Respiratory Metabolism Research Articles

Field study on the dynamics of microbial communities following biostimulation at organochlorine-contaminated sites

Chlorinated ethenes (CEs) have become widespread contaminants in soils, sediments, and groundwater due to extensive historical use, improper handling, and disposal. At many sites, biostimulation is an effective remediation strategy for treating CEs, involving the addition of electron donors to support bacteria capable of degrading these compounds. This study aimed to understand how microbial communities adapt to environmental changes induced by biostimulation interventions. We investigated changes in microbial communities on biomass carriers transferred from a non-biostimulated, CE-contaminated environment to a previously biostimulated environment at two sites. In the non-biostimulated wells, a predominance of bacteria with nitrate-reducing or iron-reducing metabolisms was evident. Some of which are known to aerobically degrade CEs or other organic pollutants. Following the transfer of the carriers, these bacteria were outcompeted by anaerobic microorganisms with respiratory and fermentative metabolisms. The newly formed microbial community on the transferred biomass carriers exhibited greater diversity and higher abundance of organohalide-respiring bacteria. This rapid adaptability indicates the potential for these bacteria to flourish in favorable conditions, particularly at Site 2, where five days after carrier transfer, Dehalococcoides abundance increased 14,200-fold, and the biomarker vcrA increased 28,500-fold. PCoA revealed that that greater differences in hydrogeochemical conditions between biostimulated and non-biostimulated wells resulted in accelerated changes in bacterial community composition and diversity. In conclusion, our study demonstrates a rapid proliferation of CE-degrading bacteria after the transfer of biomass carriers into biostimulated wells at two different sites. The transfer stimulated shifts toward organohalide-respiring and other anaerobic bacteria in biostimulated environment and increased microbial diversity.

Synthetic indole derivatives as an antibacterial agent inhibiting respiratory metabolism of multidrug-resistant gram-positive bacteria.

The survival of modern medicine depends heavily on the effective prevention and treatment of bacterial infections, are threatened by antibacterial resistance. The increasing use of antibiotics and lack of stewardship have led to an increase in antibiotic-resistant pathogens, so the growing issue of resistance can be resolved by emphasizing chemically synthesized antibiotics. This study discovered SMJ-2, a synthetic indole derivative, is effective against all multidrug-resistant gram-positive bacteria. SMJ-2 has multiple targets of action, but the primary mechanism inhibits respiratory metabolism and membrane potential disruption. SMJ-2 was discovered to interfere with the mevalonate pathway, ultimately preventing the synthesis of farnesyl diphosphate, a precursor to the antioxidant staphyloxanthin, eventually releasing reactive oxygen species, and leading phagocytic cells to destroy pathogens. Additionally, no discernible biochemical and histopathological alterations were found in the mouse acute toxicity model. This study emphasizes mechanistic insights into SMJ-2 as a potential antibacterial with an unusual method of action.

The respiratory chain of Klebsiella aerogenes in urine-like conditions: critical roles of NDH-2 and bd-terminal oxidases

Klebsiella aerogenes is an opportunistic nosocomial bacterial pathogen that commonly causes urinary tract infections. Over the past decades, K. aerogenes strains have acquired resistance to common antibiotics that has led to the rise of multidrug-resistant and even pandrug-resistant strains. Infections produced by these strains are nearly impossible to treat, which makes K. aerogenes a global priority to develop new antibiotics and there is an urgent need to identify targets to treat infections against this pathogen. However, very little is known about the metabolism and metabolic adaptations of this bacterium in infection sites. In this work, we investigated the respiratory metabolism of K. aerogenes in conditions that resemble human urine, allowing us to identify novel targets for antibiotic development. Here we describe that, unlike other gram-negative pathogens, K. aerogenes utilizes the type-2 NADH dehydrogenase (NDH-2) as the main entry point for electrons in the respiratory chain in all growth conditions evaluated. Additionally, in urine-like media, the aerobic metabolism as a whole is upregulated, with significant increases in succinate and lactate dehydrogenase activity. Moreover, our data show that the bd-I type oxidoreductases are the main terminal oxidases of this microorganism. Our findings support an initial identification of NDH-2 and bd-I oxidase as attractive targets for the development of new drugs against K. aerogenes as they are not found in human hosts.

