Lactic Acid Production Research Articles

Effects of Harvest Date and Ensiling Additives on the Optimized Ensiling of Silphium Perfoliatum to Prevent Faulty Fermentation

Silphium perfoliatum, an energy crop with a high fiber content but low concentrations of fermentable carbohydrates, presents challenges for complete fermentation in biogas production. To overcome this, a bioeconomic approach proposes the use of the fibers for paper and board production, which requires high-quality silage with minimal butyric acid, which affects the marketability of the fibers. This study aims to optimize the silaging process of Silphium perfoliatum by investigating the effects of harvest date, bacterial cultures and additives on fermentation results. Laboratory experiments were conducted to evaluate the effect of three harvest dates on fermentation acid composition, with a focus on increasing lactic acid production to inhibit butyric acid formation. Results indicate that an early harvest date (early September) is critical for achieving stable fermentation and minimizing ensiling losses. The addition of sugar-rich additives, such as syrup, was found to be essential, especially for later harvest dates. Despite these interventions, a late harvest (early November) consistently resulted in suboptimal fermentation. The results suggest that optimizing harvest timing and incorporating appropriate additives are key strategies for producing high quality silage and ensuring the suitability of Silphium perfoliatum fibers for industrial applications.

Prospective life cycle assessment of an integrated biorefinery for production of lactic acid from dairy side streams

In Ireland, the world's first-of-a-kind integrated dairy biorefinery has been developed to address waste disposal challenges in the dairy industry by converting dairy side streams into high-value biochemicals, specifically lactic acid (LA). This study aims to assess the environmental impacts of this innovative technology at a commercial scale through a comprehensive life cycle assessment (LCA) study. Experimental data from a pilot-plant facility was scaled up to a production capacity of 20,000 tons of LA per year using SuperPro Designer®. This data was combined with information from upstream processes such as milk production, cheese production, and transport, using OpenLCA. The cradle-to-gate LCA revealed that milk production had the greatest overall impact across all categories. Enteric fermentation has the most significant impact on climate change, while fertilizer and concentrate feed production primarily contributed to non-renewable energy demand, ozone formation, human toxicity, water consumption and fossil depletion. Fertilizer application substantially influenced eutrophication, acidification and ecotoxicity indicators. However, scenario analysis showed that implementing strategies like substituting biorefinery byproducts with fossil-based products, increasing renewable energy penetration, and integrating dairy beef production could result in significant environmental savings across all impact categories. Moreover, the findings highlighted that the handling of co-products would determine the magnitude of the system's impact. This study concludes that combining process design analysis with accessible data at a higher Technology readiness level (TRL) 7 offers an opportunity to identify hotspots and recommend alternative strategies to improve the environmental sustainability of the whole system at the design stage. Additionally, this study provides valuable guidance for minimizing environmental impacts during the design phase, enabling informed investment decisions before construction. Ultimately, it plays a crucial role in establishing a circular bioeconomy within the dairy industry by effectively utilizing the side streams to produce sustainable biobased chemicals, specifically LA.

Genomic Sequence of Streptococcus salivarius MDI13 and Latilactobacillus sakei MEI5: Two Promising Probiotic Strains Isolated from European Hakes (Merluccius merluccius, L.).

Frequently, diseases in aquaculture have been fought indiscriminately with the use of antibiotics, which has led to the development and dissemination of (multiple) antibiotic resistances in bacteria. Consequently, it is necessary to look for alternative and complementary approaches to chemotheraphy that are safe for humans, animals, and the environment, such as the use of probiotics in fish farming. The objective of this work was the Whole-Genome Sequencing (WGS) and bioinformatic and functional analyses of S. salivarius MDI13 and L. sakei MEI5, two LAB strains isolated from the gut of commercial European hakes (M. merluccius, L.) caught in the Northeast Atlantic Ocean. The WGS and bioinformatic and functional analyses confirmed the lack of transferable antibiotic resistance genes, the lack of virulence and pathogenicity issues, and their potentially probiotic characteristics. Specifically, genes involved in adhesion and aggregation, vitamin biosynthesis, and amino acid metabolism were detected in both strains. In addition, genes related to lactic acid production, active metabolism, and/or adaptation to stress and adverse conditions in the host gastrointestinal tract were detected in L. sakei MEI5. Moreover, a gene cluster encoding three bacteriocins (SlvV, BlpK, and BlpE) was identified in the genome of S. salivarius MDI13. The in vitro-synthesized bacteriocin BlpK showed antimicrobial activity against the ichthyopathogens Lc. garvieae and S. parauberis. Altogether, our results suggest that S. salivarius MDI13 and L. sakei MEI5 have a strong potential as probiotics to prevent fish diseases in aquaculture as an appropriate alternative/complementary strategy to the use of antibiotics.

