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L-tryptophan is the most important amino acid in the human body and plays a key role in human growth and development. In this study, a highly sensitive electrochemical sensor was prepared by modifying ferroferric oxide nanomaterials (Fe3O4 NMs) on the surface of carbon cloth (CC) for the detection of L-tryptophan samples. The introduction of Fe3O4 NMs provided the sensor with a large electrochemical area and high electrocatalytic performance, and the detection sensitivity was significantly improved due to the increase of electrode channels for the mass transfer process. The current peaks measured via differential pulse voltammetry (DPV) were linearly related to a variety of concentrations of L-tryptophan.Under the optimal conditions, the limit of detection (LOD) of this homemade sensor was as low as 1.68 μM for L-tryptophan, and the linear concentration range was 5～200 μM,with an increase in sensitivity of 1.01 mA/M·cm². In addition, the Fe3O4 NMs/CC-based sensor showed good accuracy and stability in actual sample detection like serum and urine, indicating that the system possesses the potential to be a point-of-care testing. [ABSTRACT FROM AUTHOR]

Abstract Tryptophol (IET) is a metabolite derived from L-tryptophan that can be isolated from plants, bacteria, and fungi and has a wide range of biological activities in living systems. Despite the fact that IET biosynthesis pathways exist naturally in living organisms, industrial-scale production of IET and its derivatives is solely based on environmentally unfriendly chemical conversion. With diminishing petroleum reserves and a significant increase in global demand in all major commercial segments, it becomes essential to develop new technologies to produce chemicals from renewable resources and under mild conditions, such as microbial fermentation. Here we characterized and engineered the less-studied L-tryptophan pathway and IET biosynthesis in the baker’s yeast Saccharomyces cerevisiae, with the goal of investigating microbial fermentation as an alternative/green strategy to produce IET. In detail, we divided the aromatic amino acids (AAAs) metabolism related to IET synthesis into the shikimate pathway, the L-tryptophan pathway, the competing L-tyrosine/L-phenylalanine pathways, and the Ehrlich pathway based on a modular engineering concept. Through stepwise engineering of these modules, we obtained a yeast mutant capable of producing IET up to 1.04 g/L through fed-batch fermentation, a ~ 650-fold improvement over the wild-type strain. Besides, our engineering process also revealed many insights about the regulation of AAAs metabolism in S. cerevisiae. Finally, during our engineering process, we also discovered yeast mutants that accumulate anthranilate and L-tryptophan, both of which are precursors of various valuable secondary metabolites from fungi and plants. These strains could be developed to the chassis for natural product biosynthesis upon introducing heterologous pathways.

Tryptophol (IET) is a metabolite derived from L-tryptophan that can be isolated from plants, bacteria, and fungi and has a wide range of biological activities in living systems. Despite the fact that IET biosynthesis pathways exist naturally in living organisms, industrial-scale production of IET and its derivatives is solely based on environmentally unfriendly chemical conversion. With diminishing petroleum reserves and a significant increase in global demand in all major commercial segments, it becomes essential to develop new technologies to produce chemicals from renewable resources and under mild conditions, such as microbial fermentation. Here we characterized and engineered the less-studied L-tryptophan pathway and IET biosynthesis in the baker's yeast Saccharomyces cerevisiae, with the goal of investigating microbial fermentation as an alternative/green strategy to produce IET. In detail, we divided the aromatic amino acids (AAAs) metabolism related to IET synthesis into the shikimate pathway, the L-tryptophan pathway, the competing L-tyrosine/L-phenylalanine pathways, and the Ehrlich pathway based on a modular engineering concept. Through stepwise engineering of these modules, we obtained a yeast mutant capable of producing IET up to 1.04 g/L through fed-batch fermentation, a ~ 650-fold improvement over the wild-type strain. Besides, our engineering process also revealed many insights about the regulation of AAAs metabolism in S. cerevisiae. Finally, during our engineering process, we also discovered yeast mutants that accumulate anthranilate and L-tryptophan, both of which are precursors of various valuable secondary metabolites from fungi and plants. These strains could be developed to the chassis for natural product biosynthesis upon introducing heterologous pathways. [ABSTRACT FROM AUTHOR]

AbstractCCl4 causes oxidative injury, fatty degeneration, fibrosis of the liver, renal failure, and even hepatocellular and renal carcinoma. Certain substances have the potential to neutralize the harmful effects of CCl4, so it will lead to numerous beneficial effects. Melatonin (MEL) is a powerful antioxidant that regulates circadian rhythm and has beneficial effects on organism; tryptophan (TRP) is its precursor necessary for the synthesis of MEL. The aim of the current study was to determine whether MEL and TRP, have protective effects during subchronic application of CCl4 to the liver and kidneys. Results suggest that CCl4 led to decrease of total proteins, albumins, globulins, erythrocytes, hemoglobin, and hematocrit; and increase of creatinine, AST, ALT values, and leukocytes. MEL and TRP both showing protective effects on regulation of serum proteins, albumins, globulins, A/G, AST, ALT, and creatinine levels. TRP had been shown to have potential in regulation of disbalanced hematological parameters caused by CCl4. TRP had beneficial effects on hepatocyte morphology in term of beaded chromatin and preserved cell morphology. Overall, oral supplementation of TRP had better protective effects on liver/kidneys compared to MEL. [ABSTRACT FROM AUTHOR]

It is a fluorescence-based study to examine the interaction between L-tryptophan and a selection of aldehydes, namely furfural (furan-2-carbaldehyde), 3-hydroxybenzaldehyde, salicylaldehyde (2-hydroxybenzaldehyde), 3-nitrobenzaldehyde, and 4-bromobenzaldehyde. The investigation took place in an aqueous environment, revealing that all five aldehydes induced quenching of the fluorescence intensity of L-tryptophan. By employing the Stern-Volmer equation to describe the quenching process, we constructed Stern-Volmer plots and derived Stern-Volmer constants. These constants (KSV) ranged from 2.87 × 104 mol L− 1 to 5.75 × 104 mol L− 1. Notably, the values of the Stern-Volmer constants varied among the different aldehydes, with the following order: 3-hydroxybenzaldehyde(3-HBA) > 4-bromobenzaldehyde (4-BBA) > 3-nitrobenzaldehyde > furan-2-carbaldehyde > salicylaldehyde. Consequently, our findings highlighted 3-hydroxybenzaldehyde as the most potent quencher, while 2-hydroxybenzaldehyde displayed the least sensitivity to quenching. Additionally, we determined the detection and quantification limits for the investigated aldehydes, resulting in ranges of 3.87 × 10− 12 to 8.25 × 10− 6 and 1.29 × 10− 11 to 2.75 × 10− 5, respectively. This research paves the way for the development of novel fluorescence probe-based sensors and offers valuable techniques for analyzing aldehydes within environmental and biological samples. [ABSTRACT FROM AUTHOR]

