Research On Trehalose Lipids From Rhodococcus Erythropolis XH-1

Trehalose lipids are more important groups of glycolipid biosurfactants and have very good corrosion resistance, radiation resistance, emulsifying ability. The trehalose lipids are mainly produced by the strains from the genera of Arthrobacter, Rhodococcus, Corynebacterium, Mycobacterium, Nocardia, Brevibacterium. The trehalose lipids are most widely applied in pharmaceutical engineering, environmental engineering and oil industry. They have brought great convenience in storage, transportation and use of biological molecule and biological product, and have great research value and economic benefits. This paper mainly includes the preliminary research on the nature of trehalose lipids from Rhodococcus erythropolis XH-1 and the optimization of fermentation conditions, and studies the types of the trehalose lipids.Trehalose lipids from Rhodococcus erythropolis XH-1 with glycerol as carbon source had a lower critical micelle concentration(CMC) about 100 mg/L. The emulsification index of n-hexane and n-hexadecane were respectively above 37.5% and 40% respectively, when the concentration was 5 g/L. The trehalose lipids had good stability on temperature, pH and salinity.Based on the single-factor experiments, through Plackett-Burman design and response surface method, the best medium components for: glycerol 36.2 g/L, soybean cake powder 14.0 g/L, Yeast Extract 0.2 g/L, KNO3 1.0 g/L, K2HPO4 3.0 g/L, KH2PO4 3.0 g/L, NaCl 1.0 g/L and FeCl3 0.1 g/L. The optimal fermentation conditions for: rotation speed 150 r/min, medium volume 45 m L/250 mL, initial pH 9, inoculation arnount 3%, temperature 21?, seed age 60 h. The predicted production of trehalose lipids was 8.3503 g/L, the optimized production of trehalose lipids was 8.339 g/L increased 7.907% than the production before the response surface optimization and 87.00% than its before the the single-factor experiments.The trehalose lipids from Rhodococcus erythropolis XH-1 had smaller or without inhibitory effects on gram-negative bacteria such as Escherichia coli, Proteusbacillus vulgaris, Salmonella. In addition to Listeria monocytogenes, the trehalose lipids had good inhibitory effects on gram-positive bacteria such as Staphylococcus aureus, Bacillus cereus, Aerobacter aerogenes. However, the trehalose lipids had stronger inhibitory effects on Candida albicans. But they had no inhibitory effects on the moulds in the experiments.The trehalose lipids from Rhodococcus erythropolis XH-1 were partially separated and purified through TLC and PTLC. And the structure of trehalose lipids was preliminarily analyzed by ESI-LC-MS. The trehalose lipids from Rhodococcus erythropolis XH-1 may be trehalose tetraesters, molecular weight was 957, fatty acid part was-OC(CH2)8 CH3. However, the simples still had several components, which may contain several homologues of trehalose lipids and other impurities.