Berlemont Renaud, Pipers Delphine, Delsaute Maud, Angiono Federico, Feller Georges, Galleni Moreno, Power Pablo
Laboratoire de Macromolécules Biologiques, Centre d'Ingénierie des Protéines, Université de Liège, Belgium.
Rev Argent Microbiol. 2011 Apr-May;43(2):94-103. doi: 10.1590/S0325-75412011000200005.
Metagenomic library PP1 was obtained from Antarctic soil samples. Both functional and genotypic metagenomic screening were used for the isolation of novel cold-adapted enzymes with potential applications, and for the detection of genetic elements associated with gene mobilization, respectively. Fourteen lipase/esterase-, 14 amylase-, 3 protease-, and 11 cellulase-producing clones were detected by activity-driven screening, with apparent maximum activities around 35 °C for both amylolytic and lipolytic enzymes, and 35-55 °C for cellulases, as observed for other cold-adapted enzymes. However, the behavior of at least one of the studied cellulases is more compatible to that observed for mesophilic enzymes. These enzymes are usually still active at temperatures above 60 °C, probably resulting in a psychrotolerant behavior in Antarctic soils. Metagenomics allows to access novel genes encoding for enzymatic and biophysic properties from almost every environment with potential benefits for biotechnological and industrial applications. Only intI- and tnp-like genes were detected by PCR, encoding for proteins with 58-86 %, and 58-73 % amino acid identity with known entries, respectively. Two clones, BAC 27A-9 and BAC 14A-5, seem to present unique syntenic organizations, suggesting the occurrence of gene rearrangements that were probably due to evolutionary divergences within the genus or facilitated by the association with transposable elements. The evidence for genetic elements related to recruitment and mobilization of genes (transposons/integrons) in an extreme environment like Antarctica reinforces the hypothesis of the origin of some of the genes disseminated by mobile elements among "human-associated" microorganisms.
宏基因组文库PP1是从南极土壤样本中获得的。功能宏基因组筛选和基因型宏基因组筛选分别用于分离具有潜在应用价值的新型低温适应酶，以及检测与基因转移相关的遗传元件。通过活性驱动筛选检测到14个产脂肪酶/酯酶、14个产淀粉酶、3个产蛋白酶和11个产纤维素酶的克隆，如其他低温适应酶一样，淀粉分解酶和脂肪分解酶的表观最大活性约为35℃，纤维素酶的表观最大活性为35 - 55℃。然而，至少一种被研究的纤维素酶的行为与嗜温酶更为相似。这些酶通常在60℃以上仍有活性，这可能导致南极土壤中出现耐冷行为。宏基因组学能够从几乎每个环境中获取编码酶和生物物理特性的新基因，这对生物技术和工业应用具有潜在益处。通过PCR仅检测到intI样和tnp样基因，它们编码的蛋白质与已知序列的氨基酸同一性分别为58 - 86%和58 - 73%。两个克隆，BAC 27A - 9和BAC 14A - 5，似乎呈现出独特的共线性组织，表明可能发生了基因重排，这可能是由于该属内的进化分歧或由与转座元件的关联所促成。在南极洲这样的极端环境中存在与基因募集和转移相关的遗传元件（转座子/整合子）的证据，强化了一些基因由移动元件在“人类相关”微生物中传播的起源假说。
