PDF(Pubmed)
Abstract：
Teredinibacter turnerae is a cultivable cellulolytic Gammaproeteobacterium (Cellvibrionaceae) that commonly occurs as an intracellular endosymbiont in the gills of wood-eating bivalves of the family Teredinidae (shipworms). The genome of T. turnerae encodes a broad range of enzymes that deconstruct cellulose, hemicellulose, and pectin and contribute to lignocellulose digestion in the shipworm gut. However, the mechanism by which symbiont-made enzymes are secreted by T. turnerae and subsequently transported to the site of lignocellulose digestion in the shipworm gut is incompletely understood. Here, we show that T. turnerae cultures grown on carboxymethyl cellulose (CMC) produce outer membrane vesicles (OMVs) that contain a variety of proteins identified by LC-MS/MS as carbohydrate-active enzymes with predicted activities against cellulose, hemicellulose, and pectin. Reducing sugar assays and zymography confirm that these OMVs retain cellulolytic activity, as evidenced by hydrolysis of CMC. Additionally, these OMVs were enriched with TonB-dependent receptors, which are essential to carbohydrate and iron acquisition by free-living bacteria. These observations suggest potential roles for OMVs in lignocellulose utilization by T. turnerae in the free-living state, in enzyme transport and host interaction during symbiotic association, and in commercial applications such as lignocellulosic biomass conversion.
摘要：
Teredinibacterturnerae是一种可培养的纤维素分解γ-proproeteobacterium（Cellvibrionaceae），通常作为细胞内共生体存在于Teredinidae家族的食木双壳类动物的the中。T.turnerae的基因组编码广泛的解构纤维素的酶，半纤维素,和果胶，并有助于木素纤维素的消化。然而,共生体产生的酶由T.turnerae分泌并随后转运到木素纤维素消化部位的机制尚未完全了解。这里,我们表明，在羧甲基纤维素（CMC）上生长的T.turnerae培养物产生外膜囊泡（OMVs），其中含有多种通过LC-MS/MS鉴定为碳水化合物活性酶的蛋白质，具有预测的抗纤维素活性。半纤维素,还有果胶.还原糖测定和酶谱证实这些OMV保留了纤维素分解活性，如CMC的水解所证明的。此外,这些OMV富含TonB依赖性受体，这对自由生活的细菌获得碳水化合物和铁至关重要。这些观察结果表明OMV在自由生活状态下T.turnerae木质纤维素利用中的潜在作用，在共生关联过程中的酶转运和宿主相互作用中，以及在商业应用如木质纤维素生物质转化中。
