Sucrose is an effective carbon source for creating more reliable and environmentally friendly conditions for shrimp growth by regulating bacteria in biofloc-based culture systems. However, the influence of sucrose addition on the interaction, co-occurrence networks, and assembly mechanisms of bacterial communities in biofloc-based culture systems remains largely unknown. Here, we comprehensively investigated the effects of sucrose addition on bacterial communities in three habitats (water, bioflocs, and gut). The bacterial community structures and compositions of these three habitats became more similar in groups with sucrose addition, compared with those in controls. More than 50% gut bacterial communities were mainly derived from water and biofloc communities in the sucrose addition groups, but only about 33% bacterial communities migrated from water and biofloc to the gut in the control culture system. Sucrose addition accordantly enriched core taxa belonging to the phylum Actinobacteria and the families Rhodobacteraceae and Flavobacteriaceae in water, biofloc, and gut habitats. These core taxa were important for maintaining bacterial network stability in the sucrose addition culture systems and some were identified as keystone taxa for improving shrimp growth. Furthermore, after sucrose addition, gut bacterial community assembly from water and biofloc was dominated by the heterogeneous select with the ratios of 55–91% and 67–83%, respectively, indicating that sucrose addition can directionally shape the bacterial assembly of the shrimp culture system. These results provide a basis for selectively regulating certain beneficial taxa to improve shrimp growth in culture systems.

Increasing the C/N ratio of input feed has been reported as a practical approach for improving water quality and enhancing shrimp growth through changing the bacterial community of rearing water. However, little is known about the effects of different C/N ratios of feed input on the intestinal microbiota and metabolome of shrimp. In the present study, the effects of three different C/N ratio levels (CN6, CN10, and CN15) maintained by adding sucrose on the growth, intestinal microbiota and metabolome of Litopenaeus vannamei, and bioflocs formation were investigated after 17 days of feeding. The results indicated that higher C/N ratio (10 and 15), especially CN15, of feed input significantly enhance the length and weight of shrimp individuals accompanied by a significant accumulation of bioflocs, compared to that of CN6. The increase of C/N ratio input decreased the α-diversity of the intestinal microbiota and changed the microbial community structure through increasing the relative abundance of Actinobacteria, Rhodobacteraceae (mainly consist of Roseobacter and Paracoccus groups), Alteromonadaceae, and inhibiting the growth of Cyanobacteria, certain Rhodobacteraceae, Mycoplasmataceae and Vibrio. The change of microbial community caused by increasing C/N ratio input was closely associated with various bioactive metabolites of flavonoids, benzenoids, prenol lipids, and indole derivatives, which are benefit for shrimp growth either as an antimicrobial agent or as a nutrient component. Overall, this study demonstrated that manipulating high C/N ratio of feed input helps to the growth of shrimp through increasing the relative abundance of potential beneficial bacteria and the accumulation of various bioactive metabolites to suppress the growth of detrimental bacteria.

Background: Shrimp cultured in a biofloc system (BFS) have a lower disease incidence than those farmed in a water exchange system (WES). Although a number of studies have reported that the gut bacterial community induced by BFS is highly associated with shrimp disease resistance, the causal relationship remains unknown. Here, the promotive roles of gut bacterial community induced by BFS in pathogenic Vibrio infection resistance and its potential micro-ecological and physiological mechanisms were investigated by gut bacterial consortium transplantation and synthetic community (SynCom) construction. Results: The BFS induced a more stable and resistant gut bacterial community, and significantly enriched some beneficial bacterial taxa, such as Paracoccus, Ruegeria, Microbacterium, Demequina, and Tenacibaculum. Transplantation of a gut bacterial consortium from BFS shrimp (Enrich^BFS) greatly enhanced the stability of the bacterial community and resistance against pathogenic V. parahaemolyticus infection in WES shrimp, while transplantation of a gut bacterial consortium from WES shrimp significantly disrupted the bacterial community and increased pathogen susceptibility in both WES and BFS shrimp. The addition of Enrich^BFS in shrimp postlarvae also improved the pathogen resistance through increasing the relative abundances of beneficial bacterial taxa and stability of bacterial community. The corresponding strains of five beneficial bacterial taxa enriched in BFS shrimp were isolated to construct a SynCom^BFS. The addition of SynCom^BFS could not only suppress disease development, but also improve shrimp growth, boost the digestive and immune activities, and restore health in diseased shrimp. Furthermore, the strains of SynCom^BFS well colonized shrimp gut to maintain a high stability of bacterial community. Conclusions: Our study reveals an important role for native microbiota in protecting shrimp from bacterial pathogens and provides a micro-ecological regulation strategy towards the development of probiotics to ameliorate aquatic animal diseases.

The aldehyde dehydrogenase 2 (ALDH2) rs671 polymorphism commonly exists in the East Asian populations and is associated with high risks of cardiovascular disease (CVD). However, the cellular and molecular mechanisms that underlie the ALDH2 rs671 mutant-linked high CVD remain elusive. Here, we show that macrophages derived from human ALDH2 rs671 carriers and ALDH2 knockout mice exhibited an enhanced pro-inflammatory macrophage phenotype and an impaired anti-inflammatory macrophage phenotype. Transplanting bone marrow from ALDH2^-/-ApoE^-/- to ApoE^-/- mice significantly increased atherosclerotic plaque growth and pro-inflammatory macrophage polarization in vivo. Mechanistically, ALDH2 inhibited activation of the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway in macrophages. Pharmacological inhibition of cGAS by RU.521 completely neutralized ALDH2-deficiency-induced macrophage polarization. In-depth mechanistic investigation showed that ALDH2 accelerated cGAS K48-linked polyubiquitination degradation at lysine 282 in macrophages by reducing the interaction between ubiquitin-specific protease 14 (USP14) and cGAS, mainly through its enzymatic role in mitigating 4-hydroxy-2-nonenal (4-HNE) accumulation. Consistently, USP14 knockdown in bone marrow cells alleviated proinflammatory responses in macrophages and protected against atherosclerosis. Our findings provide new mechanistic insights of ALDH2 deficiency-associated proinflammation and atherosclerosis and new therapeutic and preventive paradigms for treatment of atherosclerosis-associated CVD.

Supplementing exogenous carbon sources is a practical approach to improving shrimp health by manipulating the microbial communities of aquaculture systems. However, little is known about the microbiological processes and mechanisms of these systems. Here, the effects of glucose addition on shrimp growth performance and bacterial communities of the rearing water and the shrimp gut were investigated to address this knowledge gap. The results showed that glucose addition significantly improved the growth and survival of shrimp. Although the α-diversity indices of both bacterioplankton communities and gut microbiota were significantly decreased by adding glucose, both bacterial communities exhibited divergent response patterns to glucose addition. Glucose addition induced a dispersive bacterioplankton community but a more stable gut bacterial community. Bacterial taxa belonging to Ruegeria were significantly enriched by glucose in the guts, especially the operational taxonomic unit 2575 (OTU2575), which showed the highest relative importance to the survival rate and individual weight of shrimp, with the values of 43.8 and 40.6%, respectively. In addition, glucose addition increased the complexity of interspecies interactions within gut bacterial communities and the network nodes from Rhodobacteraceae accounted for higher proportions and linked more with the nodes from other taxa in the glucose addition group than that in control. These findings suggest that glucose addition may provide a more stable gut microbiota for shrimp by increasing the abundance of certain bacterial taxa, such as Ruegeria.