Project description:Sulfur is the third most abundant element in crude oil. Up to 70 % of sulfur in petroleum is found in the form of dibenzothiophene (DBT) and substituted DBTs. The aim of this work was to study the physiological, biochemical and genetical characteristics of Gordonia alkanivorans 135 capable of using DBT as the sole source of sulfur. The genome of G. alkanivorans 135 consists of a 5,039,827 bp chromosome and a 164,963 bp circular plasmid. We found the absence of dsz operon present in most DBT degrading bacteria, but discovered other genes that are presumably involved in DBT utilization by G. alkanivorans 135. The strain utilized 45.26 % of DBT within 150 h of growth at 26 °C. This is the first strain of Gordonia capable of absorbing thiophene sulfur without the aid of the dsz genes.
Project description:In this article, we report a method for preparing an immobilized bacterial agent of petroleum-degrading bacteria Gordonia alkanivorans W33 by combining high-density fermentation and bacterial immobilization technology and testing its bioremediation effect on petroleum-contaminated soil. After determining the optimal combination of MgCl2, CaCl2 concentration, and culture time in the fermentation conditions by conducting a response surface analysis, the cell concentration reached 7.48 × 109 CFU/mL by 5 L fed-batch fermentation. The W33-vermiculite-powder-immobilized bacterial agent mixed with sophorolipids and rhamnolipids in a weight ratio of 9:10 was used for the bioremediation of petroleum-contaminated soil. After 45 days of microbial degradation, 56.3% of the petroleum in the soil with 20,000 mg/kg petroleum content was degraded, and the average degradation rate reached 250.2 mg/kg/d.