The gut microbiota and the host maintain a conjoint relationship and together achieve optimal physiology via a multitude of interactive signalling cues. Dietary-derived L-tryptophan (L-trp) is enzymatically metabolized by the resident symbiotic gut microbiota to indole and various indole derivatives. Indole and indole metabolites secreted by the gut bacteria act locally in the intestinal cells as well as distally and modulate tissue-specific functions which are beneficial to the host. Functions attributed to these microbial indole metabolites in the host include regulation of intestinal permeability, immunity and mucosal roles, inflammation, and insulin sensitivity. On the other hand, dysregulation of gut microbiota L-trp metabolism compromises the optimal availability of indole and indole metabolites and can induce the onset of metabolic disorders, inflammation, liver steatosis, and decrease gut barrier integrity. Gut dysbiosis is regarded as one of the prime reasons for this deregulated microbial-derived indole metabolites. A number of indole metabolites from the gut bacteria have been identified recently displaying variable affinity towards xenobiotic nuclear receptors. Microbial metabolite mimicry concept can be used to design and develop novel indole-moiety-containing compounds with higher affinity towards the receptors and efficacy in preclinical studies. Such compounds may serve as therapeutic drugs in clinical trials in the future. In this article, I review L-trp metabolism in the host and gut microbiota and the various physiological functions, patho-physiologies associated with the microbial-released indole metabolites in the host, including the metabolite mimicry-based concept to develop tailored indole-containing novel experimental drugs. [ABSTRACT FROM AUTHOR]

IntroductionMelatonin and 5-hydroxytryptophan (5-HTP), known for benefits in regulating sleep and combating depression, respectively, are incorporated into dietary supplements. Rapid and accurate identification of dietary supplement types and their contents remains a significant challenge in ensuring food safety.MethodsIn this study, qualitative and quantitative analysis of melatonin and 5-HTP was performed using Raman spectroscopy, powder X-ray diffraction (PXRD), and terahertz time-domain spectroscopy (THz-TDS). Purity and crystal structures of the samples were investigated using Raman spectroscopy and PXRD, establishing the foundation for terahertz (THz) simulations.Results and discussionThe Raman spectroscopy results demonstrate that the characteristic Raman peaks of melatonin and 5-HTP in the range from 170 cm−1 to 1700 cm−1 were observed at 1356 cm−1 and 1,304 cm−1, respectively. Results of THz revealed that melatonin and 5-HTP each have five THz characteristic peaks, which distinguish these substances. The peak of melatonin at 1.23 THz shows a good linear fit with the mass fraction, while 5-HTP has a similar relationship at 1.14 THz. Then, L-tryptophan, a common contaminant in the production of melatonin and 5-HTP, was successfully identified within the mixture. Finally, it is demonstrated that THz technology can effectively detect melatonin and 5-HTP in commercial dietary supplements. This study establishes a rapid, efficient, and non-destructive approach for the regulation and quantitative analysis of dietary supplements.

Few systematic studies on the effect of content of soluble oils and dissolved organic matters on coagulation treatment of high suspended mine drainage. Therefore, the typical high suspended mine water was selected to analyze the effect of content of emulsified oil, concentrated liquid, HA (humic acid), FA (fulvic acid) and LA (L-tryptophan) on the efficiency of high suspended matter mine water treated by loading coagulation treatment with sand. The results show that emulsified oil, concentrated liquid, and excess FA were harmful for the efficiency and rate of loading coagulation treatment with sand. Whereas, the effect of HA, LA and lower FA content effect can be ignored. The results can effectively improve the operation technology of the loading coagulation with sand, realize the protection and rationalization of coal mine water resources. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) hydrates have garnered significant interest as a promising technology for CO2 capture and storage due to its high storage capacity and moderate operating conditions. The kinetics of CO2 hydrate formation is a critical factor in determining the feasibility of hydrate-based CO2 capture and storage technologies. This study systematically investigates the promotional effects of the amino acid L-tryptophan (L-trp) on CO2 hydrate formation kinetics and morphology under stirred and unstirred conditions. In the stirred system, experiments were conducted in a high-pressure 100 mL reactor with 0.05, 0.10, and 0.30 wt% L-trp solution. CO2 gas uptake kinetics and morphological evolution were monitored using a high-resolution digital camera. Results showed that L-trp promoted CO2 hydrate formation kinetics without delay, with rapid CO2 consumption upon nucleation. Morphological evolution revealed rapid hydrate formation, wall-climbing growth, and dendritic morphology filling the bulk solution. Under unstirred conditions, experiments were performed in a larger 1 L reactor with 0.1 wt% and 0.5 wt% L-trp solutions to assess the influence of additive concentration on hydrate formation thermodynamics and kinetics. Results demonstrated that L-trp influenced both thermodynamics and kinetics of CO2 hydrate formation. Thermodynamically, 0.1 wt% L-trp resulted in the highest hydrate formation, indicating an optimal concentration for thermodynamic promotion. Kinetically, increasing L-trp concentration from 0.1 wt% to 0.5 wt% reduced formation time, demonstrating a proportional relationship between L-trp concentration and formation kinetics. These findings provide insights into the role of L-trp in promoting CO2 hydrate formation and the interplay between additive concentration, thermodynamics, and kinetics. The results can inform the development of effective hydrate-based technologies for CO2 sequestration, highlighting the potential of amino acids as promoters in gas hydrate. [ABSTRACT FROM AUTHOR]

