Background Streptococcus （S.） oligofermentans is a newly identified bacteria with a yet to be defined mechanism of sucrose metabolism that results in acid production. This study aimed to investigate the biochemical ...Background Streptococcus （S.） oligofermentans is a newly identified bacteria with a yet to be defined mechanism of sucrose metabolism that results in acid production. This study aimed to investigate the biochemical mechanisms of S. oligoferm-entans glucose metaolism. Methods The S. oligofermentans LMG21532, Lactobacillus （L.） fermentum 38 and the S. mutans UA140 were used to characterize sucrose metabolism by measuring lactate dehydrogenase （LDH） activity and lactic acid production. Continuous dynamics and high performance capillary electrophoresis were used to determine LDH activity and lactic acid production, respectively, from bacteria collected at 0, 10 and 30 minutes after cultured in 10% sucrose. Results These analyses demonstrated that LDH activity of the three bacterial strains examined remained stable but significantly different throughout the sucrose fermentation process. The S. oligofermentans LDH activity （（0.61±0.05） U/mg） was significantly lower than that of L. fermentum （（52.91±8.97） U/mg）. In addition, the S. oligofermentans total lactate production （（0.048±0.021） mmol/L） was also significantly lower than that of L. fermentum （（0.958±0.201） mmol/L）. Although the S. oligofermentans LDH production was almost double of that produced by S. mutans （（0.32±0.07） U/mg）, lactic acid production was approximately one sixth that of S. mutans （（0.296±0.058） mmol/L）. Additional tests examining pyruvic acid production （the LDH substrate） demonstrated that lactic acid concentrations correlated with pyruvic acid production. That is, pyruvic acid production by S. oligofermentans was undetectable following sucrose incubation, however, （0.074±0.024） and （0.175±0.098） mmol/L pyruvic acid were produced by S. mutans and L. fermentum, respectively. Conclusion S. oligofermentans is incapable of fermenting carbohydrates to produce enough pyruvic acid, which results in reduced lactic acid production.展开更多
The wild type strain Rhizopus oryzae PW352 was mutated by means of nitrogen ion implantation （15 keV, 7.8×10^14 ～ 2.08 ×10^15 ions/cm^2） to find an industrial strain with a higher L（＋）-lactic acid yiel...The wild type strain Rhizopus oryzae PW352 was mutated by means of nitrogen ion implantation （15 keV, 7.8×10^14 ～ 2.08 ×10^15 ions/cm^2） to find an industrial strain with a higher L（＋）-lactic acid yield, and two mutants RE3303 and RF9052 were isolated. In order to discuss the mechanism primarily, Lactate Dehydrogenase of Rhizopus oryzae was studied. While the two mutants produced L（＋）-lactic acid by 75% more than the wild strain did, their specific activity of Lactate Dehydrogenase was found to be higher than that in the wild strain. The optimum temperature of Lactate Dehydrogenase in Rhizopus oryzae RF9052 was higher. Compared to the wild strain, the Michaelis constant （Km） value of Lactate Dehydrogenase in the mutants was Changed. All these changes show that L（＋）-lactic acid production has a correlation with the specific activity of Lactate Dehydrogenase. The low-energy ions, implanted into the strain, may improve the specific activity of Lactate Dehydrogenase by influencing its gene structure and protein structure.展开更多
Objective: Abnormal metabolism is the underlying reason for breast cancer progression. Decreased lactate dehydrogenase B(LDHB) has been detected in breast cancer but the function of LDHB remains unknown.Methods: Weste...Objective: Abnormal metabolism is the underlying reason for breast cancer progression. Decreased lactate dehydrogenase B(LDHB) has been detected in breast cancer but the function of LDHB remains unknown.Methods: Western blot was used to analyze LDHB expression in breast cancer cells. The impact of LDHB on tumor cell migration and invasion was determined using Transwell assays, wound healing assays, and a mouse lung metastasis model. Subcutaneous tumor formation, a natural killer(NK) cell cytotoxicity assay, and flow cytometry evaluated NK cell activation. Immunofluorescence and quantitative real-time PCR detected NK cell activation markers. Kaplan-Meier analysis evaluated the effect of immune cell infiltration on prognosis. Single-sample gene set enrichment analysis determined NK cell activation scores. A support vector machine predicted the role of LDHB in NK cell activation.Results: In this study we showed that LDHB inhibits the breast cancer cell metastasis and orchestrates metabolic reprogramming within tumor cells. Our results revealed that LDHB-mediated lactic acid clearance in breast cancer cells triggers NK cell activation within the tumor microenvironment. Our findings, which were confirmed in a murine model, demonstrated that LDHB in tumor cells promotes NK cell activation and ultimately results in the eradication of malignant cells. Clinically, our study further validated that LDHB affects immune cell infiltration and function. Specifically, its expression has been linked to enhanced NK cell-mediated cytotoxicity and improved patient survival. Furthermore, we identified LDHB expression in tumors as an important predictor of NK cell activation, with strong predictive ability in some cancers.Conclusions: Our results suggest that LDHB is a promising target for activating the tumor immune microenvironment in breast cancer, where LDHB-associated lactic acid clearance leads to increased NK cell activity. This study highlights the critical role of LDHB in regulating immune responses and its potential as a therapeutic target for breast cancer.展开更多
基金This study was supported by grants from 115-National Key Technologies R＆D Programme, the Ministry of Science and Technology of China （No. 2007BAI18B01）, National Natural Science Foundation of China （No. 8107088）, and Beijing Municipal Natural Science Foundation （No. 7102163）. Conflict of interests： None.
