Nitrogenous Waste Research Articles

(Invited) Green Ammonia Production from Electrochemically Upcycling Waste Nitrogen in an Membrane-Free Alkaline Electrolyzer

NH3 is an essential nutrient for life, but its production through anthropogenic N2-fixing process has caused alarming damages to ecosystems and human health. Excessive NO3 - leakage into water bodies due to overfertilization has led to the formation of "dead zones" in coastal areas. Denitrification generates N2O, which is 300 times more potent than CO2. Restoring the balance between the generation and elimination of Nr is an urgent task for humanity. Efforts to address the negative impact of human-generated Nr have focused on converting it to harmless N2 or improving its utilization in the nitrogen cycle. One promising method is electrochemical conversion, which can eliminate Nr without additional oxidants/reductants. However, achieving selective NO3RR toward N2 is challenging. An alternative approach is to convert other forms of Nr to NH3 in an electrochemical reactor, which could reduce the environmental impact of Nr and decrease the NH3 demand from the Haber-Bosch process, while also reducing the use of fossil-derived H2.In this work, we report our work on the development of a membrane-free alkaline electrolyzer (MFAEL), which transforms Nr into NH3 as the sole N-containing product. With the inexpensive and robust MFAEL system, we achieved an ampere-level partial current density towards NH3 production. By properly choosing the conditions of NH3 collection from MFAEL, continuous production of pure NH3-based chemicals can be realized without the need for additional separation procedures. Techno-economic analysis (TEA) suggests the potential economic feasibility of the waste-to-NH3 process by coupling electrodialysis (ED) for Nr concentration and the MFAEL process for Nr conversion, offering an all-sustainable route for upcycling waste N into the highest-demanded N-based chemical product. Our recent efforts on green-ammonia capture CO2 and reduction to valuable chemicals will also be briefly presented.

Regulation mechanism of Chlamydomanas reinhardtii responding to different waste nitrogen sources based on transcriptomics

Regulation mechanism of Chlamydomanas reinhardtii responding to different waste nitrogen sources based on transcriptomics

A novel pharmacological strategy using nanoparticles with glutathione and virgin coconut oil to treat gentamicin-induced acute renal failure in rats.

In acute renal failure (ARF), the glomerular filtration rate is reduced, and nitrogenous waste products accumulate persistently, which can last anywhere from a few hours to several days. There is hope for a reversal of the rapid loss of renal function caused by this condition. This study, with gentamicin-induced acute ARF as a prospective setting, sets out to examine the reno-protective benefits of virgin coconut oil (VCO) and GSH. Furthermore, the study evaluated the effect of medication nanoparticle compositions on several kidney function markers. The induction of ARF is achieved with the intraperitoneal injection of gentamicin. To assess renal function, rats underwent 24h of dehydration and hunger before their deaths. The study examined various aspects, including kidney function tests, markers of oxidative stress, histology of kidney tissue, inflammatory cytokines, immunohistochemistry expression of nuclear factor-kappa B (NF-κB), and specific biomarkers for kidney tissue damage, such as kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL). The results of our study indicated that the combination of VCO and GSH, using both regular and nanoparticle formulations, had a better protective impact on the kidneys compared to using either drug alone. The recovery of renal tissue and serum markers, which are symptomatic of organ damage, indicates improvement. This was also demonstrated by the reduction in tubular expression of TNF-α, IL-1β, KIM-1, and NGAL. The immunohistochemical studies showed that the combination therapy, especially with the nanoforms, greatly improved the damaged cellular changes in the kidneys, as shown by higher levels of NF-κB. The study shows that VCO and GSH, when administered individually or combined, significantly improve ARF in a gentamicin-induced rat model, highlighting potential therapeutic implications. Notably, the combined nanoparticulate formulations exhibit substantial effectiveness.