L‐tryptophan, an essential amino acid for physiological processes, metabolism, development, and growth of organisms, is widely utilized in animal nutrition and human health as a feed additive and nutritional supplement, respectively. Despite its known benefits, safety concerns have arisen due to an eosinophilia–myalgia syndrome (EMS) outbreak linked to L‐tryptophan consumed by humans. Extensive research has established that the EMS outbreak was caused by an L‐tryptophan product that contained certain impurities. Therefore, safety validations are imperative to endorse the use of L‐tryptophan as a supplement or a feed additive. This study was conducted in tertiary hybrid [(Landrace × Yorkshire) × Duroc] pigs to assess general toxicity and potential risks for EMS‐related symptoms associated with L‐tryptophan used as a feed additive. Our investigation elucidated the relationship between L‐tryptophan and EMS in swine. No mortalities or clinical signs were observed in any animals during the administration period, and the test substance did not induce toxic effects. Hematological analysis and histopathological examination revealed no changes in EMS‐related parameters, such as eosinophil counts, lung lesions, skin lesions, or muscle atrophy. Furthermore, no test substance‐related changes occurred in other general toxicological parameters. Through analyzing the tissues and organs of swine, most of the L‐tryptophan impurities that may cause EMS were not retained. Based on these findings, we concluded that incorporating L‐tryptophan and its impurities into the diet does not induce EMS in swine. Consequently, L‐tryptophan may be used as a feed additive throughout all growth stages of swine without safety concerns. L‐tryptophan, an essential amino acid for organismal functions, is commonly used in animal nutrition and human health. However, safety concerns have arisen due to an eosinophilia–myalgia syndrome (EMS) outbreak linked to L‐tryptophan. This study assessed the safety of L‐tryptophan fermentation products as a feed additive and its relationship to EMS in swine. No adverse effects, including EMS‐related symptoms, were observed during the study. The results suggest that incorporating L‐tryptophan into pig diets, along with impurities, is safe throughout their growth cycles, alleviating concerns about EMS. [ABSTRACT FROM AUTHOR]

L-tryptophan is an essential amino acid widely used in the pharmaceutical and feed industries. Enhancing its production in microorganisms necessitates activating and inactivating specific genes to direct more resources toward its synthesis. In this study, we developed a classification model based on Qualitative Perturbation Analysis and Machine Learning (QPAML). The model uses pFBA to obtain optimal reactions for tryptophan production and FSEOF to introduce perturbations on fluxes of the optima reactions while registering all changes over the iML1515a Genome-Scale Metabolic Network model. The altered reaction fluxes and their relationship with tryptophan and biomass production are translated to qualitative variables classified with GBDT. In the end, groups of enzymatic reactions are predicted to be deleted, overexpressed, or attenuated for tryptophan and 30 other metabolites in E. coli with a 92.34% F1-Score. The QPAML model can integrate diverse data types, promising improved predictions and the discovery of complex patterns in microbial metabolic engineering. It has broad potential applications and offers valuable insights for optimizing microbial production in biotechnology. [ABSTRACT FROM AUTHOR]

Simple Summary: Summer heat stress adversely affects the productivity and economic viability of lactating Holstein cows. We explored the effects of dietary supplementation with L-tryptophan or L-ascorbic acid on milk production characteristics and plasma metabolites in lactating Holstein cows during the summer. The results showed that the supplementation with L-tryptophan or L-ascorbic acid reduced heat stress in lactating Holstein cows during the summer. In particular, L-tryptophan supplementation increased the concentration of melatonin in milk. However, there were no significant differences in milk yield or composition between the treatments. Therefore, further research is needed to explore the effects of increasing the dosage of supplements and to investigate the combination strategies of the dietary supplements used in the current study. This study investigated the effects of rumen-protected L-tryptophan or L-ascorbic acid supplementation on the productivity of lactating Holstein cows during a high-temperature period. Thirty cows were assigned to three dietary groups: control (CON), treatment 1 (TRT 1; rumen-protected L-tryptophan, 20 g/cow/d), and treatment 2 (TRT 2; rumen-protected L-ascorbic acid, 20 g/cow/d). As the high-temperature period progressed, the decrease in milk yield and dry matter intake (DMI) in the TRT 1 and TRT 2 groups was lower than that in the CON group. The total protein level in the plasma of the TRT 1 group was higher than that in the CON group (p < 0.05). Milk melatonin concentration was higher in the TRT 1 group than in the CON and TRT 2 groups (p < 0.05). Thus, the present results indicate that rumen-protected L-tryptophan or L-ascorbic acid has positive effects in preventing declines in DMI and milk yield by reducing heat stress in Holstein cows. In particular, rumen-protected L-tryptophan is considered effective in increasing the melatonin concentration in milk. [ABSTRACT FROM AUTHOR]

L-tryptophan is an amino acid that is essential to the metabolism of humans. Therefore, there is a high interest for its detection in biological fluids including blood, urine, and saliva for medical studies, but also in food products. Towards this goal, we report on a new electrochemiluminescence (ECL) method for L-tryptophan detection involving the in situ production of hydrogen peroxide at the surface of boron-doped diamond (BDD) electrodes. We demonstrate that the ECL response efficiency is directly related to H2O2 production at the electrode surface and propose a mechanism for the ECL emission of L-tryptophan. After optimizing the analytical conditions, we show that the ECL response to L-tryptophan is directly linear with concentration in the range of 0.005 to 1 µM. We achieved a limit of detection of 0.4 nM and limit of quantification of 1.4 nM in phosphate buffer saline (PBS, pH 7.4). Good selectivity against other indolic compounds (serotonin, 3-methylindole, tryptamine, indole) potentially found in biological fluids was observed, thus making this approach highly promising for quantifying L-tryptophan in a broad range of aqueous matrices of interest. [ABSTRACT FROM AUTHOR]

Objectives: To investigate the effect of evening whey protein supplementation, rich in tryptophan, on sleep in elite male Australian Rules Football players. Design: Double-blinded, counterbalanced, randomized, cross-over study. Methods: Sleep was assessed using wrist activity monitors and sleep diaries in 15 elite male Australian Football League players on two training and nontraining days following evening consumption of an isocaloric whey protein supplement or placebo in preseason. A 5-day preintervention period was implemented to determine habitual dietary intake and baseline sleep measures. These habitual data were used to inform the daily dietary intake and timing of ingestion of the evening whey protein supplement or placebo on the intervention days. The whey protein supplement or placebo was consumed 3 hr prior to habitual bedtime. Results: Separate one-way repeated-measures analyses of covariance revealed no differences between the whey protein supplement and the placebo on sleep duration, sleep onset latency, sleep efficiency, or wake after sleep onset on either training or nontraining days. Conclusions: Evening whey protein supplementation, rich in tryptophan, does not improve acute sleep duration or quality in elite male Australian Football League players. However, elite athletes may be able to ingest a high protein/energy intake close to bedtime without impairing sleep, which is important for athlete recovery. Future research should investigate the effect of evening protein intake, high in tryptophan, on sleep duration and quality, including sleep staging during periods of restricted sleep and in poor-sleeping athletes. [ABSTRACT FROM AUTHOR]

