Feed types driven differentiation of microbial community and functionality in marine integrated multitrophic aquaculture system

Integrated multi trophic aquaculture (IMTA) improves the production of aquatic animals by promoting nutrient utilization through different tropical levels. Microorganisms play an important role in elements cycling, energy flow and farmed-species health. The aim of this study was to evaluate how feed types, fresh frozen fish diet (FFD) or formulated diet (FD), influence the microbial community diversity and functionality in both water and sediment in a marine IMTA system. Preferable water quality, higher animal yields and higher cost efficiency were achieved in the FD pond. Feed types changed the pond bacterial community distribution, especially in the rearing water. The FFD pond was dominated with Cyanobacteria in the water, which played an important role in nitrogen fixation through photosynthesis due to the high nitrogen input of the frozen fish diet. The high carbohydrate composition in the formulated diet triggered higher metabolic pathways related to carbon and lipid metabolism in the water of the FD pond. Sediment had significantly higher microbial diversity than the rearing water. In sediment, the dominating genus, Sulfurovum and Desulfobulbus, were found to be positively correlated by network analysis, which had similar functionality in sulfur transformation. The relatively higher rates of antibiotic biosynthesis in the FFD sediment might be related to the pathogenic bacteria introduced by the trash fish diet. The difference in microbial community composition and metabolic pathways may be associated with the different pathways for nutrient cycling and animal growth performance. The formulated diet was determined to be more ecologically and economically sustainable than the frozen fish diet for marine IMTA pond systems.</p

Efficacy of polyethylene glycol loxenatide versus insulin glargine on glycemic control in patients with type 2 diabetes: a randomized, open-label, parallel-group trial

Objective: This trial aimed to evaluate the glycemic control of polyethylene glycol loxenatide measured with continuous glucose monitoring (CGM) in patients with type 2 diabetes mellitus (T2DM), with the hypothesis that participants given PEG-Loxe would spend more time in time-in-range (TIR) than participants were given insulin glargine after 24 weeks of treatment.Methods: This 24-week, randomized, open-label, parallel-group study was conducted in the Department of Endocrine and Metabolic Diseases, Longhu Hospital, Shantou, China. Participants with T2DM, who were ≥45 years of age, HbA1c of 7.0%–11.0%, and treated at least 3 months with metformin were randomized (1:1) to receive PEG-Loxe or insulin glargine. The primary endpoint was TIR (blood glucose range: 3.9–10.0 mmol/L) during the last 2 weeks of treatment (weeks 22–24).Results: From March 2020 to April 2022, a total of 107 participants with T2DM were screened, of whom 78 were enrolled into the trial (n = 39 per group). At the end of treatment (weeks 22–24), participants given PEG-Loxe had a greater proportion of time in TIR compared with participants given insulin glargine [estimated treatment difference (ETD) of 13.4% (95% CI, 6.8 to 20.0, p &lt; 0.001)]. The tight TIR (3.9–7.8 mmol/L) was greater with PEG-Loxe versus insulin glargine, with an ETD of 15.6% (95% CI, 8.9 to 22.4, p &lt; 0.001). The time above range (TAR) was significantly lower with PEG-Loxe versus insulin glargine [ETD for level 1: −10.5% (95% CI: −14.9 to −6.0), p &lt; 0.001; ETD for level 2: −4.7% (95% CI: −7.9 to −1.5), p = 0.004]. The time below range (TBR) was similar between the two groups. The mean glucose was lower with PEG-Loxe versus insulin glargine, with an ETD of −1.2 mmol/L (95% CI, −1.9 to −0.5, p = 0.001). The SD of CGM glucose levels was 1.88 mmol/L for PEG-Loxe and 2.22 mmol/L for insulin glargine [ETD -0.34 mmol/L (95% CI: −0.55 to −0.12), p = 0.002], with a similar CV between the two groups.Conclusion: The addition of once-weekly GLP-1RA PEG-Loxe to metformin was superior to insulin glargine in improving glycemic control and glycemic variability evaluated by CGM in middle-aged and elderly patients with T2DM

Transcriptional Homeostasis of a Mangrove Species, Ceriops tagal, in Saline Environments, as Revealed by Microarray Analysis

