Preparation and characterization of the octenyl succinic anhydride (OSA) modified sphingan WL gum as novel biopolymeric surfactants.

Combining polymer and surfactant in one agent namely polymeric surfactants with both high viscosity and surface activity has become a viable alternative for the traditional enhanced oil recovery (EOR) processes. With the purpose of developing new polymeric surfactants, the biopolymer flooding agent sphingan WL gum was modified by octenyl succinic anhydride (OSA) through the esterification reaction. The effects of molecular weight (MW) of WL and the OSA: WL ratio on the properties of the products were investigated.

Identification of the Key Enzymes in WL Gum Biosynthesis and Critical Composition in Viscosity Control.

As an important microbial exopolysaccharide, the sphingan WL gum could be widely used in petroleum, food, and many other fields. However, its lower production is still limiting its wider application. Therefore, to gain insights into the bottlenecks of WL gum production by identifying the key enzymes in the WL gum biosynthesis pathway, more than 20 genes were over-expressed in sp.

Enzymatic degradation, antioxidant and rheological properties of a sphingan WL gum from Sphingomonas sp. WG.

A molecular weight (Mw) controllable degradation strategy using the lyase WelR as the efficient tool was established, and the relationship between the Mw and the rheological properties and antioxidant activity of WL gum was systematically investigated. Four different WL samples WL1-WL4 with a gradient Mw change (from 4.70 × 10 to 1.

[Development of an LB cloning system and its application in expression of fusion genes in sp. WG].

In order to overcome the challenges of insufficient restriction enzyme sites, and construct a fusion-expression vector with flexible fusion direction, we designed an LB cloning system based on the type IIS and type IIT restriction enzymes Ⅰ and CⅠ. The LB cloning system is constructed by inserting the LB fragment (GCTCTTCCTCAGC) into the multiple cloning site region of the broad-host plasmid pBBR1MCS-3 using PCR. The LB fragment contains partially overlapped recognition sites of Ⅰ and CⅠ.

Hybrid Histidine Kinase WelA of sp. WG Contributes to WL Gum Biosynthesis and Motility.

sp. WG produced WL gum with commercial utility potential in many industries. A hybrid sensor histidine kinase/response regulator WelA was identified to regulate the WL gum biosynthesis, and its function was evaluated by gene deletion strategy.