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 t...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.展开更多
In this study,we aimed to investigate spoilage bacteria in monkfish stored under vacuum and aerobic(air)refrigeration at 4℃ for the first time.In vitro bacterial cultures,coupled with Sanger sequencing of genes,were ...In this study,we aimed to investigate spoilage bacteria in monkfish stored under vacuum and aerobic(air)refrigeration at 4℃ for the first time.In vitro bacterial cultures,coupled with Sanger sequencing of genes,were used to isolate and identify 21 and 31 bacterial strains from vacuum-packed and aerobically packed monkfish,respectively.The isolated strains were back-inoculated into sterile fish blocks and inactivated fish juice.Our findings revealed that Carnobacterium,Shewanella,Vagococcus,Myroides,and Psychrobacter increased the production of total volatile base nitrogen(TVB-N)and trimethylamine(TMA)from monkfish.Monkfish showed a decrease in bacterial flora diversity with storage time,the emergence of dominant species during the spoilage process,and differences in bacterial growth tolerance in different packaging forms,resulting in variability in bacterial community structure.Shewanella accelerated the spoilage of monkfish in both packaging forms.Vagococcus and Psychrobacter were numerically dominant in both storage forms.Unlike some spoilage bacteria in refrigerated fish,Carnobacterium(11.72%)and Myroides(9.01%)were the specific spoilage bacteria in vacuum and aerobic storage at 4℃,respectively.Furthermore,a combination of nisin(NS),ε-polylysine(ε-PL),and citric acid(CA)significantly reduced the survival rate of dominant spoilage bacteria and the total viable bacterial count in monkfish.展开更多
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 ...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.展开更多
基金This work was supported by National Natural Science Foundation of China (Grant No. 30271104).
文摘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.
基金supported by the National Key R&D Program of China(2019YFD0901705).
文摘In this study,we aimed to investigate spoilage bacteria in monkfish stored under vacuum and aerobic(air)refrigeration at 4℃ for the first time.In vitro bacterial cultures,coupled with Sanger sequencing of genes,were used to isolate and identify 21 and 31 bacterial strains from vacuum-packed and aerobically packed monkfish,respectively.The isolated strains were back-inoculated into sterile fish blocks and inactivated fish juice.Our findings revealed that Carnobacterium,Shewanella,Vagococcus,Myroides,and Psychrobacter increased the production of total volatile base nitrogen(TVB-N)and trimethylamine(TMA)from monkfish.Monkfish showed a decrease in bacterial flora diversity with storage time,the emergence of dominant species during the spoilage process,and differences in bacterial growth tolerance in different packaging forms,resulting in variability in bacterial community structure.Shewanella accelerated the spoilage of monkfish in both packaging forms.Vagococcus and Psychrobacter were numerically dominant in both storage forms.Unlike some spoilage bacteria in refrigerated fish,Carnobacterium(11.72%)and Myroides(9.01%)were the specific spoilage bacteria in vacuum and aerobic storage at 4℃,respectively.Furthermore,a combination of nisin(NS),ε-polylysine(ε-PL),and citric acid(CA)significantly reduced the survival rate of dominant spoilage bacteria and the total viable bacterial count in monkfish.
基金This work was supported by the National Natural Science Foundation of China(41876166,and 31770002)Science and Technology Basic Resources Investigation Program of China(2017FY100302).
文摘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.