Biovalorizing felled oil palm trunk as a sole feedstock for lactic acid production through efficient simultaneous saccharification and fermentation

This study aimed to develop practical biorefinery process for bio-valorizing felled oil palm trunk (OPT) as a sole feedstock for lactic acid (LA) production. OPT was separated into oil palm sap (OPS), vascular bundle (OPT-VB), and parenchyma (OPT-PA) fractions. OPS containing high amounts of sugars (38.69 g/L) and nitrogen (0.63 g/L), could be used directly for LA production by Lactobacillus acidophilus and also as base medium for simultaneous saccharification and fermentation (SSF) of OTP-VB and OPT-PA. The repeated SSF efficiently utilized cellulosic OPT-VB and produced LA up to 50–71 g/L during five cycles. Due to high water-absorbing and swelling properties of OPT-PA, it could not be initially added at high loadings. It was then intermittently added through fed-batch SSF, which effectively produced LA of 72.85 ± 1.61 g/L. These strategies have shown the efficient biorefinery process for biovalorization of OPT and may also be applicable to other similar agricultural wastes.

Implementation of a Macroporous Polyhydroxyethylmethacrylate Cryogel-Based Mini-Bioreactor System to Improve Monoclonal Antibody Production.

Monoclonal antibodies (mAbs) are pioneers in the diagnosis and treatment of many diseases, such as cancer, asthma, poisoning, viral infections, etc. As the market value of mAbs increases in the biopharma industry, the demand for high quantities is met by upscaled production using bioreactor systems. Thus, disposable, porous matrices called cryogels have gained the primary focus for adherent support in the proliferation of hybridoma cells. In this study, a gelatin-immobilized polyhydroxyethylmethacrylate-based cryogel material (disc-shaped, 9 mL bed volume) was synthesized, and a mini-bioreactor set up developed for culturing hybridoma cells to produce mAbs continuously. The hybridoma clone, 1B4A2D5, secreting anti-human serum albumin monoclonal antibodies, was immobilized in the cryogel matrix (2 discs, 18 mL bed volume). The hybridoma cells were attached to the matrix within 12 h after inoculation, and the cells were in the lag phase for seven days, where they were secreted mAb into the circulation medium. During the initial exponential phase, the glucose consumption, lactic acid production, and mAb production were 3.36 mM/day, 3.67 mM/day, and 55.61 µg/mL/day, respectively. The medium was refreshed whenever the glucose in the media went below 50% of the initial glucose concentration. The cryogenic reactor was run continuously for 25 days, and the mAb concentration reached a maximum on the 17th day at 310.59 µg/mL. The cumulative amount of mAbs produced in 25 days of running was 246 µg/mL, 7.7 times higher than the mAbs produced from T-flask batch cultivation. These results demonstrate that the developed polyhydroxyethylmethacrylate-based cryogel reactor can be used efficiently for continuous mAb production.

