Optimization of different process variables for the production of an indolizidine alkaloid, swainsonine from Metarhizium anisopliae

Abstract

Swainsonine is a polyhydroxylated indolizidine alkaloid having anticancer, antimetastatic, antiproliferative and immunomodulatory activities and also potential therapeutic applications against AIDS. In the present study, ten isolates of M. anisopliae were screened and enzyme assayed for the production of swainsonine in different media (Complex oatmeal, Czapekdox media with and without lysine (8% w/v) and Sabouraud dextrose broth (SDB)). Among these strains, ARSEF 1724 (UM8) was found to produce highest amount of swainsonine (1.34 μg/l) after 72 h of incubation under shake flask conditions at 180 rpm and 28 °C in complex oatmeal media. In order to maximize the yield of swainsonine the media composition including macro and micronutrients were optimized. The process variables including the chemical factors like carbon sources, nitrogen sources of both organic and inorganic nature and pH with constant inoculum size (1 × 10(8) spores/ml) were screened using classical one-factor-at-a-time (OFAT) approach to find their optimum levels. The present study shows that the nutrient requirement is specific for each strain of Metarhizium. Oatmeal extract (6%) was found to be the best supporting media along with nitrogen source, glucose (2%) as best carbon source and pH (~5) as the best for swainsonine production.