PDF(Pubmed)
Abstract：
The large molecular weight and high viscosity of natural konjac glucomannan (KGM) limit its industrial application. Microbial degradation of low-molecular-weight KGM has health benefits and various biological functions; however, the available KGM strains used in the industry have microbial contamination and low degradation efficiencies. Therefore, exploring novelly adaptable strains is critical for industrial processes. Here, the Bacillus licheniformis Z7-1 strain isolated from decaying konjac showed high efficiency for KGM degradation. The monosaccharide composition of the degradation products had a reduced molar ratio of mannose to glucose, indicating that Z7-1 preferentially degraded glucose in KGM. The degraded component was further characterized by ESI-MS, Fourier-transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM), and it also exhibited good antibacterial activity against various food-spoilage bacteria. Genome sequencing and zymolytic analysis revealed that abundant carbohydrate-active enzymes exist in the Z7-1 genome, with at least five types of extracellular enzymes responsible for KGM degradation, manifesting multi-enzyme synergetic action. The extracellular enzymes had significant thermal stability, indicating their potential application in industry. This study provides an alternative method for obtaining low-molecular-weight KGM with antibacterial functions and supports foundational knowledge for its development as a biocatalyst for the direct conversion of biomass polysaccharides into functional components.
摘要：
天然魔芋葡甘聚糖(KGM)的大分子量和高粘度限制了其工业应用。低分子量KGM的微生物降解具有健康益处和各种生物学功能；然而，在工业中使用的可用KGM菌株具有微生物污染和低降解效率。因此,探索新的适应性菌株对于工业过程至关重要。这里,从腐烂的魔芋中分离出的地衣芽孢杆菌Z7-1菌株对KGM降解具有很高的效率。降解产物的单糖组成具有降低的甘露糖与葡萄糖的摩尔比,表明Z7-1优先降解KGM中的葡萄糖。降解的组分通过ESI-MS进一步表征，傅里叶变换红外光谱(FT-IR),和扫描电子显微镜（SEM），对各种食品腐败菌也表现出良好的抗菌活性。基因组测序和酶解分析表明，Z7-1基因组中存在丰富的碳水化合物活性酶，具有至少五种负责KGM降解的胞外酶，表现出多酶协同作用。胞外酶具有显著的热稳定性,表明它们在工业中的潜在应用。这项研究提供了一种获得具有抗菌功能的低分子量KGM的替代方法，并支持了其作为将生物质多糖直接转化为功能成分的生物催化剂的开发的基础知识。