Determination of Variable Humidity Profile for Lactic Acid Maximization in Fungal Solid-State Fermentation

Solid-state fermentation (SSF) is the bioprocess where microorganisms are cultivated in the absence of free water under controlled conditions. Lactic acid can be produced by Rhizopus oryzae SSF of grape stalks. During the microorganism’s growth, the temperature and water content of the solid bed fluctuate, leading to areas of either dry or excessive moisture in the solid substrate. Therefore, it is crucial to control the water supply to the matrix. In this work, we obtain lactic acid through SSF of grape stalks using Rhizopus oryzae NCIM 1299. The SSF was conducted at a fixed temperature of 35 °C, with five constant relative humidity (RH) levels: 50, 57, 65, 72, and 80%RH. Mathematical models, including the Logistic and First-Order Plus Dead-Time models for fungal biomass growth and the Luedeking and Piret with Delay Time model for lactic acid production, were adjusted to kinetic curves. Growth kinetic parameters (Xmax, μmax, Tp, T0, Yp/x, and td) were determined for all conditions. These kinetic parameters were then correlated with relative humidity using a second-degree polynomial relationship. We observed a decrease in Xmax with an increasing %RH, while the value of Yp/x increased at a higher %RH. Finally, the optimal variable relative humidity profile was obtained by applying the dynamic optimization technique, resulting in a 16.63% increase in lactic acid production.

Lacticaseibacillus rhamnosus inhibits the development of dental caries in rat caries model and in vitro

ObjectivesDental caries result from a microbial imbalance in the oral cavity. Probiotics ecologically modulate the oral microflora to prevent caries. This study evaluated the anti-cariogenic effects of two Lacticaseibacillus rhamnosus strains in vitro and in vivo to provide a more theoretical basis for its clinical applications in caries prevention. MethodsIn the study, cariogenic biofilms were grown with L. rhamnosus (LGG) or L. rhamnosus ATCC 7469 and analyzed. Quantitative real-time PCR (qPCR), Scanning Electron Microscope (SEM), and Confocal laser scanning microscope (CLSM) were used to detect the changes in the composition and architectures; cariogenic activity was measured by the lactic acid production and Transverse Microradiography (TMR). The effects of LGG on the 12 Sprague-Dawley rat caries model were assessed using Keyes scores and micro-CT analysis. Oral microbiome changes were evaluated through 16S rRNA gene high-throughput sequencing. ResultsL. rhamnosus can reduce cariogenic bacteria in biofilm by 14.7 % to 48.9 %, with LGG exhibiting more potent inhibitory effects. Both strains of L. rhamnosus can adhere to the surface of biofilms, reduce the extracellular polysaccharides (EPS) matrix, and loosen the biofilm structure. L. rhamnosus inhibited cariogenic activity by reducing the lactic acid production in biofilms. The bovine enamel blocks presented lower mineral loss values and lesion depth values in the group Core+L.rh and Core+LGG. LGG-ingested rats had significantly lower levels of moderate dentin lesions and higher mineral density than the control group. The 16 s rRNA gene sequencing revealed that LGG regulated the beta diversity of the oral microbial community in the rat dental caries model. ConclusionsThis study revealed the promising potential of L. rhamnosus, especially the LGG strain, in the ecological prevention of dental caries. Clinical SignificanceProbiotics may provide a strategy for preventing caries by regulating the oral microecological balance. The study revealed the promising anti-caries potential of the LGG probiotic strain in vivo and in vitro. It is expected that LGG could be used as an oral probiotic for the clinical prevention and treatment of caries.

Tracking the metabolite footprint of four lactic acid bacteria in semiskimmed milk: A chemometric analysis

This study aimed to evaluate the strain‐specific fermentative behaviour and metabolite footprint of four Lactobacillus spp., in 48‐h fermented milks. Technological properties (net cell growth, pH and lactic acid production), exopolysaccharides (EPS), short‐chain fatty acids (SCFAs), α‐amino acids and peptides <3 kDa were determined and evaluated by chemometrics. Inter‐strain differences were attributed to technological properties, SCFAs and D‐mannose/galactose/arabinose production. Three clusters (technological properties, EPS and SCFA production) were confirmed by Pearson's correlation and hierarchical clustering and principal component analysis explained 61% of LAB's differential fermentative behaviour. Post hoc chemometric analysis is useful to select LAB with better post‐ and paraprobiotic potential.

New Generation of Orthodontic Elastomeric Ligature to Prevent Enamel Demineralization In Vivo.

