Concentration Of Most Amino Acids Research Articles

Prediction of the apparent ileal digestible amino acid contents of canola meal for broilers from crude protein content

Context Canola meal is a protein-rich feedstuff with an amino acid profile that is reasonably well balanced and has the potential to replace soybean meal in poultry diets. Aim The objective of the present study was to investigate the relationship between the crude protein content and apparent ileal digestible amino acid contents of Australian canola meals. Methods Thirteen canola meal samples, processed by expeller or solvent extractions, were collected. The digestibility assay diets were based on dextrose and contained canola meal as the sole source of protein. The proportions of dextrose and canola meal were varied in each diet to obtain ~200 g/kg crude protein. Each diet was fed to three cages of six 35-day-old broilers for 7 days. At the end of the assay, digesta from the terminal ileum was collected for digestibility determination. Key results Crude protein contents were positively correlated with amino acid contents (P < 0.05 to 0.001), except that of serine (r = 0.43; P = 0.11). Significant correlations between the crude protein content and ileal digestible contents were observed for most of amino acids, with coefficients of >0.80 (P < 0.05 to 0.001). Low correlation coefficients were observed for lysine (r = 0.48; P = 0.11) and serine (r = 0.55; P = 0.06). The poor correlation for lysine may be reflective of reduced lysine availability during processing. Conclusions The results showed that the crude protein content of canola meal could serve as a predictor of apparent ileal digestible content of most amino acids for broiler chickens. Implications Regression equations developed in the present study could be used to predict the content of ileal digestible amino acids in canola meal by using analysed crude protein contents.

Nitrogen fertilizer regulates purple rice seed endophytes and grain amino acid accumulation

AbstractThe effects of different nitrogen (N) application levels on seed endophytes and grain nutritional quality are not yet clear. The impact of four N application levels on endophytes and amino acid accumulation in purple rice seeds was examined using 16S rRNA and ITS amplicon sequencing technology. This study integrates 16S rRNA, ITS amplicon sequencing technology and amino acid‐targeted detection to explore the effects of four different nitrogen application levels (0 kg hm−2, Y1N0; 180 kg hm−2, Y1N1; 270 kg hm−2, Y1N2; 360 kg hm−2, Y1N3) on the accumulation of endophytic bacteria, fungi and amino acid content in purple rice seeds and their interaction mechanisms. The findings indicated an increase in the contents of most amino acids with increasing N application. The dominant bacterial species in the community were mainly from the phyla Proteobacteria and Actinobacteriota, while the dominant fungal species were from the phyla Ascomycota and Basidiomycota. There was a significant difference in the richness of endophytic fungal communities between Y1N0 and Y1N2. Y1N1 showed significant differences in Mucoromycota compared to Y1N3. The quantity of operational taxonomic units (OTUs) in the bacterial and fungal community co‐occurrence network increased with increasing N fertilizer, showing strong correlations with Sporidiobolus, Chaetomium, Humicola, Botryotrichum, Ophiosphaeria and Dioszegia for most amino acids. These findings indicate that a high amount of N fertilizer greatly increases amino acid contents in purple rice seeds and improves the diversity and stability of endophytic fungal populations.

Increased hepatic glucagon sensitivity in totally pancreatectomised patients.

The metabolic phenotype of totally pancreatectomised patients includes hyperaminoacidaemia and predisposition to hypoglycaemia and hepatic lipid accumulation. We aimed to investigate whether the loss of pancreatic glucagon may be responsible for these changes. Nine middle-aged, normal-weight totally pancreatectomised patients, nine patients with type 1 diabetes (C-peptide negative), and nine matched controls underwent two separate experimental days, each involving a 150-min intravenous infusion of glucagon (4 ng/kg/min) or placebo (saline) under fasting conditions while any basal insulin treatment was continued. Glucagon infusion increased plasma glucagon to similar high physiological levels in all groups. The infusion increased hepatic glucose production and decreased plasma concentration of most amino acids in all groups, with more pronounced effects in the totally pancreatectomised patients compared with the other groups. Glucagon infusion diminished fatty acid re-esterification and tended to decrease plasma concentrations of fatty acids in the totally pancreatectomised patients but not in the type 1 diabetes patients. Totally pancreatectomised patients were characterised by increased sensitivity to exogenous glucagon at the level of hepatic glucose, amino acid, and lipid metabolism, suggesting that the metabolic disturbances characterising these patients may be rooted in perturbed hepatic processes normally controlled by pancreatic glucagon.

