Department of Food and Environmental Sciences, University of Helsinki, Biocenter 1, P.O. Box 56, 00014, Helsinki, Finland.
Antonie Van Leeuwenhoek. 2013 Jun;103(6):1343-57. doi: 10.1007/s10482-013-9915-3. Epub 2013 Apr 5.
Inulin is a reserve carbohydrate in about 15 % of the flowering plants and is accumulated in underground tubers of e.g. chicory, dahlia and Jerusalem artichoke. This carbohydrate consists of linear chains of β-(2,1)-linked fructose attached to a sucrose molecule. Inulinases hydrolyse inulin into fructose and glucose. To find efficient inulin degrading fungi, 126 fungal strains from the Fungal Biotechnology Culture Collection (FBCC) at University of Helsinki and 74 freshly isolated strains from soil around Jerusalem artichoke tubers were screened in liquid cultures with inulin as a sole source of carbon or ground Jerusalem artichoke tubers, which contains up to 19 % (fresh weight) inulin. Inulinase and invertase activities were assayed by the dinitrosalicylic acid (DNS) method and a freshly isolated Penicillium strain originating from agricultural soil (FBCC 1632) was the most efficient inulinase producer. When it was cultivated at pH 6 and 28 °C in 2 litre bioreactors using inulin and Jerusalem artichoke as a carbon source, inulinase and invertase activities were on day 4 7.7 and 3.1 U mL(-1), respectively. The released sugars analysed by TLC and HPLC showed that considerable amounts of fructose were released while the levels of oligofructans were low, indicating an exoinulinase type of activity. Taxonomic study of the inulinase producing strain showed that this isolate represents a new species belonging in Penicillium section Lanata-divaricata. This new species produces a unique combination of extrolites and is phenotypically and phylogenetically closely related to Penicillium pulvillorum. We propose the name Penicillium subrubescens sp. nov. (CBS 132785(T) = FBCC 1632(T)) for this new species.
菊粉是约 15%的开花植物的储备碳水化合物，积累在菊苣、大丽花和洋蓟等地下块茎中。这种碳水化合物由β-(2,1)-连接的果糖线性链与蔗糖分子连接而成。菊粉酶将菊粉水解为果糖和葡萄糖。为了找到高效的菊粉降解真菌，从赫尔辛基大学的真菌生物技术培养物收集（FBCC）中筛选了 126 株真菌菌株，从洋蓟块茎周围的土壤中新鲜分离了 74 株菌株，在液体培养基中以菊粉作为唯一碳源或研磨的洋蓟块茎（含有高达 19%（鲜重）的菊粉）进行筛选。用二硝基水杨酸（DNS）法测定菊粉酶和转化酶的活性，从农业土壤中分离出的一株新的青霉菌株（FBCC 1632）是最有效的菊粉酶产生菌。当它在 pH 6 和 28°C 的 2 升生物反应器中以菊粉和洋蓟为碳源进行培养时，第 4 天的菊粉酶和转化酶活性分别为 7.7 和 3.1 U mL(-1)。TLC 和 HPLC 分析释放的糖表明，释放了相当数量的果糖，而低聚果糖的水平较低，表明存在外切菊粉酶类型的活性。产菊粉酶菌株的分类学研究表明，该分离株代表一个属于青霉节 Lanata-divaricata 的新种。这个新种产生了一种独特的外生代谢产物组合，在表型和系统发育上与青霉属 pulvillorum 密切相关。我们提议将这种新种命名为 Penicillium subrubescens sp. nov.（CBS 132785(T) = FBCC 1632(T)）。