This study aimed to synthesize a novel elastomeric ligature with dimethylaminohexadecyl methacrylate (DMAHDM) grafted, providing a new strategy for improving the issue of enamel demineralization during fixed orthodontics. DMAHDM was incorporated into elastomeric ligatures at different mass fractions using ultraviolet photochemical grafting. The antibacterial properties were evaluated and the optimal DMAHDM amount was determined based on cytotoxicity assays. Moreover, tests were conducted to evaluate the in vivo changes in the mechanical properties of the elastomeric ligatures. To assess the actual in vivo effectiveness in preventing enamel demineralization, a rat demineralization model was established, with analyses focusing on changes in surface microstructure, elemental composition, and nanomechanical properties. Elastomeric ligatures with 2% DMAHDM showed excellent biocompatibility and the best antibacterial properties, reducing lactic acid production by 65.3% and biofilm bacteria by 50.0% within 24 h, without significant mechanical property differences from the control group (p > 0.05). Most importantly, they effectively prevented enamel demineralization in vivo, enhancing elastic modulus by 73.2% and hardness by 204.8%. Elastomeric ligatures incorporating DMAHDM have shown great potential for application in preventing enamel demineralization, providing a new strategy to solve this issue during fixed orthodontics.

Process optimization and kinetic modeling of ultrasound assisted lactic acid production

AbstractThe impact of ultrasound‐assisted fermentation using Lactobacillus species was investigated, for enhanced lactic acid production. The different ultrasound frequencies of 20, 30, and 40 Hz, with time intervals of 3, 4, and 5 min, and with corn steep liquor concentrations of 1%–3% were examined using response surface methodology‐Box–Behnken design. The growth of lactic acid production was modeled by Contois model (linear) and Baranyi–Roberts model (nonlinear), assessing the suitability of Lactobacillus paracasei, Lactobacillus plantarum, and Lactobacillus acidophilus for industrial processes. At 34 h, the maximal lactic acid generation of L. paracasei, L. plantarum, and L. acidophilus was 85.2%, 82.1%, and 79.4%, respectively. The R2, μmax, and Ks values for L. paracasei and L. plantarum were found to be 0.9158, 0.574 h−1, 54.27 g/L and 0.9426, 0.294 h−1, 22.66 g/L, respectively, using Contois model. The observed R2 values of Baranyi–Roberts model for the strains L. acidophilus, L. paracasei, and L. plantarum were 0.9947, 0.9954, and 0.9998, respectively.Practical ApplicationsLactic acid is crucial in the fermentation process for products like yogurt, sauerkraut, kimchi, and pickles, enhancing flavor, texture, and shelf life. As a precursor to biodegradable plastics, lactic acid contributes to the development of sustainable packaging materials and environmentally friendly alternatives to traditional plastics. Utilizing waste corn steep liquor (CSL) as a growth medium presents a sustainable and cost‐effective solution for lactic acid production, capitalizing on its rich nutrient profile to enhance microbial growth. As a byproduct of corn wet milling, using CSL for fermentation processes promotes waste valorization and contributes to a circular economy. The optimization of fermentation conditions using the Box–Behnken design ensures maximum yield and efficiency by systematically evaluating the effects of key process variables. Integrating advanced growth curve models like the Contois and Baranyi models further refines the understanding and prediction of microbial dynamics, enabling precise control over the fermentation process. This comprehensive approach not only promotes the efficient use of industrial by‐products but also advances the development of environmentally friendly and economically viable bioprocesses.