Enhanced cadmium absorption and tolerance of rice epiphytic microbes by iron oxide nanoparticles

Nanoparticles present a promising approach for mitigating cadmium (Cd) uptake in crops. Nevertheless, limited research has been focused on the application nanoparticles to mitigate plant Cd stress through increasing Cd absorption and tolerance of epiphytic microbes. Herein, Methylobacterium currus DSD (Meb) was isolated and identified as the type strain. The application of iron oxide nanoparticles (200 mg L−1 IONPs, including Fe2O3NPs and Fe3O4NPs) resulted in considerably enhanced adsorption capacity for Cd by Meb, accompanied by increased surface functional groups, particularly carboxyl and hydroxyl groups. The extracellular polymeric substances (EPS) of Meb-Fe3O4NPs exhibited the higher contents of proteins and polysaccharides. The introduction of Fe3O4NPs increased the mole% of ribose, arabinose, and glucose, as well as the contents of most amino acids. Fe3O4NPs might drive the glycolytic process of converting glucose to amino acids. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) analyses further confirmed the involvement of CO and C–N groups in proteins, and C–O groups in polysaccharides. Moreover, the presence of IONPs enhanced Meb tolerance to Cd, which was a highlight. This study provides a novel perspective from epiphytic microbes for nanoparticles to reduce the toxicity and accumulation of Cd in crops.

Effects of different levels of methionine in pre-starter diets on immunity function and DNA methylation in broilers

The study was carried out to determine the effects of different levels of methionine in Pre-starter diets on PPAR gene expression and immune function of broiler chickens. Methionine (Met) is necessary to achieve a fast growth rate in chickens. A total of 240 Ross 308 broilers were equally assigned to 8 treatments with 3 replicates. The treatments included T1: diet with 20% methionine less than Ross catalog recommendation. T2: Standard diet in accordance with the recommendations of the Ross catalog. T3, T4, T5, T6, T7 and T8: diets with 20, 40, 60, 80, 100 and 120 % methionine more than Ross catalog recommendation. The results showed that there was a significant difference in the expression of PPAR gene with the difference in diet methionine levels in the 8 groups. PPAR controls the expression of several genes involved in the proliferation and differentiation of adipose tissue cells. Gene expression in broiler chickens with methionine deficiency and excess may have compensated for this deficiency and excess in the birds. Also, the results indicated that increasing in the levels of methionine in Pre-starter diets of chickens the antibody production against ND increased significantly (P<0.05). Besides, the antibody production against IBD increased significantly (P<0.05). Furthermore, the antibody production against H9N1 not affected (P>0.05). Studies suggest that dietary protein deficiency reduces the concentration of most amino acids in plasma and compromises the immune system. Totally it is suggested that the high levels of Met in the diet maybe beneficial and it needs more studies.

Changes in flavor and biological activities of Lentinula edodes hydrolysates after Maillard reaction

This study aimed to elucidate how the Maillard reaction (MR) affects the flavor and bioactivities of Lentinula edodes hydrolysates (LEHs). Changes in flavor were investigated using non-targeted metabolomics techniques (GC–MS and LC-MS/MS) and sensory evaluation. Simultaneously, UV absorption, fluorescence, and FT-IR spectra were used to characterize the process of MR. We also evaluated the effects of MR on the antioxidant activity, hypoglycemic activity and antimicrobial activity of LEHs in vitro. The results revealed that MR produced many volatile aldehydes and ketones and decreased the content of most amino acids, sugars and flavonoids in the LEHs while increasing the content of l-theanine and succinic acid. MRPs had a strong caramel and like-meat flavor and an obvious improvement in umami, taste continuity, and total acceptability. Furthermore, MR improved the antioxidant and antimicrobial properties of LEHs. This research establishes a theoretical foundation for MR in the deep processing of edible mushrooms.

Effects of Storage Temperature at the Early Postharvest Stage on the Firmness, Bioactive Substances, and Amino Acid Compositions of Chili Pepper (Capsicum annuum L.).

