Gamma-aminobutyric Acid Production Research Articles

A Rare Case of Tremor Induces by Cycloserine in Drug-Resistant Tuberculosis Patient

Background: Tuberculosis is a contagious disease that generated by Mycobacterium tuberculosis. Drug-Resistant tuberculosis (DR-TB) is inculpated the use of the second-line anti-tubercular treatment which is associated with many drug side effects or so called, Adverse Drug Reactions (ADR). Cycloserine (Cs) is an important drug against drug resistant tuberculosis (DR-TB). Cycloserine has been used in tuberculosis therapy since the late 1950s. Identical with most drug, Cycloserine can cause many Adverse Drug Reactions (ADR). Case Illustration: A 23-year-old woman diagnosed with drug-resistant tuberculosis is undergoing long-term treatment. The patient received treatment for DR-TB with the Bdq-Lfx-Cfz-Cs-E regimen. After the patient underwent the 10th month of advanced phase treatment, the patient complained of shaking in both hands (tremors). The tremor is felt to be more severe in the right hand and the patient cannot grip objects tightly. Discussion: Cycloserine (Cs) play an important role in second-line drug management of DR-TB. Cs-Induced psychosis and other neurological side-effects can be detrimental towards patients yet they are rarely reports in DR-TB cases. Cs is correlated with severe psychiatric cases and Central Nervous System related ADRs. Cs-associated ADR is most likely because of production of gamma-aminobutyric acid as a result of inhibition of glutamic decarboxylase. Study Shown that among 132 patients who reported side effects in the cycloserine group, 2 (1.4%) experienced major side effects, namely tremors. Side effects possibly or probably related to Cs appeared after a median of 71 days (range 10–331 days) of Cs treatment. Conclusion: the drug side effects such as tremors are very rare in drug-resistant tuberculosis patients. In this case, the patient's complaint of tremors could be caused by cycloserine as an anti-tuberculosis drug.

Reusable Immobilized Lactobacillus futsaii CS3 for Enhanced GABA Synthesis using Low-Cost Substrates in Fermenter-Scale Batch and Fed-Batch Fermentations

On the industrial scale, the cost of commercial culture media for the production of gamma-aminobutyric acid (GABA) is a very important factor. This study employed a low-cost substrates and by-product from agri-food industry for GABA synthesis by Lact. futsaii CS3 at the fermenter-scale. Lact. futsaii CS3 cells were immobilized in 3 % (w/v) sodium alginate and employed for GABA synthesis in the optimal modified MRS medium (3.48 % (w/v) cane sugar, 3.84 % (w/v) tuna condensate waste and 10.77 % (w/v) monosodium glutamate (MSG)) with the initial pH medium of 5, fermentation temperature at 37 °C and agitation speed at 30 rpm. During the 60th h of batch fermentation without pH control, immobilized Lact. futsaii CS3 efficiently transformed MSG into the highest GABA of 19.05 g/L, achieving the volumetric productivity of 0.32 g/L/h with a bioconversion rate of 29.01 %. To further enhance GABA production, MSG (7.5 % w/v) was fed into the fermenter during the 48th h of fed-batch fermentation, aiming to amplify GABA synthesis. The maximum GABA (26.28 g/L) was synthesized at 84 h of fed-batch fermentation, and the volumetric productivity and a bioconversion rate of 0.31 g/L/h and 23.59 %, respectively, were obtained. Fed-batch fermentation significantly outperformed batch fermentation, resulting in a 37.95 % increase in GABA production. Moreover, immobilized Lact. futsaii CS3 cells could be reused in 2 batch cycles. In the 1st reusability, the maximum GABA synthesis reached 25.94 g/L, and the volumetric productivity and a bioconversion rate of 0.31 g/L/h and 23.29 %, respectively, were achieved at 84 h of fed-batch fermentation. While in the 2nd reusability, GABA synthesis decreased to 23.29 g/L, with the volumetric productivity and a bioconversion rate of 0.28 g/L/h and 20.91 %, respectively, at 84 h of fed-batch fermentation. HIGHLIGHTS GABA production utilizing agri-food industry by-product. GABA production was enhanced by cane sugar and tuna condensate waste. Immobilized futsaii CS3 produced GABA 19.05 g/L (batch). Immobilized futsaii CS3 produced GABA 26.28 g/L (fed-batch). Immobilized futsaii CS3 could be reused in 2 batch cycles on GABA production. GRAPHICAL ABSTRACT