Investigation of the thyroid function in end-stage renal failure disease in a Baquba teaching hospital/Diyala governorate - Iraq

Renal failure is the inability of the kidneys to excrete nitrogenous waste products, resulting in their retention in the bloodstream. Several correlations exist between renal and thyroid functions; however, end-stage renal failure is unlikely to be influenced by thyroid hormone function and is connected to a higher prevalence of hypothyroidism. The purpose of this study is to ascertain how thyroid status and renal function relate to renal failure patients. Serum creatinine and urea levels were tested in 50 healthy persons and 100 patients with renal failure illness. The acquired data showed that, in comparison to the control group, the average levels of creatinine and urea were significantly higher. The sick group recorded (122.98 mg/dL and 6.55 mg/dL) and (28.38 mg/dL and 0.75 mg/dL) in comparison to the control group, which has urea and creatinine values within the virtually normal range, respectively. In contrast, TSH levels showed no significant differences and have values within the normal range of TSH values, with 2.33 mIU/L for the experimental group and 2.0 mIU/L for the control group. In contrast, T4 values of the experimental group showed significantly lower levels than the control group, with 83.42 ng/dL compared to 103.77 ng/dL. T3 values, however, showed no significant changes and remained within the normal range of 1.75 to 1.64 nmol/L. In addition, the results demonstrated significant differences in the mean levels of anti-TPO, anti-Tg, and anti-TSHR antibodies. The anti-Tg showed a significant decrease in mean values, which were 28.89 IU/ml and 79.49 IU/ml compared to the control group ranges of 34.41 and 86.68 IU/mL. Finally, anti-TSHR showed a significant increase in the mean, which was 1.24 IU/L compared to 1.18 IU/L in the control group.

GARDENING THERAPY WITH BOILED WATER, ICE CUBES, CHEWING GUM REDUCES THIRST IN CKD PATIENTS: LITERATURE REVIEW

Chronic kidney failure occurs due to a failure in the body's ability to maintain metabolism and fluid and electrolyte balance resulting in uremia or retention of urea and other nitrogenous waste in the blood. The research aims to synthesize literature about gargling therapy with boiled water, ice cube therapy, and chewing gum to reduce thirst in CKD patients. The method used is content analysis with a literature search from 2020 to 2023 using the keywords Ice Cubes, gargling, chewing gum, CKD To reduce thirst by using ice there were 6 journals, 4 journals using chewing gum, and 1 journal using boiled water. All articles show that there is an effect of gargling therapy with boiled water, ice cube therapy, and chewing gum to reduce thirst in CKD patients. The literature study shows that the use of ice cubes has the most effect on reducing thirst in CKD patients, however, gargling therapy with boiled water and chewing gum are other alternatives.

The Impact of Silica Addition on Floc Volume Density in the Biofloc System for Juvenile Red Tilapia (Oreochromis niloticus)

Biofloc technology is a solution to the problem of waste management in aquaculture. Biofloc systems are beneficial because they not only reduce inorganic nitrogen waste from feed residues and fish excrement but also produce flocs. The aim of this research is to determine the effect of silica addition on floc volume density in the biofloc system for juvenile red tilapia. The research was conducted from January to March 2024 at the Center of Excellence in Science and Technology (PUI-PT) for Functional Nano Powder at Padjadjaran University. This study uses a Completely Randomized Design (CRD) experimental method with four treatments and three replications. The treatments used were (A) control, (B) 15 ppm silica, (C) 20 ppm silica, and (D) 25 ppm silica. The study used cylindrical containers with a capacity of 19 liters filled with 15 liters of water, a stocking density of 10 juvenile red tilapia per cylinder, with the juvenile measuring 3-4 cm and weighing 3-4 g. The parameters observed were floc volume density and water quality. The data on floc volume density and water quality were analyzed descriptively. The results showed that the addition of 25 ppm silica in the biofloc system was the best treatment for floc volume density. This was evidenced by the results in treatment D (25 ppm) achieving a floc volume density of 26.5 ml/L, which falls into the dense category. Therefore, the addition of silica concentration in the biofloc system can increase floc volume density.