The commercial and nutritional quality of chili peppers deteriorates rapidly after harvest. So far, little is known about the effect of temperature on postharvest chili pepper quality. This study elucidated the effects of two temperatures (20 °C and 30 °C) on chili peppers' postharvest firmness, flavor, and nutritional attributes. We found that compared to 20 °C, 30 °C escalated the decline in fruit firmness, capsaicin content, and dihydrocapsaicin content, while enhancing the increment in water loss and electrical conductivity, as well as total carotenoids and ascorbic acid content. The contents of most amino acids (AAs) decreased significantly during postharvest storage compared to their initial values, whether stored at 20 °C or 30 °C; however, 30 °C had a more substantial impact than 20 °C. Meanwhile, as for soluble protein and amino acid compositions, the effect of storage temperature was genotype-dependent, as reflected by differential changes in total AA contents, single AA contents, essential AA ratio, delicious AA ratio, etc., under the 20 °C or 30 °C treatments. In conclusion, our findings reveal the influence of temperature on pepper quality, showing that the storage temperature of 20 °C was better for maintaining chili quality than 30 °C from the perspective of overall commercial attributes.

Effects of withering time of fresh leaves on the formation of flavor quality of Taiping Houkui tea

Withering time of fresh leaves is a key factor affecting the stability of flavor quality of Taiping Houkui tea (TPHK). It's effect and mechanism on the formation of flavor in TPHK remain unelucidated. Here, metabolomics and transcriptomics were combined to comprehensively investigate changes in the main flavor compounds and the expression patterns of related genes under different withering times. The results showed that withering had the greatest influence on the content of most amino acids and aroma volatiles. The relative content of most volatiles was observed to be highest at 6–8 h of withering time, which was consistent with the results from the sensory evaluation of aroma quality. Plant hormone signal transduction pathways played a key role in the variation of the flavor compound content under different withering times, especially ABA and JA signals. WGCNA demonstrated that ABA, JA, IAA, SA and different flavor substances were significantly associated with specific modules. JA may be involved in the metabolism of theanine during withering, while ABA may be involved in the accumulation of aromatic amino acids and main aroma components of TPHK. This research may serve as a reference for the optimization of the processing technology for TPHK.

Diazo probe-based chemical isotope labeling assisted liquid chromatography-tandem mass spectrometry analysis for sensitive determination of amino acids in biofluids

Amino acids are important biomolecules and contribute to essential biological processes. Liquid chromatography tandem mass spectrometry (LC–MS) now is a powerful tool for the analysis of amino acid metabolites; however, the structural similarity and polarity of amino acids can lead to the poor chromatographic retention and low detection sensitivities. In this study, we used a pair of light and heavy isotopomers of diazo probes, d0/d5-2-(diazomethyl)-N-methyl-N-phenyl-benzamide (2-DMBA/d5 -2-DMBA) to label amino acids. The paired MS probes of 2-DMBA and d5 -2-DMBA carry diazo groups that can efficiently and specifically react with the carboxyl group on free amino acid metabolites under mild conditions. Benefiting from the transfer of the 2-DMBA/d5 -2-DMBA to carboxyl group on amino acids, the ionization efficiencies of amino acids presented great enhancement during LC–MS analysis. The results suggested that the detection sensitivities of 17 amino acids increased by 9-133-fold upon 2-DMBA labeling, and the obtained limits of detection (LODs) of amino acids on-column ranged from 0.011 fmol-0.057 fmol. With the application of the developed method, we successfully achieved the sensitive and accurate detection of the 17 amino acids in microliter level of serum sample. Moreover, the contents of most amino acids were different in the serum from normal and B16F10-tumour mice, demonstrating that endogenous amino acids may play important roles in the regulation of tumors development. This developed method of chemical labeling of amino acids with diazo probes assisted LC–MS analysis provides a potentially valuable tool to investigate the relationships between amino acids metabolism and diseases.

Metabolomics and Transcriptomics Reveal the Response Mechanisms of Mikania micrantha to Puccinia spegazzinii Infection.

