Department of Genetics & Microbiology, University of Liverpool, Liverpool L69 3BX, United Kingdom, and Unité de Physiologie et Ecologie Microbienne, Faculté des Sciences, Université Libre de Bruxelles, CERIA 1, B-1070 Brussels, Belgium.
Appl Environ Microbiol. 1990 Oct;56(10):3017-22. doi: 10.1128/aem.56.10.3017-3022.1990.
Actinomycetes grown on wheat straw solubilized a lignocarbohydrate fraction which could be recovered by acid precipitation. Further characterization of this product (APPL) during growth of Streptomyces sp. strain EC1 revealed an increase in carboxylic acid and phenolic hydroxyl content, suggesting progressive modification. This was also observed in dioxane-extracted lignin fractions of degraded straw, and some similarity was further suggested by comparative infrared spectroscopy. However, the molecular weight profile of APPL was relatively constant during growth of Streptomyces sp. strain EC1 on straw, while analysis of the dioxane-extracted lignin fractions appeared to show fragmentation followed by repolymerization. Lignocarbohydrate solubilization could be monitored in all cultures by routine assay of APPL-associated protein, which accounted for up to 20% of the extracellular culture protein in some cases. Interestingly, this protein fraction was found to include active hydrolytic and oxidative enzymes involved in the degradation of lignocellulose, and specific enzyme activities were often increased in the acid-insoluble fractions of culture supernatants. This was particularly important for peroxidase and veratryl oxidase activities, which could be readily detected in the acid-precipitable lignocarbohydrate complex but were virtually undetectable in untreated culture supernatants.
在麦草上生长的放线菌能溶解一种木质碳水化合物的组分，可以通过酸沉淀回收。在链霉菌 EC1 生长过程中对这种产物（APPL）的进一步研究发现，羧酸和酚羟基的含量增加，表明其在不断修饰。在经过降解的麦草的二氧杂环己烷提取木质素组分中也观察到这种现象，通过比较红外光谱，还有一些相似性。然而，在链霉菌 EC1 利用麦草生长过程中，APPL 的分子量分布相对稳定，而对二氧杂环己烷提取木质素的分析似乎显示了碎片的形成，随后又发生了重聚合。在所有的培养物中，通过 APPL 相关蛋白的常规测定都能监测到木质碳水化合物的溶解，在某些情况下，它占细胞外培养蛋白的 20%。有趣的是，该蛋白组分中还包括参与木质纤维素降解的具有活性的水解酶和氧化酶，在培养物上清液的酸不溶性部分中，这些酶的活性常常增加。这对过氧化物酶和藜芦醛氧化酶的活性尤其重要，因为它们可以在可沉淀的酸处理木质碳水化合物复合物中很容易地检测到，但在未经处理的培养物上清液中几乎检测不到。