Simple Summary: The peripartum period is a challenging phase in the production of dairy cattle. Tryptophan is an essential amino acid in animals and has a variety of physiological functions. This study examined the effects of L-tryptophan supplemented to Holstein cows during the prepartum period on the postpartum performance. We found that L-tryptophan supplementation in the prepartum period significantly improved the reproductive, antioxidative and anti-inflammatory performance of cows compared to the controls. All these lead to the improved quality of colostrum and milk yield, indicating a healthy transition of the cows from their prepartum to postpartum status. The negative energy balance occurring in the periparturient period of cows will impede their health and postpartum performance. To target this issue, L-tryptophan was supplied to the prepartum cows. The results showed that L-tryptophan supplementation significantly increased the serum melatonin level and was accompanied with increases in SOD activity, IL-10 and colostrum IgA levels as well as decreases in MDA and IL-6 levels compared to the control cows. The incidence of postpartum diseases was significantly lower and the pregnancy rate was significantly higher in cows fed L-tryptophan than in the control group. A striking observation was that prepartum L-tryptophan supplementation not only improved the milk production but also the quality compared to the control cows. In general, supplementation with L-tryptophan in the prepartum period can improve the postpartum reproduction and lactation performance of cows to some extent. [ABSTRACT FROM AUTHOR]

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of the feed additive consisting of l‐tryptophan produced by fermentation with Escherichia coli CGMCC 7.460 when used as a nutritional additive in feed and water for drinking for all animal species and categories. The production strain is not genetically modified. Viable cells of the production strain were not detected in the final additive. The additive does not give rise to any safety concern regarding the production strain. The use of l‐tryptophan (≥ 98%) produced with E. coli CGMCC 7.460 to supplement feed is safe for non‐ruminant species. There may be a risk for an increased production of toxic metabolites when unprotected tryptophan is used in ruminants. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) has concerns on the safety of the simultaneous oral administration of l‐tryptophan via water for drinking and feed due to possible amino acid imbalances and hygienic reasons. The use of l‐tryptophan produced with E. coli CGMCC 7.460 in animal nutrition raises no safety concerns to consumers of animal products and to the environment. In the absence of data, the FEEDAP Panel cannot conclude on the potential of the additive to be irritant to skin or eyes, or on its potential to be a dermal sensitiser. The endotoxin activity of the additive in combination with the high dusting potential may represent a risk of exposure by inhalation to endotoxins for users. The additive l‐tryptophan is regarded as an effective source of the amino acid l‐tryptophan for all non‐ruminant species. To be as efficacious in ruminants as in non‐ruminants, it should be protected from ruminal degradation. [ABSTRACT FROM AUTHOR]

(1) Background: The elderly suffer from functional constipation (FC), whose causes are not fully known, but nutritional factors may play a role. The aim of the present study was to assess the effect of a low FODMAP diet supplemented with L-tryptophan (TRP) on its metabolism and symptoms of functional constipation in elderly patients. (2) Methods: This study included 40 people without abdominal complaints (Group I, controls) and 60 patients with FC, diagnosed according to the Rome IV Criteria (Group II). Two groups were randomly selected: Group IIA (n = 30) was qualified for administration of the low FODMAP diet, and the diet of patients of Group IIB (n = 30) was supplemented with 1000 mg TRP per day. The severity of abdominal symptoms was assessed with an abdominal pain index ranging from 1 to 7 points (S-score). The concentration of TRP and its metabolites, 5-hydroxyindoleacetic acid (5-HIAA), kynurenine (KYN), and 3-indoxyl sulfate (3-IS) in urine were determined using the LC-MS/MS method. (3) Results: In Group II, 5-HIAA concentration in urine was lower, and KYN and 3-IS concentrations were higher than in the control group. A negative correlation was found between the S-score and urinary concentration of 5-HIAA (p < 0.001), and 3-IS concentration was positively correlated with the S-score. However, the correlation between the S-score and 3-IS concentration was negative (p < 0.01). After a dietary intervention, 5-HIAA concentration increased in both groups, and the severity of symptoms decreased, but the decrease was more pronounced in Group IIB. (4) Conclusion: A low FODMAP diet supplemented with L-tryptophan has beneficial effects in elderly patients suffering from functional constipation. [ABSTRACT FROM AUTHOR]

Alimentary obesity is a risk factor for the development of many pathophysiological conditions in various organs, including the pancreas. Thus, the study of mechanisms, clinical symptoms and ways to prevent the development of fatty degeneration of pancreas at obesity is a current direction of research. The aim of our work was to study the influence of L-tryptophan on the morphofunctional changes of the pancreas of rats with diet-induced obesity and to evaluate the possibility of its use for the prevention of the development of the gland fatty degeneration. The study was conducted in male Wistar rats, which were 3 months old at the experiment beginning. Histologic preparations were made from pancreas tissue samples using a standard method. Morphometric measurements were performed on digital images using “Image J” software. In biochemical studies, we determined concentration of glucose in blood serum and of triglycerides, lipids and cholesterol in pancreas tissue samples. It was found that rats fed a high-fat, high-carbohydrate diet showed marked sings of developing alimentary obesity. This was evidenced by a significant increase in the weight of visceral fat (by 147%) and obesity index (by 129%). The exposure of rats to a high-calorie diet resulted in the emergence of distinct signs indicating hypofunction in both the exocrine and, to a greater extent, endocrine sections of the pancreas. The administration of L-tryptophan reduced the intensity of accumulation of visceral fat and fat in the gland itself. This was evidenced by lower concentrations of lipids (by 53%) and triglycerides (by 32%) in the pancreatic tissue compared to high-calorie diet rats. In addition, L-tryptophan prevented an excessive decrease in the function of both the exocrine and endocrine parts of the gland from the harmful effects of dietary obesity. This may be of practical interest when using tryptophan and its derivatives in the clinic to prevent a decrease in gland activity in this pathology. [ABSTRACT FROM AUTHOR]

A thermophilic bacterial strain having the ability to produce L-tryptophan enzymatically was isolated and identified from a less explored hot spring of West Bengal. The isolate was identified using polyphasic taxonomic approach as a strain of Bacillus licheniformis. Initially, the 16S rRNA gene and later the whole genome of the isolate was sequenced and submitted to the NCBI Gene Bank for future reference. The isolate showed considerable tryptophan synthase activity and may be a potential candidate for mass production of L-tryptophan by enzymatic means.