Mikania micrantha is one of the worst invasive species globally and can cause significant negative impacts on agricultural and forestry economics, particularly in Asia and the Pacific region. The rust Puccinia spegazzinii has been used successfully as a biological control agent in several countries to help manage M. micrantha. However, the response mechanisms of M. micrantha to P. spegazzinii infection have never been studied. To investigate the response of M. micrantha to infection by P. spegazzinii, an integrated analysis of metabolomics and transcriptomics was performed. The levels of 74 metabolites, including organic acids, amino acids, and secondary metabolites in M. micrantha infected with P. spegazzinii, were significantly different compared to those in plants that were not infected. After P. spegazzinii infection, the expression of the TCA cycle gene was significantly induced to participate in energy biosynthesis and produce more ATP. The content of most amino acids, such as L-isoleucine, L-tryptophan and L-citrulline, increased. In addition, phytoalexins, such as maackiain, nobiletin, vasicin, arachidonic acid, and JA-Ile, accumulated in M. micrantha. A total of 4978 differentially expressed genes were identified in M. micrantha infected by P. spegazzinii. Many key genes of M. micrantha in the PTI (pattern-triggered immunity) and ETI (effector-triggered immunity) pathways showed significantly higher expression under P. spegazzinii infection. Through these reactions, M. micrantha is able to resist the infection of P. spegazzinii and maintain its growth. These results are helpful for us to understand the changes in metabolites and gene expression in M. micrantha after being infected by P. spegazzinii. Our results can provide a theoretical basis for weakening the defense response of M. micrantha to P. spegazzinii, and for P. spegazzinii as a long-term biological control agent of M. micrantha.

Generation of blunt snout bream without intermuscular bones by runx2b gene mutation

Blunt snout bream (Megalobrama amblycephala) is an important herbivorous freshwater economic fish cultivated in China. Its economic value has been affected by the existence of intermuscular bones (IBs). Our previous study proved that runx2b is the key gene for the IBs formation, and lack of runx2b gene could obtain a stable zebrafish mutant without IBs. We found runx2b mutant F0 generation of blunt snout bream through CRISPR/Cas9 editing technology had a significant reduction on the number of IBs. In order to further obtain the blunt snout bream without IBs, we used the runx2b mutant F0 generation to self-bred to obtain F1 generation. Subsequently, the 35 runx2b mutant F1 individuals of blunt snout bream without IBs were genotyped and found the number of runx2b targeting sites 1, 2 and 3 obtained 3 (1 insertion, 2 deletion), 13 (8 insertion, 5 deletion) and 7 (1 insertion, 6 deletion) mutation types with the mutation efficiency being 25.71%, 94.28%, and 71.43%, respectively. Alizarin red bone staining and X-ray scan analysis showed that IBs were not existed in runx2b mutant F1 individuals, and micro-CT analysis found that the mineralization of other bone in runx2b mutant was not significantly affected compared to wild type fish (P > 0.05). RT-qPCR results also exhibited that bone-related genes had a lower expression level in runx2b mutants compared to wild type fish. Subsequently, we used the national standard methods to detect nutrition composition of muscle tissue in wild type (with IBs) and runx2b mutant F1 individuals (without IBs) at 120 dpf. The results showed that the basic muscle nutritional composition (moisture, crude protein, crude lipid and crude ash), and the contents of most amino acids and fatty acids had no significant differences between wild and runx2b mutant at juvenile stage (P > 0.05). This study proves that the runx2b gene has an essential role for IBs formation in aquaculture species and lays an important foundation for obtaining a new blunt snout bream strain without IBs, which provides a good example for the application of IBs-free characters from model fish to commercial fish.

Metabolomic and Transcriptomic Changes Underlying the Effects of L-Citrulline Supplementation on Ram Semen Quality.

