Photosynthesis, fluorescence, and nutrition of Zhonglan No. 2, a new alfalfa cultivar.

BACKGROUND: The years after planting play an important role in the above-ground biomass and nutritive value of alfalfa. Zhonglan No. 2 (Medicago sativa L. cv. Zhonglan No. 2) is a new breeding alfalfa cultivar characterized by high drought tolerance and high yield. To determine the optimum time for utilization of Zhonglan No. 2, we examined growth traits, chlorophyll content, photosynthetic and fluorescence parameters, and composition and nutritive values at the late vegetative and early flowering stages of the first stubble in the second, third, fourth, sixth, and eleventh years after planting. RESULTS: In general, the height and leaf area decreased with increasing number of years after planting. At the late vegetative stage, the fourth-year alfalfa exhibited higher stomatal conductance (Gs) and intercellular CO2 concentration (Ci), and better water use efficiency, and at the early flowering stage, the fourth-year alfalfa had the highest (P < 0.05) leaf net photosynthetic rate (Pn) and carboxylation efficiency (CE). Total digestible nutrients did not differ among years, but, in the early flowering stage, crude protein content decreased with years (P < 0.05). Malondialdehyde (MDA) content and total antioxidant capacity did not differ among years after planting, suggesting aging did not impose oxidative stress on this alfalfa cultivar. CONCLUSIONS: Based on height, chlorophyll content, crude protein (CP) content, and photosynthetic and fluorescence parameters, the fourth year after planting, at the early flowering stage, was the best for using Zhonglan No. 2. © 2021 Society of Chemical Industry.

A human corneal ulcer caused by Thelazia callipaeda in Southwest China: case report.

In this study, we describe a rare human case with corneal ulcer caused by thelaziosis in a 69-year-old man in Southwest China. A male nematode was discovered and removed from the patient's right eye with a long spicule and further identified by sequencing mitochondrial cox1 gene. The ophthalmologic and molecular biological evidence demonstrates the corneal ulcer caused by T. callipaeda infection, which is mainly distributed in Asian and European countries. Most T. callipaeda infections are emerged in the conjunctiva, leading to conjunctivitis. To the best knowledge of the authors, corneal ulcers caused by T. callipaeda have not been reported yet.

Predictive Value of Troponin I, Creatinine Kinase Isoenzyme and the New Japanese Severity Score in Severe Acute Pancreatitis.

Purpose: To evaluate troponin I, creatine kinase isoenzyme, and the new Japanese Severity Score(JSS) for predicting Severe Acute Pancreatitis-Associated myocardial Injury(SACI). Patients and Methods: This retrospective study included 136 patients with Severe Acute Pancreatitis, hospitalized in grade-III hospital from June 1, 2015, to October 31, 2022; selected using convenience sampling method and divided into SACI occurrence (n =34) and SACI non-occurrence (n =102) groups. New JSS evaluated predictive value of each SACI index. Binary logistic regression model compared risk factors and constructed a prediction model. Area under receiver operating characteristic curve (AUC) and Hosmer-Lemeshow goodness of fit test evaluated model's prediction efficiency and calibration ability. Results: The incidence of SACI was 25%. Univariate analysis found that troponin I and creatine kinase isoenzyme were significantly different (P < 0.05) and independent risk factors for SACI. The new JSS, troponin I, and creatine kinase isoenzyme were included in the prediction model. The prediction model had a good calibration ability, and its predicted value and the actual observed value were not significantly different (Hosmer-Lemeshow χ2 = 5.408, P = 0.368). AUC of the model was 0.803 (95% CI: 0.689-0.918), and the optimal threshold of the prediction model was 0.318 with the maximum Youden index (0.488). The AUC for internal validation was 0.788 (95% CI: 0.657-0.876), and external validation was 0.761 (95% CI: 0.622-0.832). Conclusion: Troponin I and creatine kinase isoenzymes combined with the new JSS have a high predictive value for SACI, improving the early prediction and treatment of at-risk patients.