<div><h3>Background</h3><p>Differential responses to the environmental stresses at the level of transcription play a critical role in adaptation. Mangrove species compose a dominant community in intertidal zones and form dense forests at the sea-land interface, and although the anatomical and physiological features associated with their salt-tolerant lifestyles have been well characterized, little is known about the impact of transcriptional phenotypes on their adaptation to these saline environments.</p> <h3>Methodology and Principal findings</h3><p>We report the time-course transcript profiles in the roots of a true mangrove species, <em>Ceriops tagal</em>, as revealed by a series of microarray experiments. The expression of a total of 432 transcripts changed significantly in the roots of <em>C. tagal</em> under salt shock, of which 83 had a more than 2-fold change and were further assembled into 59 unigenes. Global transcription was stable at the early stage of salt stress and then was gradually dysregulated with the increased duration of the stress. Importantly, a pair-wise comparison of predicted homologous gene pairs revealed that the transcriptional regulations of most of the differentially expressed genes were highly divergent in <em>C. tagal</em> from that in salt-sensitive species, <em>Arabidopsis thaliana</em>.</p> <h3>Conclusions/Significance</h3><p>This work suggests that transcriptional homeostasis and specific transcriptional regulation are major events in the roots of <em>C. tagal</em> when subjected to salt shock, which could contribute to the establishment of adaptation to saline environments and, thus, facilitate the salt-tolerant lifestyle of this mangrove species. Furthermore, the candidate genes underlying the adaptation were identified through comparative analyses. This study provides a foundation for dissecting the genetic basis of the adaptation of mangroves to intertidal environments.</p> </div

Effects of Once-Weekly Exenatide on Cardiovascular Outcomes in Type 2 Diabetes.

Abstract BACKGROUND: The cardiovascular effects of adding once-weekly treatment with exenatide to usual care in patients with type 2 diabetes are unknown. METHODS: We randomly assigned patients with type 2 diabetes, with or without previous cardiovascular disease, to receive subcutaneous injections of extended-release exenatide at a dose of 2 mg or matching placebo once weekly. The primary composite outcome was the first occurrence of death from cardiovascular causes, nonfatal myocardial infarction, or nonfatal stroke. The coprimary hypotheses were that exenatide, administered once weekly, would be noninferior to placebo with respect to safety and superior to placebo with respect to efficacy. RESULTS: In all, 14,752 patients (of whom 10,782 [73.1%] had previous cardiovascular disease) were followed for a median of 3.2 years (interquartile range, 2.2 to 4.4). A primary composite outcome event occurred in 839 of 7356 patients (11.4%; 3.7 events per 100 person-years) in the exenatide group and in 905 of 7396 patients (12.2%; 4.0 events per 100 person-years) in the placebo group (hazard ratio, 0.91; 95% confidence interval [CI], 0.83 to 1.00), with the intention-to-treat analysis indicating that exenatide, administered once weekly, was noninferior to placebo with respect to safety (P<0.001 for noninferiority) but was not superior to placebo with respect to efficacy (P=0.06 for superiority). The rates of death from cardiovascular causes, fatal or nonfatal myocardial infarction, fatal or nonfatal stroke, hospitalization for heart failure, and hospitalization for acute coronary syndrome, and the incidence of acute pancreatitis, pancreatic cancer, medullary thyroid carcinoma, and serious adverse events did not differ significantly between the two groups. CONCLUSIONS: Among patients with type 2 diabetes with or without previous cardiovascular disease, the incidence of major adverse cardiovascular events did not differ significantly between patients who received exenatide and those who received placebo. (Funded by Amylin Pharmaceuticals; EXSCEL ClinicalTrials.gov number, NCT01144338 .)

