pH Regulation Research Articles

CNSC-23. ROLE OF GLIAL PH-DEPENDENT METABOLIC REGULATION IN GLIOMA PROGRESSION

Abstract Malignant glioma is a devastating brain cancer with barely any improvement in prognosis over decades. One key mechanism for glioma invasiveness is the dynamic metabolic communication between glioma and surrounding cells shaping the tumor microenvironment. While extracellular acidosis is a pathological hallmark of glioma, pH-dependent mechanisms underlying tumor metabolic reprogramming remain poorly defined. Our study focuses on a glial-enriched sodium-bicarbonate cotransporter, Slc4a4, which was previously identified as intracellular and extracellular pH regulator. While Slc4a4-mediated pH regulation is important for physiological brain function and responses after injury, its role in glioma progression is largely undefined. To begin addressing this question, we analyzed The Cancer Genome Atlas (TCGA) database, finding high Slc4a4 expression correlates with prolonged survival in glioma patients. Corroboratively, Slc4a4 gain-of-function (GOF) drastically decreases tumorigenesis and angiogenesis in patient-derived-xenograft and CRISPR-mediated de novo mouse glioma models. These results are further complemented by loss-of-function (LOF) studies using glial-specific Slc4a4 knockout mice, suggesting an inhibitory role of Slc4a4 in glioma growth and associated angiogenesis. A combination of unbiased metabolomic and cancer-targeted proteomic profiling of Slc4a4 GOF/LOF mouse glioma reveals an inverse correlation between Slc4a4 and a key lipid metabolism protein, FABP5 (Fatty Acid Binding Protein 5), which is coupled with dysregulated lipid metabolism. Moreover, analysis of TCGA database shows inverse expression and survival correlation of Slc4a4 and FABP5 in glioma patients. Further functional study shows that overexpression of FABP5 reverses Slc4a4’s inhibitory effects on glioma growth in immunocompetent mouse glioma model, supporting a functional antagonism between Slc4a4 and FABP5. Together, our study indicates that Slc4a4 plays a protective role in glioma progression by regulating metabolic activities, providing critical insights into pH-dependent metabolic reprogramming in glioma.

Carbonic anhydrase versatility: from pH regulation to CO2 sensing and metabolism.

While the carbonic anhydrase (CA, EC 4.2.1.1) superfamily of enzymes has been described primarily as involved only in pH regulation for decades, it also has many other important functions. CO2, bicarbonate, and protons, the physiological substrates of CA, are indeed the main buffering system in organisms belonging to all life kingdoms; however, in the last period, relevant progress has been made in the direction of elucidating the involvement of the eight genetically distinct CA families in chemical sensing, metabolism, and several other crucial physiological processes. Interference with CA activity, both by inhibiting and activating these enzymes, has thus led to novel applications for CA inhibitors and activators in the field of innovative biomedicine and environment and health. In this perspective article, I will discuss the recent advances which have allowed for a deeper understanding of the biochemistry of these versatile enzymes and various applications of their modulators of activity.

Dual-reinforcement strategy: Fabrication of CMC-Na/SPI aerogel-templated oleogels through electrostatic adsorption and chemical crosslinking

Recently, the use of aerogel templates for preparing oleogels has gained significant attention. In this study, we fabricated a CMC-Na/SPI composite aerogel-templated oleogel using a dual-reinforcement strategy involving electrostatic adsorption and chemical crosslinking. Citric acid was utilized as both a pH regulator and a crosslinking agent. Firstly, it adjusted the pH of the solution, facilitating the formation of soluble complexes through electrostatic interactions between SPI and CMC-Na. Secondly, it enhanced the strength of the oleogel by crosslinking the cellulose. Scanning electron microscopy images revealed the formation of multiple layers of SPI along the CMC-Na framework as the SPI content increased. Mechanical tests demonstrated that the oleogel exhibited a maximum compressive strength of 0.343 MPa and a Young's modulus of 0.604 MPa. The oleogels also displayed excellent strain memory effect and remarkable structural resilience. Furthermore, the CMC-Na/SPI composite aerogel templates exhibited outstanding oil absorption capacity (53.8 g/g aerogel), oil holding capacity (77.8%), and thermal stability. This study introduces a novel approach for designing protein/cellulose-based aerogel-templated oleogels, which have the potential to replace fat in artificial meat products.

