Cephalosporins are widely used antibiotics owing to their broad activity spectra and low toxicity. Many of these medically important compounds are made chemically from 7-aminodeacetoxycephalosporanic acid. At present, this intermediate is made by synthetic ring-expansion of the inexpensive penicillin G to form G-7-ADCA, followed by enzymatic removal of the side chain to obtain 7-ADCA. The chemical synthetic process is expensive, complicated and environmentally unfriendly. Environmentally compatible enzymatic process is favorable compared with chemical synthesis. In our previous research, metabolic engineered Escherichia coli strain (H7/PG15) was constructed and used as whole-cell biocatalyst for the production of G-7-ADC with penicillin G as substrate. The whole-cell biocatalysis was studied by single factor experiment, including the composition of substrates and the conversion conditions (OD600, pH, concentration of penicillin G, MOPS, glucose, time and FeSO4). After optimization, 15 mmol/L of G-7-ADCA was obtained. The process is convenient, efficient and economic. This work would facilitate the industrial manufacturing and further product research.
Anti-Bacterial Agents ; biosynthesis ; Biocatalysis ; Cephalosporins ; biosynthesis ; Escherichia coli ; metabolism ; Metabolic Engineering

s] Objective To analyze the diagnostic value of combined detection of sFIt-1, PLGF and Survivin in early onset preeclampsia. Methods From January 2017 to January 2018, 100 patients with early-onset PE were selected as observation group and 100 healthy pregnant women as control group in Tangshan Maternal and Child health Hospital Gynecology and Obstetrics. The expression levels of sFIt-1, PLGF and Survivin in serum were detected by enzyme-linked immunosorbent assay (ELISA), and the diagnostic value of each index was analyzed separately and jointly. Results The levels of sFIt-1 in the observation group were significantly higher than those in the control group: (36.58 ± 18.34) μg/L vs. (28.43 ± 3.28) μg/L (P<0.05), and the levels of PLGF and Survivin in the observation group were significantly lower than those in the control group: (213.18 ± 48.23) ng/L vs. (398.17 ± 41.19) ng/L, (0.72 ± 0.29) μg/L vs. (1.43 ± 0.32) μg/L (P<0.05); 103 cases of positive sFIt-1, 108 cases of positive PLGF, 107 cases of positive Survivin, 121 cases of positive parallel combined diagnosis and 121 cases of positive series combined diagnosis were found. The sensitivity and negative predictive value of parallel combined diagnosis were significantly higher than those of individualized diagnosis (P<0.05), and the specificity and positive predictive value of series combined diagnosis were significantly higher than those of individualized diagnosis (P < 0.05). Conclusions The combined detection of sFIt-1, PLGF and Survivin in serum can effectively improve the diagnostic accuracy of early-onset preeclampsia and has high clinical value.