Changes in bud bank and their correlation with plant community composition in degraded alpine meadows.

Bud banks are considered a crucial factor in regulating the species composition of grassland communities and maintaining the ecological function of alpine grasslands. However, few studies have paid attention to the dynamic changes of bud banks from undisturbed to severely degraded alpine meadows. Therefore, this study examined the correlations between plant diversity and bud bank traits at different stages of alpine meadows degradation. Grass biomasses and plant diversity were found to be highest in moderately degraded meadows, and sedge biomasses were highest in lightly degraded meadows. Lack of disturbance and moderate disturbance by herbivores increased the bud bank density of alpine meadows. Consistent with the changes in bud bank density, bud bank diversity was highest in undisturbed meadows. The structural equation model indicated that the densities of rhizome and the densities and diversities of tiller buds play crucial roles in facilitating the greater diversity of the plant community. Our findings suggest that the diversities and densities of rhizome and tiller buds in the degradation stages are synchronized with changes in plant diversity, and in the regenerative ability of bud banks, which largely determine the outcome of restoration in degraded meadows. These findings could provide a frame of reference for effectively restoring degraded alpine regions by regenerating bud banks. The potential driving force and renewal capacity of bud banks should be taken into account in restoring the Qinghai-Tibet Plateau's degraded meadow.

Effect of Epichloë Endophyte on the Growth and Carbon Allocation of Its Host Plant Stipa purpurea under Hemiparasitic Root Stress.

Epichloë endophytes not only affect the growth and resistance of their host plants but also confer nutrient benefits to parasitized hosts. In this study, we used Pedicularis kansuensis to parasitize Stipa purpurea, both with and without endophytic fungi, and to establish a parasitic system. In this study, endophytic fungal infection was found to increase the dry weight of the leaf, stem, and leaf sheath, as well as the plant height, root length, tiller number, aboveground biomass, and underground biomass of S. purpurea under root hemiparasitic stress. Meanwhile, the 13C allocation of the leaf sheaths and roots of S. purpurea increased as the density of P. kansuensis increased, while the 13C allocation of the leaf sheaths and roots of E+ S. purpurea was lower than that of E- S. purpurea. The 13C allocation of the stem, leaf sheath, and root of E+ S. purpurea was higher than that of its E- counterpart. Furthermore, the content of photosynthetic 13C and the 13C partition rate of the stems, leaves, roots, and entire plant of S. purpurea and P. kansuensis transferred from S. purpurea increased as the density of P. kansuensis increased. These results will generate new insights into the potential role of symbiotic microorganisms in regulating the interaction between root hemiparasites and their hosts.

Effect of Plateau Pika Disturbance on Plant Aboveground Biomass of Alpine Meadows at Two Different Scales.

Disturbance by small burrowing herbivores often has an impact on plant aboveground biomass of grassland because it makes grasslands into a mosaic of discrete vegetated surfaces and bare soil patches. This study focuses on the plateau pika (Ochotona curzoniae) to investigate the effect of the disturbance by a small burrowing herbivore on plant aboveground biomass through upscaling the quadrat scale to the plot scale across five sites. This study showed that the plateau pika disturbance reduced sedge biomass and increased forb biomass. In contrast, they did not affect plant community biomass, grass biomass and legume biomass at the quadrat scale across the five sites. At the plot scale, that is, when the bare soil patches with a lack of plants were considered, plateau pika disturbance induced lower aboveground biomass of the plant community, sedge and legumes, while it had no relationship with grass biomass and forb biomass. As the disturbance intensity increased, the aboveground biomass of the plant community and sedge decreased, whereas the grass biomass showed a hump-shaped trend. These results indicate that plateau pika disturbance might be not beneficial to alpine meadows given the aboveground biomass of the plant community at the plot scale. In contrast, the intermediate disturbance intensity improves the grazing quality of alpine meadows through the higher grass biomass. The findings of this study imply that the plot scale is better than the quadrat scale to investigate the influence of the disturbance by a small burrowing herbivore on the plant aboveground biomass, and that management of a small burrowing herbivore needs to consider its disturbance intensity.