The effect of induced changes in gut microbiota on fish performance

Fish-microbe interactions play an important role in the feed digestion, nutrient absorption, immune system development and disease susceptibility of the host. Therefore, a healthy and stable gut microbiota contributes to the growth and overall health status of the host. To improve the microbial management in aquaculture, it is important to know the main the factors governing fish gut microbiota development and to understand to which extent the induced changes in gut microbiota composition affect fish performance.The aim of this thesis was to modulate fish gut microbiota by culturing the fish under different rearing conditions and by dietary supplementation of feed additives, with the expectation to improve the growth of the fish and gut microbiota homeostasis.The recent development and challenges faced by the aquaculture industry are summarized in Chapter 1. To improve the productivity and sustainability of aquaculture, the importance of environment-microbes-host interactions is highlighted. Furthermore, the factors mainly affecting fish gut microbiota composition and dynamics are reviewed, providing potential strategies to modulate fish gut microbiota. Besides, the analytical method of gut microbiota and the model species used are described. This chapter ends with an overview of the experimental work done during the thesis.In Chapter 2, the effect of different rearing conditions on the initial colonisation of the fish gut microbiota was investigated. To do so, Nile tilapia embryos were incubated and the hatched larva were cultured for 26 days in a flow-through system (FTS) or a recirculating aquaculture system (RAS) or RAS with dietary probiotic Bacillus subtilis supplementation. FTS showed significantly lower survival than those in RAS and RASB, while no differences were observed in fish growth and the apparent feed conversion ratio between treatments. Different treatments resulted in different gut microbiota compositions, which strongly correlated with the survival rate and standard body length at harvest.in Chapter 3, the effect of in-situ biofloc (LW) and dietary supplementation of ex-situ live (LF) or dead biofloc (DF) on fish gut microbiota composition and growth performance was compared to a biofloc-free control treatment. We identified a core gut prokaryotic community among all treatments. The relative abundance of the core community was significantly influenced by LW treatment, while the DF or LF treatments only caused minor changes on taxa not belonging to the core gut microbiota. The distinct microbial community in the biofloc water was associated with the modulatory effect of LW on tilapia gut microbiota. A growth-promoting effect on tilapia was observed from the LW treatment, while DF and LF treatments had no effect on fish growth performance as compared to the control treatment. Our study highlights the probiotic effect of in-situ biofloc water, in contrast to processed biofloc which showed little nutritional or probiotic effect. &nbsp;Chapter 4 was designed to verify how dietary supplementation with probiotics and enzymes influence the nutrient digestibility and volatile fatty acid (VFA) content along the gastrointestinal tract and the microbial composition in the distal gut of juvenile Nile tilapia. We showed an increase in VFA content with probiotic supplementation in the proximal gut, and a decrease in lactate content with enzymes along the gut. Besides, enzyme supplementation enhanced crude protein, Ca and P digestibility in proximal and middle gut. These results suggest that supplementation with exogenous enzymes and probiotics increases nutrient availability. Enzymes and probiotics supplementation had no effect on the gut microbial diversity of Nile tilapia, but enhanced microbial interactions according to network analysis. Such results, together with increased abundance of beneficial gut microbes such as Lactobacillus and Bacillus species, indicate positive impacts on fish gut health and contribute to a more stable microbial environment.In Chapter 5, we tested the legacy effect of early life rearing history on the gut microbiota succession. For this, we performed a 4-month study, during which Nile tilapia larvae were exposed during the first two weeks of life to different microbial environments (i.e. flow-through system and biofloc system), and thereafter, fish were reared during two consecutive 2-month periods, per period in a different RAS environment. In accordance with the results from chapters 2 and 3, we show that the early life rearing environment can have significant effects on fish performance, with the biofloc system leading to healthier gut microbiota compositions and better fish growth. We observed a temporal effect on the gut microbiota development with compositions gradually converging when fish were transferred to shared environments. Long-term effects on growth, nutrient digestibility, nitrogen and energy balances were not observed during later life. Despite that, interestingly, we show that early life exposure to different environments had a long-term effect on the gut microbial interactions, with more complex networks coming from fish exposed to the biofloc system during early life.In Chapter 6 the main results of this thesis are discussed and recommendations on the microbial management in aquaculture as well as future perspectives on fish microbiome research are presented. By comparing all the results from this thesis, we show that the gut microbiota of Nile tilapia is strongly affected by the rearing conditions during early life stage, with RAS and BFS resulting in a more stable gut microbiota, while FTS exhibiting large individual variation in gut microbiota composition. A microbial rich environment (BFS) or supplementation with probiotics can result in more species interactions in the gut microbiome and a better fish performance. A meta-analysis on all the gut microbiota data from all experiments shows a temporal effect and highlights the importance of fish age when comparing gut microbiota of Nile tilapia.Overall, this thesis highlights the significant impact of the early life rearing environment in aquaculture and its long-term effect on microbiome development and microbial interactions. We show high plasticity of fish gut microbiota during early life, which is ultimately shaped by the environment and dietary additives (e.g. probiotics and enzymes), resulting in distinct fish survival, growth and nutrient digestibility. The research provides strategies to manipulate the fish gut microbiota composition. Immunological and fish health research are suggested to further improve our understanding of the role of microbiota in aquaculture rearing systems

