L-citrulline is a nonprotein amino acid that plays an important role in human health and has great market demand. Although microbial cell factories have been widely used for biosynthesis, there are still challenges such as genetic instability and low efficiency in the biosynthesis of L-citrulline. In this study, an efficient, plasmid-free, non-inducible L-citrulline-producing strain of Escherichia coli BL21(DE3) was engineered by combined strategies. Firstly, a chassis strain capable of synthesizing L-citrulline was constructed by block of L-citrulline degradation and removal of feedback inhibition, with the L-citrulline titer of 0.43 g/L. Secondly, a push-pull-restrain strategy was employed to enhance the L-citrulline biosynthesis, which realized the L-citrulline titer of 6.0 g/L. Thirdly, the NADPH synthesis and L-citrulline transport were strengthened to promote the synthesis efficiency, which achieved the L-citrulline titer of 11.6 g/L. Finally, fed-batch fermentation was performed with the engineered strain in a 3 L fermenter, in which the L-citrulline titer reached 44.9 g/L. This study lays the foundation for the industrial production of L-citrulline and provides insights for the modification of other amino acid metabolic networks.
Citrulline/biosynthesis* ; Escherichia coli/genetics* ; Metabolic Engineering/methods* ; Fermentation ; NADP/biosynthesis*

Objective:To investigate the pregnancy outcome and the maternal and infant follow-up in the puer-peral period(42 days after delivery)of cesarean section with SARS-CoV-2 Omicron variant in different periods of pregnancy.Methods:330 pregnant women who were diagnosed with SARS-CoV-2 infection and delivered by ce-sarean section in Guangdong Women and Children Hospital from November 20,2022 to January 25,2023 were selected as the research subjects.They were divided into the early(80 cases),middle(151 cases)and late(99 cases)pregnancy group according to the gestational age of infection.The general information,pregnancy compli-cations and comorbidities,pregnancy outcomes,and postpartum maternal and infant follow-up of each group of pregnant women were compared.Results:The clinical classification of pregnant women was asymptomatic and mild,with 9 cases of asymptomatic and 321 cases of mild.The incidence of gestational diabetes mellitus(GDM)in the early and late group was higher than that in the middle group(P＜0.05).There was no statistically significant difference in the incidence of placental abruption,fetal growth restriction,fetal distress,amniotic fluid contamina-tion,preterm labor,postpartum hemorrhage,macrosomia,low-birth-weight infants and the maternal intensive care unit(MICU)transfer rate,newborn birth weight,neonatal asphyxia rate and NICU transfer rate among the three groups(P＞0.05).The incidence of preterm rupture of membranes in the middle group was higher than that in the late group(P＜0.05).Puerperal follow-up results showed that there was no statistically significant difference in the incidence of poor maternal uterine incision healing,poor uterine involution,vaginal microecological imbal-ance and neonatal acute upper respiratory tract infection,pneumonia,digestive system disease,cardiovascular system disease among the three groups(P＞0.05).Conclusions:The majority of pregnant women with Omicron infection during pregnancy are mild.Omicron infection in different periods of pregnancy has no significant effect on pregnancy outcome and puerperal follow-up of cesarean section.No evidence was found that GDM and prema-ture rupture of membranes are significantly associated with Omicron infection in different periods of pregnancy.