Engineered production of 5-aminolevulinic acid in recombinant Escherichia coli BL21.

5-aminolevulinic acid (ALA) is a non-protein amino acid that has been widely used in the fields of medicine and agriculture. This study aims to engineer the C5 pathway of the ALA biosynthesis in Escherichia coli BL21 to enhance ALA production. The ALA synthase genes gltX, hemA, and hemL were overexpressed in E. coli BL21 to lead to the increase in the production of ALA. The sRNA RyhB was also overexpressed to downregulate the expression of ALA dehydratase to reduce the downstream bioconversion of ALA to porphobilinogen. Next, the gene arcA was knocked out by CRISPR-Cas9 technology to open the TCA cycle to promote the respiratory metabolism of the strain to reduce the feedback inhibition of heme to ALA. The fermentation conditions of the engineered strain were optimized by response surface experiments. The time-course analysis of the ALA production was carried out in a 1 L shake flask. Through these efforts, the production of ALA in engineered strain reached 2953 mg/L in a 1 L shake flask. This study contributes to the industrial production of ALA by the engineered E. coli in the future.

Morphological, physiological, and biochemical responses of rice (Oryza sativa L.) varieties to drought stress via regulating respiration and ROS metabolism during germination

Germination marks a pivotal and sensitive phase in the life cycle of crops, with drought stress, precipitated by water scarcity, posing a significant impediment to the germination process in rice. Despite this, the regulation mechanism of respiratory and reactive oxygen species (ROS) metabolism during rice germination under drought stress remains to be fully elucidated. This manuscript presents an integrative analysis encompassing morphological, physiological, biochemical, and molecular attributes of germinated seeds from a cultivated drought-sensitive rice variety (JN10) and a drought-resistant rice variety (NG36). Our findings revealed that drought stress adversely affected the germination of both rice varieties, with NG36 exhibiting a more rapid germination rate compared to JN10 under such stress conditions. This differential response was attributed to the heightened activity of key enzymes, elevated levels of metabolic intermediates, and upregulated expression of genes encoding enzymes involved in ROS and respiratory metabolic pathways in NG36. To further dissect the interplay between these metabolic pathways, we selected specific enzyme activities for detailed examination. Notably, a robust positive linear correlation was established among phosphofructokinase (PFK), α-ketoglutarate dehydrogenase (KGDH), citrate synthase (CS), and isocitrate dehydrogenase (ICDH) in NG36. This correlation underscores the pivotal role of glycolytic pathways, particularly the tricarboxylic acid (TCA) cycle, in conferring drought resistance to NG36 during the germination phase under drought stress. To encapsulate our findings, the results of this investigation suggest that the rice cultivar NG36 manifests a heightened degree of drought tolerance relative to JN10. This is primarily achieved through the adept modulation of its respiratory metabolic pathways and the stringent preservation of ROS homeostasis during the germination phase under conditions of water deficit. These revelations provide unprecedented insights into the intricate regulatory mechanisms that subserve rice's drought resistance, potentially paving the way for the development of novel strategies in the breeding of rice cultivars with improved drought resilience.