文摘Background Streptococcus （S.） oligofermentans is a newly identified bacteria with a yet to be defined mechanism of sucrose metabolism that results in acid production. This study aimed to investigate the biochemical mechanisms of S. oligoferm-entans glucose metaolism. Methods The S. oligofermentans LMG21532, Lactobacillus （L.） fermentum 38 and the S. mutans UA140 were used to characterize sucrose metabolism by measuring lactate dehydrogenase （LDH） activity and lactic acid production. Continuous dynamics and high performance capillary electrophoresis were used to determine LDH activity and lactic acid production, respectively, from bacteria collected at 0, 10 and 30 minutes after cultured in 10% sucrose. Results These analyses demonstrated that LDH activity of the three bacterial strains examined remained stable but significantly different throughout the sucrose fermentation process. The S. oligofermentans LDH activity （（0.61±0.05） U/mg） was significantly lower than that of L. fermentum （（52.91±8.97） U/mg）. In addition, the S. oligofermentans total lactate production （（0.048±0.021） mmol/L） was also significantly lower than that of L. fermentum （（0.958±0.201） mmol/L）. Although the S. oligofermentans LDH production was almost double of that produced by S. mutans （（0.32±0.07） U/mg）, lactic acid production was approximately one sixth that of S. mutans （（0.296±0.058） mmol/L）. Additional tests examining pyruvic acid production （the LDH substrate） demonstrated that lactic acid concentrations correlated with pyruvic acid production. That is, pyruvic acid production by S. oligofermentans was undetectable following sucrose incubation, however, （0.074±0.024） and （0.175±0.098） mmol/L pyruvic acid were produced by S. mutans and L. fermentum, respectively. Conclusion S. oligofermentans is incapable of fermenting carbohydrates to produce enough pyruvic acid, which results in reduced lactic acid production.
基金National Natural Science Foundation of China(No.20576132)
文摘The wild type strain Rhizopus oryzae PW352 was mutated by means of nitrogen ion implantation （15 keV, 7.8×10^14 ～ 2.08 ×10^15 ions/cm^2） to find an industrial strain with a higher L（＋）-lactic acid yield, and two mutants RE3303 and RF9052 were isolated. In order to discuss the mechanism primarily, Lactate Dehydrogenase of Rhizopus oryzae was studied. While the two mutants produced L（＋）-lactic acid by 75% more than the wild strain did, their specific activity of Lactate Dehydrogenase was found to be higher than that in the wild strain. The optimum temperature of Lactate Dehydrogenase in Rhizopus oryzae RF9052 was higher. Compared to the wild strain, the Michaelis constant （Km） value of Lactate Dehydrogenase in the mutants was Changed. All these changes show that L（＋）-lactic acid production has a correlation with the specific activity of Lactate Dehydrogenase. The low-energy ions, implanted into the strain, may improve the specific activity of Lactate Dehydrogenase by influencing its gene structure and protein structure.
基金supported by the Shenzhen Science and Technology Program (Grant no. JCYJ20230807090459001)the Joint Research Fund of the National Science Fund of China Science and Technology Development Fund of Macao SAR (No. 32161160303 for NSFC and No. 0010/2021/AFJ for FDCT)the Translational Medicine and Interdisciplinary Research Joint Fund of Zhongnan Hospital of Wuhan University (Grant no. ZNJC202330)。
文摘Objective: Abnormal metabolism is the underlying reason for breast cancer progression. Decreased lactate dehydrogenase B(LDHB) has been detected in breast cancer but the function of LDHB remains unknown.Methods: Western blot was used to analyze LDHB expression in breast cancer cells. The impact of LDHB on tumor cell migration and invasion was determined using Transwell assays, wound healing assays, and a mouse lung metastasis model. Subcutaneous tumor formation, a natural killer(NK) cell cytotoxicity assay, and flow cytometry evaluated NK cell activation. Immunofluorescence and quantitative real-time PCR detected NK cell activation markers. Kaplan-Meier analysis evaluated the effect of immune cell infiltration on prognosis. Single-sample gene set enrichment analysis determined NK cell activation scores. A support vector machine predicted the role of LDHB in NK cell activation.Results: In this study we showed that LDHB inhibits the breast cancer cell metastasis and orchestrates metabolic reprogramming within tumor cells. Our results revealed that LDHB-mediated lactic acid clearance in breast cancer cells triggers NK cell activation within the tumor microenvironment. Our findings, which were confirmed in a murine model, demonstrated that LDHB in tumor cells promotes NK cell activation and ultimately results in the eradication of malignant cells. Clinically, our study further validated that LDHB affects immune cell infiltration and function. Specifically, its expression has been linked to enhanced NK cell-mediated cytotoxicity and improved patient survival. Furthermore, we identified LDHB expression in tumors as an important predictor of NK cell activation, with strong predictive ability in some cancers.Conclusions: Our results suggest that LDHB is a promising target for activating the tumor immune microenvironment in breast cancer, where LDHB-associated lactic acid clearance leads to increased NK cell activity. This study highlights the critical role of LDHB in regulating immune responses and its potential as a therapeutic target for breast cancer.