Objective:To investigate the pregnancy outcome and the maternal and infant follow-up in the puer-peral period(42 days after delivery)of cesarean section with SARS-CoV-2 Omicron variant in different periods of pregnancy.Methods:330 pregnant women who were diagnosed with SARS-CoV-2 infection and delivered by ce-sarean section in Guangdong Women and Children Hospital from November 20,2022 to January 25,2023 were selected as the research subjects.They were divided into the early(80 cases),middle(151 cases)and late(99 cases)pregnancy group according to the gestational age of infection.The general information,pregnancy compli-cations and comorbidities,pregnancy outcomes,and postpartum maternal and infant follow-up of each group of pregnant women were compared.Results:The clinical classification of pregnant women was asymptomatic and mild,with 9 cases of asymptomatic and 321 cases of mild.The incidence of gestational diabetes mellitus(GDM)in the early and late group was higher than that in the middle group(P＜0.05).There was no statistically significant difference in the incidence of placental abruption,fetal growth restriction,fetal distress,amniotic fluid contamina-tion,preterm labor,postpartum hemorrhage,macrosomia,low-birth-weight infants and the maternal intensive care unit(MICU)transfer rate,newborn birth weight,neonatal asphyxia rate and NICU transfer rate among the three groups(P＞0.05).The incidence of preterm rupture of membranes in the middle group was higher than that in the late group(P＜0.05).Puerperal follow-up results showed that there was no statistically significant difference in the incidence of poor maternal uterine incision healing,poor uterine involution,vaginal microecological imbal-ance and neonatal acute upper respiratory tract infection,pneumonia,digestive system disease,cardiovascular system disease among the three groups(P＞0.05).Conclusions:The majority of pregnant women with Omicron infection during pregnancy are mild.Omicron infection in different periods of pregnancy has no significant effect on pregnancy outcome and puerperal follow-up of cesarean section.No evidence was found that GDM and prema-ture rupture of membranes are significantly associated with Omicron infection in different periods of pregnancy.

Objective:To investigate the pregnancy outcome and the maternal and infant follow-up in the puer-peral period(42 days after delivery)of cesarean section with SARS-CoV-2 Omicron variant in different periods of pregnancy.Methods:330 pregnant women who were diagnosed with SARS-CoV-2 infection and delivered by ce-sarean section in Guangdong Women and Children Hospital from November 20,2022 to January 25,2023 were selected as the research subjects.They were divided into the early(80 cases),middle(151 cases)and late(99 cases)pregnancy group according to the gestational age of infection.The general information,pregnancy compli-cations and comorbidities,pregnancy outcomes,and postpartum maternal and infant follow-up of each group of pregnant women were compared.Results:The clinical classification of pregnant women was asymptomatic and mild,with 9 cases of asymptomatic and 321 cases of mild.The incidence of gestational diabetes mellitus(GDM)in the early and late group was higher than that in the middle group(P＜0.05).There was no statistically significant difference in the incidence of placental abruption,fetal growth restriction,fetal distress,amniotic fluid contamina-tion,preterm labor,postpartum hemorrhage,macrosomia,low-birth-weight infants and the maternal intensive care unit(MICU)transfer rate,newborn birth weight,neonatal asphyxia rate and NICU transfer rate among the three groups(P＞0.05).The incidence of preterm rupture of membranes in the middle group was higher than that in the late group(P＜0.05).Puerperal follow-up results showed that there was no statistically significant difference in the incidence of poor maternal uterine incision healing,poor uterine involution,vaginal microecological imbal-ance and neonatal acute upper respiratory tract infection,pneumonia,digestive system disease,cardiovascular system disease among the three groups(P＞0.05).Conclusions:The majority of pregnant women with Omicron infection during pregnancy are mild.Omicron infection in different periods of pregnancy has no significant effect on pregnancy outcome and puerperal follow-up of cesarean section.No evidence was found that GDM and prema-ture rupture of membranes are significantly associated with Omicron infection in different periods of pregnancy.