Nitrate recovery from groundwater and simultaneous upcycling into single-cell protein using a novel hybrid biological-inorganic system

Nitrate pollution in groundwater is a serious problem worldwide, as its concentration in many areas exceeds the WHO-defined drinking water standard (50 mg/L). Hydrogen-oxidizing bacteria (HOB) are a group of microorganisms capable of producing single-cell protein (SCP) using hydrogen and oxygen. Furthermore, HOB can utilize various nitrogen sources, including nitrate. This study developed a novel hybrid biological-inorganic (HBI) system that coupled a new submersible water electrolysis system driven by renewable electricity with HOB fermentation for in-situ nitrate recovery from polluted groundwater and simultaneously upcycling it together with CO2 into single-cell protein. The performance of the novel HBI system was first evaluated in terms of bacterial growth and nitrate removal efficiency. With 5 V voltage applied and the initial nitrate concentration of 100 mg/L, the nitrate removal efficiency of 85.52 % and raw of 47.71 % (with a broad amino acid spectrum) were obtained. Besides, the HBI system was affected by the applied voltages and initial nitrogen concentrations. The water electrolysis with 3 and 4 V cannot provide sufficient H2 for HOB and the removal of nitrate was 57.12 % and 59.22 % at 180 h, while it reached 65.14 % and 65.42 % at 5 and 6 V, respectively. The nitrate removal efficiency reached 58.40 % and 50.72 % within 180 h with 200 and 300 mg/L initial nitrate concentrations, respectively. Moreover, a larger anion exchange membrane area promoted nitrate removal. The monitored of the determination of different forms of nitrogen indicated that around 60 % of the recovered nitrate was assimilated into cells, and 40 % was bio-converted to N2. The results demonstrate a potentially sustainable method for remediating nitrate contaminant in groundwater, upcycling waste nitrogen, CO2 sequestration and valorization of renewable electricity into food or feed.

Electrocatalysts for Inorganic and Organic Waste Nitrogen Conversion.

Anthropogenic activities have disrupted the natural nitrogen cycle, increasing the level of nitrogen contaminants in water. Nitrogen contaminants are harmful to humans and the environment. This motivates research on advanced and decarbonized treatment technologies that are capable of removing or valorizing nitrogen waste found in water. In this context, the electrocatalytic conversion of inorganic- and organic-based nitrogen compounds has emerged as an important approach that is capable of upconverting waste nitrogen into valuable compounds. This approach differs from state-of-the-art wastewater treatment, which primarily converts inorganic nitrogen to dinitrogen, and organic nitrogen is sent to landfills. Here, we review recent efforts related to electrocatalytic conversion of inorganic- and organic-based nitrogen waste. Specifically, we detail the role that electrocatalyst design (alloys, defects, morphology, and faceting) plays in the promotion of high-activity and high-selectivity electrocatalysts. We also discuss the impact of wastewater constituents. Finally, we discuss the critical product analyses required to ensure that the reported performance is accurate.

Nitrogen and phosphorus budgets of the bullfrog (Aquarana catesbeiana) in different body weights

Aquaculture water eutrophication is primarily driven by nitrogen (N) and phosphorus (P), partly derived from animal excretions. Understanding the N and P metabolism is crucial for mitigating environmental pollution caused by aquaculture. This study investigated N and P budgets in bullfrogs (Aquarana catesbeiana) of varying body weights: 52.63 ± 0.33 (50 g), 98.64 ± 0.55 (100 g), 159.97 ± 0.58 (150 g) and 250.01 ± 2.61 (250 g). Our findings highlighted the significant influence of body size on N and P budgets in bullfrogs. As body weight increased, feed intake rate, N and P intake rates, growth rate, N and P growth rates, N and P metabolism rates, feces rate, while the N and P feces rates all decreased. The relationship between each index and body weight was expressed as a power function (Y = aWb). The N and P budget equations for bullfrogs were established as follows: 100 Intake N (IN) = 30.75 Growth N (GN) + 62.48 Metabolism N (MN) + 2.10 Feces N (FN) + 4.67 Others (ON), and 100 P Intake P (IP) = 74.16 Growth P (GP) + 4.18 Metabolism P (MP) + 7.92 Feces P (FP) + 13.75 Others (OP). In conclusion, daily feeding per body weight of bullfrog should be reduced as their body weight increased. Consequently, the dietary protein should be progressively lowered to minimize nitrogen waste, while bullfrogs demonstrated effective utilization of P in the soybean meal diet.