Background: Coronary thrombosis events continue to be the leading cause of morbidity and mortality worldwide. Recently, emerging evidence has highlighted the role of gut microbiota in cardiovascular disease, but few studies have systematically investigated the gut microbiota variation associated with atherothrombosis. Methods: We conducted multi-omics analysis (metagenomics sequencing and serum metabolomics) on 146 subjects from Peking Union Medical College Hospital-Coronary Artery Disease (PUMCH-CAD) cohort. We analyzed the key strains and metabolic pathways related to coronary artery disease (CAD) development, explored the bacterial functional pathway which contributes to atherothrombosis at strain level in depth. Single strain colonization procedures on germ free mice demonstrated the promotion of platelet activation and thrombotic phenotypes of the disordered gut microbiota. Results: Gut microbiome and serum metabolome shifts were apparent in cases of CAD progression, Bacteroides spp. disturbed the development of CAD by participating in lipopolysaccharide (LPS), menaquinone and methanogenesis pathways. Particularly, coronary thrombosis is characterized by increased circulatory levels of L-tryptophan, which correlate with Bacteroides thetaiotaomicron that has enriched biosynthetic potential. In germ free mice we demonstrate that Bacteroides thetaiotaomicron colonization could induce thrombosis, aggravate platelet hyperreactivity and augment fecal levels of L-tryptophan. Conclusions: The disordered gut microbiota of CAD contributed to the occurrence and development of atherothrombosis. The key members of the bacterial and metabolic features may become biomarkers for predicting the cardiovascular thrombosis event. Targeting the microbial pathway may have the potential to reduce the incidence of cardiovascular disorders. Clinical Trial Registration: ChiCTR2000033897, https://www.chictr.org.cn/showproj.html?proj=55023.

The cost-effective, efficient, and environmentally friendly corrosion inhibitors have become increasingly significant within the oil and gas sector. Consequently, this research was conducted to evaluate the corrosion inhibition behavior of the amino acids DL-Met and L-Tryp on carbon steel in acidic (0.05 M HCl), alkaline (0.05 M NH4OH), and neutral (3% NaCl) environments. This study used Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Polarization (PDP) to assess the performance of amino acids as corrosion inhibitors. The EIS and PDP measurements revealed that DL-Met and L-Tryp exhibited corrosion inhibition effects exclusively in acidic conditions. In this environment, DL-Met demonstrated a corrosion inhibition efficiency (η) of 49.7% at a concentration of 525 ppm, while L-Tryp reached an efficiency of 87.08% at a concentration of 25 ppm. Under the same conditions, DL-Met reduced the corrosion rate from 10 mm/year to 4.468 mm/year, and L-Tryp reduced it from 10.95 mm/year to 5.003 mm/year. However, the corrosion inhibition activity of DL-Met and L-Tryp in neutral and alkaline conditions did not yield positive results according to EIS measurements. In neutral conditions, 100 ppm DL-Met exhibited -22.46% inhibitory activity. Meanwhile, in alkaline conditions, 150 ppm DL-Met and 5 ppm L-Tryp exhibited inhibition efficiencies of -72.39% and -81.9%, respectively. This research aims to provide the oil and gas industry with a natural-based corrosion inhibitor alternative, offering a solution to corrosion-related challenges in acidic conditions.

In the pond culture of Chinese mitten crabs (Eriocheir sinensis), high stocking densities usually increase the frequency of agonistic behavior, which can directly impact crab integrity, survival, and growth and result in economic losses. We hoped to reduce agonistic behavior by adding additives to feed. In this study, we first observed the agonistic behavior of E. sinensis in 5 molting periods (from first molting to puberty molting) during the adult grow-out stage. Then, we assessed the effects of L-TRP as a feed additive on the agonistic behavior of juvenile, precocious, subadult, and adult crabs. Finally, we performed 106 days of cage culture to assess the effects of L-TRP on feeding behavior, animal vitality, growth performance, and nutritional composition. The results showed that the intensity of agonistic behavior was significantly higher after puberty molting than in other molting periods during the adult grow-out stage. Moreover, L-TRP supplementation inhibited the agonistic behavior of juvenile, subadult, and adult crabs, but it did not affect the precocious crabs. During cage culture, L-TRP significantly improved crab vitality after 3 weeks but not after 6 and 9 weeks, but it reduced the ingestion rate after 9 weeks. Moreover, the L-TRP group showed a significant increase in the weight gain rate and specific growth rate after the fourth molting. After 106 days of culture, the content of proline and fatty acids in the muscle decreased significantly after L-TRP diet supplementation. Some long-chain polyunsaturated fatty acids also decreased significantly in the hepatopancreas. However, we must focus on the adverse effects of L-TRP on Pro and fatty acid composition. Further research is required on the balance between inhibition of agonistic behavior and effects of L-TRP on the nutritional quality of E. sinensis.

L‐tryptophan has been utilized as a feed additive in animal nutrition to improve growth performance, as well as a dietary supplement to alleviate various emotional symptoms in humans. Despite its benefits, concerns regarding its safety arose following the outbreak of eosinophilia‐myalgia syndrome (EMS) among individuals who consumed L‐tryptophan. The causative material of EMS was determined to be not L‐tryptophan itself, but rather L‐tryptophan impurities resulting from a specific manufacturing process. To investigate the effect of L‐tryptophan and its impurities on humans who consume meat products derived from animals that were fed L‐tryptophan and its impurities, an animal study involving broiler chickens was conducted. The animals in test groups were fed diet containing 0.065%–0.073% of L‐tryptophan for 27 days. This study aimed to observe the occurrence of toxicological or EMS‐related symptoms and analyze the residues of L‐tryptophan impurities in meat products. The results indicated that there was no evidence of adverse effects associated with the test substance in the investigated parameters. Furthermore, most of the consumed EMS‐causing L‐tryptophan impurities did not remain in the meat of broiler chickens. Thus, this study demonstrated the safety of L‐tryptophan and some of its impurities as a feed additive. To investigate the effect of L‐tryptophan and its impurities related to eosinophilia‐myalgia syndrome (EMS), an animal study was conducted on broiler chickens. The occurrence of toxicological or EMS‐related symptoms and the residues of L‐tryptophan impurities in meat products were investigated. There were no adverse effects associated with the test substance, and most of the consumed EMS‐causing L‐tryptophan impurities were not remained in the meat of broiler chickens, demonstrating the safety of L‐tryptophan and some of its impurities as a feed additive. [ABSTRACT FROM AUTHOR]