PH-temperature coupled regulation for promoted nanofluidic osmotic energy conversion

pH and temperature regulation effectively enhance the performance of nanofluidic osmotic energy conversion, but their combination is rarely studied numerically, causing unclear influences on selective ion transport and power generation. In this study, a model considering the coupled influence of pH and temperature on interfacial reactions is established for osmotic energy conversion. The increases in pH and temperature synergistically promote the interfacial deprotonation reaction and increase the surface charge density. Accordingly, the dimensionless number called the electrical double layer intensity is defined to describe the neutral deviation of the electrical double layer, which is obviously enhanced by raising the pH and temperature at low pH. Moreover, according to the pH value and ion selectivity, the energy conversion performance under temperature regulation is divided into the interface-dominant zone and the solution-dominant zone. The elevated temperature improves the osmotic energy conversion mainly by improving the interface property at a low pH but mainly by altering the solution properties at a high pH. Finally, fluid convection plays an important role at a relatively high pH value. This work provides a comprehensive understanding of the pH and temperature coupled regulation mechanisms and points out the design route for high output power.

Vesicular CLC chloride/proton exchangers in health and diseases.

Chloride is one of the most abundant anions in the human body; it is implicated in several physiological processes such as the transmission of action potentials, transepithelial salt transport, maintenance of cellular homeostasis, regulation of osmotic pressure and intracellular pH, and synaptic transmission. The balance between the extracellular and intracellular chloride concentrations is controlled by the interplay of ion channels and transporters embedded in the cellular membranes. Vesicular members of the CLC chloride protein family (vCLCs) are chloride/proton exchangers expressed in the membrane of the intracellular organelles, where they control vesicular acidification and luminal chloride concentration. It is well known that mutations in CLCs cause bone, kidney, and lysosomal genetic diseases. However, the role of CLC exchangers in neurological disorders is only now emerging with the identification of pathogenic CLCN gene variants in patients with severe neuronal and intellectual dysfunctions. This review will provide an overview of the recent advances in understanding the role of the vesicular CLC chloride/proton exchangers in human pathophysiology.

Adjustment of light-responsive NADP dynamics in chloroplasts by stromal pH

Cyclic electron transfer (CET) predominates when NADP+ is at basal levels, early in photosynthetic induction; however, the mechanism underlying the subsequent supply of NADP+ to fully drive steady-state linear electron transfer remains unclear. Here, we investigated whether CET is involved in de novo NADP+ supply in Arabidopsis thaliana and measured chloroplastic NADP dynamics to evaluate responsiveness to variable light, photochemical inhibitors, darkness, and CET activity. The sum of oxidized and reduced forms shows that levels of NADP and NAD increase and decrease, respectively, in response to light; levels of NADP and NAD decrease and increase in the dark, respectively. Moreover, consistent with the pH change in the stroma, the pH preference of chloroplast NAD+ phosphorylation and NADP+ dephosphorylation is alkaline and weakly acidic, respectively. Furthermore, CET is correlated with upregulation of light-responsive NADP level increases and downregulation of dark-responsive NADP level reductions. These findings are consistent with CET helping to regulate NADP pool size via stromal pH regulation under fluctuating light conditions.

Acidification of intracellular pH in MM tumor cells overcomes resistance to hypoxia-mediated apoptosis in vitro and in vivo.

