Isolation Of Hydrocarbon Degradation Fungi And Their Effect On Bioremediation

Petroleum plays an impotent role in modern life,because it is not only an energy source, but also a raw material of many industrial products. During the process of exploitation and utilization, a lot of crude oil spilled or leaked, which has brought negative impacts to the ecological environment seriously. Microbial remediation technique attracts people's attention due to its economy, high efficiency and no second contamination, while it is considered a kind of the most promising technology of remedying hydrocarbon contamination.According to the actual state of saline-alkali soil polluted by petroleum oil in Dagang Oilfield and the development trend of microbial remediation of oil polluted soil. After isolating,screening and secondary screening, 2 strains of fungi were got from the petroleum-contaminated saline soil , which exhibited better biodegrading ability. DNA sequencing showed they were Trichosporon coremiiform and Penicillium citrinum.The bioremediation of petroleum-contaminated soil was studied using the mixed cultures of the 2 isolated strains in different concentration. The biodegradation efficiency, dehydrogenase activity and microbial diversity of the studied soil were monitored for different treatments in pot experiments. The results showed that compared with the control(CK), addition of mixed microbes notably improved the biodegradation efficiency and dehydrogenase activity and stimulated both the abundance and diversity of the soil microbe. With addition of 0%, 2%, 4%, 8% microbial mixture, the total concentration of petroleum hydrocarbon reached 43.48%, 53.07%, 57.20%, 63.03% after 70 days of incubation. The biodegradation rate increased with higher inoculation amount of microbial consortium. However, the degradation rate of petroleum hydrocarbons increases was not proportionate to the mixed cultures concentration and considering the economic factor, addition of 4% of microbial mixture was the best.In order to adjust the soil salt content to different degree, times of flush salt were controlled, which simulated using flood irrigation to flush salt in field. The effects of two methods, pure biostimulation and bioaugmentation & biostimulation , on petroleum biodegradation were systematically compared. The results showed that, no matter pure biostimulation or bioaugmentation with biostimulation was added, the oil degrading rate significantly increased, when the soil salt content declined to a certain level. In the group of bioaugmentation & biostimulation treatment, after 3 days of incubation, the highest oil degrading rate can reach up to 24.98%, which the soil salt content of it was adjusted to 0.22% by flushing salt 2 times. Under the same condition, the degradation of the biostimulation treatment was 1.1 times higher than that of bioaugmentation & biostimulation treatmen. While under the same conditions,the degradation of the 0.10% salt content soil by flushing salt 3 times was 1.22 times that of the 2.86% salt content soil without flushing salt. Bacterial community responded differently upon pure biostimulation and bioaugmentation & biostimulation treatment,which were indexed by the changes of diversity, richness and evenness in PCR-DGGE analysis.