Abstract:

The optimal fermentation conditions of recombinant Diasporangium sp. strain D-A1 for Se accumulation in its mycelia were investigated in this study. First, single factor experiments were conducted for exploring the effects of various factors including kinds of carbon source and nitrogen source, carbon source concentration, culture temperature, shaking speed, pH, inoculation amount and culture medium volume poured into 250 ml flask on selenium accumulation in D-A1 mycelia. Subsequently, the most important affecting factors such as kinds of carbon source and nitrogen source, culture temperature and shaking speed were optimized using orthogonal array design. Results showed that after fermentation at 18 with a shaking speed of 120 r/min in a culture medium consisting of 100 g/L maltose and 10 g/L yeast extract with an initial concentration of sodium selenite of 90 g/ml, D-A1 mycelia exhibited a Se content of 3266.79 g/g dry weight and a percentage of organic Se accounting for total Se of 85.08%. Compared with non-Se-enriched mycelia, Se-enriched mycelia had higher unsaturated fatty acids content with 1.20, 1.24 and 1.71-fold enhancements for linoleic acid, arachidonic acid and EPA, respectively.

Key words: Diasporangium sp., Seaccumulation, organic Se, polyunsaturated fatty acids