Solid-State Fermentation of Mucuna deeringiana Seed Flour Using Lacticaseibacillus rhamnosus

The genus Mucuna is a potential protein source, but it has been underutilized due to the presence of antinutritional factors, especially L-DOPA. Solid-state fermentation with lactic acid bacteria could be an effective and simple method for reducing these antinutritional factors while simultaneously enriching the protein content. In this work, an experimental analysis identified the variables with the greatest influence on the solid-state fermentation of Mucuna deeringiana. In general, we observed a decrease in pH due to the production of and increase in lactic acid, resulting in a 91% (6.40 to 0.55 g/100 g sample) reduction in L-DOPA, 51% decrease in phenolic compounds (11.65 to 5.70 g/100 g sample), 97% decrease in tannins (1.26 to 0.04 g/100 g sample), and the antioxidant capacity of the fermented flour was 97%, with an increase in protein content of 12%. Furthermore, it demonstrated greater stability over 24 days compared to the control samples, which remained stable for only 3 days. These results suggest that the bacterium has a positive effect on the production of lactic acid, and the nutritional composition can be enhanced by reducing antinutritional factors, especially L-DOPA, that limit the use of this legume. This process proves to be a cost-effective and sustainable method for developing nutritious feed products derived from Mucuna flours.

Overexpression of the transcriptional activators Mxr1 and Mit1 enhances lactic acid production on methanol in Komagataellaphaffii

A bio-based production of chemical building blocks from renewable, sustainable and non-food substrates is one key element to fight climate crisis. Lactic acid, one such chemical building block is currently produced from first generation feedstocks such as glucose and sucrose, both requiring land and water resources. In this study we aimed for lactic acid production from methanol by utilizing Komagataella phaffii as a production platform. Methanol, a single carbon source has potential as a sustainable substrate as technology allows (electro)chemical hydrogenation of CO2 for methanol production. Here we show that expression of the Lactiplantibacillus plantarum derived lactate dehydrogenase leads to L-lactic acid production in Komagataella phaffii, however, production resulted in low titers and cells subsequently consumed lactic acid again. Gene expression analysis of the methanol-utilizing genes AOX1, FDH1 and DAS2 showed that the presence of lactic acid downregulates transcription of the aforementioned genes, thereby repressing the methanol-utilizing pathway. For activation of the methanol-utilizing pathway in the presence of lactic acid, we constructed strains deficient in transcriptional repressors Nrg1, Mig1-1, and Mig1-2 as well as strains with overrepresentation of transcriptional activators Mxr1 and Mit1. While loss of transcriptional repressors had no significant impact on lactic acid production, overexpression of both transcriptional activators, MXR1 and MIT1, increased lactic acid titers from 4 g L−1 to 17 g L−1 in bioreactor cultivations.

Sensor model fusion reveals the dynamics of lactobacillus fermentation with real time concentrations of lactic and acetic acids in ensiling of maize and ryegrass

Anaerobic lactobacillus (LAB) fermentation is key to production of silage. Tracking the dynamics of bacterial metabolism is important for the improvement of LAB fermentation and for evaluation of potential additives. This is currently limited by available ex situ analytical methods, while commercial sensors of lactic and acetic acid content remain unavailable. Here we validate an in situ pH sensor and devise a model-sensor package and a mini-fermenter system (1.5 L) for on-line analysis of LAB fermentation. By the fusion of the model based on mirror mapping principle and the time course of pH measured in situ, a general solution of the dynamic accumulation of organic acid (DAOA) and percentage yield of organic acid (PYOA, 0 ∼ 100 %) is obtained as a function of time. We link PYOA to the initial and final values of lactic and acetic concentrations analyzed ex situ to obtain specific solutions for the time courses of lactic and acetic acid production. We demonstrate the model-sensor system with fermentation of both maize and ryegrass, capturing the dynamic patterns of fermentation, including the rapid depletion of O2 in the initial aerobic phase (maize: ≈ 1.5 h, ryegrass: ≈ 9.2 h), the exponential decline of pH (R2 ≥ 0.99, RMSE ≤ 0.043) in the subsequent anaerobic phase, and metabolic feedbacks of pH on instantaneous acid production (ΔpH; inflection at pH 5), and on cumulative yields of total acidity and specific organic acids. These are all previously unavailable data streams.