Characterizing and optimizing glutamate decarboxylase from Priestia flexa for efficient biosynthesis of γ-aminobutyric acid from l-glutamic acid powder

Gamma-aminobutyric acid (GABA) is widely applied in the food and pharmaceutical industries, and is experiencing a continually growing market demand. Nevertheless, the efficient and stable production of GABA confronts challenges, especially the instability of its core enzyme, glutamate decarboxylase (GAD). GAD exhibits high activity under acidic conditions but very poor stability. This limitation severely restricts its application in large-scale industrial production. In this study, we identified and characterized a GAD from Priestia flexa (PfGAD) with high activity. We further developed a variant with significantly enhanced acidic st ability. The specific activity of the variant achieved 139.8 U/mg, and its residual activity remained approximately 90 % after overnight incubation in pH 3.0 buffer. Moreover, we engineered a strain by overexpressing a transporter protein for GABA and l-glutamic acid, while deleting the pepD gene. The yield of GABA led to 251.8 g L−1, accompanied by a conversation rate of 97.8 %, meanwhile the cell growth maintained normal. Our approach successfully addresses the challenge of balancing cell growth and GABA accumulation. Our findings offer valuable insights into acid resistance modification of the enzyme, and optimizing GABA production through strain modification, holding significant potential for the industrial application of GABA.

Overproduction of gamma-aminobutyric acid and increased antioxidant capacity by Lactiplantibacillus pentosus TEJ4 through optimization by response surface methodology

Lactic Acid bacteria (LAB) are the main producers of bioactive compounds (peptides, exopolysaccharides, antioxidant compounds, gamma-aminobutyric acid-GABA, etc.). Different strains produce at least one metabolite in high quantities as part of their metabolism, however, there are few reports of LAB with the capacity to produce two or more metabolites simultaneously. Due, the ability of 35 LAB strains previously isolated from dairy products, fermented beverages, and honey to produce gamma-aminobutyric acid (GABA) and the antioxidant capacity was determined. Based on analysis of variance and subsequent comparison of means, the Lactiplantibacillus pentosus strain was selected, and subsequently, using a Draper-Lin small composite design, the conditions of the culture medium (MRS broth) were optimized to achieve the highest production of GABA and increase the antioxidant capacity evaluated by the DPPH assay. The optimal conditions for obtaining 7.99 mg/mL of GABA were 100 mM glutamic acid, a pH of 6, a temperature of 40 °C, and 72 h of fermentation. To obtain the highest antioxidant capacity (6.87 µmol TE/mL), 200 mM glutamic acid and a pH of 4.0 were used. We reported an isolated strain of nondairy product (L. pentosus TEJ4) with the capacity to produce both bioactive, GABA, and antioxidants in a single fermentation process in a non-dairy defined medium, which is a feasible alternative to the normal process of producing bioactive compounds.

Abstract C042: Identification of a non-canonical pathway used by CAF to deliver gamma-aminobutyric acid in pancreatic cancer