Multiple myeloma (MM) is an incurable cancer of malignant plasma cells that engraft in the bone marrow (BM). It is more than likely that the poorly investigated physical parameters of hypoxia and pH in the tumor microenvironment (TME) is critical for MM survival. Here, we explore the effects of a hypoxic environment on pH regulation and its role in MM survival. We used in vitro models of MM, in which the culturing medium was modified to specific pH and pO2 levels and then measured the effects on cell survival that was correlated with changes in intracellular (pHi) and extracellular pH (pHe). In a MM xenograft model, we used PET/CT to study hypoxia-mediated effects on tumor growth. Hypoxia-mediated apoptosis of MM cells is correlated with acidic intracellular pHi (less than < 6.6) that is dependent on HIF activity. Using a polyamide HIF responsive element binding compound, a carbonic anhydrase inhibitor (acetazolamide), and an NHE-1 inhibitor (amiloride) acidified the pHi and lead to cell death. In contrast, treatment of cells with an alkalization agent, Na-lactate, rescued these cells by increasing the pHi (pH > 6.6). Finally, treatment of mice with acetazolamide decreased cell growth in the tumor nodules. Targeting hypoxia and HIF have been proposed as an anti-tumor therapy but the clinical efficacy of such strategies are modest. We propose that targeting the pHi may be more effective at treating cancers within a hypoxic TME.

Regeneration behavior of FePO4·2H2O from spent LiFePO4 under extremely acidic condition (pH < 0.8): Mechanism study and the properties of regenerated LiFePO4

With the large-scale application of LiFePO4 batteries in electric vehicles and energy storage, the recycling of spent LiFePO4 cathode materials is receiving increasing attention. Hydrometallurgical derived full-component separation strategy has been verified as the most capable recycling process for LiFePO4 cathode. During which, complete elements (i.e., Li, Fe and P) are dissolved into a solution of excessive acidic leachate, and subsequently separated to obtain battery-grade FePO4·2H2O and lithium salt, enabling high element recovery rates of up to 100 %. However, the use of excessive leaching agent leads to high acidity of the leaching solution (pH < 0.8), which brings a necessary of pH regulation prior to the regeneration of FePO4·2H2O, markedly complicating the succedent separation and purification. In this investigation, a practical method for directly regenerating FePO4·2H2O from H2SO4-based full-component leaching solution is proposed. In this process, H2SO4 as leaching agent is used to digest LiFePO4 completely, and then Fe and P are premeditatedly recovered from the extremely acidic filtrate (pH < 0.8) as FePO4·2H2O via direct precipitation without any pH regulator. Consequently, there are no extra impurities affecting the recovery of Fe and P during regeneration. The regeneration behavior of FePO4·2H2O under extremely acidic condition are investigated and the growth mechanism is also clarified by monitoring the overall microstructure and phase evolutions. The results demonstrate that the above regeneration is found to be an exponential growth process driven by the quantity of nucleation site, and meanwhile influenced by the dissolution-reprecipitation equilibrium of amorphous iron phosphate. Specifically, the process can be accelerated by introducing FePO4·2H2O or amorphous iron phosphate to increase the nucleation sites. Additionally, the primary nanosheet size of regenerated FePO4·2H2O causes a smaller primary particle size of the corresponding LiFePO4/C material, contributing to its better physical and electrochemical properties. This work provides a guidance for the direct regeneration of FePO4·2H2O from excessive acidic leachate and has potential industrial applications.

Interactions Among Temperature, pH, and Agitation May Cause Instability in an Oil-in-water Emulsion

