Maryam Azizi - Faculty of Life Sciences, Islamic Azad University, North Tehran Branch,Tehran
Davood Zare - Department of Biotechnology, Iranian Research Organization for Science and Technology, Tehran, P. O. Box ۳۳۵۳-۵۱۱۱, Iran.
Abbas Akhavan Sepahy - Department of Microbiology, North Tehran Branch of Islamic Azad University, ۱۶۶۷۹۳۴۷۹۱ Tehran, Iran
Mehrdad Azin - Department of Biotechnology, Iranian Research Organization for Science and Technology, Tehran, P. O. Box ۳۳۵۳-۵۱۱۱, Iran.

Abstractβ-carotene is a lipophilic pigment that belongs to the carotenoid family and is the most widely utilized carotenoid in the industry which is produced by plants and microorganisms as a secondary metabolite. Blakeslea trispora is one of the most significant industrial sources of β-carotene production among microorganisms. The present study aims to investigate the effect of K. rhizophila as microbial stimulant and butylated hydroxytoluene (BHT) as oxidative stress on increasing β-carotene production in B.trispora. B. trispora was cultivated in the production medium with and without butylated hydroxytoluene (BHT), and after ۲۴ hours ۱۰ % K. rhizophila cultures with ۱۰۱۱ CFU/mL was added in each medium and incubated for another ۴ days. The percentage of carotenoid isomers produced in each sample was determined using high-performance liquid chromatography (HPLC). K. rhizophila and BHT, each alone, could increase the carotenoid production by ۲.۳ and ۲.۴ times (respectively) compared to the control. The maximum concentration of carotenoids (۷۹۳ mg/L) was found in samples containing both BHT and K.rhizophila, representing a ۷.۵-time increase over the control sample. HPLC analysis of carotenoids showed two main peaks including β-carotene and γ-carotene. The main carotenoid was β-carotene found in all samples, followed by a lesser amount of γ-carotene. Overall, microbial stimulant and oxidative stress were effective strategies for increasing β-carotene production in this microorganism.

β -carotene, microbial stimulant, Oxidative stress, butylated hydroxytoluene, K.rhizophila, B.trispora