Carotene production from agro-industrial wastes by Arthrobacter globiformis in shake-flask culture.

Industrial waste substrates, sugarcane molasses, and corn steep liquor were used for production of carotenes by Arthrobacter globiformis in this study. At the first stage, a one-factor-at-a-time approach was used for optimization of different media components such as carbon, nitrogen, MgSO(4) · 7H(2)O, and KH(2)PO(4), as well as pH, temperature, liquid medium volume, and inoculums level. The response surface method was further applied to determination of optimum values of process variables for maximum carotenes concentration. Results showed that the optimum combination for carotenes formation was as follows (g/L): sugarcane molasses, 40.00; corn steep liquor, 50.00; MgSO(4) · 7H(2)O, 0.75; KH(2)PO(4), 1.00. The maximum carotene concentration of 1.19 ± 0.02 mg/g dry biomass, about 113% of 1.05 ± 0.02 mg/g dry biomass growing in basal medium, was demonstrated by confirmatory experiments to be the optimum in liquid medium at 100 rpm, 30°C, initial pH of 7.5, and cultivation for 60 hr. In a second stage, detailed studies showed about 1.64-fold and 1.43-fold increase in carotene concentration (mg/g dry biomass) in the presence of addition of ethanol (4%, v/v) and addition of hydrogen peroxide (4%, v/v) at 40 hr, and 32 hr in liquid medium, separately.