Introduction: Two key features of an emulsion, stability and viscosity, are not only considered dependent on ingredient quantities but also delicately affected by emulsification conditions, such as pH, temperature, and mixing conditions. Methods: In the laboratory, we formulated an O/W emulsion made up of 41% water, 9.8% silicon (polydimethylsiloxane), 22.1% liquid sucrose (700 mg/ml), 22.1% light liquid paraffin, and 1.5 to 5% paraffin emulsifier by volume % purposed for large-scale production as a rubber coating for decorative purposes. Results: This emulsion became faulty after large-scale production, while it was fine on the laboratory scale. This study investigated the probability of a complicated interaction among pH, temperature, solutes, and agitation intensity on the stability and viscosity of our emulsion by focusing on sugar degradation effects on these parameters. This emulsion was made in two different temperatures and agitation rates, and the emulsification time was 20 minutes for all samples. The critical roles of appropriate pH regulators or buffers in the stability were also investigated. Conclusion: It was found that applying intense agitations at 1500 rpm during emulsifications in high temperatures may lead to absurdly high emulsion viscosity, accompanied by a sharp pH fall.

It Is Time to Develop Sustainable Management of Agricultural Sulfur

AbstractGlobally, sulfur (S) applications to croplands result in S inputs that often exceed historical atmospheric deposition. Sulfur is applied to crops as a fertilizer, fungicide, soil conditioner, pH regulator, and carrier for other elements. However, excess S in soils and aquatic ecosystems can have detrimental ecological and biogeochemical consequences, including soil base cation depletion, surface water acidification, hydrogen sulfide toxicity, and increased production of methyl mercury. The dichotomy between S benefits to crops and environmental consequences parallels that of nitrogen and phosphorus; however, there has not yet been a focus on developing sustainable S management plans in agriculture. We review the current literature on S cycling in agricultural systems and propose solutions that reduce S inputs, losses, and ecological consequences, including field applications of organic matter, adaptation of precision agriculture, and implementation of total maximum daily loads. We suggest opportunities for technological innovation, including analysis of remote sensing imagery to identify location and timing of S deficiencies and stresses, crop genetic modification to reduce S requirements, inoculation of plants with arbuscular mycorrhizal fungi to enhance plant S acquisition, and remediation of wetlands and other anoxic environments with high S loads. We conclude with areas for continued research on S biogeochemistry.

Complex dynamics of coral gene expression responses to low pH across species.

Coral capacity to tolerate low pH affects coral community composition and, ultimately, reef ecosystem function. Low pH submarine discharges ('Ojo'; Yucatán, México) represent a natural laboratory to study plasticity and acclimatization to low pH in relation to ocean acidification. A previous >2-year coral transplant experiment to ambient and low pH common garden sites revealed differential survivorship across species and sites, providing a framework to compare mechanistic responses to differential pH exposures. Here, we examined gene expression responses of transplants of three species of reef-building corals (Porites astreoides, Porites porites and Siderastrea siderea) and their algal endosymbiont communities (Symbiodiniaceae) originating from low pH (Ojo) and ambient pH native origins (Lagoon or Reef). Transplant pH environment had the greatest effect on gene expression of Porites astreoides hosts and symbionts and P. porites hosts. Host P. astreoides Ojo natives transplanted to ambient pH showed a similar gene expression profile to Lagoon natives remaining in ambient pH, providing evidence of plasticity in response to ambient pH conditions. Although origin had a larger effect on host S. siderea gene expression due to differences in symbiont genera within Reef and Lagoon/Ojo natives, subtle effects of low pH on all origins demonstrated acclimatization potential. All corals responded to low pH by differentially expressing genes related to pH regulation, ion transport, calcification, cell adhesion and stress/immune response. This study demonstrates that the magnitude of coral gene expression responses to pH varies considerably among populations, species and holobionts, which could differentially affect acclimatization to and impacts of ocean acidification.

Regulation of pH on inflation and deflation of biosynthetic gas vesicles used as ultrasound molecular imaging probes

Gas vesicles (GVs) are gas-filled protein nanostructures that can regulate the buoyancy of microorganisms such as cyanobacteria and archaea. Recent studies have shown that GVs have the potential to be used as ultrasound molecular imaging probes in disease diagnosis and treatment. However, the mechanism of the inflation and deflation of GVs remains unclear, which hampers the preservation of GVs and gas replacement. In the present study, the environmental pH value was found to be an important factor in regulating the inflation and deflation of GVs. It can not only regulate the inflation and deflation of GVs in vivo to make Microcystis sp. cells present distinct levitation state, but also regulate the inflation and deflation of purified GVs in vitro, and the regulation process is reversible. Our results may provide a technical support for the large-scale production and preservation of biosynthetic ultrasound molecular imaging probes, especially for gas replacement to meet different diagnostic and therapeutic needs, and would facilitate the application of biosynthetic ultrasound molecular imaging probes.