Effect of rearing systems and dietary probiotic supplementation on the growth and gut microbiota of Nile tilapia (Oreochromis niloticus) larvae

The establishment of the early-life gut microbiota plays an important role in fish development and influences the host's health status and growth performance. Different rearing conditions can impact the initial colonization of the gut microbiota, while the addition of probiotics may also affect such colonization. However, how this may affect fish larvae survival and growth remains largely unexplored. In this study, 3-day old Nile tilapia embryos were hatched until 9 days post fertilization (dpf) in three systems, including one flow-through system (FTS) and two identical recirculating aquaculture systems (RAS). When feeding started at 10 dpf, tilapia larvae in the FTS and one of the RAS were fed with a control diet, while larvae in the second RAS were fed with the control diet coated with B. subtilis spores (RASB). The feeding trial lasted 26 days, from larvae to fry stage, during which the survival, growth performance and gut microbiota were analyzed. The larvae reared in FTS showed significantly lower survival than those in RAS and RASB, while no differences were observed in fish growth and apparent feed conversion ratio between treatments. Different rearing systems resulted in different gut microbiota compositions, which strongly correlated with the survival rate and standard body length at harvest. Cetobacterium was enriched in RAS and RASB, while was barely detected in the gut of FTS-reared tilapia fry. Probiotic supplementation increased the relative abundance of beneficial Bacillus in fish gut. Our findings indicate that rearing fish larvae in RAS supports better survival compared to FTS, while dietary probiotic supplementation further modulates the gut bacterial composition and stimulates presence of beneficial bacteria during early life

Impact of early-life rearing history on gut microbiome succession and performance of Nile tilapia

BackgroundFish gut microbial colonisation starts during larval stage and plays an important role in host’s growth and health. To what extent first colonisation could influence the gut microbiome succession and growth in later life remains unknown. In this study, Nile tilapia embryos were incubated in two different environments, a flow-through system (FTS) and a biofloc system (BFS); hatched larvae were subsequently cultured in the systems for 14 days of feeding (dof). Fish were then transferred to one common recirculating aquaculture system (RAS1, common garden, 15–62 dof), followed by a growth trial in another RAS (RAS2, growth trial, 63–105 dof). In RAS2, fish were fed with two types of diet, differing in non-starch polysaccharide content. Our aim was to test the effect of rearing environment on the gut microbiome development, nutrient digestibility and growth performance of Nile tilapia during post-larvae stages.ResultsLarvae cultured in the BFS showed better growth and different gut microbiome, compared to FTS. After the common garden, the gut microbiome still showed differences in species composition, while body weight was similar. Long-term effects of early life rearing history on fish gut microbiome composition, nutrient digestibility, nitrogen and energy balances were not observed. Still, BFS-reared fish had more gut microbial interactions than FTS-reared fish. A temporal effect was observed in gut microbiome succession during fish development, although a distinct number of core microbiome remained present throughout the experimental period.ConclusionOur results indicated that the legacy effect of first microbial colonisation of the fish gut gradually disappeared during host development, with no differences in gut microbiome composition and growth performance observed in later life after culture in a common environment. However, early life exposure of larvae to biofloc consistently increased the microbial interactions in the gut of juvenile Nile tilapia and might possibly benefit gut health

Using poly(β-hydroxybutyrate-β-hydroxyvalerate) as carbon source in biofloc-systems : Nitrogen dynamics and shift of Oreochromis niloticus gut microbiota