Comparison of the effect of temperature and water potential on the seed germination of five Pedicularis kansuensis populations from the Qinghai-Tibet plateau.

Temperature and water potentials are considered the most critical environmental factors in seed germinability and subsequent seedling establishment. The thermal and water requirements for germination are species-specific and vary with the environment in which seeds mature from the maternal plants. Pedicularis kansuensis is a root hemiparasitic weed that grows extensively in the Qinghai-Tibet Plateau's degraded grasslands and has seriously harmed the grasslands ecosystem and its utilization. Information about temperatures and water thresholds in P. kansuensis seed germination among different populations is useful to predicting and managing the weed's distribution in degraded grasslands. The present study evaluated the effects of temperature and water potentials on P. kansuensis seed germination in cool and warm habitats, based on thermal time and hydrotime models. The results indicate that seeds from cool habitats have a higher base temperature than those from warm habitats, while there is no detectable difference in optimum and ceiling temperatures between habitats. Seed germination in response to water potential differed among the five studied populations. There was a negative correlation between the seed populations' base water potential for 50% (Ψ b(50)) germination and their hydrotime constant (θ H). The thermal time and hydrotime models were good predictors of five populations' germination time in response to temperature and water potentials. Consequently, future studies should consider the effects of maternal environmental conditions on seed germination when seeking effective strategies for controlling hemiparasitic weeds in alpine regions.

Association between vitamin D3 levels and insulin resistance: a large sample cross-sectional study.

Previous studies have shown that vitamin D3 may be a potential factor in insulin resistance, but the relationship between vitamin D3 and insulin resistance still remains controversial. At present, more research is needed to explore the relationship between vitamin D3 and insulin resistance. The samples from 2009 to 2018 in NHANES database were analyzed to Investigate the relationship and the potential mechanism. We performed a cross-sectional study of five periods in the NHANES database. Finally, 9298 participants were selected through strict inclusion and exclusion criteria, Multivariate logistic regression analysis and curve fitting were conducted to explore the relationship between vitamin D3 level and insulin resistance. Moreover, subgroup analysis was used to further prove the association. The results revealed that there was a strong association between vitamin D3 and insulin resistance (OR 0.82, 95% CI 0.72-0.93). However, subgroup analyses indicated that this correlation varied between individuals and races. There was a negative correlation between vitamin D3 level and insulin resistance, which provides a new proof for exploring the influencing factors of insulin resistance. More well-designed studies are still needed to further elaborate on these associations.

The effects of native lactic acid bacteria on the microbiome, fermentation profile, and nutritive value of Napier grass silage prepared with different legume ratios.

Mixing grass with legumes before ensiling is beneficial for improving dry matter and crude protein yield, but additional information is needed to balance nutrient content and fermentation quality. In this study, the microbial community, fermentation characteristics, and nutrient content of Napier grass mixed with alfalfa at different proportions were assessed. Tested proportions included: 100:0 (M0), 70:30 (M3), 50:50 (M5), 30:70 (M7), and 0:100 (MF). Treatments included: (CK) sterilized deionized water; (IN) selected lactic acid bacteria: Lactobacillus plantarum CGMCC 23166 and Lacticaseibacillus rhamnosus CGMCC 18233 (1.5 × 105 cfu/g of fresh weight for each inoculant); and (CO) commercial lactic acid bacteria: L. plantarum (1 × 105 cfu/g of fresh weight). All mixtures were ensiled for 60 days. Data analysis was used as a completely randomized design with a 5-by-3 factorial arrangement of treatments. The results showed that with increasing alfalfa mixing ratio, dry matter, and crude protein increased, while neutral detergent fiber and acid detergent fiber decreased both before and after ensiling (p < 0.05), which was not influenced by fermentation. Inoculation with IN and CO decreased pH and increased the lactic acid content compared to CK (p < 0.05), especially in silages M7 and MF. The highest Shannon index (6.24) and Simpson index (0.93) were observed in the MF silage CK treatment (p < 0.05). The relative abundance of Lactiplantibacillus decreased with increasing alfalfa mixing ratio, while the abundance of Lactiplantibacillus was significantly higher in the IN-treated group than in other treatment groups (p < 0.05). A higher alfalfa mixing ratio improved the nutrient value, but also made fermentation more difficult. Inoculants improved the fermentation quality by increasing the abundance of Lactiplantibacillus. In conclusion, the groups M3 and M5 achieved the optimal balance of nutrients and fermentation. If a higher proportion of alfalfa needs to be used, it is recommended to use inoculants to ensure sufficient fermentation.