Abstract Cancer-associated fibroblasts (CAFs) are cells responsible for deposition and remodeling of the extracellular matrix, and modification of the stromal microenvironment, which facilitates tumor growth. Moreover, CAFs are extremely immunosuppressive because they produce large amounts of inhibitory cytokines, growth factors and metabolites. Thus, understanding how CAFs impart severe immunosuppression in the tumor microenvironment is critical to make PDAC amenable to immunotherapies. The link between metabolism and immunosuppression in tumors has become clearer in recent years, and we postulate that one such metabolite, gamma-aminobutyric acid (GABA), a key inhibitory neurotransmitter, can act as a major immunosuppressive metabolite in PDAC. Our preliminary data shows that CAFs produce high levels of glutamate (Glu) and that metabolites derived from glutamate, such as GABA, are immunosuppressive to NK cells. Moreover, we found that CAFs could produce GABA, de novo, as determined by heavy isotope tracing. Thus, our goal is to uncover the mechanisms used by CAFs to produce GABA, and to evaluate the immunosuppressive mechanisms behind CAF- derived GABA. GABA production was measured in the conditioned media of CAFs grown in 3D culture, where it was observed that inhibition of glutaminase (GLS) and glutamine synthetase (GS) enzymes was not able to decrease the GABA levels. In addition, CAFs did not express glutamate decarboxylase (GAD), the canonical enzyme responsible for the conversion of Glu to GABA, which led us to explore the expression of a non-canonical GABA synthesis pathways in CAFs. Intriguingly, we found that CAFs derived from patient tumors expressed the enzymes of non-canonical pathway (ODC1, DAO, ALDH1A1 and ALDH9A1), and to a greater degree when compared to normal fibroblasts isolated from donor pancreata (Gift of Life Program). CRISPRi mediated knockdown (KD) of aldehyde dehydrogenase 1 (ALDH1a1) in CAFs decreased GABA production compared to control CAFs. On the other hand, CAFs knocked down for diamine oxidase (DAO), showed increased GABA production, suggesting a compensatory mechanism for GABA production upstream of ALDH1a1. Overall, our preliminary data demonstrate that CAFs produce GABA de novo, via a putative alternative GABA synthesis pathway. Our next steps are to identify the cytokine profile of KDs CAFs and perform functional assays utilizing our 3D co-culturing system, uncovering natural killer cell responses to tumor cells in the presence of CAFs with and without the enzymes necessary for GABA production. Translationally, we are analyzing the tumor interstitial fluid from PDAC patients to uncover metabolites/cytokines (secreted factors) that can be correlated with patient parameters (ex. overall survival) and immune cell activation and functionality. It is our hope that the insight provided by this study can lead to a novel set of prognostic or diagnostic factors to improve clinical outcomes in this devasting disease. Citation Format: Ariana Musa de Aquino, Myree Graves, Farrah Ali Ali, David A. Rangel, Langley Kyra, Julie Clark, David Kwon, Guillaume Cognet, Alex Muir, Débora Barbosa Vendramini Costa, Ralph Francescone. Identification of a non-canonical pathway used by CAF to deliver gamma-aminobutyric acid in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr C042.

Engineered Halomonas for production of gamma-aminobutyric acid and 2-pyrrolidone

Gamma-Aminobutyric acid (GABA) is a derivative of L-glutamate, also a precursor for the synthesis of 2-pyrrolidone, which is a monomer of nylon-4. This study achieved a one-step biosynthesis of GABA and 2-pyrrolidone by Halomonas bluephagenesis overexpressing key genes involved in GABA and 2-pyrrolidone synthesis and deleting GABA degradation genes combined with reducing the degradation of 2-pyrrolidone precursor. The resulting H. bluephagenesis strain WLp07 was employed in whole-cell catalysis, producing 357 g/L of GABA and 72 wt% of PHA. Furthermore, a self-flocculating H. bluephagenesis allowed rapid, convenient recycling of the cells, achieving 880 g/L of GABA over three cycles. Shake flask studies showed that engineered H. bluephagenesis harboring β-alanine CoA transferase was able to synthesized 2-pyrrolidone from GABA. H. bluephagenesis as a chassis of next generation industrial biotechnology (NGIB), demonstrated its diverse ability to produce GABA and 2-pyrrolidone in addition to intracellular PHA.

Improved fermentative gamma-aminobutyric acid production from glucose by the inactivation of respiratory chain components NDH-I and Cytbo₃ in Escherichia coli

Gamma-aminobutyric acid (GABA), which is synthesized from l-glutamic acid via glutamate decarboxylase (Gad), is used as food, supplements, and biodegradable plastics. Our previous study demonstrated an Escherichia coli mutant (ΔΔ) strain, lacking type I NADH dehydrogenase (NDH-I) and cytochrome bo3 oxidase (Cytbo3), produced 7g/L glutamic acid on MS1 glucose-minimal medium. In this study, the ΔΔ strain was used for improving GABA production. A plasmid (pMBL19-gadB') expressing a mutated E.coli GadB (Glu89Gln/Δ452-466), retaining activity at neutral pH, was introduced into the ΔΔ strain and its parent strain (W1485). The ΔΔ strain carrying pMBL19-gadB' exhibited a twofold increase in GABA production compared to the W1485 strain carrying pMBL19-gadB'. Deleting the C-terminal (Δ471-511) of GadC antiporter in the ΔΔ strain further improved GABA yield by 1.5g/L when cultured in MS1 glucose-minimal medium. On the other hand, a large amount of glutamic acid produced by the ΔΔ strain was not fully converted to GABA, likely due to the inhibition of GadB activity by the accumulation of acetic acid. Although there is room for improvement, these results indicate the efficacy of the ΔNDH-IΔCytbo3 double mutation in augmenting GABA production.