Objective:To investigate the pregnancy outcome and the maternal and infant follow-up in the puer-peral period(42 days after delivery)of cesarean section with SARS-CoV-2 Omicron variant in different periods of pregnancy.Methods:330 pregnant women who were diagnosed with SARS-CoV-2 infection and delivered by ce-sarean section in Guangdong Women and Children Hospital from November 20,2022 to January 25,2023 were selected as the research subjects.They were divided into the early(80 cases),middle(151 cases)and late(99 cases)pregnancy group according to the gestational age of infection.The general information,pregnancy compli-cations and comorbidities,pregnancy outcomes,and postpartum maternal and infant follow-up of each group of pregnant women were compared.Results:The clinical classification of pregnant women was asymptomatic and mild,with 9 cases of asymptomatic and 321 cases of mild.The incidence of gestational diabetes mellitus(GDM)in the early and late group was higher than that in the middle group(P＜0.05).There was no statistically significant difference in the incidence of placental abruption,fetal growth restriction,fetal distress,amniotic fluid contamina-tion,preterm labor,postpartum hemorrhage,macrosomia,low-birth-weight infants and the maternal intensive care unit(MICU)transfer rate,newborn birth weight,neonatal asphyxia rate and NICU transfer rate among the three groups(P＞0.05).The incidence of preterm rupture of membranes in the middle group was higher than that in the late group(P＜0.05).Puerperal follow-up results showed that there was no statistically significant difference in the incidence of poor maternal uterine incision healing,poor uterine involution,vaginal microecological imbal-ance and neonatal acute upper respiratory tract infection,pneumonia,digestive system disease,cardiovascular system disease among the three groups(P＞0.05).Conclusions:The majority of pregnant women with Omicron infection during pregnancy are mild.Omicron infection in different periods of pregnancy has no significant effect on pregnancy outcome and puerperal follow-up of cesarean section.No evidence was found that GDM and prema-ture rupture of membranes are significantly associated with Omicron infection in different periods of pregnancy.

Objective:To investigate the pregnancy outcome and the maternal and infant follow-up in the puer-peral period(42 days after delivery)of cesarean section with SARS-CoV-2 Omicron variant in different periods of pregnancy.Methods:330 pregnant women who were diagnosed with SARS-CoV-2 infection and delivered by ce-sarean section in Guangdong Women and Children Hospital from November 20,2022 to January 25,2023 were selected as the research subjects.They were divided into the early(80 cases),middle(151 cases)and late(99 cases)pregnancy group according to the gestational age of infection.The general information,pregnancy compli-cations and comorbidities,pregnancy outcomes,and postpartum maternal and infant follow-up of each group of pregnant women were compared.Results:The clinical classification of pregnant women was asymptomatic and mild,with 9 cases of asymptomatic and 321 cases of mild.The incidence of gestational diabetes mellitus(GDM)in the early and late group was higher than that in the middle group(P＜0.05).There was no statistically significant difference in the incidence of placental abruption,fetal growth restriction,fetal distress,amniotic fluid contamina-tion,preterm labor,postpartum hemorrhage,macrosomia,low-birth-weight infants and the maternal intensive care unit(MICU)transfer rate,newborn birth weight,neonatal asphyxia rate and NICU transfer rate among the three groups(P＞0.05).The incidence of preterm rupture of membranes in the middle group was higher than that in the late group(P＜0.05).Puerperal follow-up results showed that there was no statistically significant difference in the incidence of poor maternal uterine incision healing,poor uterine involution,vaginal microecological imbal-ance and neonatal acute upper respiratory tract infection,pneumonia,digestive system disease,cardiovascular system disease among the three groups(P＞0.05).Conclusions:The majority of pregnant women with Omicron infection during pregnancy are mild.Omicron infection in different periods of pregnancy has no significant effect on pregnancy outcome and puerperal follow-up of cesarean section.No evidence was found that GDM and prema-ture rupture of membranes are significantly associated with Omicron infection in different periods of pregnancy.