Anaerobic Fermentation with Lactobacillus acidophilus LA-3 for the Production of Lactic Acid and Protein-Rich Biomass from Waste of the Non-centrifugal Cane Sugar Agroindustry

Anaerobic Fermentation with Lactobacillus acidophilus LA-3 for the Production of Lactic Acid and Protein-Rich Biomass from Waste of the Non-centrifugal Cane Sugar Agroindustry

Changes in microbial dynamics and fermentation characteristics of alfalfa silage: A potent approach to mitigate greenhouse gas emission through high-quality forage silage

Feeding ruminants with high-quality forage can enhance digestibility and reduce methane production. Development of high-quality silage from leguminous plants with lactic acid bacteria can improve digestibility and it mitigate the greenhouse gas emissions. In this study, we developed a high-quality alfalfa silage with improved fermentation index and microbial dynamics using Levilactobacillus brevis-KCC-44 at low or high moisture (LM/HM) conditions and preserved it for 75 or 150 days. Alfalfa fermentation with L. brevis enhances acidification and fermentation characteristics primarily due to the dominance of lactic acid bacteria (LAB) L. brevis (>95%) compared to alfalfa fermented with epiphytic LAB. The inoculant L. brevis improved the anaerobic fermentation indexes resulting in a higher level of lactic acid in both high (10.0 ± 0.12 & 8.90 ± 0.31%DM) and low moisture (0.55 ± 0.08 & 0.39 ± 0.0 %DM) in 75 and 150 days respectively, compared to control silage. In addition, the marginal amount of acetic acid (range from 0.23 ± 0.07 to 2.04 ± 0.27 %DM) and a reduced level of butyric acid (range between 0.03 ± 0.0 to 0.13 ± 02 %DM) was noted in silage treated with LAB than the control. The LAB count and abundance of Levilactobacillus were higher in alfalfa silage fermented with L. brevis. Microbial richness and diversity were reduced in alfalfa silage treated with L. brevis which prompted lactic acid production at a higher level even for a prolonged period of time. Therefore, this L.brevis is an effective inoculant for producing high-quality alfalfa silage since it improves fermentation indexes and provides reproducible ensiling properties.

Iron regulatory protein 2 contributes to antimicrobial immunity by preserving lysosomal function in macrophages

Colorectal cancer and Crohn's disease patients develop pyogenic liver abscesses due to failures of immune cells to fight off bacterial infections. Here, we show that mice lacking iron regulatory protein 2 (Irp2), globally (Irp2-/-) or myeloid cell lineage (Lysozyme 2 promoter-driven, LysM)-specifically (Irp2ΔLysM), are highly susceptible to liver abscesses when the intestinal tissue was injured with dextran sodium sulfate treatment. Further studies demonstrated that Irp2 is required for lysosomal acidification and biogenesis, both of which are crucial for bacterial clearance. In Irp2-deficient liver tissue or macrophages, the nuclear location of transcription factor EB (Tfeb) was remarkably reduced, leading to the downregulation of Tfeb target genes that encode critical components for lysosomal biogenesis. Tfeb mislocalization was reversed by hypoxia-inducible factor 2 inhibitor PT2385 and, independently, through inhibition of lactic acid production. These experimental findings were confirmed clinically in patients with Crohn's disease and through bioinformatic searches in databases from Crohn's disease or ulcerative colitis biopsies showing loss of IRP2 and transcription factor EB (TFEB)-dependent lysosomal gene expression. Overall, our study highlights a mechanism whereby Irp2 supports nuclear translocation of Tfeb and lysosomal function, preserving macrophage antimicrobial activity and protecting the liver against invading bacteria during intestinal inflammation.

Identification of lantibiotic producing lactic acid bacteria and its use combined with irradiation for food preservation

Identification of lantibiotic producing lactic acid bacteria and its use combined with irradiation for food preservation

Optimising butyric and lactic acid yield from xylose by adjusting pH

This work studies the pH effect in xylose mixed culture fermentation, focusing on lactic and butyric acid production. Batch tests showed a complete substrate consumption at slightly acidic (pH 6) and alkaline conditions (pH 8), but a great inhibition of xylose conversion was observed at pH 4. Acetic acid was the only product at pH 8, while at pH 6, butyric and propionic acids were quantified as well with a large proportion of unidentified compounds. Continuous reactor operation showed that changes within the acidic pH range (pH 4.5 to pH 6) affect the acidification degree but not the product distribution, reaching the maximum butyric acid yield (0.38 Cmol/Cmol-s) at pH 5, while lactic acid was only detected when xylose conversion or butyric acid concentration dropped. Batch tests demonstrated that butyric acid was not inhibitory for xylose or lactic acid conversion and that the main product of lactic acid fermentation was butyric acid. Although pH is an essential variable steering the fermentation yield and selectivity, this study demonstrates that it must be combined with other operational conditions in order to obtain a stable production of lactic and butyric acids.