Contributions of Gamma-Aminobutyric Acid (GABA) Produced by Lactic Acid Bacteria on Food Quality and Human Health: Current Applications and Future Prospects.

The need to increase food safety and improve human health has led to a worldwide increase in interest in gamma-aminobutyric acid (GABA), produced by lactic acid bacteria (LABs). GABA, produced from glutamic acid in a reaction catalyzed by glutamate decarboxylase (GAD), is a four-carbon, non-protein amino acid that is increasingly used in the food industry to improve the safety/quality of foods. In addition to the possible positive effects of GABA, called a postbiotic, on neuroprotection, improving sleep quality, alleviating depression and relieving pain, the various health benefits of GABA-enriched foods such as antidiabetic, antihypertension, and anti-inflammatory effects are also being investigated. For all these reasons, it is not surprising that efforts to identify LAB strains with a high GABA productivity and to increase GABA production from LABs through genetic engineering to increase GABA yield are accelerating. However, GABA's contributions to food safety/quality and human health have not yet been fully discussed in the literature. Therefore, this current review highlights the synthesis and food applications of GABA produced from LABs, discusses its health benefits such as, for example, alleviating drug withdrawal syndromes and regulating obesity and overeating. Still, other potential food and drug interactions (among others) remain unanswered questions to be elucidated in the future. Hence, this review paves the way toward further studies.

Optimization of Fermentative Parameters to Improve Gamma-Aminobutyric Acid (GABA) Production by Lactiplantibacillus plantarum B13

Gamma-aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the mammalian brain, and it possesses several physiological properties, such as depression reduction and anxiety release. GABA production by microbial synthesis is favoured over other methods like enzymatic and chemical synthesis due to the ease of operation and less formation of harmful pollutants. Lactic acid bacteria are widely applied for GABA production because of high GABA yield and their Generally Recognized as Safe (GRAS) status , which is critical in food and ingredient safety. In this study, various fermentation conditions, including incubation time, pH, temperature, monosodium glutamate (MSG) concentration, pyridoxal-5’-phosphate (PLP) concentration and glucose concentration were screened by one-factor-at-a-time strategy to achieve the optimal GABA production by a potential probiotic strain, Lactiplantibacillus plantarum B13. The result revealed the strain exhibited the optimal GABA production of 19.073 ± 0.5214 g/L with the highest GABA productivity of 0.424 g/L/h under fixed conditions: incubation time of 66 hours, pH 5.5, temperature of 35°C, MSG concentration of 5% (w/v), PLP concentration of 0.7 mM PLP and glucose concentration of 60 g/L. The findings of this study show that fermentation parameters are dependent on species and strains due to the different properties of glutamic acid decarboxylase enzymes and optimization of single parameters is important as a preliminary step to identify the range of fermentation factors that affect GABA yield prior further research endeavours. This study also has great implications for GABA production by L. plantarum B13 and provides a prerequisite for developing new healthy products enriched with GABA as daily supplements to support relaxation and regulate mood, reduce stress and promote better sleep.

Beneficial effect of GABA-producing Lactiplantibacillus strain LPB145 isolated from cheese starters evaluated in anxiety- and depression-like behaviours in rats.