A rapid, novel and cost‐effective spectrofluorimetric method developed to determine moxifloxacin (MFX) in pharmaceutical preparations because MFX in a pH 10 medium could reduce the fluorescence intensity of l‐tryptophan. The maximum fluorescence excitation and emission wavelengths were found to be 280 and 363 nm respectively. A range of factors affecting fluorescence quenching and the effect of co‐existing substances were investigated. Fluorescence quenching values (ΔF = FL‐tryptophan − FMoxi‐L‐tryptophan) displayed a strong linear relationship with the MFX concentration ranging from 0.2 to 8.0 μg/ml under optimum conditions. The limit of detection was found to be 6.1 × 10−4 μg/ml. The proposed method was shown to be suitable for MFX determination in pharmaceutical tablets and biological fluids by the linearity, recovery and limit of detection. The spectrofluorimetric approach that has been developed is extremely eco‐friendly, as evidenced by the fact that all the experimental components and solvents were safe for the environment. [ABSTRACT FROM AUTHOR]

The kinetics of Os(VIII)-accelerated L-tryptophan (Trp) oxidation by hexacyanoferrate(III) in CTAB micellar medium were investigated by measuring the decline in absorbance at 420 nm, which corresponds to [Fe(CN)6]3–. By adjusting one variable at a time, the progression of the reaction has been inspected as a function of [OH–], ionic strength, [CTAB], [Os(VIII)], [Trp], [Fe(CN) ], and temperature using the pseudo-first-order condition. The results show that [CTAB], [Trp], and [OH–] are the critical parameters with a discernible influence on reaction rate. The reaction rate is independent of the [Fe(CN) ]; hexacyanoferrate(III) is merely used up to regenerate the Os(VIII) during the reaction. In the investigated concentration range of Os(VIII), as well as at lower [OH–] and [Trp], the reaction displays first-order kinetics with respect to [Os(VIII)], [OH–], and [Trp] but follows less than unit order at larger Trp and alkali concentrations. The linear increase in reaction rate with added electrolyte is indicative of a positive salt effect. CTAB significantly catalyzes the process, and once at a maximum, the rate remains almost constant as [CTAB] increases. The observed decrease in CTAB CMC could be attributed to reduced repulsion between the positive charge heads of surfactant molecules caused by the negatively charged [Fe(CN)6]3–, OH–, and [OsO5(OH)]3–. [ABSTRACT FROM AUTHOR]

The present study aims to explore the kinetics of Fe(II) catalyzed L-tryptophan (Trp) oxidation in micellar media by persulfate ion (S2O8 2-). The reaction's progress has been analyzed as an indicator of [S2O8 2-], temperature, [Trp], [Fe(II)], [Surfactant], ionic strength, and [H+]. The S2O8 2- undergoes a 1:1 stoichiometric interaction with Trp. The observed reaction exhibits first-order kinetics with regards to [S2O8 2-], fractional-first-order with respect to [H+], linear reliance to [Fe(II)], and invariance with respect to [Trp] within the range of concentrations investigated. The observed decrement in reaction rate upon electrolyte introduction is suggestive of a negative salt effect. The oxidation rate is significantly enhanced by Fe(II) solution (as a catalyst) at lower concentrations. Both the cationic cetyltrimethylammonium bromide (CTAB) and the anionic sodium dodecyl sulfate (SDS) have been shown to inhibit the oxidation rate, while the non-ionic Triton X-100 (TX-100) does not have a noticeable impact on the reaction rate. [ABSTRACT FROM AUTHOR]

Indole Acetic Acid (IAA), a phytohormone, has been considered as the most important native auxin. The Amla (Phyllanthus emblica Linn.) serve as an abundance of IAA-producing sources fungus and produce significant quantities of IAA in tryptophan-added medium. Different concentration of L-tryptophan between 1, 2 and 5 mg/ml were chosen for the IAA production. The study shows that the corresponding L-tryptophan concentration was associated with a progressive rise in IAA generation. The impact on IAA production was anticipated to last up to 10 days, with the maximum IAA production being shown in an incubation period of 15 days. Four isolates in total were found to be IAA-producing strains, two of these produced IAA through medium components, and physical conditions were tuned for IAA production. The Amla stem and leaf tissues have the strongest growth-promoting effect in Aspergillus ustus (72 g/20 ml) among the isolates. The positive effects on crop development and yield are attributed to the presence of such growth-promoting fungus. [ABSTRACT FROM AUTHOR]

Escherichia coli RclA and Staphylococcus aureus MerA are part of the Group I flavoprotein disulfide reductase (FDR) family and have been implicated in the contribution to bacterial pathogenesis by defending against the host immune response. Fusobacterium nucleatum is a pathogenic, anaerobic Gram-negative bacterial species commonly found in the human oral cavity and gastrointestinal tract. In this study, we discovered that the F. nucleatum protein FN0820, belonging to the Group I FDR family, exhibited a higher activity of a Cu2+-dependent NADH oxidase than E. coli RclA. Moreover, FN0820 decreased the dissolved oxygen level in the solution with higher NADH oxidase activity. We found that L-tryptophan and its analog 5-hydroxytryptophan inhibit the FN0820 activities of NADH oxidase and the concomitant reduction of oxygen. Our results have implications for developing new treatment strategies against pathogens that defend the host immune response with Group I FDRs. [ABSTRACT FROM AUTHOR]

A thermophilic bacterial strain having the ability to produce L-tryptophan enzymatically was isolated and identified from a less explored hot spring of West Bengal. The isolate was identified using polyphasic taxonomic approach as a strain of Bacillus licheniformis. Initially, the 16S rRNA gene and later the whole genome of the isolate was sequenced and submitted to the NCBI Gene Bank for future reference. The isolate showed considerable tryptophan synthase activity and may be a potential candidate for mass production of L-tryptophan by enzymatic means. [ABSTRACT FROM AUTHOR]

Here, a pot experiment was carried out to assess the effectiveness of co-application of a microbial consortium and L-tryptophan (L-TRP) on bioremediation of glyphosate and growth of mungbean (Vigna radiata L.) in glyphosate-contaminated soil. Mungbean seeds (untreated or treated with L-TRP) were sown in the soil that was spiked with glyphosate (600 mg kg−1) and the microbial consortium (comprising of Achromobacter xylosoxidans strain MH-13, Stenotrophomonas sp. strain MH-18, Alcaligenes faecalis strain MH-22 and Stenotrophomonas rhizophila strain MH-24) was applied to the selected pots. Results depicted that the microbial consortium and L-TRP considerably ameliorated the physiology, nutrient uptake, growth, and yield attributes of mungbean plants, and their co-application significantly increased agronomic (57–70%), nutrient uptake (19–38%), and physiological (24–78%) and yield (37–72%) attributes of mungbean over un-amended contaminated controls. Furthermore, successful removal of glyphosate was observed by the sole addition of microbial consortium (73%) and L-TRP (49%), and this removal of glyphosate was further increased by co-addition of microbial consortium and L-TRP (61% and 82% in unplanted and planted treatments, respectively) over respective controls. Findings from this study imply that the co-addition of a microbial consortium with L-TRP could be a sustainable strategy for improving the glyphosate remediation and productivity of mungbean in glyphosate-contaminated soil. [ABSTRACT FROM AUTHOR]

