Optimization of critical medium components for enhancing antibacterial thiopeptide nocathiacin I production with significantly improved quality / 中国天然药物

Nocathiacin I, a glycosylated thiopeptide antibiotic, displays excellent antibacterial activities against multidrug resistant bacterial pathogens. Previously, a novel nocathiacin I formulation for intravenous administration has been successfully developed and its aqueous solubility is greatly enhanced for clinical application. The purpose of the present study was to increase the fermentation titer of nocathiacin I and reduce or eliminate analogous impurities by screening the medium ingredients using response surface methodology. After a sysmatic optimization, a water-soluble medium containing quality-controllable components was developed and validated, resulting in an increase in the production of nocathiacin I from 150 to 405.8 mg·L at 150-L scale. Meanwhile, the analogous impurities existed in reported processes were greatly reduced or eliminated. Using optimized medium for fermentation, nocathiacin I with pharmaceutically acceptable quality was easily obtained with a recovery of 67%. In conclusion, the results from the present study offer a practical and efficient fermentation process for the production of nocathiacin I as a therapeutic agent.

Bioactive Betulin produced by marine Paecilomyces WE3-F.

Objective: Marine fungi play an important role in human and animal health, leading compounds to new drug discoveries and prospects for their bioactivity potential. Materials and Methods: Paecilomyces WE3-F was isolated from marine sediment (Red Sea, Shalateen, Egypt). Fungal isolate was screened for their antagonistic activity against four Gram-positive (Bacillus cereus, Lesteria monocytogenes, Micrococcus luteus and Staphylococcu aureus) and four Gram-negative (Aeromonas hydrophila, Flavobacteruim sp, Pseudomonas aeruginosa and Vibrio cholera,) pathogenic bacteria. Paecilomyces WE3-F was identified using 18S rRNA technology. Seven factors were chosen to be screened for bioactivity using the Placket Burman experimental design: sucrose, yeast extract, Na NO3, temperature, initial pH, inoculum size, and incubation period. Results: Among conditional factors, acidic pH and 1.5 ml inoculum size favored the bioactive metabolites. Furthermore, a number of solvents have been experimented for the extraction of the bioactive metabolite(s). Dichloromethane (DCM) crude extract from the fermentation broth of a marine Paecilomyces WE3-F showed the highest activity with averages of 26 and 24 mm against G-ve and G+ve, respectively. Under optimal culture conditions, the maximum extractable compound concentration in a 10-L culture medium reached 83.4 mg/L. Based on data obtained by thin layer chromatogram (TLC), gas chromatography - mass spectrum (GC-MS) and Fourier Transform Infrared (FTIR) the major compound, betulin was structurally identified. Conclusions: The isolated marine Paecilomyces WE3-F, therefore, showed the ability to produce a betulin yield after optimal operating conditions for antibacterial potential.

Optimization of media composition for D-amino acid oxidase production by Trigonopsis variabilis using biostatistical analysis.

D-amino acid oxidase (DAAO) is biotechnologically relevant enzyme that is used in various food and pharmaceutical industries. DAAO from the yeast Trigonopsis variabilis is an important agent for use in commercial applications because of its high activity with cephalosporin C and is reasonable resistant to the oxidants O2 and H2O2 byproducts of reaction. In this study, response surface methodology (RSM) in shake flask culture was used to enhance the production of DAAO from T. variabilis by optimization of fermentation media composition. The effects of six factors (DL-alanine, glucose, pH, ZnSO4, (NH4)2SO4 and temperature) were evaluated on DAAO production. Results of Placket-Burman design showed that DL-alanine, pH, glucose and ZnSO4 were significant factors for DAAO production (P<0.05). The optimum values of media components as predicted by the central composite design were inducer (DL-alanine) concentration 3 g/L, pH 7.7, glucose 17 g/L and ZnSO4 34 mg/L. At these optimum values of media composition, maximum production of DAAO was 153 U/g yeast dry weight. Two-fold increase in DAAO production was achieved after optimization of the physical parameters by RSM.