In a previous study, we reported the in vitro potential probiotic and gamma-aminobutyric acid (GABA) production, of several strains from a collection of Lactiplantibacillus (Lpb) strains within the community of natural whey starters from the artisanal cheese industry. GABA is a non-protein amino acid widely distributed in nature and produced in animals, plants, and microorganisms. However, the best known role of GABA is its function as the major inhibitory neurotransmitter of the central nervous system. Preclinical and clinical evidence suggests that the GABAergic system has a relevant role in mental health disorders, such as anxiety and major depression. The modulation of the GABAergic system has been suggested as a potential strategy for treatment, one such mechanism of modulation is the influence of the microbiota-gut-brain axis through probiotic treatments. The present study was designed to investigate the in vivo probiotic potential of LPB145, a Lactiplantibacillus strain previously characterised as a GABA-producing potentially probiotic strain. Therefore, we evaluated the behavioural effects of chronic oral administration of LPB145 on rats' anxiety- and depression-like behaviours, using the elevated plus maze, open field, and the forced swimming test. The impact of LPB145 strain treatment on the gut microbiota structure and diversity was assessed to discern a possible mechanism of action of the LPB145 treatment through the microbiota-gut-brain axis. Our results showed that LPB145 administration induced an antidepressive-like behaviour without changes in locomotor activity. In contrast, the treatment did not modify the experimental anxiety. The structure and diversity of the intestinal microbiota remained unaffected by the treatment when compared to the control. However, specific clades that could be implicated in the behavioural changes did show differences in their relative abundance. These findings provide evidence regarding the potential of probiotic strains isolated from alimentary sources, to modulate the microbiota-gut-brain axis and positively impact mental health.

Enhanced production of gamma‐aminobutyric acid in fermented carrot juice by utilizing pectin hydrolysate derived from pomegranate waste

AbstractIn this study, a functional fermented beverage enriched with gamma‐aminobutyric acid (GABA) was produced. To achieve this, the prebiotic abilities of pectin obtained from pomegranate peel and its enzymatic hydrolysates were evaluated. Additionally, a functional fermented beverage enriched with GABA was produced by fermenting carrot juice with pectin hydrolysates. First, pectin was obtained at a yield of 8.91% from pomegranate peels. Pectinase‐catalyzed hydrolysis of the obtained pectin was applied using different enzyme concentrations and hydrolysis times, and the effect of these hydrolysates on the growth of Levilactobacillus brevis was determined. Although the Fourier transform infrared (FT‐IR) spectra of the resulting hydrolysates were similar, their degree of esterification compared to that of pectin was statistically different (p < .05). Considering the viability analysis and GABA production of L. brevis in the liquid medium supplemented with pectin or its hydrolysate, the hydrolysate obtained by treatment with 400 μL enzyme for 2 h and having a high glucose content (216.80 mg/100 g) was selected for application in fermented carrot juice. During fermentation (24, 48, and 72 h), a remarkable change was observed, especially in the amounts of lactic acid and malic acid, while the amount of GABA in carrot juice varied between 25 and 46 mg/mL and increased with the increase in hydrolysate concentration. It was observed that the total phenolic content and antioxidant activity of carrot juice were highly affected by the hydrolysate concentration. This study demonstrated that pectin hydrolysate obtained from food waste could be a potential prebiotic and could be used in the production of a functional beverage with improved GABA content.

Whole-genome analysis, evaluation and regulation of in vitro and in vivo GABA production from Levilactobacillus brevis YSJ3

Gamma-aminobutyric acid (GABA) produced by lactic acid bacteria (LAB) is safe and has several health benefits. Levilactobacillus brevis YSJ3 was selected from 110 LAB. It exhibited the highest in vitro GABA production level of 970.10 μg/mL. Whole-genome analysis revealed that L. brevis YSJ3 contained gadR, gadC, gadB and gadA. Furthermore, the Luedeking–Piret model was fitted, which indicated that GABA production was divided into three stages. The gadR 0079, gadC 0080, and gadB 0081 were confirmed to promote GABA synthesis. Moreover, 55 metabolites, particularly those involved in arginine metabolism, were significantly different at 6 and 20 h of cultivation. Notably, L. brevis YSJ3 significantly improved sleep in mice and increased GABA levels in the mice's gut compared with the control group. This suggests that the oral administration of L. brevis YSJ3 improves sleep quality, probably by increasing intestinal GABA levels. Overall, L. brevis YSJ3 was confirmed as a GABA-producing strain in vitro and in vivo, making it a promising probiotic candidate for its application in food and medicine.