Optimization of a rapid, sensitive, and high throughput molecular sensor to measure canola protoplast respiratory metabolism as a means of screening nanomaterial cytotoxicity

Nanomaterial-mediated plant genetic engineering holds promise for developing new crop cultivars but can be hindered by nanomaterial toxicity to protoplasts. We present a fast, high-throughput method for assessing protoplast viability using resazurin, a non-toxic dye converted to highly fluorescent resorufin during respiration. Protoplasts isolated from hypocotyl canola (Brassica napus L.) were evaluated at varying temperatures (4, 10, 20, 30 ˚C) and time intervals (1–24 h). Optimal conditions for detecting protoplast viability were identified as 20,000 cells incubated with 40 µM resazurin at room temperature for 3 h. The assay was applied to evaluate the cytotoxicity of silver nanospheres, silica nanospheres, cholesteryl-butyrate nanoemulsion, and lipid nanoparticles. The cholesteryl-butyrate nanoemulsion and lipid nanoparticles exhibited toxicity across all tested concentrations (5-500 ng/ml), except at 5 ng/ml. Silver nanospheres were toxic across all tested concentrations (5-500 ng/ml) and sizes (20–100 nm), except for the larger size (100 nm) at 5 ng/ml. Silica nanospheres showed no toxicity at 5 ng/ml across all tested sizes (12–230 nm). Our results highlight that nanoparticle size and concentration significantly impact protoplast toxicity. Overall, the results showed that the resazurin assay is a precise, rapid, and scalable tool for screening nanomaterial cytotoxicity, enabling more accurate evaluations before using nanomaterials in genetic engineering.

Engineered bacterium-metal-organic framework biohybrids for boosting radiotherapy with multiple effects

Hypoxia and lactate-overexpressed tumor microenvironment always lead to poor therapeutic effect of radiotherapy. Here, platinum nanoparticles-embellished hafnium metal-organic framework (Hf-MOF-Pt NPs) were elaborately integrated with Shewanella oneidensis MR-1 (SO) to construct an engineered biohybrid platform (SO@Hf-MOF-Pt) for enhancing radiotherapy. Benefiting from the tumor-targeting and metabolic respiration characteristics of SO, SO@Hf-MOF-Pt could enrich in tumor sites and continuously metabolize the overexpressed lactate, which specifically downregulated the expression of hypoxia-inducible factor (HIF-1α), thereby relieving the radiosuppressive tumor microenvironment to some extent. Moreover, SO@Hf-MOF-Pt would react with tumor-overexpressed hydrogen peroxide (H2O2) to generate oxygen (O2) and further inhibit the expression of HIF-1α, resulting in the downregulation of lactate dehydrogenase (LDHA) and subsequently reducing the lactate production. Under these multiple cascaded effects, the radiosuppressive tumor microenvironment was significantly reshaped, thus potentiating the radiosentization of SO@Hf-MOF-Pt and remarkably amplifying the therapeutic outcomes of radiotherapy. The designed biohybrid SO@Hf-MOF-Pt represented promising prospects in sensitizing radiotherapy via bacterium-based metabolic regulation.

Association between allostatic load and accelerated white matter brain aging: findings from the UK biobank.

White matter (WM) brain age, a neuroimaging-derived biomarker indicating WM microstructural changes, helps predict dementia and neurodegenerative disorder risks. The cumulative effect of chronic stress on WM brain aging remains unknown. In this study, we assessed cumulative stress using a multi-system composite allostatic load (AL) index based on inflammatory, anthropometric, respiratory, lipidemia, and glucose metabolism measures, and investigated its association with WM brain age gap (BAG), computed from diffusion tensor imaging data using a machine learning model, among 22 951 European ancestries aged 40 to 69 (51.40% women) from UK Biobank. Linear regression, Mendelian randomization, along with inverse probability weighting and doubly robust methods, were used to evaluate the impact of AL on WM BAG adjusting for age, sex, socioeconomic, and lifestyle behaviors. We found increasing one AL score unit significantly increased WM BAG by 0.29years in association analysis and by 0.33years in Mendelian analysis. The age- and sex-stratified analysis showed consistent results among participants 45-54 and 55-64years old, with no significant sex difference. This study demonstrated that higher chronic stress was significantly associated with accelerated brain aging, highlighting the importance of stress management in reducing dementia and neurodegenerative disease risks.