PH Regulator on Digital Microfluidics with Pico-Dosing Technique.

Real-time pH control on-chip is a crucial factor for cell-based experiments in microfluidics, yet difficult to realize. In this paper, we present a flexible pH regulator on a digital microfluidic (DMF) platform. The pico-dosing technology, which can generate and transfer satellite droplets, is presented to deliver alkali/acid into the sample solution to change the pH value of the sample. An image analysis method based on ImageJ is developed to calculate the delivered volume and an on-chip colorimetric method is proposed to determine the pH value of the sample solution containing the acid-base indicator. The calculated pH values show consistency with the measured ones. Our approach makes the real-time pH control of the on-chip biological experiment more easy to control and flexible.

A pH-Sensitive Fluorescent Chemosensor Turn-On Based in a Salen Iron (III) Complex: Synthesis, Photophysical Properties, and Live-Cell Imaging Application.

pH regulation is essential to allow normal cell function, and their imbalance is associated with different pathologic situations, including cancer. In this study, we present the synthesis of 2-(((2-aminoethyl)imino)methyl)phenol (HL1) and the iron (III) complex (Fe(L1)2Br, (C1)), confirmed by X-ray diffraction analysis. The absorption and emission properties of complex C1 were assessed in the presence and absence of different physiologically relevant analytes, finding a fluorescent turn-on when OH- was added. So, we determined the limit of detection (LOD = 3.97 × 10-9 M), stoichiometry (1:1), and association constant (Kas = 5.86 × 103 M-1). Using DFT calculations, we proposed a spontaneous decomposition mechanism for C1. After characterization, complex C1 was evaluated as an intracellular pH chemosensor on the human primary gastric adenocarcinoma (AGS) and non-tumoral gastric epithelia (GES-1) cell lines, finding fluorescent signal activation in the latter when compared to AGS cells due to the lower intracellular pH of AGS cells caused by the increased metabolic rate. However, when complex C1 was used on metastatic cancer cell lines (MKN-45 and MKN-74), a fluorescent turn-on was observed in both cell lines because the intracellular lactate amount increased. Our results could provide insights about the application of complex C1 as a metabolic probe to be used in cancer cell imaging.

Study on Cu- and Pb-contaminated loess remediation using electrokinetic technology coupled with biological permeable reactive barrier

Although the electrokinetic (EK) remediation has drawn great attention because of its good maneuverability, the focusing phenomenon near the cathode and low removal efficiency remain to be addressed. In this study, a novel EK reactor was proposed to remediate Cu and Pb contaminated loess where a biological permeable reactive barrier (bio-PRB) was deployed to the middle of the EK reactor. For comparison, three test configurations, namely, CG, TG-1, and TG-2, were available. CG considered the multiple enzyme-induced carbonate precipitation (EICP) treatments, while TG-1 considered both the multiple EICP treatments and pH regulation. TG-2 further considered NH4+ recovery based on TG-1. CG not only improved Cu and Pb removals by the bio-PRB but also depressed the focusing phenomenon. TG-1 causes more Cu2+ and Pb2+ to migrate toward the bio-PRB and aggravates Cu and Pb removals by the bio-PRB, depressing the focusing phenomenon. TG-2 depressed the focusing phenomenon the most because Cu2+ and Pb2+ can combine with not only CO32− but PO43−. The removal efficiency of Cu and Pb is 34% and 36%, respectively. A NH4+ recovery of about 100% is attained.

