Penicillin is historically important as the first discovered drug against bacterial infections in human. Although the penicillin biosyn- thetic pathway and regulatory mechanism have been well studied in Penicillium chrysogenum, the compartmentation and molecular transport of penicillin or its precursors are still poorly understood. In search of the genomic database, more than 830 open reading frames （ORFs） were found to encode transmembrane proteins of P. chrysogenum. In order to investigate their roles on penicillin production, one of them （penT） was selected and cloned. The deduced protein ofpenTbelongs to the major facilitator superfamily （MFS） and contains 12 transmembrane spanning domains （TMS）. During fermentation, the transcription of penT was greatly induced by penicillin precursors phenylacetic acid （PAA） and phenoxyacetic acid （POA）. Knock-down of penT resulted in significant decrease of penicillin production, while over-expression of penT under the promoter of trpC enhanced the penicillin production. Introduction of an additional penT in the wild-type strain of P. chrysogenurn doubled the penicillin production and enhanced the sensitivity of P. chrysogenum to the penicillin precursors PAA or POA. These results indicate that penT stimulates penicillin production probably through enhancing the translocation of penicillin precursors across fungal cellular membrane. Penicillin is historically important as the first discovered drug against bacterial infections in human. Although the penicillin biosyn- thetic pathway and regulatory mechanism have been well studied in Penicillium chrysogenum, the compartmentation and molecular transport of penicillin or its precursors are still poorly understood. In search of the genomic database, more than 830 open reading frames （ORFs） were found to encode transmembrane proteins of P. chrysogenum. In order to investigate their roles on penicillin production, one of them （penT） was selected and cloned. The deduced protein ofpenTbelongs to the
A universal quantitative model was developed to determine the azithromycin content in granules using near infrared （NIR） diffuse reflectance spectroscopy. The diffuse reflection spectra were recorded with the integrating sphere at 8 cm-1 resolution in 4000–12 000 cm-1 spectral range. During each measurement, 32 co-added scans were performed. This quantitative model was constructed with 103 batches of azithromycin granules from 21 different manufacturers. The azithromycin content ranges from 3.0% to 24.5%. The root mean square error of prediction （RMSEP） of model was 0.613. In addition, the quantitative model was evaluated in terms of specificity, linearity, accuracy, and precision according to ICH guidelines. In conclusion, it is feasible to construct a universal quantitative model for azithromycin granules by choosing suitable training set samples and selecting an appropriate wavelength range. The quantitative model could be applied in the quick assay of azithromycin granules produced by domestic manufacturers （content： 3.0%–24.5%）.
L-Serine plays a critical role as a building block for cell growth, and thus it is difficult to achieve the direct fermentation of L-serine from glucose. In this study, Corynebacterium glutamicum ATCC 13032 was engineered de novo by blocking and at- tenuating the conversion of L-serine to pyruvate and glycine, releasing the feedback inhibition by L-serine to 3-phosphoglycerate dehydrogenase （PGDH）, in combination with the co-expression of 3-phosphoglycerate kinase （PGK） and feedback-resistant PGDH （PGDHr）. The resulting strain, SER-8, exhibited a lower specific growth rate and significant differ- ences in L-serine levels from Phase I to Phase V as determined for fed-batch fermentation. The intracellular L-serine pool reached （14.22_＋1.41） ~trnol gcoM-1, which was higher than glycine pool, contrary to fermentation with the wild-type strain. Furthermore, metabolic flux analysis demonstrated that the over-expression of PGK directed the flux of the pentose phosphate pathway （PPP） towards the glycolysis pathway （EMP）, and the expression of PGDHr improved the L-serine biosynthesis pathway. In addition, the flux from L-serine to glycine dropped by 24%, indicating that the deletion of the activator GlyR re- sulted in down-regulation of serine hydroxymethyltransferase （SHMT） expression. Taken together, our findings imply that L-serine pool management is fundamental for sustaining the viability of C. glutamicum, and improvement of C1 units genera- tion by introducing the glycine cleavage system （GCV） to degrade the excessive glycine is a promising target for L-serine pro- duction in C. glutamicum.
LAI ShuJuanZHANG YunLIU ShuWenLIANG YongSHANG XiuLingCHAI XinWEN TingYi
Three new caryophyllene sesquiterpenoids,cytosporinols A-C(1-3),have been isolated from solid cultures of Cytospora sp.The structures of 1-3 were elucidated primarily by NMR spectroscopy,and 3 was further confirmed by X-ray crystallography.The absolute configurations of the C-11 secondary alcohol in 1 and the 6,8-diol moiety in 3 were deduced using the modified Mosher and Snatzke’s method,respectively.Compounds 2 and 3 showed moderate cytotoxicity against HeLa cells.
Yan LIChang-Wei LICheng-Bin CUIXing-Zhong LIUYong-Sheng CHE
The general strategy and method of constructing universal calibration model for levofioxacin injections by near-infrared spectroscopy have been investigated and discussed. Firstly, a constant-temperature homogeneous liquid calibration model for levofloxacin hydrochloride injections with the same composition but different active principal ingredient （API） content was established as the basic unit for universal model. Then, samples of levofloxacin hydrochloride injections containing propylene glycol or levofloxacin lactate injections were added to develop a primary constant-temperature liquid universal model. Temperature- amended final universal model was established to apply to samples under different temperatures. The final model was built from 61 calibration samples and 77 validation samples. The value of the root mean square error of cross validation （RMSECV） and coefficient of determination （r2） of leave-one-out cross-validation （LOOCV） were 0.792 and 0.9993, respectively, the root mean square error of prediction （RMSEP） of test set validation （TSV） was 0.87, and the average relative deviation was 1.44%. According to the ICH guidelines, the universal calibration model was evaluated. Based on the experimental statistical results, the recommended number of calibration samples for a constant-temperature homogeneous liquid quantitative model was no less than 15.
