地衣素的结构和分子特性及其与表面活性的关系。

Structural and molecular characteristics of lichenysin and its relationship with surface activity.

机构信息

Department of Microbiology, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara-390 002, Gujarat, India.

出版信息

Adv Exp Med Biol. 2010;672:304-15. doi: 10.1007/978-1-4419-5979-9_23.

DOI:10.1007/978-1-4419-5979-9_23

PMID:20545292

Abstract

Lichenysins are most potent anionic cyclic lipoheptapeptide biosurfactants produced by Bacillus licheniformis on hydrocarbonless medium with mainly glucose as carbon source. They have the capacity to lower the surface tension of water from 72 to 27 mN/m. Based on species specific variations they are named lichenysin A, B, C, D, G and surfactant BL86. The lowest ever interfacial tension against decane of 0.006 mN/m is obtained with acid precipitated lichenysin B. Surfactant BL86 and lichenysin B have recorded lowest ever CMC of 10 mg/L by any surfactant under optimal conditions. Surface and interfacial tension lowering ability bears significance in the context of oil recovery from oil reservoir. Similarity exists between structure and biosynthesis of surfactin and lichenysin. Surfactin being the most studied of the two, understanding its structure and biosynthesis gives an insight into the structure and biosynthesis of lichenysin. Lichenysin is synthesized by a multienzyme complex, lichenysin synthetase (LchA/Lic) encoded by 32.4 (26.6 kb) lichenysin operon lchA (lic). The structure of lichenysin and its operon indicate the nonribosomal biosynthesis with the same multifunctional modular arrangement as seen in surfactin synthetase SrfA. The lchA operon consists of lchAA-AC (lic A-C) and lchA TE (licTE) genes encoding the proteins LchAA, LchAB, LchAC and thioesterase LchA-TE. The licA (lchAA) gene is 10,746 bp and codes for a 3,582 amino acids protein, licB (lchAB) gene is 10,764 bp and codes for a similar sized protein, while licC (lchAC) gene is 3,864 bp and codes for protein containing 1,288 amino acid. The biotechnological potential of lichenysin in MEOR has triggered research on structure-activity relationship. Both the nature of peptide and fatty acid dictate the activity of the biosurfactant. Tailormade biosurfactant with desired attributes can be obtained from engineered synthetases. Basic studies are lacking on mechanism of biosynthesis by lichenysin synthetase however, studies on various aspects of lichenysin including regulation are expected to swell in coming years.

摘要

lichenysins 是由地衣芽孢杆菌在无烃类培养基上以葡萄糖为主要碳源产生的最强阴离子环状脂肽生物表面活性剂。它们能够将水的表面张力从 72 毫牛顿/米降低到 27 毫牛顿/米。根据种属特异性变化，它们被命名为 lichenysin A、B、C、D、G 和 surfactant BL86。用酸沉淀的 lichenysin B 获得了有史以来最低的癸烷界面张力，为 0.006 mN/m。在最佳条件下，surfactant BL86 和 lichenysin B 通过任何表面活性剂记录到的最低 CMC 为 10 mg/L。表面和界面张力降低能力在从油藏中回收石油方面具有重要意义。表面活性剂和 lichenysin 的结构和生物合成存在相似性。由于 surfactin 是研究最多的一种，因此了解其结构和生物合成可以深入了解 lichenysin 的结构和生物合成。lichenysin 是由多酶复合物 lichenysin 合成酶（LchA/Lic）合成的，该酶由 32.4（26.6 kb）lichenysin 操纵子 lchA（lic）编码。lichenysin 的结构及其操纵子表明，其非核糖体生物合成具有与 surfactin 合成酶 SrfA 相同的多功能模块化排列。lchA 操纵子由 lchAA-AC（lic A-C）和 lchA TE（licTE）基因组成，编码 LchAA、LchAB、LchAC 和硫酯酶 LchA-TE 蛋白。licA（lchAA）基因长 10746 bp，编码一个 3582 个氨基酸的蛋白质，licB（lchAB）基因长 10764 bp，编码一个大小相似的蛋白质，而 licC（lchAC）基因长 3864 bp，编码一个含有 1288 个氨基酸的蛋白质。lichenysin 在 MEOR 中的生物技术潜力引发了对结构-活性关系的研究。肽和脂肪酸的性质共同决定了生物表面活性剂的活性。可以通过工程化的合成酶获得具有所需属性的定制生物表面活性剂。然而，关于 lichenysin 合成酶生物合成机制的基础研究还很缺乏，但是，预计未来几年将有更多关于 lichenysin 包括调控在内的各个方面的研究。