Energy costs of the sponge pump

Sponges pump large volumes of water to obtain nutrition from a dilute suspension of food particles and dissolved organic matter. Our review of the literature shows pumping power ranging from 0.85% up to 28% of the total metabolic respiration rate Rtot, where the pumping power (Pp = pumping rate × pump pressure) is the energy per unit time transferred to the water flow. Some published values of pumping costs are high while others are low due to incorrect estimates of some pressure losses in the aquiferous system of sponges. However, as improved descriptions of detailed structures and function, especially of the filter apparatus of the choanocytes, have become available, our corrected values for pressure losses show the respiration-specific pumping costs of Pp/Rtot = 1.3 to 22%. The stated pumping cost is based on the minimal (theoretical) pump power delivered to the water, which excludes a mechanical efficiency of pump action and a metabolic efficiency that expresses the fraction of total metabolism that is devoted to driving the pump action, considerations that should be included in future studies.

Application of Analytical Solutions of the Reactive Transport Equation for Underground Methanation Reactors

AbstractFluctuations in the production of renewable-based electricity have to be compensated by converting and storing the energy for later use. Underground methanation reactors (UMR) are a promising technology to address this issue. The idea is to create a controlled bio-reactor system in a porous underground formation, where hydrogen obtained from renewable energy sources by electrolysis and carbon dioxide from industrial sources are fed into the reactor and converted into methane. Microorganisms, known as methanogenic archaea, catalyze the chemical reaction by using the two non-organic substrates as nutrients for their growth and for their respiratory metabolism. The generated synthetic methane is renewable and capable to compete with the fossil methane. Mathematical models play an important role in the design and planning of such systems. Usually, a numerical solution of the model is required since complex initial-boundary problems cannot be solved analytically. In this paper, an existing bio-reactive transport model for UMR is simplified to such an extent that an analytical solution of the advection-dispersion-reaction equation can be applied. A second analytical solution is used for the case without dispersion. The analytical solutions are shown for both the educt (hydrogen) and the reaction product (methane). In order to examine the applicability of the analytical models, they are compared with the significantly more complex numerical model for a 1D case and a 3D case. It was shown that there is an acceptable agreement between the two analytical solutions and the numerical solution in different spatial plots of hydrogen and methane concentration and in the methane concentration in the withdrawn gas. The mean absolute error in the mole fraction is well below 0.015 in most cases. The spatial distribution of the hydrogen concentration in the comparison to the 3D case shows a higher deviation with a mean absolute error of approx. 0.023. As expected, the model with dispersion shows a slightly lower error in all cases, as only here the gas mixing resulting in smeared displacement fronts can be represented. It is shown that analytical modeling is a good tool to get a first estimation of the behavior of an UMR. It allows to help in the design of well spacing in combination with the injection rate and injected gas composition. Nevertheless, it is recommended to use more complex models for the later detailed analysis, which require a numerical solution.

Long lasting degradation of all alkanes in soil by Pseudomonas activated after Fenton pre-oxidation

This study investigated the function and mechanism of Fenton pre-oxidation on the long lasting degradation of all alkanes in soil contaminated by petroleum. The findings demonstrated that the biological removal amount of all alkanes in the respiratory regulation group reached 4083.46 mg/kg, which was twice that of the non-regulation group, and the removal amount gradually increased in the four stages of bioremediation. In addition, the removal amount of all alkanes in the non-regulated group did not change much and showed a downward trend, indicating that long lasting degradation of all alkanes could be achieved by the respiratory regulation group, and the biodegradation cycle was saved by 251 days compared with the non-regulated group. Furthermore, the total number of bacteria in the respiratory regulation group (6.73 log CFU/g) was significantly higher than that in the non-regulation group (2.25 log CFU/g). Pseudomonas became the dominant genus in the respiratory regulation group with an average relative abundance of 32.17 %. In the respiratory regulation group, a large amount of ammonia nitrogen (1703.62 mg/kg) was consumed during the degradation process, which stimulated the tricarboxylic acid cycle respiratory metabolism process of Pseudomonas and accelerated the hydrocarbon conversion. This may be the reason why the long lasting degradation of all alkanes in soil could be achieved by the respiratory regulation group.