Determining the cause of intrauterine fetal death in monochorionic twins: A case report.

Background: Determining the cause of intrauterine fetal death is essential for patients to manage their next pregnancy. However, in the majority of cases of fetal death, the cause remains unexplained despite comprehensive evaluation, especially in the cases of twins. Among twin pregnancies, conditions of monochorionic twinning, commonly regarded as monozygotic, are more complicated than dichorionic ones. Case summary: We systematically evaluated the cause of fetal death for a Han Chinese woman with monochorionic twinning following in vitro fertilization/embryo transfer. Discrepant karyotypes were unexpectedly discovered between the twins. One fetus had an aneuploid male karyotype (46, XY), dup (9) (p24.3-q13), and the other had a normal female karyotype (46, XX). We considered that the male died of aberration of chromosome 9 and the female died of subsequent acute exsanguination through vascular anastomosis. Conclusion: This study demonstrated the importance of recognizing the presence of monochorionic dizygotic twinning and the challenges of clinical management for twins following in vitro fertilization/double embryo transfer.

The association between vitamin D3 and diabetes in both hyperuricemia and non-hyperuricemia populations.

BACKGROUND: Previous studies have shown that hyperuricemia is involved in diabetes, obesity, hypertension, chronic kidney disease, and other diseases. At the same time, studies have shown that vitamin D3 levels in the body are linked to the onset of diabetes. However, there is currently no sufficient evidence to prove whether this connection is affected by the uric acid level. Therefore, we attempted to investigate the association between vitamin D3 content and the occurrence of diabetes in populations with different uric acid levels though the data of NHANES database from 2009 to 2018. METHOD: Using the NHANES database, we performed a cross-sectional analysis. The participants were chosen based on stringent inclusion and exclusion requirements. This study finally included a total number of 16,735 individuals. Multivariate logistic regression analysis was used to investigate the association between vitamin D3 and diabetes mellitus in hyperuricemia and non-hyperuricemia patients after complete adjustment, and multivariate linear regression analysis was used to illustrate the association between vitamin D3 and uric acid. RESULT: The results showed that the association between vitamin D3 and diabetes was weakened in hyperuricemia patients (OR 0.95 (0.92,0.98)). An independent association was discovered between vitamin D3 and uric acid (ß -0.12 (-0.16, -0.07)) in all groups of population. CONCLUSIONS: This study shows that vitamin D3 content is associated with the incidence of diabetes in people with high level of uric acid. This study offers a fresh perspective on the elements that influence the etiology of diabetes in hyperuricemia patients.

Characterization of the complete chloroplast genome of Puccinellia distans.

