Rhamnolipid Production and Application in Microbial Enhanced Oil Recovery from Metabolically Engineered Bacteria

摘要

The rhamnolipids, as the extensively studied biosurfactants, are a subclass of glycolipids (Nitschke et al., 2005; Soberon-Chavez et al., 2005b). Besides the comprehensive application in the field of envionment (Mulligan, 2005) and petroleum (Van Hamee et al., 2003), rhamnolipids also have potential application in medicine, such as antimicrobial activity and anti-adhesive acitivity (Rodrigues et al., 2006). Rhamnolipids, maily from Pseudomonas aeruginosa, are produced as mixtures in various proportions, including two rhamnoses attached to β-hydroxyalkanoic acid or one rhamnose connected to the identical fatty acid (Soberon-Chavez et al., 2005b). The type of rhamnolipid produced depends on the bacterial strain, the carbon source used, and the process strategy (Mulligan et al., 1993). The lengths of the fatty acid chains of rhamnolipids can vary significantly, resulting in a multitude of diffefferent rhamnolipd compositions. Fatty acyl chains composed of 8, 10, 12, and 14 carbons in length, as well as 12- or 14-carbon chains with double bonds. Hence, the simple form of rhamnolipid could be designated as Rha-Rha-C_m-C_n or Rha-C_m-C_n (m and n: 8, 10, 12, or 14).