Lipid extraction alters amino acid composition and bulk, but not amino acid, carbon and nitrogen isotope values.

Concerns exist over observed shifts in value and variance of nitrogen isotopes following physicochemical extraction of lipids from organic matter. The mechanisms behind these apparent changes in bulk tissue δ15N values are not fully understood yet have major implications for analytical costs and integrity of data interpretations. Changes in proximate analysis, amino acid composition, C:N ratios, bulk tissue and amino acid δ13C and δ15N values, and resulting isotope-based food web metrics were compared between lipid-intact and lipid-extracted muscle tissue of fishes spanning <1% to >20% muscle fat content to identify mechanisms of nitrogen isotope fractionation associated with physicochemical lipid extraction. Bulk δ13C and δ15N values increased and %N, C:N ratios and crude protein content decreased following lipid extraction. Resulting bulk isotope niche spacing and overlap varied significantly between lipid-intact and lipid-extracted tissues. While amino acid composition significantly changed during lipid extraction, particularly for lipid-associated amino acids (e.g., Glu, Lys, Ser), individual amino acid δ13C and δ15N values, and their associated compound-specific isotope analysis of amino acids (CSIA-AA)-based food web metrics, did not. Physicochemical lipid extraction caused significant tissue composition changes (e.g., leaching of amino acids and 15N-deplete nitrogenous waste) that affected δ13C and δ15N values and tissue %C and %N beyond simply removing lipids. However, lipid extraction did not alter individual amino acid δ13C or δ15N values or their associated CSIA-AA-based food web metrics.

Disruption in glutathione metabolism and altered energy production in the liver and kidney after ischemic acute kidney injury in mice

Acute kidney injury (AKI) is a systemic disease that affects energy metabolism in various remote organs in murine models of ischemic AKI. However, AKI-mediated effects in the liver have not been comprehensively assessed. After inducing ischemic AKI in 8–10-week-old, male C57BL/6 mice, mass spectrometry metabolomics revealed that the liver had the most distinct phenotype 24 h after AKI versus 4 h and 7 days. Follow up studies with in vivo [13C6]-glucose tracing on liver and kidney 24 h after AKI revealed 4 major findings: (1) increased flux through glycolysis and the tricarboxylic (TCA) cycle in both kidney and liver; (2) depleted hepatic glutathione levels and its intermediates despite unchanged level of reactive oxygen species, suggesting glutathione consumption exceeds production due to systemic oxidative stress after AKI; (3) hepatic ATP depletion despite unchanged rate of mitochondrial respiration, suggesting increased ATP consumption relative to production; (4) increased hepatic and renal urea cycle intermediates suggesting hypercatabolism and upregulation of the urea cycle independent of impaired renal clearance of nitrogenous waste. Taken together, this is the first study to describe the hepatic metabolome after ischemic AKI in a murine model and demonstrates that there is significant liver-kidney crosstalk after AKI.

Ammonia excretion by the fish gill: discoveries and ideas that shaped our current understanding.

The fish gill serves many physiological functions, among which is the excretion of ammonia, the primary nitrogenous waste in most fishes. Although it is the end-product of nitrogen metabolism, ammonia serves many physiological functions including acting as an acid equivalent and as a counter-ion in mechanisms of ion regulation. Our current understanding of the mechanisms of ammonia excretion have been influenced by classic experimental work, clever mechanistic approaches, and modern molecular and genetic techniques. In this review, I will overview the history of the study of ammonia excretion by the gills of fishes, highlighting the important advancements that have shaped this field with a nearly 100-year history. The developmental and evolutionary implications of an ammonia and gill-dominated nitrogen regulation strategy in most fishes will also be discussed. Throughout the review, I point to areas in which more work is needed to push forward this field of research that continues to produce novel insights and discoveries that will undoubtedly shape our overall understanding of fish physiology.

A case of suicide secondary to diethylene glycol intentional ingestion.

