源的培养基上,NK104的ChA产量最高,可达到14.88 mg/L发酵液。利用已测序的球毛壳菌CBS148.51的基因组信息,寻找到119个编码纤维素半纤维素酶的基因、8个编码漆酶的基因和2个编码锰过氧化物酶的基因,球毛壳菌具有完整的降解纤维素半纤维素的酶体系,在木质纤维素降解真菌的开发过程中具有重要的研究价值。结论:本研究为球毛壳菌木质纤维素降解过程的研究及该菌种的开发利用奠定了基础。
Objective: The decomposition abilities of lignocellulosic materials by Chaetomium globosum NK102, NK103, NK104 and NK105, endophytes from different plants were evaluated. Methods: The cellulose utilizing ca pability of the C.globosum isolates were tested on carboxymethylcellulose agar and cellulose-congo red agar. The lignin utilizing experiments were performed on Bavendamm plates, and the degradative activity was compared by measuring the respective zone of color change. The lignocellulases production potential of these isolates using mi crocrystalline cellulose, the leaves of Populus sp. and wood powder as the sole carbon source in liquid fermenta tion was assessed. In addition, secondary metabolites produced by the C.globosum isolates were detected after 12 days cultivation. In the sequenced genome of C.globosum CBS148.51, genes encoding enzymes involved in lignocel luloses degrading were identified by sequence homology alignment. Results: C.globosum NK102, NK103, NK104 and NK105 formed clear zones when cultured on carboxymethylcellulose or cellulose-congo red agar. In addition, all four isolates exhibited biodegradation capabilities against lignin and the strong-to-weak sequence was NK103, NK102, NK105 and NK104 by Bavendamm reaction. In liquid culture, all isolates secreted cellulases and laccase on agar containing microcrystalline cellulose, the leaves of Populus sp., and wood powder. The highest activity ofcellulase(0.76 U/mL) was obtained by NK102 when cultured on wood powder medium supplemented with peptone. The highest activity of laccase was obtained by NK103 when cultured on the leaves of Populus sp. medium. Chae toglobosin A(ChA) was detected in the cultue broth of all four isolates. The yield of ChA was affected by carbon biomass and the highest yield was obtained by NK104 when cultured on the leaves of Populus with a yield of 14.88 mg/L. In the sequenced genome of C.globosum CBS148.51, we defined 119 genes encoding enzymes in volved in cellulose and hemicellulose degradation, 8 genes for laccase and 2 genes for manganese peroxidase by sequence homology alignment, suggesting that C.globosum had a complete enzyme system on lignocelluloses utiliza- tion and deserved for further study for possible industrial and environmental application. Conclusion: This study shed lights on the molecular mechanism of lignocellulose-degrading in C.globosum and provided information for strain screening.
出处
《生物技术通讯》
CAS
2014年第1期1-8,共8页
Letters in Biotechnology
基金
国家自然科学基金(31170138)
高等学校博士学科点专项科研基金(20100031120023)
天津市应用基础与前沿技术研究计划(11JCYBJC09400)