Exploring Phenotype, Genotype, and the Production of Promising GABA Postbiotics by Lactiplantibacillus plantarum: A Comprehensive Investigation

This study aims to investigate the probiotic properties of various isolated strains of Lactiplantibacillus plantarum. Specifically, the focus is on examining the expression of the glutamic acid decarboxylase (GAD) gene and its role in the production of gamma-aminobutyric acid (GABA), a promising postbiotic metabolite. The investigation includes comprehensive analyses of morphology, genetics, resilience against bile, NaCl, and simulated pancreatin juice (SPJ), carbohydrate fermentation patterns, antibacterial activity, susceptibility to antibiotics, and the presence of β-D-galactosidase and GAD enzymes. Six L. plantarum strains exhibited remarkable resilience against bile, NaCl, and SPJ, as well as susceptibility to antibiotics and antagonistic behavior against pathogens. These strains also showed the presence of β-D-galactosidase. Additionally, five L. plantarum strains were found to harbor the gad gene. Further biochemical analysis of four specific L. plantarum strains revealed promising profiles consisting of antibiotics, vitamins, hormones, and a diverse array of metabolites with potential immunotherapeutic properties. This study highlights the substantial potential of Lactiplantibacillus plantarum in generating beneficial postbiotic metabolites. The identified strains offer exciting avenues for further exploration, with potential applications in functional foods and pharmaceuticals. This research opens up possibilities for harnessing the probiotic and postbiotic potential of L. plantarum to develop novel products with health-promoting properties.

Evaluation of the probiotic, technological, safety attributes, and GABA-producing capacity of microorganisms isolated from Iranian milk kefir beverages.

Kefir beverage has beneficial microorganisms that have health-giving properties; therefore, they have a good potential to be probiotic. This study evaluated the probiotic potential, technological, and safety characteristics of Enterococcus faecalis, Lactococcus lactis, and Pichia fermentans isolated from traditional kefir beverages. First, isolates were evaluated in terms of resistance to acid, alkali, bile salts, trypsin, and pepsin of the gastrointestinal tract. The auto-aggregation and co-aggregation ability of isolates were measured using spectrophotometry. Antimicrobial activities were assayed against important food-borne pathogens using the agar well diffusion method. Moreover, gamma-aminobutyric acid (GABA) production was investigated by thin-layer chromatography (TLC). Among the isolates, P. fermentans had an 85% total survival rate, but its amount reached below 6 log CFU/ml which is considered non-resistant, and it showed the highest auto-aggregation (74.67%). Moreover, only L. lactis showed antimicrobial activity and had the highest co-aggregation with E. coli PTCC 1338 (54.33%) and L. monocytogenes ATCC 7644 (78%). Finally, an evaluation of the technological and safety characteristics of the strains showed that the strains produced GABA and were safe. Although the isolates were not resistant to the gastrointestinal tract, their supernatant contained valuable natural compounds, including antioxidants, GABA, and antimicrobials, which can be used to produce functional foods and medicines. In addition, other approaches, such as increasing the initial number of strains, using foods as carriers of isolates, and encapsulating the isolates, can effectively increase the survivability of isolates in the gastrointestinal tract.

Regulation of gut microbiota and serum neurotransmitters in mice by Streptococcus thermophilus GA8- and Lacticaseibacillus rhamnosus HAO9-fermented milk containing high levels of gamma-aminobutyric acid.

Gamma-aminobutyric acid (GABA) is an important neurotransmitter in the human body, with several negative emotions reported as being associated with GABA dysregulation. This study investigates the safety and modulatory effects of GABA-enriched milk, fermented by Streptococcus thermophilus GA8 and Lacticasebacillus rhamnosus HAO9, on the gut microbiota and neurotransmitter profiles in mice. Through rigorous culturing and fermentation processes, we achieved consistent GABA production in milk, with concentrations reaching 4.6 and 8.5 g L-1 for GA8-fermented and co-fermented milk, respectively, after 48 h. Using SPF male C57BL/6J mice, we administered either mono-culture or combined-culture milk treatments and monitored physiological impacts. The treatments did not affect mouse body weight but induced significant changes in gut microbiota composition. Beta diversity analysis revealed distinct microbial profiles between treatment groups, highlighting fermentation-specific microbial shifts, such as an increase in Verrucomicrobia for the GA8 group and a modulation in Saccharibacteria_genera_incertae_sedis for the GA8 + HAO9 group. Serum neurotransmitter levels were elevated in both treatment groups, with significant increases in l-glutamine, l-tryptophan and, notably, serotonin hydrochloride in the GA8 + HAO9 group. Correlation analysis identified a positive association between specific bacterial genera and neurotransmitter levels, suggesting a probiotic effect on neuroactive substances. These findings suggest that fermented milk has potential as a probiotic supplement for mood improvement and stress relief, highlighting its role in modulating the gut-brain axis. © 2024 Society of Chemical Industry.

