The soil microbial function of Kandelia candel mangroves:: Degradation of diesel oil

This paper deals with the degradation of diesel oil by mangrove soil microbes in the laboratory. The study was conducted by static and shake culture methods. The main results are summarized as follows: (1), When diesel oil was introduced to the soil for one week, the total degradation rate (TDR) was 70% (microbe degradation rate (MDR) was about 50%) two weeks later, the TDR increased to 80% (MDR increased to 65%), one month later, the TDR was >96% (MDR was >70%). This shows that the degradation capability is strong. (2), Investigations also indicated that the degradation rate of diesel oil by the dominant bacteria in the mangrove soil, after one week, the TDR was 13-19% (degradation rate of the dominant bacteria group was 5-10%); one month later, the TDR was 90% (degradation rate of the dominant bacteria group was 60%). Bacteria (engineering bacteria) with hard degradation rates can be screened. (3), Static culture was better than shake culture in the degradation of diesel oil. This is due to greater soil capacity in static culture which can provide more microbes, abundant nutrients and a suitable pH for the degradation of diesel oil by microbes. Results also prove that the degradation rates of alkane, i.e., both TDR and MDR, were higher than aromatic hydrocarbons. (4), The degradation rates of microbes in non-mangrove soil were lower than those in mangrove soil. When diesel oil was introduced to the soil for one week, the TDR was 78% in mangrove soil and 55% in non-mangrove soil. The MDR in mangrove soil and non-mangrove soil were 61% and 38%, respectively.