Objective:To investigate the pregnancy outcome and the maternal and infant follow-up in the puer-peral period(42 days after delivery)of cesarean section with SARS-CoV-2 Omicron variant in different periods of pregnancy.Methods:330 pregnant women who were diagnosed with SARS-CoV-2 infection and delivered by ce-sarean section in Guangdong Women and Children Hospital from November 20,2022 to January 25,2023 were selected as the research subjects.They were divided into the early(80 cases),middle(151 cases)and late(99 cases)pregnancy group according to the gestational age of infection.The general information,pregnancy compli-cations and comorbidities,pregnancy outcomes,and postpartum maternal and infant follow-up of each group of pregnant women were compared.Results:The clinical classification of pregnant women was asymptomatic and mild,with 9 cases of asymptomatic and 321 cases of mild.The incidence of gestational diabetes mellitus(GDM)in the early and late group was higher than that in the middle group(P＜0.05).There was no statistically significant difference in the incidence of placental abruption,fetal growth restriction,fetal distress,amniotic fluid contamina-tion,preterm labor,postpartum hemorrhage,macrosomia,low-birth-weight infants and the maternal intensive care unit(MICU)transfer rate,newborn birth weight,neonatal asphyxia rate and NICU transfer rate among the three groups(P＞0.05).The incidence of preterm rupture of membranes in the middle group was higher than that in the late group(P＜0.05).Puerperal follow-up results showed that there was no statistically significant difference in the incidence of poor maternal uterine incision healing,poor uterine involution,vaginal microecological imbal-ance and neonatal acute upper respiratory tract infection,pneumonia,digestive system disease,cardiovascular system disease among the three groups(P＞0.05).Conclusions:The majority of pregnant women with Omicron infection during pregnancy are mild.Omicron infection in different periods of pregnancy has no significant effect on pregnancy outcome and puerperal follow-up of cesarean section.No evidence was found that GDM and prema-ture rupture of membranes are significantly associated with Omicron infection in different periods of pregnancy.

Objective:To investigate the pregnancy outcome and the maternal and infant follow-up in the puer-peral period(42 days after delivery)of cesarean section with SARS-CoV-2 Omicron variant in different periods of pregnancy.Methods:330 pregnant women who were diagnosed with SARS-CoV-2 infection and delivered by ce-sarean section in Guangdong Women and Children Hospital from November 20,2022 to January 25,2023 were selected as the research subjects.They were divided into the early(80 cases),middle(151 cases)and late(99 cases)pregnancy group according to the gestational age of infection.The general information,pregnancy compli-cations and comorbidities,pregnancy outcomes,and postpartum maternal and infant follow-up of each group of pregnant women were compared.Results:The clinical classification of pregnant women was asymptomatic and mild,with 9 cases of asymptomatic and 321 cases of mild.The incidence of gestational diabetes mellitus(GDM)in the early and late group was higher than that in the middle group(P＜0.05).There was no statistically significant difference in the incidence of placental abruption,fetal growth restriction,fetal distress,amniotic fluid contamina-tion,preterm labor,postpartum hemorrhage,macrosomia,low-birth-weight infants and the maternal intensive care unit(MICU)transfer rate,newborn birth weight,neonatal asphyxia rate and NICU transfer rate among the three groups(P＞0.05).The incidence of preterm rupture of membranes in the middle group was higher than that in the late group(P＜0.05).Puerperal follow-up results showed that there was no statistically significant difference in the incidence of poor maternal uterine incision healing,poor uterine involution,vaginal microecological imbal-ance and neonatal acute upper respiratory tract infection,pneumonia,digestive system disease,cardiovascular system disease among the three groups(P＞0.05).Conclusions:The majority of pregnant women with Omicron infection during pregnancy are mild.Omicron infection in different periods of pregnancy has no significant effect on pregnancy outcome and puerperal follow-up of cesarean section.No evidence was found that GDM and prema-ture rupture of membranes are significantly associated with Omicron infection in different periods of pregnancy.