Puccinellia distans is a perennial gramineous plant with the characteristics of drought and salt tolerance. It is a special pioneer plant for saline-alkali land improvement and is increasingly used for ecological restoration of saline-alkali grassland. However, the evolutionary relationship of P. distans is limited in study. In this study, the complete chloroplast genome sequence of P. distans was evaluated. The complete chloroplast genome of P. distans was 135,647 bp in length, containing a pair of inverted repeated (IR) regions (21,444 bp) that are separated by a large single-copy (LSC) region of 800,15 bp, and a small single-copy (SSC) region of 12,744 bp. A total of 129 functional genes were annotated, including 83 protein-coding genes (mRNA), 38 tRNA genes, and 8 rRNA genes. The phylogenetic relationships of 12 species indicated that P. distans was closely related to P. muttalliana. This complete chloroplast genome will provide a theoretical basis for species identification and biological research.

Associations between TG/HDL ratio and insulin resistance in the US population: a cross-sectional study.

BACKGROUND: Clinical data on the relationship between triglycerides (TG)/HDL ratio and insulin resistance (IR) suggest that TG/HDL ratio may be a risk factor for IR. However, there is evidence that different races have different risk of developing IR. The relationship on TG/HDL ratio and IR in various populations needs to be improved. Therefore, we investigated whether TG/HDL ratio was linked to IR in different groups in the United States after controlling for other covariates. METHODS: The current research was conducted in a cross-sectional manner. From 2009 to 2018, the National Health and Nutrition Examination Survey (NHANES) had a total of 49,696 participants, all of whom were Americans. The target-independent variable was TG/HDL ratio measured at baseline, and the dependent variable was IR. Additionally, the BMI, waist circumference, education, race, smoking, alcohol use, alanine transaminase, aspartate transaminase, and other covariates were also included in this analysis. RESULTS: The average age of the 10,132 participants was 48.6 ± 18.4 years, and approximately 4936 (48.7%) were males. After correcting for confounders, fully adjusted logistic regression revealed that TG/HDL ratio was correlated with IR (odds ratio = 1.51, 95% CI 1.42-1.59). A nonlinear interaction between TG/HDL ratio and IR was discovered, with a point of 1.06. The impact sizes and CIs on the left and right sides of the inflection point were 6.28 (4.66-8.45) and 1.69 (1.45-1.97), respectively. According to subgroup analysis, the correlation was strong in females, alcohol users, and diabetes patients. Meanwhile, the inverse pattern was observed in the aged, obese, high-income, and smoking populations. CONCLUSION: In the American population, the TG/HDL ratio is positively associated with IR in a nonlinear interaction pattern.

Characterization of the complete chloroplast genome of Bromus inermis Leyss.

Bromus Inermis Leyss 1761 is a perennial herb with large yield and famous for its high nutritional value and long utilization season. The study of B. inermis chloroplast (cp) genome provides an important basis for the study of chloroplast genetic engineering and system evolution. Its cp genome was 137,153 bp in length, containing a pair of inverted repeated (IR) regions (21,699 bp), separated by a large single copy region (LSC) of 81,137 bp, and a small single copy (SSC) region of 12,618 bp. Moreover, a total of 129 functional genes were annotated, including 83 mRNA, 38 tRNA genes, and 8 rRNA genes. The phylogenetic relationships of 15 species indicated that B. inermis was closely related to Bromus biebersteinii. This study might contribute to provide a theoretical basis for species identification and biological research.

Characterization of the complete chloroplast genome of Elymus kamoji (Ohwi) S. L. Chen.

Elymus kamoji (Ohwi) S. L. Chen is a perennial herb, had high grazing value and were important forage resources, the study of E. kamoji chloroplast genome (cp genome) provides an important basis for the study of chloroplast genetic engineering and system evolution. Its chloroplast genome was 135,075 bp in length, containing a pair of inverted repeated (IR) regions (20,813 bp), separated by a large single copy region (LSC) of 80,681 bp, and a small single copy (SSC) region of 12,768 bp. Moreover, a total of 129 functional genes were annotated, including 83 mRNA, 38 tRNA genes, and 8 rRNA genes. The phylogenetic relationships of 15 species indicated that E. kamoji was closely related to Elymus sibiricus. This study might contribute to provide a theoretical basis for species identification and biological research.

