FOOD SCIENCE ›› 2018, Vol. 39 ›› Issue (24): 108-115.doi: 10.7506/spkx1002-6630-201824017

• Bioengineering • Previous Articles     Next Articles

Identification of a Carotenoid-Producing Strain and Optimization of Fermentation Medium

KONG Weibao, YANG Yang, CHEN Dong, WANG Yang, DA Wenyan, NIU Shiquan   

  1. (College of Life Sciences, Northwest Normal University, Lanzhou 730070, China)
  • Online:2018-12-25 Published:2018-12-17

Abstract: A strain K-1 with carotenoid-producing potential was identified using morphological, physiological, biochemical tests and rDNA-ITS sequence analysis. A colorimetric method was used to determine mycelial growth and the stability of carotenoids produced by this strain. The fermentation conditions of strain K-1 were optimized by one-factor-at-a-time and orthogonal array design methods. The results indicated that K-1 was identified as Rhodotorula mucilaginosa. The optimum temperature for growth of the strain was 30 ℃, and it could be grown well in the initial pH range from 2 to 7. The characteristic absorption peak indicated that the acetone extract of cultured cells of K-1 contained torulene. The carotenoids produced by K-1 had good stability, but the stability was decreased under the conditions of high temperature (> 60 ℃), intense light and oxidant H2O2. The optimum fermentation conditions were determined as follows: glucose 20 g/L, (NH4)2SO4 20 g/L, anhydrous CaCl2 2 g/L, trisodium citrate 5 g/L, temperature 30 ℃, inoculum size 10%, shaking speed 150 r/min, medium volume 50 mL/250 mL, initial pH 5.5, and time 5 d. The yield of carotenoids on a dry mycelial mass basis was (180.14 ± 2.45) μg/g under the optimum culture conditions. Strain K-1 has the potential to produce a high yield of carotenoids, and the pigment produced by it has good stability. This strain represents a new microbial resource for carotenoids production.

Key words: carotenoids, Rhodotorula mucilaginosa, identification, pigment stability, fermentation process

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