Inorganic‑nitrogen removal is essential for the sustainable operation of aquaculture industry and also influences the health of aquatic animals, which may be accomplished by utilizing biofloc technology. In this paper, we studied the use of three different carbon sources 1) longan seed powder (LP), 2) Poly(β-hydroxybutyrate-β-hydroxyvalerate) (PHBV) and 3) synthesized PHBV and LP (PHBVL) in biofloc systems for 90 days to investigate the nitrogen dynamics and gut microbiota of Nile tilapia (Oreochromis niloticus). The PHBVL and PHBV groups had higher total inorganic‑nitrogen removal efficiencies (70.99 ± 19.45% and 63.54 ± 19.44%) than the LP group (35.02 ± 11.21%), which had an accumulation of nitrate. Meanwhile, the biofloc in PHBVL and PHBV group generally had a higher amino acid composition, particularly for methionine and lysine, but was not reflected in the tilapia muscle. High-throughput sequencing indicated that the different carbohydrates shaped different bacterial community compositions in the fish gut after exposure in the three environments for 90-day. These differences, which resulted in different gut digestive enzyme activities (amylase, lipase and trypsin), and growth performance, which the food conversion ratio in the PHBVL group was lower than LP and PHBV group, the final body weight in PHBVL group was average 4.33% and 3.65% bigger than in LP and PHBV group. Network analysis revealed that the keystone taxa (90.33%) were Proteobacteria, Chloroflexi, Actinobacteria, Planctomycetes, Verrucomicrobia and Bacteroidetes, which relative abundance varied in the fish gut in the three groups. The experiment verified the feasibility and advantage to use biodegradable polymers (BDPs) as carbohydrates for biofloc systems.</p

Integration of Marine Macroalgae (Chaetomorpha maxima) with a Moving Bed Bioreactor for Nutrient Removal from Maricultural Wastewater

Rather than direct nutrient removal from wastewaters, an alternative approach aimed at nutrient recovery from aquacultural wastewaters could enable sustainable management for aquaculture production. This study demonstrated the feasibility of cultivating marine macroalgae (Chaetomorpha maxima) with a moving bed bioreactor (MBBR-MA), to remove nitrogen and phosphorus in aquaculture wastewater as well as to produce macroalgae biomass. MBBR-MA significantly increased the simultaneous removal of nitrate and phosphate in comparison with only MBBR, resulting in an average total nitrogen (TN) and total phosphorus (TP) removal efficiency of 42.8±5.5% and 83.7±7.7%, respectively, in MBBR-MA while MBBR had no capacity for TN and TP removal. No chemical oxygen demand (COD) removal was detected in both reactors. Phosphorus could be a limiting factor for nitrogen uptake when N: P ratio increased. The recovered nitrogen and phosphorus resulted in a specific growth rate of 3.86%-10.35%/day for C. maxima with an uptake N: P ratio of 6. The presence of macroalgae changed the microbial community in both the biofilter and water by decreasing the relative abundance of Proteobacteria and Nitrospirae and increasing the abundance of Bacteroidetes. These findings indicate that the integration of the macroalgae C. maxima with MBBR could represent an effective wastewater treatment option, especially for marine recirculating aquaculture systems. </p

Denitrification-potential evaluation and nitrate-removal-pathway analysis of aerobic denitrifier strain Marinobacter hydrocarbonoclasticus RAD-2

An aerobic denitrifier was isolated from a long-term poly (3-hydroxybutyrate-co-3- hydroxyvalerate) PHBV-supported denitrification reactor that operated under alternate aerobic/anoxic conditions. The strain was identified as Marinobacter hydrocarbonoclasticus RAD-2 based on 16S rRNA-sequence phylogenetic analysis. Morphology was observed by scanning electron microscopy (SEM), and phylogenetic characteristics were analyzed with the API 20NE test. Strain RAD-2 showed efficient aerobic denitrification ability when using NO3 - -N or NO2 --N as its only nitrogen source, while heterotrophic nitrification was not detected. The average NO3 --N and NO2 --N removal rates were 6.47 mg/(L·h)and 6.32 mg/(L·h), respectively. Single-factor experiments indicated that a 5:10 C/N ratio, 25-40 °C temperature, and 100-150 rpm rotation speed were the optimal conditions for aerobic denitrification. Furthermore, the denitrifying gene napA had the highest expression on a transcriptional level, followed by the denitrifying genes nirS and nosZ. The norB gene was found to have significantly low expression during the experiment. Overall, great aerobic denitrification ability makes the RAD-2 strain a potential alternative in enhancing nitrate management for marine recirculating aquaculture system (RAS) practices.</p