Novozymes A/S, Kalundborg, DK-4400, Denmark.
Novozymes A/S, Lyngby, DK-2800, Denmark.
J Ind Microbiol Biotechnol. 2021 Apr 30;48(1-2). doi: 10.1093/jimb/kuab008.
This study evaluates peptidoglycan hydrolysis by a microbial muramidase from the fungus Acremonium alcalophilum in vitro and in the gastrointestinal tract of broiler chickens. Peptidoglycan used for in vitro studies was derived from 5 gram-positive chicken gut isolate type strains. In vitro peptidoglycan hydrolysis was studied by three approaches: (a) helium ion microscopy to identify visual phenotypes of hydrolysis, (b) reducing end assay to quantify solubilization of peptidoglycan fragments, and (c) mass spectroscopy to estimate relative abundances of soluble substrates and reaction products. Visual effects of peptidoglycan hydrolysis could be observed by helium ion microscopy and the increase in abundance of soluble peptidoglycan due to hydrolysis was quantified by a reducing end assay. Mass spectroscopy confirmed the release of hydrolysis products and identified muropeptides from the five different peptidoglycan sources. Peptidoglycan hydrolysis in chicken crop, jejunum, and caecum samples was measured by quantifying the total and soluble muramic acid content. A significant increase in the proportion of the soluble muramic acid was observed in all three segments upon inclusion of the microbial muramidase in the diet.
本研究评估了来自嗜碱性枝顶孢霉（Acremonium alcalophilum）的微生物黏肽酶在体外和肉鸡胃肠道中的黏肽水解作用。用于体外研究的黏肽来自 5 株革兰氏阳性鸡肠道分离株。通过三种方法研究体外黏肽水解：（a）氦离子显微镜鉴定水解的可见表型，（b）还原末端测定法定量黏肽片段的溶解，以及（c）质谱估计可溶性底物和反应产物的相对丰度。通过氦离子显微镜可以观察到黏肽水解的视觉效果，通过还原末端测定法定量了由于水解而增加的可溶性黏肽的含量。质谱证实了水解产物的释放，并从五种不同的黏肽来源中鉴定了肽聚糖。通过定量测定鸡嗉囊、空肠和盲肠样品中的总和可溶性胞壁酸含量来测量黏肽水解。在日粮中添加微生物黏肽酶后，在所有三个肠段中都观察到可溶性胞壁酸的比例显著增加。
