Actinomycetes scale-up for the production of the antibacterial, nocathiacin

Optimization of critical medium components for enhancing antibacterial thiopeptide nocathiacin I production with significantly improved quality

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^-1 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.

Biologically active secondary metabolites from Actinomycetes

Secondary metabolites obtained from Actinomycetales provide a potential source of many novel compounds with antibacterial, antitumour, antifungal, antiviral, antiparasitic and other properties. The majority of these compounds are widely used as medicines for combating multidrug-resistant Gram-positive and Gram-negative bacterial strains. Members of the genus Streptomyces are profile producers of previously-known secondary metabolites. Actinomycetes have been isolated from terrestrial soils, from the rhizospheres of plant roots, and recently from marine sediments. This review demonstrates the diversity of secondary metabolites produced by actinomycete strains with respect to their chemical structure, biological activity and origin. On the basis of this diversity, this review concludes that the discovery of new bioactive compounds will continue to pose a great challenge for scientists.

Novel Pyridinium compound from marine actinomycete, Amycolatopsis alba var. nov. DVR D4 showing antimicrobial and cytotoxic activities in vitro

Marine sediment samples from Visakhapatnam coast of Bay of Bengal, India, were investigated as a source of actinomycetes to screen for the production of antibiotics and cytotoxic compounds. Actinomycete strain DVR D4 with interesting bioactivity profile was isolated during our systematic study of marine actinomycetes. Based on biochemical properties and 16S rDNA analysis the isolate DVR D4 was identified as a strain of Amycolatopsis alba. A solvent extraction followed by a chromatographic purification helped to isolate a cytotoxic compound, which was identified as 1(10-aminodecyl) Pyridinium salt antibiotic, on the basis of spectral data. The compound showed potent cytotoxic activity against cancer cell lines of cervix (HeLa), breast (MCF-7) and brain (U87MG) in vitro and also exhibited antibacterial activities against Gram-positive and Gram-negative bacteria.