Integrating Microbial Protein Production and Harvest Systems into Pilot-Scale Recirculating Aquaculture Systems for Sustainable Resource Recovery: Linking Nitrogen Recovery to Microbial Communities

Abstract

In aquaculture, it is important to raise the nitrogen recovery efficiency (NRE) to improve sustainability. To achieve this, recovery of microbial protein (RMP), instead of nitrification/denitrification in conventional wastewater treatment, is a promising approach whose microbiological mechanisms must be characterized. Here, periodic RMP was conducted in an in situ biofloc-based aquaculture system (IBAS) and a separating assimilation reactor-based recirculating aquaculture system (SRAS). Kinetic analysis indicated that a microbial biomass level of 3 g L −1 was optimal for inorganic N removal, and excess biomass was harvested to improve the NRE. Unlike the IBAS, the SRAS eliminated the fluctuation in water quality caused by the RMP. Periodic RMP significantly increased the NRE to 44−57% by promoting the filamentous bacterium Herpetosiphon and suppressing anaerobic denitrifiers. Aerobic chemoheterotrophy was the main microbial metabolic process for energy. After RMP, nitrate reductase-encoded functional genes (napA and narG) significantly decreased, while nitrite reductase-encoded functional genes, especially nirK, significantly increased. Co-occurrence networks analysis indicated that the cooperation and competition among organic matter degraders, filamentous bacteria, nitrifiers, and denitrifiers determined the microbial protein yield. These results provide fundamental insights into the influence of the RMP on microbial communities and functions, which is important for realizing sustainable aquaculture.

Farmland Microhabitat Mediated by a Residual Microplastic Film: Microbial Communities and Function

“…Unearthing the changes in microbial biodiversity and keystone species is vital to predicting ecosystem response to environmental changes, ecological restoration, and improvement of biological processes (such as soil remediation). ,,, In this study, to explore the impacts of residual microplastic film on soil microhabitats, the composition and diversity of the microbial community in the soil and the residual microplastic film were investigated. As shown in Figure A,B, there was a significant difference ( p < 0.05) in the microbial community structure (including bacteria and fungi) between the soil and the residual microplastic film.…”

Dynamic Simulation of Nitrifying Microbial Communities for Establishing Acidic Partial Nitritation in Suspended Activated Sludge

“…So far, the influence of DO, − temperature, FA, , FNA, and pH ,, on the AOB and NOB have been evaluated in classic nitrification models to identify operational boundaries of PN. ,, These conventional models were built based on the aggregated bulk biomass rather than the microbial community and have never considered various acid-tolerant microorganisms that have an important role in acidic PN. Simulation of the dynamics of the microbial community is thus needed for accurate prediction and regulation of the PN process …”

“…Simulation of the dynamics of the microbial community is thus needed for accurate prediction and regulation of the PN process. 36 This study set up a laboratory-scale SBR to track the establishment process of acidic PN. During the operation of the reactor, the dynamics of nitrifying microbial communities were monitored regularly.…”

Microbial biogeochemical cycling reveals the sustainability of the rice-crayfish co-culture model

“…Aquaculture is an indispensable source of global food and nutrition supply, feeding approximately 12% of the population (1 billion people) around the world. 1 , 2 , 3 As one of the most important resources of nutrients, the aquaculture ecosystem contains diverse biologically available essential elements, such as carbon (C), nitrogen (N), and sulfur (S). 4 , 5 Microbes in this ecosystem represent one of the most important drivers of biogeochemical cycling, as they are responsible for the re-mineralization of organic matter and energy exchange.…”