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Differential synthesis of secondary metabolites by Streptomyces chrestomyceticus strain ADP4 in response to modulation in nitrogen source and its anti- Candida activity
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1  Department of Biological Sciences and Engineering, Netaji Subhas University of Technology, Dwarka, New Delhi 110078, India


Streptomyces spp. are known producer of therapeutically important secondary metabolites with diversity in structure and function. Optimization of different bioprocess parameters towards the improved productivity and activity profile is always considered to be of high significance. Peptone is an acclaimed source of nutrients that had been studied for its effect on the bioactivity of metabolites produced during media development. In the present communication we report remarkable variation on the profile and anti-Candida activity of metabolites produced by Streptomyces chrestomyceticus strain ADP4 in response to variation in the source of peptone. It was found that peptone procured from different manufactures (Himedia, CDH and Diffco) have shown noteworthy variation when used as a component of Sabouraud Dextrose Broth (SDB). The zone of inhibition, values of minimum inhibitory concentration (MIC90) against C. krusei and yield of the metabolites varied significantly when the metabolites were produced in SDB medium using peptones from above mentioned sources. CDH-peptone was found to be the best for anti-Candida activity with highest zone of inhibition of 38 ± 2.0 mm and MIC90 value of 2.877± 0.22 µg/mL against C. krusei ATCC 6258. Activity against C. albicans ATCC 10231, C. tropicalis ATCC 750, C. parapsilosis ATCC 90028 and C. auris CBS 12372 was also better as compared to the activities obtained using other peptones. The yield of the metabolite extract was noted to be twice in CDH-peptone as compared to those from HiMedia and Diffco when grown under same conditions like pH, temperature and carbon source. Analyses of the metabolites by using TLC and HPLC demonstrated a clear and significant difference in the metabolite-profile of S. chrestomyceticus strain ADP4. Since peptone is a major nitrogen source, it may be inferred that nitrogen source may play a critical role in regulation of biosynthetic gene clusters associated with synthesis of anti-Candida compounds.

Keywords: Streptomyces spp., anti-Candida, Minimum Inhibitory concentration, Peptone, Secondary Metabolites