Enhancing ergogenic performance and antioxidant benefits of red sugarcane juice through probiotic fermentation

The potential of red sugarcane as a functional probiotic drink was investigated, with a focus on determining its physicochemical, ergogenic, and antioxidant activities. Three different variants of Malaysian red sugarcane, namely Ragnar, Kapur, and Serai, were selected for analysis. The concentrations of electrolytes (Na, K, Ca, Mg, Zn, and Fe) in sugarcane juice were determined using an inductively coupled plasma mass spectrophotometer (ICP-MS), while the antioxidant activity and Vitamin C were assessed through colorimetric assays. Additionally, the functionality of the optimal variant, Ragnar, was enhanced by inoculating it with lactic acid bacteria (LAB) Lactobacillus plantarum ATCC8014 and Lactobacillus casei Shirota. High antioxidative properties (TPC: 71.63 mg GAE/mL, FRAP: 2.76 mmol TE/mL, DPPH EC50: 55.66 µg/mL, and Vitamin C: 0.72 mg/100 g) were observed in the Ragnar, which tends to exhibit an attractive blue-yellow hue. K exhibited the highest concentration in all samples (126.31 – 229.95 mg/mL), followed by Na, Mg, Fe, and Zn, which exceeded the commercial isotonic drink. The viability of LAB (above 107 CFU/mL) and the production of gamma-aminobutyric acid (GABA) were satisfactory while reducing sugars were generally lower after the fermentation. The findings present red sugarcane as a potential natural source for the development of functional drinks.Graphical

Integrative metabolomics-genomics analysis identifies key networks in a stem cell-based model of schizophrenia

Schizophrenia (SCZ) is a neuropsychiatric disorder, caused by a combination of genetic and environmental factors. The etiology behind the disorder remains elusive although it is hypothesized to be associated with the aberrant response to neurotransmitters, such as dopamine and glutamate. Therefore, investigating the link between dysregulated metabolites and distorted neurodevelopment holds promise to offer valuable insights into the underlying mechanism of this complex disorder. In this study, we aimed to explore a presumed correlation between the transcriptome and the metabolome in a SCZ model based on patient-derived induced pluripotent stem cells (iPSCs). For this, iPSCs were differentiated towards cortical neurons and samples were collected longitudinally at various developmental stages, reflecting neuroepithelial-like cells, radial glia, young and mature neurons. The samples were analyzed by both RNA-sequencing and targeted metabolomics and the two modalities were used to construct integrative networks in silico. This multi-omics analysis revealed significant perturbations in the polyamine and gamma-aminobutyric acid (GABA) biosynthetic pathways during rosette maturation in SCZ lines. We particularly observed the downregulation of the glutamate decarboxylase encoding genes GAD1 and GAD2, as well as their protein product GAD65/67 and their biochemical product GABA in SCZ samples. Inhibition of ornithine decarboxylase resulted in further decrease of GABA levels suggesting a compensatory activation of the ornithine/putrescine pathway as an alternative route for GABA production. These findings indicate an imbalance of cortical excitatory/inhibitory dynamics occurring during early neurodevelopmental stages in SCZ. Our study supports the hypothesis of disruption of inhibitory circuits to be causative for SCZ and establishes a novel in silico approach that enables for integrative correlation of metabolic and transcriptomic data of psychiatric disease models.