Associations of Triglycerides/High-Density Lipoprotein Cholesterol Ratio With Insulin Resistance, Impaired Glucose Tolerance, and Diabetes in American Adults at Different Vitamin D3 Levels.

Background: Previous studies have shown that vitamin D3 (VD3) may be a protective factor for diabetes mellitus (DM), while triglycerides/high-density lipoprotein (TG/HDL) may be a risk factor for diabetes. However, no existing study has elucidated the interaction between TG/HDL and VD3. Therefore, this work aimed to investigate the relationships of TG/HDL with insulin resistance (IR), impaired glucose tolerance (IGT), and DM at different VD3 levels. Methods: With the use of the data from five National Health and Nutrition Examination Survey (NHANES) cycles, a total of 2,929 males and 3,031 females were divided into 4 groups according to their VD3 levels. Logistic regression was performed to observe the associations of TG/HDL ratio with IR, IGT, and DM in different groups. Results: The relationships of TG/HDL with IR, IGT, and DM showed a threshold effect, with the cutoff values of 1.094, 1.51, and 1.11, respectively. On both sides of the cutoff values, the correlation was first weakened and then enhanced with the increase in VD3 levels. Conclusion: TG/HDL is a risk factor for IR, IGT, and DM. Both too low and too high levels of VD3 can strengthen this association, whereas keeping VD3 at a reasonable level helps to reduce the associations of TG/HDL with IR, IGT, and DM.

Complete chloroplast genome of Hordeum brevisubulatum: Genome organization, synonymous codon usage, phylogenetic relationships, and comparative structure analysis.

BACKGROUND: Hordeum brevisubulatum, known as fine perennial forage, is used for soil salinity improvement in northern China. Chloroplast (cp) genome is an ideal model for assessing its genome evolution and the phylogenetic relationships. We de novo sequenced and analyzed the cp genome of H. brevisubulatum, providing a fundamental reference for further studies in genetics and molecular breeding. RESULTS: The cp genome of H. brevisubulatum was 137,155 bp in length with a typical quadripartite structure. A total of 130 functional genes were annotated and the gene of accD was lost in the process of evolution. Among all the annotated genes, 16 different genes harbored introns and the genes of ycf3 and rps12 contained two introns. Parity rule 2 (PR2) plot analysis showed that majority of genes had a bias toward T over A in the coding strand in all five Hordeum species, and a slight G over C in the other four Hordeum species except for H. bogdanil. Additionally, 52 dispersed repeat sequences and 182 simple sequence repeats were identified. Moreover, some unique SSRs of each species could be used as molecular markers for further study. Compared to the other four Hordeum species, H. brevisubulatum was most closely related to H. bogdanii and its cp genome was relatively conserved. Moreover, inverted repeat regions (IRa and IRb) were less divergent than other parts and coding regions were relatively conserved compared to non-coding regions. Main divergence was presented at the SSC/IR border. CONCLUSIONS: This research comprehensively describes the architecture of the H. brevisubulatum cp genome and improves our understanding of its cp biology and genetic diversity, which will facilitate biological discoveries and cp genome engineering.

Was Antiphospholipid Syndrome a Risk Factor of Stroke? A Systemic Review and Meta-Analysis of Cohort Studies.

Antiphospholipid syndrome (APS) is characterized by thrombosis. This systemic review and meta-analysis was to verify the hypothesis that APS might increase the risk of stroke. Studies were identified after literature searching of PubMed, Embase, and Cochrane. Newcastle-Ottawa Quality Assessment Scale Cohort Studies (NOQAS-C) was used to assess the quality of studies. The pooled effect with 95% confidence interval (95% CI) was calculated by random-effect model. I-square (I 2) was used to test heterogeneity. Funnel plot was used to evaluate publication bias. A total of 17 cohort studies with overall high quality were included. There was no publication bias. Pooled hazard ratio of stroke occurrence in APS patients was 1.76 (1.39-2.21) with low heterogenicity and stable result from sensitivity analysis. In the analysis of subgroups, pooled risk ratios of stroke occurrence in patients with only positive antibodies of APS diagnosis were 1.75 (0.99-3.09), which for the APS patients with other autoimmune diseases were 14.70 (7.56-28.56). APS might be a risk factor of stroke, especially in patients with other autoimmune diseases.

