Biodegradation Characteristics of Environmental Endocrine Disruptor Di-n-butyl Phthalate

Objective The biodegradation characteristics of di-n-butyl phthalate (DBP), an environmental endocrine disruptor, were studied by the method of dominant bacteria and immobilized microorganisms. Methods Taking DBP as the only carbon source to acclimatize the collected activated sludge, the concentration of DBP increased progressively in the process of acclimatization. Plate streaking was used to separate 1 strain of the degradation dominant bacteria after acclimatization. Better conditions to degrade DBP by the bacterium could be obtained through orthogonal experiments and the bacterium was identified. Then the acclimated activated sludge was made to immobilize the microorganism using polyvinyl alcohol as entrapment agent. The immobilized microorganism degraded DBP at different conditions. Results The appropriate conditions to degrade DBP by the dominant bacteria were: degradation time, 32 h; DBP concentration, 200 mg/L; rate of shaking incubator, 100 r/min; pH, 7 and temperature, 30℃. DBP could be degraded by more than 95% under such conditions. The bacteria were identified as pseudomonas. The proliferated immobilized microorganisms degraded DBP more effectively and more adapted to temperature and pH than the free acclimated activated sludge. Conclusion One strain of DBP degradation dominant bacteria was separated from the acclimatized activated sludge. It could grow with DBP as the only carbon source and energy, and degraded DBP effectively. After having been immobilized and proliferated, the dominant bacteria could keep a higher biological activity and degrade DBP more effectively than activated sludge.

Strategies for culturing active/dormant marine microbes

Microorganisms are ubiquitous in the ocean environment and they play key roles in marine ecosystem function and service.However,many of their functions and phenotypes remain unknown because indigenous marine bacteria are mostly difficult to culture.Although many novel techniques have brought previously uncultured microbes into laboratory culture,there are still many most-wanted or key players that need to be cultured from marine environments.This review discusses possible reasons for‘unculturable microbes’and categorizes uncultured bacteria into three groups:dominant active bacteria,rare active bacteria,and dormant bacteria.This review also summarizes advances in cultivation techniques for culturing each group of unculturable bacteria.Simulating the natural environment is an effective strategy for isolating dominant active bacteria,whereas culturomics and enrichment culture methods are proposed for isolating rare active bacteria.For dormant bacteria,resuscitation culture is an appropriate strategy.Furthermore,the review provides a list of the most-wanted bacteria and proposes potential strategies for culturing these bacteria in marine environments.The review provides new insight into the development of strategies for the cultivation of specific groups of uncultured bacteria and therefore paves the way for the detection of novel microbes and their functions in marine ecosystems.