Toltrazuril alkalizer-modifying solid dispersions against Toxoplasma gondii: A pharmacotechnical strategy to improve the efficacy of the drug

Toxoplasma gondii is a zoonotic protozoan that can parasitize nucleated cells of all warm-blooded animals, and seriously harm human and livestock. Toltrazuril (TOL) has insecticidal activity against parasites of the phylum Apicomplexan at multiple development stages, but the clinical application is limited by its poor water solubility. To improve the dissolution of TOL, nine ternary solid dispersions (SD) were prepared with PEG6000 as the carrier and various alkalizers as the pH modifier. Compared with the binary SD, all ternary SDs had improved TOL dissolution although dissolution rates differed. The complete dissolution was achieved for the Ca(OH)2-SD, associated with a gradual release of the alkalizer and adequate pH regulation of the microenvironment. DSC, PXRD and FTIR analyses indicated that TOL in the Ca(OH)2-SD was present in an amorphous form and had a strong hydrogen bond with Ca(OH)2. Within the drug concentration of 100 μg/mL, Ca(OH)2-SD was proved to have no damage to host cells by in vitro cytotoxicity analysis, and its anti-T. gondii efficacy was significantly higher than that of TOL and binary SD. The in vivo efficacy of Ca(OH)2-SD against T. gondii in mice further confirmed that Ca(OH)2-SD could be used as a new strategy to prevent T. gondii from killing mice and treat toxoplasmosis. In conclusion, Ca(OH)2-SD is expected to eventually turn into a clinical candidate for toxoplasmosis treatment in the future.

Probing binding mode between sodium acid pyrophosphate and albumin: multi-spectroscopic and molecular docking analysis

Sodium acid pyrophosphate (SAPP) food additive is widely used as a preservative, bulking agent, chelating agent, emulsifier and pH regulator. It is also used as an improver of color and water retention capacity in the processing of various types of seafood, canned food, cooked meat and flour products. For the first time, we evaluated the SAPP interaction with bovine serum albumin (BSA) using spectroscopic methods including UV-Vis absorption, fluorescence spectroscopy, and surface plasmon resonance, and docking analysis to understand the mechanisms of complex formation and binding. The fluorescence intensity of BSA reduces when titrated with various concentrations of SAPP by forming a complex with BSA via a static quenching mechanism. The binding constant between BSA and SAPP decreased from 123,300 to 15,800 (M−1) with rising temperature, which indicates a decrement in complex formation owing to the interaction of SAPP with BSA. A negative ΔG° value means that SAPP binds spontaneously to BSA at all temperatures, and both ΔH° and ΔS° negative values indicate that hydrogen bonds (H-bonding) and van der Waals forces are the primary forces involved in the binding processes. The UV-Vis spectrum of BSA reduced upon increasing SAPP concentrations due to forming a new ground state complex between SAPP and BSA. Molecular docking study shows that residues Arg256, Ser259, Ser286, Ile 289 and Ala 290 play an important role in SAPP binding process to site I (subdomain IIA) of BSA through H-bonding and van der Waals forces, which is supported by the thermodynamic study. Communicated by Ramaswamy H. Sarma

Dynamic Regulation of the Interfacial pH for Highly Reversible Aqueous Zinc Ion Batteries.

An electrolyte additive, with convenient operation and remarkable functions, has been regarded as an effective strategy for prolonging the cycle life of aqueous zinc ion batteries. However, it is still difficult to dynamically regulate the unstable Zn interface during long-term cycling. Herein, tricine was introduced as an efficient regulator to achieve a pH-stable and byproduct-free interface. The functional zwitterion of tricine not only inhibits interfacial pH perturbation and parasitic reactions by the trapping effect of an anionic group (-COO-) but also simultaneously creates a uniform electric field by the electrostatic shielding effect of a cationic group (-NH2+). Such synergy accordingly eliminates dendrite formation and creates a chemical equilibrium in the electrolyte, endowing the Zn||Zn cell with long-term Zn plating/stripping for 2060 h at 5 mA cm-2 and 720 h at 10 mA cm-2. As a result, the Zn||VS2 full cell under a high cathodic loading mass (8.6 mg cm-2) exhibits exceptional capacity retention of 93% after 1000 cycles.