We aimed to describe a case of acute kidney injury (AKI) with an uncommon case. We described a previously health 24 years old male that presented acute kidney injury associated with neurological and respiratory symptoms. He was initially admitted at the hospital with nausea, vomiting, blurred vision, and reduced urine output. The patient's condition got worse approximately in one week. Laboratory tests revealed high levels of nitrogenous waste, hyponatremia, metabolic acidosis with an increased anion gap, and the presence of proteinuria and hematuria. The patient experienced paresthesia, seizures, respiratory alterations, and altered consciousness. The initial diagnostic hypothesis of rapidly progressive glomerulonephritis was not confirmed. A deeper investigation of the case exposed that it could have occurred an intentional exogenous poisoning with diethylene glycol (DEG). Renal biopsy unveil findings suggestive of poison-induced nephrotoxicity, which corroborated the suspicion. Despite therapeutic efforts, the patient died due to pulmonary complications. This case report shows the need to consider DEG poisoning as a etiology of AKI, especially in patients with neurological symptoms. Laboratory and histopathological analysis were crucial for the diagnosis.

Biological removal of nitrogenous waste compounds in the biofloc aquaculture system: a review

Abstract Aquaculture has experienced significant global expansion and is considered one of the fastest-growing sectors in food production. However, there exist additional challenges that restrict the capacity to achieve maximum efficiency in aquaculture systems, such as issues over water quality and shortages of appropriate live feeds. Intensive aquaculture systems involve the use of protein-rich prepared feed for feeding the cultured animals. This may give rise to the discharge of nitrogenous compounds into the water, which can pose a risk to the environment when present in excessive quantities beyond the acceptable levels. In recent years, an innovative method called biofloc technology (BFT) has become a practical solution to this issue. Undoubtedly, BFT offers a groundbreaking method for nutrient disposal that eradicates the requirement for excessive water use or equipment maintenance. Three primary types of microorganisms are crucial in alleviating the adverse impacts of nitrogen compounds in this technique. Photoautotrophs participate in the processes of removal and absorption, whereas chemoautotrophs promote nitrification and conversion. Heterotrophs contribute to the absorption process. Biofloc predominantly consists of heterotrophic bacteria, alongside algae, protozoa, rotifers, and nematodes. While there have been reviews carried out on multiple aspects of biofloc technology, there exists a lack of literature that tackles this particular field of research progress. This article discusses every aspect and techniques of biological management used for removing nitrogenous waste compounds in biofloc aquaculture systems.

Nitrogen and me — How little did we, and do we know about “stikstof – azote – nitrogen”?

This retrospective article reflects on the complex and evolving relationship between humans and nitrogen over several decades. Raised on a Flemish farm, the author's early experiences with nitrogen in agriculture – both its benefits and dangers – laid the foundation for a lifelong interest in this element. The article traverses a broad range of topics related to nitrogen, highlighting its critical role in various historical, agricultural, environmental, and industrial contexts. The narrative begins with a historical overview of nitrogen's role in agriculture and warfare. The development of industrial processes like the Haber and Ostwald methods transformed nitrogen into a key ingredient for both fertilizers and explosives. The dual nature of nitrogen – as a life-giver in agriculture and a destructive component in warfare and also in biodiversity – is an important theme. The article delves into the environmental impacts of nitrogen, particularly in the context of modern agriculture and industrialization. Issues like fertilization, water contamination, and the challenges of managing nitrogenous waste highlight the complex interplay between human activities and environmental health. Technological advancements are explored, including the development of bioaugmentation methods and the potential of genetic engineering in optimizing nitrogen fixation. Throughout the narrative, personal anecdotes are weaved with scientific information, offering a unique perspective on the historical and contemporary challenges of managing nitrogen. The discussion extends to the broader implications of nitrogen management in the context of sustainability, climate change, and global food security and its overall regulatory space. All these considerations call for a re-evaluation of our relationship with nitrogen, advocating for innovative solutions and systemic thinking to address the multifaceted challenges posed by this essential, yet often problematic element.

Black soldier fly larvae mitigate greenhouse gas emissions from domestic biodegradable waste by recycling carbon and nitrogen and reconstructing microbial communities.