Improving sugar and respiratory metabolism in pear wounds by postharvest dipping with chitosan and chitooligosaccharide

Chitosan (CTS) and its degradation product, chitooligosaccharide (COS), promote fruit healing by activating phenylpropanoid metabolism. This study investigates their effects on sucrose metabolism in pear wounds. CTS and COS were found to activate neutral invertase, acid invertase, sucrose synthase, and sucrose phosphate synthase, increasing sucrose, glucose, and fructose levels in fruit wounds. They also enhanced sorbitol dehydrogenase activity and promoted sorbitol accumulation. In addition, CTS and COS improved the activities of hexokinase, phosphofructokinase, and pyruvate kinase, increasing phosphoenolpyruvate and ATP production. They activated glucose-6-phosphate dehydrogenase and increased erythrose-4-phosphate, NADPH, and shikimic acid levels. In conclusion, CTS and COS support the formation of the healing closing layer by supplying carbon skeletons, energy, and reducing power through the activation of sugar and respiratory metabolism during the healing process. Compared to CTS, COS was superior in activating the above metabolisms, which is expected to be widely used as a chitin product in postharvest fruit and vegetable preservation and provide new insights into preserving pear freshness.

Comparison of behavioral responses, respiratory metabolism-related enzyme activities, and metabolomics of the juvenile Chinese mitten crab Eriocheir sinensis with different tolerance to air exposure

Air exposure is a common stressor for Chinese mitten crab (Eriocheir sinensis) during rearing and transport, and air exposure tolerance can serve as a crucial indicator for assessing the quality of juvenile E. sinensis. In this study, juvenile E. sinensis were divided into two groups based on their behavioral responses: Group S, which exhibited strong tolerance to air exposure, and Group W, which exhibited weak tolerance. Immersed crabs, not exposed to air, served as a control group (Group C). Whole body morphological characteristics and enzyme activities related to respiratory metabolism in the hemolymph and anterior gills were compared among the three groups. Non-targeted LC-MS metabolomic analysis was conducted on anterior gills. The results showed that, independent of developmental stage, crabs that were larger and had higher condition factor were more tolerant to air exposure. Additionally, compared to Group W, air exposure had a relatively small effect on glycolysis and anaerobic respiratory metabolic processes in the hemolymph and anterior gills of Group S. In response to air exposure, E. sinensis experienced increased energy demand, and switched from aerobic to anaerobic respiration to increase energy supply. Simultaneously, air exposure induced oxidative stress in the hemolymph and anterior gills. This study enhances our understanding of the response mechanism of E. sinensis to air exposure and provides a theoretical reference for the identification of high-quality juvenile E. sinensis.

Effects of deep-sea water on training efficiency, locomotor function and respiratory metabolism in young and aged mice

Deep sea water (DSW) contains many trace minerals, and its applications, which include its use as drinking water, have gradually been expanding. Generally, humans tend to be lacking in mineral intake and deficiencies of trace minerals may increase the risk of several health problems. In recent years, the lack of exercise among the elderly has become an issue, leading to the onset of frailty and sarcopenia, which in turn increases the risk of dementia. Therefore, we investigated whether the daily intake of DSW-extract-added water (DSW; hardness 300 mg/L) impacted the training effect in aged mice. Treatment with DSW significantly induced a training effect in aged mice subjected to treadmill exercise. Locomotor function and metabolic capacity were also significantly increased in aged mice after DSW treatment. The results indicate that daily intake of DSW may enhance the training effect of exercise and affect locomotor performance.

The role of NMDA receptors in fish stress response: Assessments based on physiology of the caudal neurosecretory system and defensive behavior.

