Characterization of low temperature microorganisms inhabiting in moss in Polar Regions on species identification, enzyme production and cold resistance.

对极地地区低温微生物特别是植物寄生真菌的菌种鉴定、产酶特性和抗寒性进行了研究，并对2002年从斯匹茨卑尔根岛分离到的6株木霉菌进行了菌种鉴定和产酶鉴定。根据培养条件下的形态特征和rDNA ITS区序列，所有菌株均被鉴定为多孢木霉。对北极多孢霉的三个代表性菌株进行了胞外酶的产生性试验。所有菌株在甜菜提取液中均能分泌木聚糖酶和聚半乳糖醛酸酶。在这些酶中，提纯了一种聚半乳糖醛酸酶(PG)。以从德国分离的多孢子丝菌分离株纯化的PG为对照。来自北极株的PG在40℃时表现出最高活性，即使在0℃时也有14%~47%的最大活性。而来自德国菌株的PG在50℃时活性最高，在0℃时达到最大值的0~4%。结果表明，北极多孢霉菌株是一株具有低温活性的腐霉的潜在来源。对来自斯皮茨卑尔根岛、格陵兰和乔治王岛的物种进行了鉴定。314个菌株被归类为未知腐霉属1~5种。在体外接种试验中，大多数菌株对苔藓和小麦叶片表现出致病活性。在琼脂上菌丝生长的最适温度为22~28℃。至少有一个北极腐霉菌株比其形态上相关的腐霉菌株具有更强的抗寒性。这些结果表明，极地地区生活着独特的腐霉物种。在本次调查中，我们开发了从自然环境条件中分离它们的腐霉选择性培养基。在本研究中，挪威斯瓦尔巴特群岛上的一种黑穗病真菌被鉴定为双孢小球菌属。

Low temperature microorganisms especially plant parasitic fungi inhabiting in Polar Regions were characterized on species identification, enzyme production and cold resistance.Six Trichoderma strains isolated from Spitsbergen Island in 2002 were examined on species identification and enzyme production. The all strains were identified as Trichoderma polysporum by their morphology in a cultivation condition and sequences of rDNA ITS regions. Three representative strains of the Arctic T. polysporum were tested on production of extracellular enzymes. The all strains were secreted xylanase and polygalacturonase in a sugar beet extract liquid medium. Among these enzymes, a polygalacturonase (PG) was purified. The purified PG from T. polysporum strains isolated from Germany was used as comparison. PG from the Arctic strain showed optimum activity at 40℃ and 14 to 47% of maximum even at 0℃. While PG from the German strain showed optimum activity at 50℃ and 0 to 4% of maximum at 0℃. The results indicate that the Arctic T. polysporum strains are potential source of a cold active PG.Pythium spp. from Spitsbergen Island, Greenland and King George Island were examined on species identification. The total 314 isolates were categorized as unknown Pythium species 1 to 5. Most of them showed pathogenicity to a moss (Sanionia uncinata) and wheat leaves in an in vitro inoculation test. Their optimum temperatures for hyphal growth on an agar culture were 22 to 28℃. At least one isolate of Arctic Pythium strains has greater resistance to freezing than a strain of its morphologically related Pythium speices. These results suggest unique species of Pythium inhabiting in Polar Regions. During this investigation, Pythium selective media for isolation them from natural environmental conditions were developed.A smut fungus on Polygonum viviparum in Svalbard, Norway was identified as Microbotryum bistortarum during this study.