Black soldier fly larvae have been proven to reduce greenhouse gas emissions in the treatment of organic waste. However, the microbial mechanisms involved have not been fully understood. The current study mainly examined the dynamic changes of carbon and nitrogen, greenhouse gas emissions, the succession of microbial community structure, and changes in functional gene abundance in organic waste under larvae treatment and non-aeration composting. Thirty percent carbon and 55% nitrogen in the organic waste supplied were stored in larvae biomass. Compared to the non-aeration composting, the larvae bioreactor reduced the proportion of carbon and nitrogen converted into greenhouse gases (CO2, CH4, and N2O decreased by 62%, 87%, and 95%, respectively). 16S rRNA sequencing analysis indicated that the larvae bioreactor increased the relative abundance of Methanophaga, Marinobacter, and Campylobacter during the bioprocess, enhancing the consumption of CH4 and N2O. The metagenomic data showed that the intervention of larvae reduced the ratio of (nirK + nirS + nor)/nosZ in the residues, thereby reducing the emission of N2O. Larvae also increased the functional gene abundance of nirA, nirB, nirD, and nrfA in the residues, making nitrite more inclined to be reduced to ammonia instead of N2O. The larvae bioreactor mitigated greenhouse gas emissions by redistributing carbon and nitrogen and remodeling microbiomes during waste bioconversion, giving related enterprises a relative advantage in carbon trading.

High-Performance Ammonia Electrosynthesis from Nitrate in a NaOH-KOH-H2O Ternary Electrolyte.

A glut of dinitrogen-derived ammonia (NH3) over the past century has resulted in a heavily imbalanced nitrogen cycle and consequently, the large-scale accumulation of reactive nitrogen such as nitrates in our ecosystems has led to detrimental environmental issues. Electrocatalytic upcycling of waste nitrogen back into NH3 holds promise in mitigating these environmental impacts and reducing reliance on the energy-intensive Haber-Bosch process. Herein, we report a high-performance electrolyzer using an ultrahigh alkalinity electrolyte, NaOH-KOH-H2O, for low-cost NH3 electrosynthesis. At 3,000 mA/cm2, the device with a Fe-Cu-Ni ternary catalyst achieves an unprecedented faradaic efficiency (FE) of 92.5±1.5 % under a low cell voltage of 3.83 V; whereas at 1,000 mA/cm2, an FE of 96.5±4.8 % under a cell voltage of only 2.40 V was achieved. Techno-economic analysis revealed that our device cuts the levelized cost of ammonia electrosynthesis by ~40 % ($30.68 for Fe-Cu-Ni vs. $48.53 for Ni foam per kmol-NH3). The NaOH-KOH-H2O electrolyte together with the Fe-Cu-Ni ternary catalyst can enable the high-throughput nitrate-to-ammonia applications for affordable and scalable real-world wastewater treatments.

High‐Performance Ammonia Electrosynthesis from Nitrate in a NaOH−KOH−H2O Ternary Electrolyte

AbstractA glut of dinitrogen‐derived ammonia (NH3) over the past century has resulted in a heavily imbalanced nitrogen cycle and consequently, the large‐scale accumulation of reactive nitrogen such as nitrates in our ecosystems has led to detrimental environmental issues. Electrocatalytic upcycling of waste nitrogen back into NH3 holds promise in mitigating these environmental impacts and reducing reliance on the energy‐intensive Haber–Bosch process. Herein, we report a high‐performance electrolyzer using an ultrahigh alkalinity electrolyte, NaOH−KOH−H2O, for low‐cost NH3 electrosynthesis. At 3,000 mA/cm2, the device with a Fe−Cu−Ni ternary catalyst achieves an unprecedented faradaic efficiency (FE) of 92.5±1.5 % under a low cell voltage of 3.83 V; whereas at 1,000 mA/cm2, an FE of 96.5±4.8 % under a cell voltage of only 2.40 V was achieved. Techno‐economic analysis revealed that our device cuts the levelized cost of ammonia electrosynthesis by ~40 % ($30.68 for Fe−Cu−Ni vs. $48.53 for Ni foam per kmol‐NH3). The NaOH−KOH−H2O electrolyte together with the Fe−Cu−Ni ternary catalyst can enable the high‐throughput nitrate‐to‐ammonia applications for affordable and scalable real‐world wastewater treatments.

