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

Objective To observe the effect of pigplacenta ins tead of Ziheche (P lacenta Hominis) for the treatment of senile dementia. Methods Seventy Kunming mice were divided into blank group, model group, pos itive control group, Zih eche low and high dosage groups, and pigplacenta low and high dosage grou ps, wi th 10 in each. The senile dementia models were established with the D-Galactose subcutaneous injection. The blank group was not administered any medicines. The model group was prescribed normal saline instead of the tested medicine; the pos itive control group was given Naofukang by gavage; the Zih eche low and high dosage groups were given 2g/kg and 4g/kg Ziheche respectivel y by gavage; while the pigplacenta low and high dosage groups were treated wi th p igplacenta 4g/kg and 8g/kg respectively by gavage. After treatment for 6 week s, the behavior experimental dark-avoiding test and step-down test were applied to test the effect of the medicines on the learning memory of mice, and acetylchol inesterase and monoamine levels in brain tissues. Results There was no s ignificant difference between the effect of pigplacenta and Ziheche in resi stin g senile dementia. In the latency of dark-avoiding test, the effect of high d osa ge of pigplacenta was significantly better than that of Ziheche (P