Stress strongly influences the physiology and behavior of animals, and leads into a pathological condition and disease. NMDA receptors (NMDARs) play a crucial role in the modulation of neural activity. To understand the role of NMDARs in fish stress response, we used NMDARs agonist aspartate to test the functional role of its input on the Dahlgren cell population in the caudal neurosecretory system (CNSS) of the olive flounder. In addition, the effect of the NMDARs antagonist D-AP5 on the expression of genes of the main secretory products of the CNSS after stress was investigated by using qPCR technology and the effect of the NMDARs antagonist D-AP5 on post-stress behavior was explored by behavioral methods. Ex vivo electrophysiological experiments showed that the NMDARs agonist aspartate enhanced the firing frequency of Dahlgren cells. Additionally, aspartate treatment increased the incidence of cells exhibiting bursting firing pattern, this result is corroborated by the observed upregulation in the expression of ion channels and major hormone genes in the CNSS. Furthermore, the excitatory influence of aspartate was effectively counteracted by NMDARs antagonist D-AP5. Interestingly, NMDARs antagonist D-AP5 treatment also significantly decreased the plasma cortisol levels and the expression of CRH, UI, and UII in CNSS after acute stress. Treatment with D-AP5 effectively attenuated the stress response, as evidenced by alterations in respiratory metabolism, sand-burying behavior, swimming distance, simulated capture, and escape response. In conclusion, modulation of Dahlgren cell excitability in the CNSS by NMDARs contributes to the regulation of the stress response, NMDARs antagonist D-AP5 can effectively suppress stress response in flounder by regulating the stress hormone expression and secretion. CLINICAL TRIAL REGISTRATION: Project code SHOU-DW-2022-032.

Cardiometabolic effects of sacubitril/valsartan in a rat model of heart failure with preserved ejection fraction

The promising results obtained in the PARADIGM-HF trial prompted the approval of sacubitril/valsartan (SAC/VAL) as a first-in-class treatment for heart failure with reduced ejection fraction (HFrEF) patients. The effect of SAC/VAL treatment was also studied in patients with heart failure with preserved ejection fraction (HFpEF) and, although improvements in New York Heart Association (NYHA) class, HF hospitalizations, and cardiovascular deaths were observed, these results were not so promising. However, the demand for HFpEF therapies led to the approval of SAC/VAL as an alternative treatment, although further studies are needed. We aimed to elucidate the effects of a 9-week SAC/VAL treatment in cardiac function and metabolism using a preclinical model of HFpEF, the Zucker Fatty and Spontaneously Hypertensive (ZSF1) rats. We found that SAC/VAL significantly improved diastolic function parameters and modulated respiratory quotient during exercise. Ex-vivo studies showed that SAC/VAL treatment significantly decreased heart, liver, spleen, and visceral fat weights; cardiac hypertrophy and percentage of fibrosis; lipid infiltration in liver and circulating levels of cholesterol and sodium. Moreover, SAC/VAL reduced glycerophospholipids, cholesterol, and cholesteryl esters while increasing triglyceride levels in cardiac tissue. In conclusion, SAC/VAL treatment improved diastolic and hepatic function, respiratory metabolism, reduced hypercholesterolemia and cardiac fibrosis and hypertrophy, and was able to modulate cardiac metabolic profile. Our findings might provide further insight into the therapeutic benefits of SAC/VAL treatment in obese patients with HFpEF

Unveiling the antibacterial potential of anthocyanins - a comprehensive review on this natural plant extract.