Objective:To investigate the impact of abnormal patterns of 75 g oral glucose tolerance test (OGTT) in the second trimester on the risk of large for gestational age (LGA) newborn deliveries.Methods:General clinical data and OGTT results of 66 290 pregnant women who received regular prenatal care and delivered in Guangdong Maternal and Child Health Hospital from December 24, 2016 to July 26, 2022 were collected. According to the results of OGTT, the pregnant women were divided into 8 groups: normal blood glucose group (normal fasting blood glucose, 1-hour and 2-hour after oral glucose, 54 518 cases), gestational diabetes mellitus (GDM) 0 group (only abnormal fasting blood glucose, 1 430 cases), GDM 1 group (only abnormal blood glucose at 1-hour after oral glucose, 2 150 cases), GDM 2 group (only abnormal blood glucose at 2-hour after oral glucose, 3 736 cases), GDM 0+1 group (both fasting blood glucose and 1-hour after oral glucose were abnormal, 371 cases), GDM 0+2 group (both fasting blood glucose and 2-hour after oral glucose were abnormal, 280 cases), GDM 1+2 group (abnormal blood glucose at 1-hour and 2-hour after oral glucose, 2 981 cases) and GDM 0+1+2 group (abnormal fasting blood glucose, 1-hour and 2-hour after oral glucose, 824 cases). Multivariate logistic regression was used to analyze the effects of different abnormal OGTT patterns on LGA. In addition, the blood glucose measurements at the three time points of OGTT were combined and used as continuous variables in the receiver operating characteristic (ROC) curve to evaluate the predictive value of each blood glucose measurement mode for LGA and the area under the curve (AUC) was compared.Results:(1) Multivariate logistic regression analysis showed that the risks of LGA were significantly increased in GDM 0 group ( OR=1.76, 95% CI: 1.50-2.08; P<0.001), GDM 0+1 group ( OR=2.29, 95% CI: 1.72-3.04; P<0.001), and GDM 0+1+2 group ( OR=1.98, 95% CI: 1.61-2.43; P<0.001). (2) ROC curve analysis showed that fasting blood glucose, 1-hour after oral glucose, 2-hour after oral glucose, fasting+1-hour after oral glucose, fasting+2-hour after oral glucose, 1-hour+2-hour after oral glucose, and fasting+1-hour+2-hour after oral glucose had certain predictive value for LGA (all P<0.001). The AUC of fasting blood glucose measurement was higher than that of 2-hour blood glucose measurement in predicting LGA, and the difference was statistically significant ( P<0.05). There was no significant difference in the AUC between fasting blood glucose and other blood glucose measurement modes for predicting LGA (all P>0.05). Conclusions:In the abnormal OGTT patterns, pregnant women with abnormal fasting blood glucose, abnormal fasting+1-hour after oral glucose, and abnormal fasting+1-hour+2-hour after oral glucose have an increased risk of LGA. Fasting blood glucose measurement is of great significance for the prediction of LGA, and could be used as an optimal indicator to evaluate the risk of LGA in clinical practice.

Objective:To investigate the pregnancy outcome and the maternal and infant follow-up in the puer-peral period(42 days after delivery)of cesarean section with SARS-CoV-2 Omicron variant in different periods of pregnancy.Methods:330 pregnant women who were diagnosed with SARS-CoV-2 infection and delivered by ce-sarean section in Guangdong Women and Children Hospital from November 20,2022 to January 25,2023 were selected as the research subjects.They were divided into the early(80 cases),middle(151 cases)and late(99 cases)pregnancy group according to the gestational age of infection.The general information,pregnancy compli-cations and comorbidities,pregnancy outcomes,and postpartum maternal and infant follow-up of each group of pregnant women were compared.Results:The clinical classification of pregnant women was asymptomatic and mild,with 9 cases of asymptomatic and 321 cases of mild.The incidence of gestational diabetes mellitus(GDM)in the early and late group was higher than that in the middle group(P＜0.05).There was no statistically significant difference in the incidence of placental abruption,fetal growth restriction,fetal distress,amniotic fluid contamina-tion,preterm labor,postpartum hemorrhage,macrosomia,low-birth-weight infants and the maternal intensive care unit(MICU)transfer rate,newborn birth weight,neonatal asphyxia rate and NICU transfer rate among the three groups(P＞0.05).The incidence of preterm rupture of membranes in the middle group was higher than that in the late group(P＜0.05).Puerperal follow-up results showed that there was no statistically significant difference in the incidence of poor maternal uterine incision healing,poor uterine involution,vaginal microecological imbal-ance and neonatal acute upper respiratory tract infection,pneumonia,digestive system disease,cardiovascular system disease among the three groups(P＞0.05).Conclusions:The majority of pregnant women with Omicron infection during pregnancy are mild.Omicron infection in different periods of pregnancy has no significant effect on pregnancy outcome and puerperal follow-up of cesarean section.No evidence was found that GDM and prema-ture rupture of membranes are significantly associated with Omicron infection in different periods of pregnancy.