基于木质素单体含量的园林生物质降解菌评价

基于降解剩余物中木质素单体含量变化,对园林生物质降解菌的酶解效果进行评价。以羧甲基纤维素钠为唯一碳源,对天然林下腐植质层降解菌进行功能筛选和分子鉴定;通过正交实验优化酶活力、降解试验分析降解失重率,经气相色谱-质谱联用技术测定降解剩余物中木质素单体含量,并综合评价降解效率。结果表明:酶活力较高的株菌QL-1、QL-4分别为曼氏假单胞菌(Pseudomonas mandelii)和烟曲霉(Aspergillus fumigatus),其纤维素酶活力分别为14.10 U·mL~(-1)和8.15 U·mL~(-1);培养10 d时两株菌的降解失重率达到最高,分别为9.48%和13.91%,是未添加降解菌株即空白对照组的2.49倍和3.66倍;愈创木基和紫丁香基木质素单体含量均有显著减少,10 d时QL-4试验组的净降解率为15.57%,是QL-1的3.15倍。研究表明,筛选所得烟曲霉具更强降解活力,其降解剩余物中木质素单体含量均有不同程度下降。

Evaluation of garden biomass-degrading bacteria based on lignin monomer content

Based on the change in the lignin monomer content in the degradation residue, the enzymatic hydrolysis effect of garden biomass-degrading bacteria was evaluated. Using sodium carboxymethyl cellulose as the sole carbon source, functional screening and molecular identification of natural understory humus layer-degrading bacteria were conducted. The enzyme activity was optimized through orthogonal experiments and a degradation test was used to analyze the degradation weight loss rate. Gas chromatography-mass spectrometry was used to determine the lignin monomer content in the degradation residue and comprehensively evaluate the degradation efficiency. Strains QL-1 and QL-4, which had a higher enzyme activity, were Pseudomonas mandelii and Aspergillus fumigatus, respectively, and their cellulase activities were 14.10 U·mL^-1 and 8.15 U·mL^-1, respectively. The degradation rates of the two strains reached the highest levels of 9.48% and 13.91%, respectively, when they were cultured for 10 days, which were 2.49 times and 3.66 times greater than that of the blank control group, respectively. There was a significant reduction in the lignin monomer contents of the guaiacyl and syringyl units. The net degradation rate of the QL-4 test group was 15.57% at 10 days, which was 3.15 times greater than that of QL-1. The screened Aspergillus fumigatus had a stronger degradation activity, and the lignin monomer content in the degradation residues decreased to different degrees.