With the gradual prohibition of antibiotic fungicides, it is of great significance to develop high-efficient, nontoxic and environmental-friendly antimicrobial agents. Anthocyanin is a natural plant polyphenol pigment which shows antibacterial, anti-inflammatory and antioxidant effects through inhibiting the synthesis of bacterial cell wall, interfering bacterial respiratory metabolism, and inducing bacterial autolysis. As a typical antibacterial agent, anthocyanins have been widely used in various fields, including biological pesticides or feed additives in agricultural production, anti-inflammatory and antibacterial wound dressings in medicine, etc. However, the structure of anthocyanins is unstable, which limits its practical application. In this article, the biological activity, antibacterial mechanism and stabilization strategy of anthocyanins as antibacterial agents were reviewed. The safety, application scope and methods of anthocyanins were discussed. In addition, the challenges and development prospects of anthocyanin extract antibacterial technology were also prospected. This will be the direction for researchers to further explore and better apply anthocyanins to practical production and application.

Bionic modified atmosphere film Inspired by plant stomata with curcumin as controllable gas “Switches” for fruit preservation

Modified atmosphere packaging (MAP) is a promising preservation technology for the fruits with the characteristics of respiration metabolism. However, traditional MAP cannot precisely control and regulate the selective permeation of gas. Inspired by the fact that plants control respiration through leaf stomata, we innovatively construct a bionic intelligent MAP of curcumin-porous starch/chitosan (Cur-PS/CS) with leaf stomata structure. Herein, PS is used as the bionic stomata, and Cur is used as the gas switch controlled by changing the pH and temperature. As a result, the CO2/O2 selectivity values are precisely controlled from 2.60 to 5.51 by controlling the amount of Cur released from PS. In which, the 10.3 % Cur-PS/CS displays the highest CO2/O2 selectivity value (5.51). In addition to outstanding tensile strength (51.54 MPa) and antioxidant activity (91.03 %), the inhibition zone diameters of 10.3 % Cur-PS/CS film against Escherichia coli, Staphylococcus aureus and Aspergillus niger reach 8 mm, 7.8 mm and 9.1 mm, respectively. Therefore, the 10.3 % Cur-PS/CS film effectively extends the shelf life of the non-climacteric fruit (cherries) and climacteric fruit (apple slices). More importantly it does not bring any issues with food safety and environmental contamination due to the excellent biodegradability of Cur-PS/CS film.

Black pepper essential oil nanoemulsion inhibits Colletotrichum gloeosporioides by regulating respiratory metabolism

Black pepper essential oil nanoemulsion inhibits Colletotrichum gloeosporioides by regulating respiratory metabolism

Effects of Bifidobacterium-Fermented Milk on Obesity: Improved Lipid Metabolism through Suppression of Lipogenesis and Enhanced Muscle Metabolism.

Obesity is a major global health concern. Studies suggest that the gut microflora may play a role in protecting against obesity. Probiotics, including lactic acid bacteria and Bifidobacterium, have garnered attention for their potential in obesity prevention. However, the effects of Bifidobacterium-fermented products on obesity have not been thoroughly elucidated. Bifidobacterium, which exists in the gut of animals, is known to enhance lipid metabolism. During fermentation, it produces acetic acid, which has been reported to improve glucose tolerance and insulin resistance, and exhibit anti-obesity and anti-diabetic effects. Functional foods have been very popular around the world, and fermented milk is a good candidate for enrichment with probiotics. In this study, we aim to evaluate the beneficial effects of milks fermented with Bifidobacterium strains on energy metabolism and obesity prevention. Three Bifidobacterium strains (Bif-15, Bif-30, and Bif-39), isolated from newborn human feces, were assessed for their acetic acid production and viability in milk. These strains were used to ferment milk. Otsuka-Long-Evans Tokushima Fatty (OLETF) rats administered Bif-15-fermented milk showed significantly lower weight gain compared to those in the water group. The phosphorylation of AMPK was increased and the expression of lipogenic genes was suppressed in the liver of rats given Bif-15-fermented milk. Additionally, gene expression related to respiratory metabolism was significantly increased in the soleus muscle of rats given Bif-15-fermented milk. These findings suggest that milk fermented with the Bifidobacterium strain Bif-15 can improve lipid metabolism and suppress obesity.