Panwar Deepesh, Stewart William A, Rodd Andrew, Brumer Harry
Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada.
Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada.
J Bacteriol. 2025 Aug 21;207(8):e0019825. doi: 10.1128/jb.00198-25. Epub 2025 Jul 21.
Synthetic ethers of cellulose (β(1,4)-glucan) are widely used in the food and pharmaceutical industry as thickeners, gelling agents, emulsifiers, and stabilizers. Consequently, humans ingest significant amounts of artificial cellulose derivatives in diets containing processed foods and through oral drug formulations. In the present study, we examined the potential of mixed-linkage β-glucan (MLG) and xyloglucan (XyG) polysaccharide utilization loci of autochthonous human gut (gastrointestinal tract) Bacteroidota to enable metabolism of artificial cellulose derivatives, based on the commonality of their backbone linkages. Two representative and six representative (syn. ) strains all failed to grow on carboxymethyl cellulose (CMC, E466), methyl cellulose (MC, E461), hydroxypropyl methyl cellulose (HPMC, E464), and hydroxyethyl cellulose (HEC) as sole carbohydrate sources. However, remarkably, collateral metabolism of cellulose ethers was observed when bacteria were primed with low levels of cereal MLG or dicot XyG, in a species-dependent, strain-dependent, and polysaccharide-dependent manner. Using the type strain DSM18205 as an example, cellulose derivative utilization was rationalized by demonstrating that outer membrane-localized -glucanases were both transcriptionally upregulated and possessed side activities toward CMC, MC, HPMC, and/or HEC. On one hand, our results counter the conventional wisdom that soluble cellulose derivatives are non-metabolizable in the human gut. On the other hand, our study suggests that broader analysis of this underappreciated metabolic ability is warranted in a wider range of taxa, especially in consideration of potential physiological effects in the context of balanced diets comprising plant polysaccharides.IMPORTANCEOur data reveal a previously unknown potential among members of the human gut microbiota to metabolize artificial cellulose derivatives used in processed food and oral pharmaceuticals, which is driven by plant glycans ubiquitous in well-balanced diets containing natural dietary fiber. These results challenge the conventional wisdom that cellulose ethers are not broken down and metabolized in monogastric animals and motivate broader exploration of this phenomenon across the numerous autochthonous taxa.
纤维素（β(1,4)-葡聚糖）的合成醚作为增稠剂、胶凝剂、乳化剂和稳定剂，在食品和制药工业中被广泛使用。因此，人类在食用含有加工食品的饮食以及通过口服药物制剂时，会摄入大量的人造纤维素衍生物。在本研究中，我们基于其主链连接的共性，研究了人类肠道（胃肠道）拟杆菌门中混合连接β-葡聚糖（MLG）和木葡聚糖（XyG）多糖利用位点使人工纤维素衍生物代谢的潜力。两株代表性的[具体菌株1]和六株代表性的[具体菌株2]（同义词[具体名称]）菌株均不能以羧甲基纤维素（CMC，E466）、甲基纤维素（MC，E461）、羟丙基甲基纤维素（HPMC，E464）和羟乙基纤维素（HEC）作为唯一碳源生长。然而，值得注意的是，当用低水平的谷物MLG或双子叶植物XyG对细菌进行预处理时，观察到了纤维素醚的旁系代谢，且这种代谢具有物种依赖性、菌株依赖性和多糖依赖性。以模式菌株[具体菌株名称] DSM18205为例，通过证明外膜定位的β-葡聚糖酶在转录水平上上调且对CMC、MC、HPMC和/或HEC具有副活性，解释了纤维素衍生物的利用情况。一方面，我们的结果与传统观念相悖，即可溶性纤维素衍生物在人类肠道中不可代谢。另一方面，我们的研究表明，鉴于在包含植物多糖的均衡饮食背景下的潜在生理效应，有必要在更广泛的分类群中对这种未被充分认识的代谢能力进行更广泛的分析。重要性我们的数据揭示了人类肠道微生物群成员中一种以前未知的代谢加工食品和口服药物中使用的人工纤维素衍生物的潜力，这种潜力是由富含天然膳食纤维的均衡饮食中普遍存在的植物聚糖驱动的。这些结果挑战了纤维素醚在单胃动物中不会被分解和代谢的传统观念，并促使人们对众多本土分类群中的这一现象进行更广泛的探索。
