Response Of Bacterial Community Structures And Functions To Bioremediation Of Mudflat Sediments In Fujian Coastal Areas, Southeast China

In this study, the nereid polychaetes and bivalves cardiidae were introduced to the mudflat sediments for in situ bioremediation of environment in Sansha bay, and the nereid was also used in bioremediation experiment in laboratory. The bacterial community structure, activity and their response to bioturbation of macrobenthos bioremediation were investifated using clone library construction, RFLP, DGGE, Biolog, and Illumina sequencing. The relationship between microbial communities, physiochemical characteristics, and macrobenthos bioturbation were analysed, and the results were as follows:1. The investigation and assessment of physicochemical characteristics and heavy metal contents of mudflat sediments in Sansha Bay and Jimei: In Sansha Bay, compared with the standard values of nonmetal pollutants, the Org C content did not exceed the standard, while the Org N exceeded, and the TP and Org S far exceeded the standard values. In mudflat sediment of Jimei, the Org C, Org N and TPcontent did not exceed the standard, while the Org S far exceeded the standard. All the values of nonmetal pollutants in Jimei were lower than those in Sansha bay. No matter in Sansha bay or in Jimei, the physicochemical characteristics and heavy metal values were stable and did not changed significantly after introducing macrobenthos.2. 16 S r RNA gene-Illumina Miseq sequencing of microbial communities and their response to bioremediation in mudflat sediments of Sansha Bay: A total of 50 microbial phyla were identified. Proteobacteria was dominant and occupied over 50% of total sequences. Others, such as Bacteroidetes, Acidobacteria, Planctomycetes, Chloroflexi and Thaumarchaeota, and so on. About 0.02% of total sequences could not be classified into any phylum.The microbial communities responsed rapidly to bioturbation and seasonal change. They clustered into different clusters according to different sampling times. Macrobenthos bioturbation had changed the microbial community structure, the benthos-introduced samples clustered together while were separated from the control sample in the same sampling time. The abundance of a few ecologically important genera increased after introducing benthos to the sediments, such as Saprospiraceae, Robiginitalea, and so on. The abundance of a few genera decreased after introducing benthos to the sediments, such as Marinicella, Halioglobus, Haliea, Deferrisoma, and so on.3. Investigation of ammonia-oxidizing bacterial community structures and their response to bioremediation by clone libraries construction in mudflat sediments of Sansha Bay: The main groups of ammonia oxidizing bacteria in Sansha bay were Nitrosomonas sp. and Nitrospira sp., and Nitrosomonas sp. was dominant, it could be further divided into 4 clusters, such as Nitrosomonas marina cluster, and so on. The ammonia-oxidizing bacteria responsed rapidly to macrobenthos bioturbation and seasonal change. The diversity is lowest in winter, and the percentage of Nitrospira sp. is lower in summer than in other seasons. The ammonia-oxidizing bacterial diversity and the percentage of Nitrosomonas sp. had a trend of decrease after introducing macrobenthos to the mudflat sediments.4. 16 S r RNA gene-Illumina Miseq sequencing of microbial communities and their response to bioremediation in mudflat sediments of Jimei in laboratory bioremediation model: A total of 48 phyla of microbial were identified in mudflat sediments in Jimei. A total of 48 microbial phyla were identified. Proteobacteria was dominant and occupied over 40% of total sequences. Others, such as Bacteroidetes, Chloroflexi,Thaumarchaeota and Planctomycetes Cyanobacteria, and so on. About 0.08% of total sequences could not be classified into any phylum. The abundance of a few ecologically important genera increased after introducing the polychaetes nereid to the sediments, such as Nitrosococcus, Spirochaeta, Gaetbulibacter, Fusibacter, Sulfurimonas, Pseudospirillum, and so on. Different sowing density of nereid had difference effects on some genera abundance.5. Investigation of the microbial community activities and their response in mudflat sediments of Jimei in laboratory bioremediation model: The bacterial utilization for carbohydrates, polymer, and amino acids were higher than those for carboxylic acids, amines/amides or other compounds. Introducing nereid to the sediments enhanced the bacterial activity, and in a certain sowing range, higher sowing density of nereid seemed to have a more enhancement effect. The bacterial utilization for carbohydrates, polymer, and amino acids increased, while the utilization for amino acids decreased after introducing nereid to the mudflat sediments.6. Compared with physicochemical characteristics, microbial communities responded rapidly and obviously to the macrobenthos bioturbation and seasonal changes. The microbial communities significantly correlated with p H and Org N, and high significantly correlated with sampling times, thus microbial community structure can serve as a good sentinel for indicating environmental changes.