This study examined the effects of L-Cit supplementation on ram semen quality through metabolomics and transcriptomics. A total of 16 rams were randomly categorized into two groups. The control group was fed a basic diet, whereas the experimental group received feed supplemented with 12 g/d of L-Cit. Semen and blood were collected from the rams on days 0 and 72 to measure sugar, pyruvate, amino acid, and nontargeted metabolite contents. Additionally, hypothalamic and testicular tissues were collected for a transcriptomic analysis. We found 27 differential metabolites between the control and experimental groups, of which 21 were downregulated (p < 0.05) and 6 were upregulated (p < 0.05). Compared with the control group, xylose and pyruvate contents in seminal plasma increased by 43.86% and 162.71%, respectively (p < 0.01). Additionally, the levels of 11 amino acids showed a significant increase in seminal plasma (p < 0.01). Furthermore, 961 and 715 differentially expressed genes were detected in the hypothalamic and testicular tissues, respectively. The pathways of significant enrichment in the hypothalamus and testes were protein digestion, absorption, glycolysis/gluconeogenesis, and amino as well as nucleotide sugar metabolisms. In the present study, L-Cit improved protein synthesis and blood metabolism, consequently increasing the contents of most amino acids in ram seminal plasma. Specifically, the hypothalamus controlled the expression of glycolysis/gluconeogenesis-related genes in the testes through its metabolites released into the serum, thereby providing energy for sperm production, which led to a decrease in the sugar content of seminal plasma.

Transcriptomic dissection underlying physiological and anatomical characteristics of poplar wood in response to changes in light intensity and nitrogen availability

To dissect the transcriptomic reprograming underlying the physiological and anatomical characteristics in the wood of Populus species in response to changes in light and nitrogen (N) availability, the saplings of P. alba × P. glandulosa were exposed to either control or high light intensity in combination with one of low, normal and high N levels. High light caused greater CO2 assimilation rate, higher concentrations of soluble sugars and starch, decreased enzymatic activities of NR and GS and increased activities of GOGAT and GDH, higher IAA and lower ABA, JA and SA contents, narrower fibers, and thinner thickness of fiber wall in the wood of poplars under normal N condition. Low N supply led to greater levels of sucrose and starch, lower contents of most amino acids, IAA, ABA and JA, and narrower vessels and fibers, and high N caused the opposite effects in poplar wood exposed to control light. Transcriptomic reprograming occurred underlying the physiological and anatomical changes of P. alba × P. glandulose in acclimation to high light in combination with one of low, normal and high N levels. High light- and low/high N-induced differential expression of the key genes including neutral invertases, ASN1, JAZ1, and TIP1;3, involved in the metabolism of carbohydrate, amino acids and phytohormones, and water transport, corresponded well to changes in physiological and anatomical characteristics in poplar wood in response to high light and altered N availability. These results suggest that physiological and anatomical characteristics are altered in the wood and the underlying transcriptomic reprograming is critical for the wood in acclimation to high light in combination with changing N availability.

Integration of multiplatform metabolomics and multivariate analysis for geographical origin discrimination of Panax ginseng

As the health food industry grows, the market for ginseng also expands globally. Korean ginseng (Panax ginseng C. A. Meyer) is cultivated in East Asian countries such as Korea, China, and Japan. The metabolic profile of plants can vary depending on the cultivation environment. As such, in this study, we aimed to compare the differences in the metabolic profiles of P. ginseng cultivated in Korea, China, and Japan, and to construct a library of these metabolite data. Using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS), we profiled 62 types of secondary metabolites, ginsenosides, using optimized analysis conditions to separate peaks with a high-resolution for about 30 min. In addition, we selected ginsenosides showing differences between their origins were selected among the possible origins in the S-line plot of orthogonal partial least squares discriminant analysis (OPLS-DA), which we quantitatively analyzed using UPLC-tandem mass spectrometry (UPLC-MS/MS). The contents of ginsenosides Ra1, Ra2, Ra3, and Rk1 were high in Korean P. ginseng; the contents of ginsenosides Rb1, Rb2, and Rc were high in Japanese P. ginseng; and the contents of the ginsenoside Ro was high in Chinese P. ginseng. We also analyzed the primary metabolite contents using nuclear magnetic resonance (NMR) spectroscopy and gas chromatography time-of-flight mass spectrometry (GC-TOF/MS). Japanese P. ginseng showed a high sucrose content and Korean P. ginseng showed high contents of most amino acids and organic acids. In the PLS-DA results of multivariate statistical analysis using the data obtained from each analysis instrument, we observed a clear clustering among the three origins. Although a genetically identical species, the metabolic profile substantially differs depending on the cultivation environment. Because ginsenoside, having many biological activities, showed origin-dependent origins, when P. ginseng is used for medicinal purposes, its content by origin should be considered. After disclosing the profiling results of these metabolites, we expect that they will be used in future ginseng research.