Mechanisms of neurocentral-eyestalk-intestinal immunotoxicity in whiteleg shrimp Litopenaeus vannamei under ammonia nitrogen exposure

Ammonia-N, as the most toxic nitrogenous waste, has high toxicity to marine animals. However, the interplay between ammonia-induced neuroendocrine toxicity and intestinal immune homeostasis has been largely overlooked. Here, a significant concordance of metabolome and transcriptome–based “cholinergic synapse” supports that plasma metabolites acetylcholine (ACh) plays an important role during NH4Cl exposure. After blocking the ACh signal transduction, the release of dopamine (DA) and 5-hydroxytryptamine (5-HT) in the cerebral ganglia increased, while the release of NPF in the thoracic ganglia and NE in the abdominal ganglia, and crustacean hyperglycemic hormone (CHH) and neuropeptide F (NPF) in the eyestalk decreased, finally the intestinal immunity was enhanced. After bilateral eyestalk ablation, the neuroendocrine system of shrimp was disturbed, more neuroendocrine factors, such as corticotropin releasing hormone (CRH), adrenocorticotropic-hormone (ACTH), ACh, DA, 5-HT, and norepinephrine (NE) were released into the plasma, and further decreased intestinal immunity. Subsequently, these neuroendocrine factors reach the intestine through endocrine or neural pathways and bind to their receptors to affect downstream signaling pathway factors to regulate intestinal immune homeostasis. Combined with different doses of ammonia-N exposure experiment, these findings suggest that NH4Cl may exert intestinal toxicity on shrimp by disrupting the cerebral ganglion-eyestalk axis and the cerebral ganglion-thoracic ganglion-abdominal ganglion axis, thereby damaging intestinal barrier function and inducing inflammatory response.

Gamma ray irradiation enhances defatted Hermetia illucens larvae meal as a dietary alternative to fishmeal for Acanthopagrus schlegelii juveniles

The current research investigated whether gamma (γ)-irradiation could improve the viability of defatted Hermetia illucens larvae (HIL) meal as a fishmeal alternative in black sea bream (Acanthopagrus schlegelii) diets. Three diets were formulated with equal protein (420 g/kg) and lipid (80 g/kg) contents. A diet containing 400 g/kg fishmeal was served as the control diet (C), and 50% of fishmeal in diet C was replaced by either defatted HIL meal or γ-irradiated defatted HIL meal to produce diet HR and diet HR10, respectively. Fish fed diet HR exhibited lower final body weight and weight gain compared to those fed diet C, while no statistically significant differences were found between fish fed diets C and HR10. Additionally, fish fed diet HR10 exhibited significantly lower feed intake, feed conversion rate, nitrogen waste, hepatic malondialdehyde content, relative usage of fishmeal and fish oil, fish-in to fish-out ratio, and economic conversion ratio, and meanwhile significantly higher nitrogen retention efficiency, hepatic total antioxidant capacity, economic profitability index and profitability, than those fed diet C. Fish fed different test diets showed statistically equal alpha diversity of intestinal microbiota, whereas the beta diversity of intestinal microbiota in group HR was far from groups C and HR10. Compared to fish fed diet C, the gut microbiota composition of fish fed diet HR showed significant alterations at both the phylum and genus levels. However, the altered composition of intestinal bacteria was partially restored in fish fed diet HR10. The above findings indicate that treating defatted HIL meal with γ-ray can reduce dietary fishmeal content for black sea bream to 200 g/kg without any adverse effects on growth, proximate composition and intestinal microbial diversity, and meanwhile ameliorates the feed utilization, hepatic antioxidant capacity, and intestinal microbiological composition of black sea bream. Furthermore, feeding γ-irradiated defatted HIL meal enhances the economic profitability, while reduces the waste output and reliance on fishery resource of black sea bream aquaculture.