Sulforaphane reverses the enhanced NSCLC metastasis by regulating the miR-7-5p/c-Myc/LDHA axis in the acidic tumor microenvironment

BackgroundThe presence of distant metastasis at the time of initial diagnosis is a prevalent issue in non-small cell lung cancer (NSCLC), affecting around 30–40 % of the patients. Acidic tumor microenvironment (TME) provides favorable conditions that increase the invasiveness and aggressiveness of NSCLC. The activity of the glycolytic enzyme lactate dehydrogenase (LDHA) increases intracellular lactate accumulation, which creates an acidic TME. However, it is not yet known whether LDHA is involved in enhancing the metastatic potential of NSCLC and if LDHA is a druggable therapeutic target for NSCLC. PurposeWe aimed to investigate the molecular mechanisms underlying the enhanced NSCLC metastasis in acidic TME, and to explore whether sulforaphane (SFN), an active compound in Raphani Semen, can serve as a LDHA inhibitor to inhibit NSCLC metastasis in the acidic TME. MethodsTo mimic the acidic TME, NSCLC cells were cultured in acidic medium (pH 6.6), normal medium (pH 7.4) served as control. Western blotting, bioinformatic analysis, luciferase assay and rescue experiments were used to explore the mechanism and investigate the anti-metastatic effect of SFN both in vitro and in vivo. ResultsAcidic environment increases the expression of LDHA which in turn increases the production of lactic acid that contributes to the acidity of TME. Interestingly, elevated LDHA expression results from increased c-Myc expression, which transactivates LDHA. c-Myc expression is directly regulated by miR-7-5p. In vitro study shows that overexpression of miR-7-5p reverses the acidic pH-enhanced c-Myc and LDHA expressions and also abolishes the enhanced NSCLC cell migration. More importantly, SFN significantly inhibits NSCLC growth and metastasis by reducing lactate production via the miR-7-5p/c-Myc/LDHA axis. Besides, it also regulates the expressions of monocarboxylate transporter 1 (MCT1) and MCT4 that transport lactate across cell membrane. ConclusionsThe miR-7-5p/c-Myc/LDHA axis is involved in the enhanced NSCLC metastasis in the acidic TME. SFN, a novel LDHA inhibitor, reduces lactate production by targeting the miR-7–5p/c-Myc/LDHA axis, and hence inhibits NSCLC metastasis. Our findings not only delineate a novel mechanism, but also support the clinical translation of SFN as a novel therapeutic agent for treating metastatic NSCLC.

Ir(triNHC)-Catalyzed Upcycling of Waste PET for Lactic Acid Production with Sustainable Isolation via Bipolar Membrane Electrodialysis.

For the upcycling of waste polyethylene terephthalate (PET), encompassing both colored and fabric PET materials, we investigated the Ir(triNHC)-catalyzed dehydrogenative coupling of PET and methanol, leading to the production of sodium lactate with good yields. We proposed a sustainable method for isolating lactic acid from the catalytic reaction mixture of sodium lactate and regenerating the base using bipolar membrane electrodialysis (BMED). This isolation method demonstrated high effectiveness, achieving isolation of lactic acid while maintaining economic feasibility at $ 0.10 per kg of lactic acid, and enabling sustainable NaOH regeneration with complete resource circulation. We assessed the recyclability of the catalyst and elucidated the mechanism involving base-mediated depolymerization and catalyst-promoted dehydrogenation, highlighting the importance of triNHC ligands in enhancing catalytic activity.