Alleviating effect of vagus nerve cutting in Salmonella-induced gut infections and anxiety-like behavior via enhancing microbiota-derived GABA

The vagus nerve, a pivotal link within the gut-brain axis, plays a critical role in maintaining homeostasis and mediating communication between the gastrointestinal tract and the brain. It has been reported that gastrointestinal infection by Salmonella typhimurium (S. typhimurium) triggers gut inflammation and manifests as anxiety-like behaviors, yet the mechanistic involvement of the vagus nerve remains to be elucidated. In this study, we demonstrated that unilateral cervical vagotomy markedly attenuated anxiety-like behaviors induced by S. typhimurium SL1344 infection in C57BL/6 mice, as evidenced by the open field test and marble burying experiment. Furthermore, vagotomy significantly diminished neuronal activation within the nucleus of the solitary tract and amygdala, alongside mitigating aberrant glial cell activation in the hippocampus and amygdala. Additionally, vagotomy notably decreases serum endotoxin levels, counters the increase in splenic Salmonella concentration, and modulates the expression of inflammatory cytokines—including IL-6, IL-1β, and TNF-α—in both the gastrointestinal tract and brain, with a concurrent reduction in IL-22 and CXCL1 expression. This intervention also fostered the enrichment of beneficial gut microbiota, including Alistipes and Lactobacillus species, and augmented the production of gamma-aminobutyric acid (GABA) in the gut. Administration of GABA replicated the vagotomy’s beneficial effects on reducing gut inflammation and anxiety-like behavior in infected mice. However, blockade of GABA receptors with picrotoxin abrogated the vagotomy’s protective effects against gut inflammation, without influencing its impact on anxiety-like behaviors. Collectively, these findings suggest that vagotomy exerts a protective effect against infection by promoting GABA synthesis in the colon and alleviating anxiety-like behavior. This study underscores the critical role of the vagus nerve in relaying signals of gut infection to the brain and posits that targeting the gut-brain axis may offer a novel and efficacious approach to preventing gastrointestinal infections and associated behavioral abnormalities.

Microbial chassis design and engineering for production of gamma-aminobutyric acid.

Gamma-aminobutyric acid (GABA) is a non-protein amino acid which is widely applied in agriculture and pharmaceutical additive industries. GABA is synthesized from glutamate through irreversible α-decarboxylation by glutamate decarboxylase. Recently, microbial synthesis has become an inevitable trend to produce GABA due to its sustainable characteristics. Therefore, reasonable microbial platform design and metabolic engineering strategies for improving production of GABA are arousing a considerable attraction. The strategies concentrate on microbial platform optimization, fermentation process optimization, rational metabolic engineering as key metabolic pathway modification, promoter optimization, site-directed mutagenesis, modular transporter engineering, and dynamic switch systems application. In this review, the microbial producers for GABA were summarized, including lactic acid bacteria, Corynebacterium glutamicum, and Escherichia coli, as well as the efficient strategies for optimizing them to improve the production of GABA.

Specific transcription factors Ascl1 and Lhx6 attenuate diabetic neuropathic pain by modulating spinal neuroinflammation and microglial activation in mice

Gamma-aminobutyric acid (GABA) neuronal system-related transcription factors (TFs) play a critical role in GABA production, and GABA modulates diabetic neuropathic pain (DNP). The present study investigated the therapeutic effects of intrathecal delivery of two TFs achaete-scute homolog 1 (Ascl1) and LIM homeobox protein 6 (Lhx6) in a mouse model of DNP and elucidated their underlying mechanisms. GABA-related specific TFs, including Ascl1, Lhx6, distal-less homeobox 1, distal-less homeobox 5, the Nkx2.1 homeobox gene, and the Nkx2.2 homeobox gene, were investigated under normal and diabetic conditions. Among these, the expression of Ascl1 and Lhx6 was significantly downregulated in mice with diabetes. Therefore, a single intrathecal injection of combined lenti-Ascl1/Lhx6 was performed. Intrathecal delivery of lenti-Ascl1/Lhx6 significantly relieved mechanical allodynia and heat hyperalgesia in mice with DNP. Ascl1/Lhx6 delivery also reduced microglial activation, decreased the levels of pro-inflammatory cytokines including tumor necrosis factor-α and interleukin (IL)-1β, increased the levels of anti-inflammatory cytokines including IL-4, IL-10, and IL-13, and reduced the activation of p38, c-Jun N-terminal kinase, and NF-κB in the spinal cord of mice with DNP, thereby reducing DNP. The results of this study suggest that intrathecal Ascl1/Lhx6 delivery attenuates DNP via upregulating spinal GABA neuronal function and inducing anti-inflammatory effects.