Optimization Of Fermentation Conditions For Producing Surfactant Oil Recovery

Microbial Enhanced Oil Recovery (MEOR) was a comprehensive technique, which could raise oil recovery efficiency by metabolites of the microorganism. As one kind of MEOR, biosurfactant has demonstrated a favourable application perspective and attracted widespread attentions because of its outstanding characteristics:excellent displacement efficiency,lower toxicity,no contamination,higher biodegradation,lower price. Therefore, there has important significance of exploratory development of the MEOR to screen the high performance producing strain, to optimize its fermentation conditions, and to raise the yield of the biosurfactant.This article did comprehensive researches in following aspects:screening the producing strain of biosurfactant, identifying the strain, optimizing the fermentation conditions. The main research and experimental results were as follows:1. Microorganism strain DN4-3 which could synthesize biosurfactant with the highest performance had been screened in two steps:assaying hemolytic activity on blood agar plates in the first and then assaying oil displacement activity from oil slurry. The result of TLC analysis showed that biosurfactant generated by the strain DN4-3 was lipopeptide.2. The strain DN4-3 was identified by the morphological characteristics of colony, physiological and biochemical characterization and sequence analysis of 16Sr DNA. The experimental results showed that strain DN4-3 had more than 98 percent homogenous with Bacillus subtilis, therefore, strain was identified as Bacillus subtilis DN4-3.3. Based on the single factor experiments, the optimal medium composition and fermentation conditions were determined as follows by Plackett-Burman design and response surface analysis:glucose 27.83g/L,yeast extract power 2.73g/L NaC12.37g/L,KH2PO4 9g/L,K2HPO4 3g/L,CaCl2 0.16g/L,MgSO4·7H2O 0.5g/L,inoculation amount 4％,seed age 16h,medium volume 250mL/500mL,temperature 37℃,initial pH 7.0,rotation speed 160r/min,fermentation period 72h.Under the optimal conditios, the strain DN4-3 produced 1025.98mg/L lipopeptide which increased about 35.43% than before.