Integrated metabolomic and transcriptomic analyses of two peanut (Arachis hypogaea L.) cultivars differing in amino acid metabolism of the seeds

Peanut is an important economic crop worldwide. The content of amino acids, especially essential amino acids, is an important nutritional quality trait of peanut seeds. However, the regulation of amino acid metabolism in peanut seeds is poorly understood. Here, two peanut cultivars, Zhonghuahei 1 and Zhongkaihua 151, with high and low free amino acids in mature seeds, respectively, were selected to investigate the regulatory mechanisms of amino acids during seed development. Zhonghuahei 1 is composed of significantly higher arginine (Arg), asparagine (Asn), and glutamate (Glu) contents than Zhongkaihua 151. However, the metabolomic analyses indicated that the contents of most amino acids were significantly lower in Zhonghuahei 1 at the early developmental stage, while they were reverse at the middle and late stages. Transcriptomic analyses also revealed that the differentially expressed genes between the two cultivars during different stages were enriched in multiple pathways associated with amino acid metabolism. Among them, the Arg biosynthesis pathway showed different regulatory profiles between the two cultivars according to the temporal analysis of gene expression patterns. Subsequent gene co-expression network analysis showed that the gene module darkorange was significantly correlated with Arg content, with an enriched Arg biosynthesis pathway. Accordingly, a gene regulatory network for Arg biosynthesis and metabolism, including key genes (ALDH, ASS1, OTC, and GAD) and transcription factors (GATA, HEX, and ATF), was constructed. These findings provide insights into the regulatory network of amino acid metabolism in peanuts and provide candidate genes that can be applied to facilitate peanut breeding with desirable seeds.

Quantitative Detection of Amino Acids and Carnitine in Human Blood and Quality Control of Peptide Drugs

In order to deal with the biochemical metabolic disorder and the lack of end metabolites caused by hereditary metabolic diseases, a quantitative detection method of amino acids and carnitine in human blood and the quality control method of polypeptide drugs were proposed. First, a method for the detection of 10 amino acids and 32 acylcarnitine metabolites in human blood was established and analyzed by liquid chromatography tandem mass spectrometry. Through the experimental research on typical peptide drugs, combined with the classical synthesis process and the PLS-DA model of human body in different regions, the relevant detection methods for the quality control of peptide drugs were established, which provided a reference for the formulation of peptide drug quality standards. The experimental results show that the quantitative detection method proposed in this paper can effectively detect the content of most amino acids and acylcarnitine. The classical detection method achieved a loss of 16.74% smaller mass-to-charge ratio, and based on this, the quantitative standard for polypeptide drug delivery was determined, which verifies the correctness and superiority of the detection method in this paper.

Analysis of Metabolomic Changes in Xylem and Phloem Sap of Cucumber under Phosphorus Stresses

Cucumber xylem and phloem sap is a key link in nutrient distribution, transportation and signal transduction of cucumber plants; however, the metabolic response mechanism of cucumber xylem and phloem sap under phosphorus stress has not been clearly revealed. In this study, gas chromatography-mass spectrometry (GC-MS) combined with principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were used to analyze the metabolites in cucumber xylem and phloem sap under different phosphorus stress. A total of 22 differential metabolites were screened from xylem and phloem sap, respectively. Through the analysis of metabolic pathways of differential metabolites, four and three key metabolic pathways were screened, respectively. The results showed that compared with the normal phosphorus level, the content of most amino acids in the key metabolic pathway increased in xylem but decreased in phloem both under low and high phosphorus stress levels. The contents of sucrose and glucose in phloem glycolysis pathway showed a positive correlation with the change of phosphorus nutrient levels. The tricarboxylic acid cycle was promoted in xylem and phloem of cucumber under low and high phosphorus nutrient levels, and the contents of malic acid and citric acid increased significantly. This study provided abundant biochemical information for the metabolic response and regulation strategies of cucumber xylem and phloem under phosphorus stress, and is committed to looking for more sensitive markers to evaluate the supply level of phosphorus nutrients in cucumber.