Associations of TG/HDL Ratio with the Risk of Prediabetes and Diabetes in Chinese Adults: A Chinese Population Cohort Study Based on Open Data.

BACKGROUND: In the global chronic diseases, type 2 diabetes shows a significant upward trend, and there are more people before prediabetes (impaired glucose tolerance). Many patients with impaired glucose tolerance and undiagnosed diabetes do not know that their glucose metabolism system has been in a state of disorder. Every year, about 5% to 10% of prediabetics develop diabetes. One of the important achieving factors may be the increase in blood lipids. However, it is not clear whether the triglyceride/high-density lipoprotein ratio is associated with impaired glucose tolerance and diabetes in the Chinese population. Therefore, we investigated the relationship between triglyceride/high-density lipoprotein and impaired glucose tolerance and diabetes in the Chinese population. METHODS: We conducted a retrospective cohort study using data from the health screening program. The study included 116,855 participants from 32 locations in China, all of whom were adults over 20. Participants measured fasting blood glucose levels at each visit and collected information about their diabetes history. Impaired glucose tolerance was diagnosed as fasting blood glucose ≥6.00 mmol and self-reported diabetes mellitus. The patient was measured on the date of diagnosis or on his last visit (whichever comes first). RESULTS: The results showed that, after adjusting the potential confounding factors, the ratio of TG/HDL was positively correlated with the occurrence of prediabetes and diabetes, and there was a saturation effect. The inflection points were 1.04 and 1.33, respectively. The effect value and 95% confidence interval before and after the inflection point of impaired glucose tolerance patients were 1.57 and (1.42, 1.73) and 1.03 and (1.01, 1.05), respectively. The effect value and 95% confidence interval before and after the inflection point in patients with diabetes were 2.07 and (1.80, 2.39) and 1.08 and (1.04, 1.12).

Microbial production of meso-2,3-butanediol by metabolically engineered Escherichia coli under low oxygen condition.

A metabolically engineered Escherichia coli has been constructed for the production of meso-2,3-butanediol (2,3-BD) under low oxygen condition. Genes responsible for 2,3-BD formation from pyruvate were assembled together to generate a high-copy plasmid pEnBD, in which each gene was transcribed with a constitutive promoter. To eliminate by-product formation under low oxygen condition, genes including ldhA, pta, adhE, and poxB which functioned for the mixed acid fermentation pathways were deleted in E. coli JM109. Compared with the wild type, the quadruple gene deletion mutant produced smaller amounts of acetate, succinate, and ethanol from glucose when cultivated in LB medium in shake flasks under low-aeration. When 2,3-BD producing pathway was introduced via pEnBD into the mutant, higher glucose consumption and faster 2,3-BD production rate compared with that of the wild-type control were observed under aerobic condition in shake flasks. In a 6-L fermentor supplied with only 3% dissolved oxygen (DO), the mutant harboring pEnBD converted glucose to 2,3-BD much faster than the control did. When DO supply was further lowered to 1% DO, the recombinant mutant grew much slower but produced 2,3-BD as a major fermentation metabolic product. In addition, the 2,3-BD yield showed an increase from 0.20 g BD/g glucose for the control to 0.43 g BD/g glucose for the mixed acid pathway deleted mutant grown in fermentors under 1% DO. These results reveals the potential of production of enantiomerically pure 2,3-BD isomer by recombinant E. coli under low oxygen condition.