Isolation Of Marine Oil-degrading Bacteria And The Development And Application Of Immobilization Prepared From Algal Materials

The frequent accidents of marine oil spills have brought great harm to the marine ecological environment and the health of the people in the coastal areas.Bioremediation has many advantages,such as e environment-friendly,high efficiency,low cost and so on.It is considered to be the most promising method to remove marine oil pollution.The acquisition of oil-degrading bacteria is the prerequisite for bioremediation.Microbial immobilization technology is the technological base of solving the complex environmental conditions of marine oil pollution.Taking 5 rhizosphere soil samples from Beidaihe coastal wetland as research materials,22 strains of oil-degrading bacteria were obtained,8 of them had the ability of producing surfactants.The results showed that the oil degradation rate of 22 strains of oil-degrading bacteria isolated increased by 7%-28% at 25℃ and 21 days after degradation.Among them,the degradation rate of strain qhd2 B was the highest,increased by 28.0%.Of the 22 strains,8 strains belonged to Actinobacteria,13 strains belonged to Proteobacteria,and one strain belonged to Bacteroidetes.5 strains of highly efficient petroleum degrading bacteria had good degradation effect on most alkanes and PAHs.Among them,the total degradation rate of strain qhd2 B to alkanes and PAHs was 79.9% and 76.7% respectively,which was an excellent oil degrading bacteria.We investigated the immobilization carrier by two kinds of algal materials,Enteromorpha residue and Kelp residue.Bacillus sp.E3 was immobilized by adsorption to prepare immobilizations.Results showed the absorption rates of Enteromorpha residue and kelp residue for diesel were 411% and 273% respectively and remained approximately 105% and 120% after 2 hours of erosion in simulated seawater system.After immobilized of Bacillus sp.E3 and 21 days of degradation,the oil degradation rate of the non-sterilized kelp residue group was 75.9%,the oil degradation rate of the sterilized kelp residue group was 70%,the oil degradation rate of the non-sterilized Enteromorpha residue group was 65.4%,the oil degradation rate of the sterilization Enteromorpha residue group was 64.7%,but the free bacterial liquid was only 59.4%.The degradation rates of total alkanes and PAHs were 72.9% and 73% respectively.The degradation rates of total alkanes and PAHs were 67.6% and 75.9%,respectively,and 63% of total alkanes and 66% PAHs were degraded by free bacteria solution.The bacteria immobilized by non-sterilized kelp residue showed a considerably higher degradation rate than that using sterilized kelp residue.The experiments show the two algae materials,especially the kelp residue,present potential application in bioremediation of marine oil spills.The immobilized bacteria adapted to the repair of the oil pollution in the sediments were developed by the pressing method.The marine oil-degrading bacteria Bacillus sp.E3 was immobilized with kelp residue and kaolin.t is found that the immobilization has larger density.when adding 30% kaolin.When the amount of water is 700g/kg(dry weight),the survival rate of the bacteria is higher,which is 76.90%.When adding the final concentration of 1.5%(dry weight)sodium alginate as adhesive,the dissolubility of the bacteria is low.The immobilization prepared by the above method has many pores,which can provide living space for bacteria and improve the exchange efficiency of bacteria and environment.In the simulation experiment,the oil degradation rate of 0~30d was increased by 11.75~13.60% when the immobilizations were compared with the control group.It shows that the immobilization developed by this method has obtained good oil degradation effect and can be applied to the repair experiment.The immobilized bacteria developed by the research and development were applied to repair the sediments contaminated by explosion of Huangdao oil pipeline.11 days after repair,the oil pollution of A3 area was degraded effectively,and the petroleum hydrocarbon concentration was reduced by about 18.8%.After 75 days of repair,the medium and short chain alkanes and some PAHs in the sediments were effectively degraded.The application of immobilized bacteria has a certain influence on the structure of microbial community in sediment.Both PCoA and cluster analysis showed significant changes in microbial communities in the A3 region after repair.Many of these strains are associated with biodegradation of oil pollution.This shows that immobilized bacteria may provide an environment conducive to the growth of oildegrading bacteria,thus promoting the growth and reproduction of indigenous oildegrading bacteria.