摘 要：
Aquaponics,which is widely considered as an efficient,ecological,and healthy aquaculture mode with notable implications for addressing issues such as aquaculture pollution,freshwater resource scarcity,and aquatic product quality,integrates the aquaculture and hydroponics.The definition of aquaponics remains controversial;however,the key lies in the symbiosis of aquatic animals and vegetables within a single system.Aquaponics encompasses various modes,such as the in situ mode combining pond aquaculture with ecological floating beds and the ex situ mode combining tank-based recirculating aquaculture and vegetable cultivation.Extensive research and discussion have been conducted on system design,aeration and filtration techniques,selection of plants and fish,nutrient balance,environmental control,disease management,and intelligent monitoring,providing technical support for constructing and operating aquaponic systems.Within the aquaponics system,microorganisms are crucial in nutrient transformation and the health of plants and animals,profoundly impacting the ecological balance of the system.Recently,with the rapid development of molecular biology and bioinformatics,genomic techniques such as amplicon-based high-throughput sequencing and qPCR have provided powerful support for analyzing the complex diversity,compositions,and functions of microbial communities in aquaponic systems.Regarding the diversity of microbial communities,studies have indicated higher bacterial community diversity in aquaponic systems than that in aquaculture systems.However,other studies have found no remarkable difference in bacterial diversity between aquaponic and aquaculture systems.Within the aquaponics system,notable differences were observed in the microbial community diversity among different microhabitats.Generally,the bacterial community diversity was the highest in the plant rhizosphere and biofilter and the lowest in the fish feces,with the bacterial diversity in the aquaculture water lying between the two.Various factors drive the spatial distribution of microbial diversity within the aquaponics system,profoundly impacting the functionality of microbial communities and system stability.Additionally,the composition of microbial communities in aquaponic systems are crucial in reflecting system characteristics and indicating the health and growth status of aquatic organisms.The composition of microbial communities in aquaponic systems differed from that in aquaculture and plant growth environments.Studies have identified core microbial taxa comprising bacteria belonging to the genus Bdellovibrio,Luteolibacter,Rhodobacter,and Nitrospira shared in different modes of aquaponic systems.Furthermore,research has shown that dominant bacterial groups vary between different functional units within the aquaponics system.In the biofilter,bacterial taxa belonging to the phylum Actinobacteria were enriched,whereas bacterial taxa belonging to the orders Sphingomonadales and Xanthomonadales inhabited the biofilm of the fish tank.The rhizosphere bacterial communities were dominated by taxa affiliated with the order Methylophilales.Generally,the presence of plants greatly influences the composition of bacterial communities in aquaponics systems.However,the effect of the presence of aquatic animals on plant-related microbial community compositions remains largely unexplored.Regarding microbial functions,nitrogen cycling is one of the most critical elemental cycling processes in aquaponics systems.Establishing efficient"nitrification"functional unit(i.e.,biofilters)is a key aspect of system design and construction.The nitrifying microorganisms involved in the nitrification process are considered as beneficial microbial communities in the aquaponics system,typically colonizing the biofilter or the plant rhizosphere environment.For example,aerobic ammonia-oxidizing,anaerobic ammonia-oxidizing,nitrite-oxidizing,and complete ammonia-oxidizing microorganisms have all been detected in aquaponics systems.Additionally,denitrification,nitrogen fixation,and anaerobic reduction of nitrate to ammonium processes have also been identified in aquaponics systems.However,the existing research has primarily relied on taxonomic annotations of amplicon-based sequencing data according to the current database.Whether the nitrogen cycling microorganisms are functionally active and what the contributions of different nitrogen cycling processes are in the aquaponics system remain unclear.Furthermore,research on functional microorganisms involved in the cycling of other elements such as carbon,phosphorus,sulfur,and iron in the aquaponics system lacks,limiting our understanding of the operational mechanisms of aquaponics systems.In aquaponic systems,pathogenic microorganisms that pose risks to the health of fish and plants may be introduced during the construction and operation of the system.Their dispersal and colonization could be facilitated by the water flow in the aquaponics system.Therefore,the prevention and control of pathogenic microorganisms are crucial.One study has indicated that the aquaculture unit of the aquaponic system harbored microbes beneficial for plant health.However,whether these beneficial microorganisms could colonize the plant roots and consequently regulate plant health remain unclear.Additionally,the gut microbiota and rhizosphere microbial communities are key factors in promoting host health.Given the close correlation between the health of fish and plants in aquaponics systems,these host microorganisms interact.However,the interactions between these host microorganisms and host disease resistance in aquaponics systems remain unclear.The microbial communities in aquaponic systems exhibit dynamic characteristics,with their diversity and compositions being jointly influenced by multiple ecological processes.Drawing on microbial ecology theory of community assembly mechanisms and considering the unique features of aquaponic systems,we propose a framework for the formation of microbial communities within aquaponic systems.Abiotic environmental factors,biotic interactions,host selection,dispersal,speciation,and drift processes collectively govern the assembly of microbial communities in aquaponic systems;however,the relative contributions of these processes still require investigation.For a better understanding of the role of microbial communities in the stable and efficient operation of aquaponics systems the distribution characteristics and assembly mechanisms of the diversity,compositions,and functions of different microbial domains in aquaponics systems(e.g.,eukaryotic microorganisms)must be systematically investigated.Additionally,the key microbial functional taxa in aquaponics systems and their impacts on the stability and efficiency of the system must be revealed,with the goal of potentially controlling aquaponic systems through microbial methods in the future.