Severe cannibalism can result in a significant loss of productivity during the nursery phase of Asian seabass, Lates calcarifer. The present study aimed to determine the effect of dietary tryptophan on growth, feed utilization, cannibalism, survival, and muscle proximate composition of Asian seabass juveniles (initial size, 2.77 ± 0.04 cm in length and 0.29 ± 0.01 g in weight) in a recirculating aquaculture system (RAS) at different stocking densities. The tryptophan levels were set at 0.41% (control diet, standard dosage for normal growth and survival of Asian seabass), 1.00% (Diet 1), and 1.50% (Diet 2), while the stocking densities were set at 0.5 ind./L and 1.5 ind./L. The results indicated that dietary supplementation with L-tryptophan (TRP) and fish stocking density had a significant effect on fish growth parameters, feed utilization, cannibalism, survival, and muscle lipid content (p < 0.05) over the 45-day trial. The maximum length, weight, WG, and SGR were 11.64 ± 0.35 cm, 22.93 ± 2.67 g, 22.64 ± 2.67 g, and 9.63 ± 0.27%, respectively, in the fish fed Diet 2, and 11.35 ± 0.22 cm, 24.38 ± 1.28 g, 24.09 ± 1.28 g, and 9.82 ± 0.11% at a 1.5 ind./L stocking density. The lower FCR (0.81 ± 0.04) and higher PER (2.98 ± 0.16) ensured better utilization of Diet 1 than the other diets. Moreover, significant interaction effects between diet and stocking density were observed in total yield, cannibalism, and survival of the Asian seabass. Significantly higher survival rates of 76.11 ± 3.90% in the Diet 1 group and 76.28 ± 2.88% in 0.5 ind./L stocking density were obtained, which is promising. The study concludes that dietary supplementation with 1.00% TRP was effective in reducing cannibalism and increasing the survival of the Asian seabass nursery reared in RAS at a lower stocking density (i.e., 0.5 ind./L), whereas 1.50% supplemental TRP at a higher stocking density (i.e., 1.5 ind./L) significantly increased the cannibalism and growth, which in turn reduced the survival rate.

The adsorption of l-tryptophan (l-Trp) was studied based on the hydrophobic interaction/ion exchange/ion exclusion mixed-mode adsorption resin D301. Firstly, the interaction mode between l-Trp and resin was analyzed by studying the influence of pH variation on the adsorption capability and the dissociation state of l-Trp. Secondly, the adsorption mechanism was illuminated by studying the adsorption equilibrium and kinetic behaviors. The adsorption equilibrium and a kinetics model were constructed. The augmentation of pH gradually elicited an enhancement in the adsorption capacity of l-Trp. l-Trp existing in varied dissociation states could be adsorbed by the resin, and the interaction mode relied upon the pH of the solution. An integrated adsorption equilibrium model with the coadsorption of different dissociation states of l-Trp was developed and could predict the adsorption isotherms at various pH levels satisfactorily. Both external mass transfer and intra-particle diffusion collectively imposed constraints on the mass transfer process of l-Trp onto the resin. An improved liquid film linear driving force model (ILM) was constructed, and the model provided a satisfactory fit for the adsorption kinetics curves of l-Trp at various pH levels. l-Trp molecules had a high mass transfer rate at a relatively low solution pH.

Summary: Animal welfare is a priority in the laying hen industry, with feather pecking being a major issue to address challenge. Feather pecking is a behavior derived from exploration and involves gently pecking the feathers of other hens. However, when pecking becomes severe, such as pecking or eating the feathers or tissues of others, it can lead to stress, decreased productivity, and even mortality. Studies have reported on a variety of methods to control these behaviors including nutrition, facilities, and management. L-tryptophan (TRP) is one of the essential amino acids and is a precursor to serotonin, a neurotransmitter known to control stress, aggression, and mood. The objective of this study was to investigate the effects of different supplementation levels of TRP on egg performance, stress parameters of blood, and welfare indices in laying hens. A total of 700 Hy-Line Brown layer, aged 70 weeks, were randomly assigned to four treatment groups. Each group fed a basal diet, based on maize and soybean meal, supplemented with 0.0 %, 0.25 %, 1.0 %, and 2.0 % TRP for 4 weeks. The addition of 0.25 and 1.0 % TRP were improved the hen-day egg production and egg mass compared to control group. Also, the level of corticosterone and serotonin in serum were positively affected by the 1.0 % TRP supplementation. Hens fed a diet with 1.0 % TRP resulted lower feather damage score than control. Furthermore, eggshell thickness improved with the addition of TRP to the diet. In conclusion, our findings suggest that supplementation with 1.0 % TRP may mitigate stress and improve egg production and welfare indices of laying hens in barn system

L-tryptophan and its derivatives are widely used in the chemical, pharmaceutical, food, and feed industries. Microbial fermentation is the most commonly used method to produce L-tryptophan, which calls for an effective cell factory. The mechanism of L-tryptophan biosynthesis in Escherichia coli, the widely used producer of L-tryptophan, is well understood. Saccharomyces cerevisiae also plays a significant role in the industrial production of biochemicals. Because of its robustness and safety, S. cerevisiae is favored for producing pharmaceuticals and food-grade biochemicals. However, the biosynthesis of L-tryptophan in S. cerevisiae has been rarely summarized. The synthetic pathways and engineering strategies of L-tryptophan in E. coli and S. cerevisiae have been reviewed and compared in this review. Furthermore, the information presented in this review pertains to the existing understanding of how L-tryptophan affects S. cerevisiae’s stress fitness, which could aid in developing a novel plan to produce more resilient industrial yeast and E. coli cell factories.