Transcriptomics of Lactobacillus paracasei: metabolism patterns and cellular responses under high-density culture conditions.

Lactobacillus paracasei has significant potential for development and application in the environmental field, particularly in addressing malodor pollution. This study aims to investigate the cellular response of L. paracasei B1 under high-density culture conditions. The selected strain has previously shown effective deodorizing and bacteriostatic abilities. Transcriptomics techniques are employed to dissect the nutrient metabolism pattern of L. paracasei B1 and its response mechanism under environmental stress. The study characterizes the functions of key differentially expressed genes during growth before and after optimizing the culture conditions. The optimization of fermentation culture conditions provides a suitable growth environment for L. paracasei B1, inducing an enhancement of its phosphotransferase system for sugar source uptake and maintaining high levels of glycolysis and pyruvate metabolism. Consequently, the strain is able to grow and multiply rapidly. Under acid stress conditions, glycolysis and pyruvate metabolism are inhibited, and L. paracasei B1 generates additional energy through aerobic respiration to meet the energy demand. The two-component system and quorum sensing play roles in the response and regulation of L. paracasei B1 to adverse environments. The strain mitigates oxygen stress damage through glutathione metabolism, cysteine and methionine metabolism, base excision repair, and purine and pyrimidine metabolism. Additionally, the strain enhances lysine synthesis, the alanine, aspartate, and glutamate metabolic pathways, and relies on the ABC transport system to accumulate amino acid-compatible solutes to counteract acid stress and osmotic stress during pH regulation. These findings establish a theoretical basis for the further development and application of L. paracasei B1 for its productive properties.

Metabolic flux analysis of coenzyme Q10 synthesized by Rhodobacter sphaeroides under the influence of different pH regulators

Coenzyme Q10 (CoQ10) is crucial for human beings, especially in the fields of biology and medicine. The aim of this experiment was to investigate the conditions for increasing CoQ10 production. At present, microbial fermentation is the main production method of CoQ10, and the production process of microbial CoQ10 metabolism control fermentation is very critical. Metabolic flux is one of the most important determinants of cell physiology in metabolic engineering. Metabolic flux analysis (MFA) is used to estimate the intracellular flux in metabolic networks. In this experiment, Rhodobacter sphaeroides was used as the research object to analyze the effects of aqueous ammonia (NH3·H2O) and calcium carbonate (CaCO3) on the metabolic flux of CoQ10. When CaCO3 was used to adjust the pH, the yield of CoQ10 was 274.43 mg·L−1 (8.71 mg·g−1 DCW), which was higher than that of NH3·H2O adjustment. The results indicated that when CaCO3 was used to adjust pH, more glucose-6-phosphate (G6P) entered the pentose phosphate (HMP) pathway and produced more NADPH, which enhanced the synthesis of CoQ10. At the chorismic acid node, more metabolic fluxes were involved in the synthesis of p-hydroxybenzoic acid (pHBA; the synthetic precursor of CoQ10), enhancing the anabolic flow of CoQ10. In addition, Ca2+ produced by the reaction of CaCO3 with organic acids promotes the synthesis of CoQ10. In summary, the use of CaCO3 adjustment is more favorable for the synthesis of CoQ10 by R. sphaeroides than NH3·H2O adjustment. The migration of metabolic flux caused by the perturbation of culture conditions was analyzed to compare the changes in the distribution of intracellular metabolic fluxes for the synthesis of CoQ10. Thus, the main nodes of the metabolic network were identified as G6P and chorismic acid. This provides a theoretical basis for the modification of genes related to the CoQ10 synthesis pathway.