VTT Technical Research Centre of Finland, Helsinki, Finland.
J Basic Microbiol. 2012 Apr;52(2):184-94. doi: 10.1002/jobm.201100053. Epub 2011 Jul 21.
Fungal infection of barley and malt, particularly by the Fusarium species, is a direct cause of spontaneous overfoaming of beer, referred to as gushing. We have shown previously that small fungal proteins, hydrophobins, act as gushing-inducing factors in beer. The aim of our present study was to isolate and characterize hydrophobins from a gushing-active fungus, Fusarium graminearum (teleomorph Gibberella zeae) and related species. We generated profile hidden Markov models (profile HMMs) for the hydrophobin classes Ia, Ib and II from the multiple sequence alignments of their known members available in public domain databases. We searched the published Fusarium graminearum genome with the Markov models. The best matching sequences and the corresponding genes were isolated from F. graminearum and the related species F. culmorum and F. poae by PCR and characterized. One each of the putative F. graminearum and F. poae hydrophobin genes were expressed in the heterologous host Trichoderma reesei. The proteins corresponding to the genes were purified and identified as hydrophobins and named GzHYD5 and FpHYD5, respectively. Concentrations of 0.003 ppm of these hydrophobins were observed to induce vigorous beer gushing.
大麦和麦芽的真菌感染，特别是镰刀菌属（Fusarium species），是啤酒自发过度发泡（喷涌）的直接原因。我们之前已经表明，小真菌蛋白——疏水性蛋白（hydrophobin）在啤酒中充当喷涌诱导因子。我们目前研究的目的是从喷涌活性真菌——禾谷镰刀菌（Gibberella zeae 的有性型）和相关物种中分离和表征疏水性蛋白。我们从公共数据库中已知成员的多重序列比对生成了疏水性蛋白类 Ia、Ib 和 II 的轮廓隐马尔可夫模型（profile HMM）。我们用 Markov 模型搜索已发表的禾谷镰刀菌基因组。通过 PCR 从禾谷镰刀菌和相关物种尖孢镰刀菌（F. culmorum）和匍匐镰刀菌（F. poae）中分离出最佳匹配的序列和相应的基因，并对其进行了表征。从禾谷镰刀菌和匍匐镰刀菌中各表达了一个假定的基因，在异源宿主里氏木霉（Trichoderma reesei）中表达。相应基因的蛋白被纯化并鉴定为疏水性蛋白，分别命名为 GzHYD5 和 FpHYD5。观察到这些疏水性蛋白的浓度为 0.003 ppm 时，可诱导强烈的啤酒喷涌。