Phosphorescence is considered one of the non-invasive glioblastoma testing methods based on studying molecular energy and the metabolism of L-tryptophan (Trp) through KP, which provides essential information on regulating immunity and neuronal function. This study aimed to conduct a feasibility study using phosphorescence in clinical oncology as an early prognostic test in detecting Glioblastoma. This study was conducted on 1039 patients who were operated on with follow-up between January 1, 2014, and December 1, 2022, and retrospectively evaluated in participating institutions in Ukraine (the Department of Oncology, Radiation Therapy, Oncosurgery, and Palliative Care at the Kharkiv National Medical University). Method of protein phosphorescence detection included two steps. During the first step, of luminol-dependent phosphorescence intensity in serum was carried out after its activation by the light source, according to the spectrofluorimeter method, as follows. At a temperature of 30 °C, serum drops were dried for 20 min to form a solid film. After that, we put the quartz plate with dried serum in a phosphoroscope of luminescent complex and measured the intensity. With the help of Max-Flux Diffraction Optic Parallel Beam Graded Multilayer Monochromator (Rigaku Americas Corporation) following spectral lines as 297, 313, 334, 365, 404, and 434 nm were distinguished and absorbed by serum film in the form of light quantum. The monochromator exit split width was 0.5 mm. Considering the limitations of each of the non-invasive tools currently available, phosphorescence-based diagnostic methods are ideally integrated into the NIGT platform: a non-invasive approach for visualizing a tumor and its main tumor characteristics in the spatial and temporal order. Because trp is present in virtually every cell in the body, these fluorescent and phosphorescent fingerprints can be used to detect cancer in many different organs. Using phosphorescence, it is possible to create predictive models for GBM in both primary and secondary diagnostics. This will assist clinicians in selecting the appropriate treatment option, monitoring treatment, and adapting to the era of patient-centered precision medicine. [ABSTRACT FROM AUTHOR]

L-tryptophan (L-TRP) is an essential amino acid responsible for the establishment and maintenance of a positive nitrogen equilibrium in the nutrition of human beings. Therefore, it is vital to quantify the amount of L-tryptophan in our body. Herein, we report the MoS2/S@g-CN-modified glassy carbon electrode for the electrochemical detection of L-tryptophan (L-TRP). The MoS2/S@g-CN composite was successfully synthesized using an efficient and cost-effective hydrothermal method. The physical and chemical properties of the synthesized composite were analyzed using powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray analysis (EDX). The crystallite size of the composite was calculated as 39.4 nm, with porous balls of MoS2 decorated over the S@g-CN surface. The XPS spectrum confirmed the presence of Mo, S, O, C, and N elements in the sample. The synthesized nanocomposite was further used to modify the glassy carbon (GC) electrode (MoS2/S@g-CN/GC). This MoS2/S@g-CN/GC was used for the electrochemical detection of L-TRP using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. For the purpose of comparison, the effects of the scanning rate and the concentration of L-TRP on the current response for the bare GC, S@g-CN/GC, MoS2/GC, and MoS2/S@g-CN/GC were studied in detail. The MoS2/S@g-CN-modified GC electrode exhibited a rational limit of detection (LoD) of 0.03 µM and a sensitivity of 1.74 µA/ µMcm2, with excellent stability, efficient repeatability, and high selectivity for L-TRP detection. [ABSTRACT FROM AUTHOR]

The effects of potato starch (PS) coating containing amino acids (AAs) on the formation of 2‐amino‐1‐methyl‐6‐phenylimidazo [4,5‐b] pyridine (PhIP) in chicken breasts were evaluated. PhIP is classified as a Group 2B carcinogen by the International Agency for Research on Cancer (IARC). The 5% (w/w) gelatinized PS coating solution was incorporated with tryptophan (Trp) or lysine (Lys) at 0.25%, 0.5%, and 0.75% (w/w of the coating solution) concentrations. Chicken breast cuts with the same dimensions (5 × 2 × 1.5 cm) were dipped in the PS coating solution for 15 min before frying. After frying the chicken at 195°C for 7.5 min on each side, PhIP levels, color, cooking loss, tenderness, and texture profile assay were evaluated. The average PhIP concentration was decreased from 92.62 ng/g for the control chicken breast without coating to 6.30 ng/g (0.25% Lys), 6.76 ng/g (0.5% Lys), and 11.98 ng/g (0.75% Lys), accounting for an 89%–92% reduction in PhIP levels compared to the controls. However, dipping in Trp‐containing PS coating had a significantly lower (p < 0.05) PhIP reduction effect (34%–67%). There was no significant difference in cooking loss percentage, tenderness, texture profile parameters, and color parameters of PS‐coated chicken. Triangle test results showed that consumers did not detect a significant difference in the PS‐coated chicken breasts (p < 0.001). Overall, this study suggests that the application of PS‐based coatings incorporated with AAs on chicken breast reduces the PhIP formation. [ABSTRACT FROM AUTHOR]

This research shows the exact detection of riboflavin (RF), dopamine (DA), and L‐tryptophan (Trp) through molecularly imprinted polymer (MIP) based on the electropolymerization method. MIP was placed on the surface of the glassy carbon electrode (GCE) by electropolymerization of monomers such as catechol and para‐aminophenol, in the presence of all three analytes. The introduced sensor was investigated using field emission scanning electron microscopy (FE‐SEM), atomic force microscopy (AFM), Fourier‐transform infrared spectroscopy (FTIR), and electrochemical methods, for example, electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and differential pulse voltammetry (DPV). The MIP/GCE performs well in terms of selectivity, reproducibility, repeatability, and stability. This sensor revealed good linear ranges of 0.005–500 μM for RF, 0.05–500 μM for DA, and 0.1–250 μM for Trp with limits of detection (LOD) as 0.0016 μM, 0.016 μM, and 0.03 μM for RF, DA, and Trp, respectively. The modified GCE was successfully applied to detect RF, DA, and Trp in serum and milk samples with satisfactory results. [ABSTRACT FROM AUTHOR]

High- throughput screening combining with biosensors is a powerful tool for identifying high- yield L- tryptophan producing strains, but current L- tryptophan biosensors generally have the disadvantage of low operational and dynamic ranges. By expressing the violacein biosynthetic pathway in Escherichia coli and testing different sources of VioA enzyme and RBS engineering, a novel enzyme- coupled L- tryptophan biosensor was developed. It was found that the VioA enzyme from Chromobacterium violaceum expanded detection limit of the biosensor up to 0-10 g/L of exogenously added L- tryptophan. Reducing its translation initiation rate to approximately 2 000 expanded the dynamic range of the biosensor by 55- fold. Different strains of E. coli with varying L- tryptophan yields could be visually distinguished with the naked eye. This novel L- tryptophan biosensor can play a significant role in identifying high- yield L- tryptophan and its high- value derivatives producing strains through combining methods such as high- throughput screening. [ABSTRACT FROM AUTHOR]