Coculture of the Pacific white shrimp Litopenaeus vannamei and the macroalga Ulva linza enhances their growth rates and functional properties

Integrated multi-trophic aquaculture (IMTA) has been proposed as a potential solution to supply aquatic food in an environmentally friendly way. However, little is known regarding the impacts of IMTA on the growth rates and food quality of both animals and plants, as well as the seasonal effects. In this study, we conducted field mesocosm experiments using monoculture and coculture systems with the shrimp Litopenaeus vannamei and the macroalga Ulva linza for four weeks in different seasons (autumn, spring and summer) to address the research gap. To evaluate the environmental pollution caused by shrimp culture, there was no water exchange for culture systems including shrimps. Compared to monoculture of L. vannamei, coculture with U. linza significantly reduced dissolved inorganic nitrogen (DIN, 98.5–99.0%) and dissolved inorganic phosphorus (DIP, 98.2–98.8%) but enhanced dissolved oxygen (DO, 56.2–68.7%) and pH (10.7–18.6%) by the end of culture. Compared to monoculture, coculture stimulated the growth rates of L. vannamei by 38.1–58.8% and U. linza by 241.9–290.4% in all seasons, and increased the lipid content of L. vannamei by 24.2% in autumn and by 37.9% in summer and the contents of protein and ash of U. linza by 23.8–29.0% and by 27.6–68.6%, respectively, in all seasons. Coculture enhanced the content of most amino acids in U. linza and the content of total fatty acids (FA) and polyunsaturated fatty acids in L. vannamei in all seasons in comparison with monoculture. In addition, coculture lifted swelling capacity by 28.9–40.5%, water holding capacity by 39.8–43.3% and oil holding capacity by 31.4–32.4% for U. linza in autumn and summer. Apart from relieving eutrophication, deoxygenation and acidification, IMTA increased growth rates of both shrimp and Ulva and improved functional properties of U. linza, suggesting a green and productive aquaculture mode.

Physicochemical properties and volatile components of pea flour fermented by Lactobacillus rhamnosus L08

Pea (Pisum sativum L.) is an important source of plant proteins. However, the use of pea flour as a food ingredient is greatly limited due to its strong beany flavor. In this work, we investigated the effects of Lactobacillus rhamnosus L08 (L. rhamnosus L08) fermentation on the physicochemical characteristics, amino acids composition and volatile flavor compounds of pea flour. We found that L. rhamnosus L08 had the probiotic potential of utilizing pea flour as fermentation substrate. L. rhamnosus L08 fermentation significantly increased the content of most amino acids, and total amino acid content increased from 222.18 mg/g at 0 h to 262.35 mg/g at 6 h. A total of 44 volatile compounds were identified in pea flour. L. rhamnosus L08 fermentation increased the variety of acids and esters, while reduced the unpleasant flavor such as nonanal, decanal, octanal, 1-hexanol and 2-ethyl-1-hexanol. The emulsifying stability and foam stability of pea flour were slightly enhanced during fermentation. Our results illustrate that lactic acid bacteria fermentation is a promising approach to eliminate undesirable aroma of pea flour. Moreover, this study provides theoretical support for the application of peas as high-quality protein source.

Effects of electrolysed water combined with ultrasound on inactivation kinetics and metabolite profiles of Escherichia coli biofilms on food contact surface

This study aimed to better understand the overall metabolic responses of Escherichia coli biofilms to the combined stresses of ultrasound and low concentration acidic electrolysed water (LcAEW, free available chlorine: 4 mg/L). The inactivation kinetics of all E. coli strains (ATCC 25922, ATCC 35150 and ATCC 43895) were simulated well by the modified Weibull model (R2: 0.81–0.97; RMSE: 0.04–0.71). By analysing metabolite profiles, ultrasound mainly disrupted nucleotide metabolism in E. coli cells within biofilms, as most intracellular nucleotide-related compounds (e.g., uridine, ATP, ADP) showed decreased trend especially in ATCC 25922 and ATCC 35150. Increased contents of most amino acids and decreased contents of most carbohydrates were shown in all strains after LcAEW treatment. Under combined treatment, adaptive strategies like glutamate decarboxylase system and mixed acid fermentation were activated to different extents among the three strains. These findings revealed that NMR-based metabolomics technology is promising in identifying strain-specific metabolic responses of biofilms to different antimicrobial treatments, providing guidance for future mechanism studies related to food contact surface sanitisation.