Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile (USACH), Alameda 3363, Estación Central, 9170022, Santiago, Chile.
Appl Biochem Biotechnol. 2014 Jan;172(1):524-32. doi: 10.1007/s12010-013-0551-1. Epub 2013 Oct 6.
Despite their potential biotechnological applications, cold-active xylanolytic enzymes have been poorly studied. In this work, 38 fungi isolated from marine sponges collected in King George Island, Antarctica, were screened as new sources of cold-active xylanases. All of them showed xylanase activity at 15 and 23 °C in semiquantitative plate assays. One of these isolates, Cladosporium sp., showed the highest activity and was characterized in detail. Cladosporium sp. showed higher xylanolytic activity when grown on beechwood or birchwood xylan and wheat bran, but wheat straw and oat bran were not so good inducers of this activity. The optimal pH for xylanase activity was 6.0, although pH stability was slightly wider (pH 5-7). On the other hand, Cladosporium sp. showed high xylanase activity at low temperatures and very low thermal stability. Interestingly, thermal stability was even lower after culture media were removed and replaced by buffer, suggesting that low molecular component(s) of the culture media could be important in the stabilization of cold-active xylanase activity. To the best of our knowledge, this study is the first report on extracellular xylanase production by fungi associated with Antarctic marine sponges.
尽管冷活性木聚糖酶具有潜在的生物技术应用价值，但对其研究甚少。在这项工作中，从南极乔治王岛采集的海洋海绵中分离出的 38 株真菌被筛选为新型冷活性木聚糖酶的来源。所有这些真菌在 15 和 23°C 的半定量平板测定中都表现出木聚糖酶活性。其中一株分离株，即 Cladosporium sp.，表现出最高的活性，并进行了详细的特征描述。Cladosporium sp. 在以山毛榉木或桦木木聚糖和麦麸为碳源，以及在小麦秸秆和燕麦麸上生长时，显示出更高的木聚糖酶活性，但小麦秸秆和燕麦麸并不是该活性的良好诱导物。木聚糖酶活性的最适 pH 值为 6.0，尽管 pH 值稳定性稍宽（pH 5-7）。另一方面，Cladosporium sp. 在低温下和非常低的热稳定性下显示出高木聚糖酶活性。有趣的是，在培养基被去除并用缓冲液代替后，热稳定性甚至更低，这表明培养基中的低分子成分可能对冷活性木聚糖酶活性的稳定非常重要。据我们所知，这项研究是首次报道与南极海洋海绵相关的真菌产生细胞外木聚糖酶。
