Rhodotorula mucilaginosa C2.5t1 Modulates Carotenoid Content and CAR Genes Transcript Levels to Counteract the Pro-Oxidant Effect of Hydrogen Peroxide.

Sara Landolfo,Ilaria Mannazzu,Rossella Chessa,Giacomo Zara,Severino Zara,Marilena Budroni

doi:10.3390/microorganisms7090316

Sara Landolfo, Ilaria Mannazzu + Show 4 more

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https://doi.org/10.3390/microorganisms7090316

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Journal: Microorganisms	Publication Date: Sep 4, 2019
Citations: 10	License type: CC BY 4.0

Affiliation: University of Sassari

Abstract

In order to contribute to the elucidation of the biological role of carotenoids, the cellular response to hydrogen peroxide was analyzed in the red yeast R. mucilaginosa. For that, the wild strain C2.5t1, that produces β-carotene, torulene, and torularhodin, and the albino mutant 200A6 that is incapable of producing detectable amounts of these carotenoids, were grown in the presence of increasing concentrations of hydrogen peroxide. In spite of the difference in carotenoid content, the two strains presented comparable resistance to the pro-oxidant that showed a minimum inhibitory concentration of 6 mM. When subject to 1 h treatment with 16 mM hydrogen peroxide the two strains increased catalase but not superoxide activity, suggesting that catalase plays a major role in cell protection in both the wild strain and the albino mutant. Moreover, C2.5t1 reduced its carotenoid content by about 40% upon hydrogen peroxide treatment. This reduction in carotenoids was in agreement with a significant decrease of the transcript levels of genes involved in carotenoid biosynthesis. Since an excess of β-carotene may enhance reactive oxygen species toxicity, these results suggest that C2.5t1 modulates carotenoid content to counteract the pro-oxidant effect of hydrogen peroxide.

Highlights

Carotenoids are the most common class of pigments occurring in nature
Since an excess of β-carotene may enhance reactive oxygen species toxicity, these results suggest that C2.5t1 modulates carotenoid content to counteract the pro-oxidant effect of hydrogen peroxide
Oxidative stress induced by hydroxytoluene butylate [10] and hydrogen peroxide [11] increases the production of β-carotene in red yeasts, and the inhibition of carotenoid biosynthesis determines an increase in antioxidant enzymes activity in Rhodotorula mucilaginosa [12]

Summary

Introduction

Carotenoids are the most common class of pigments occurring in nature. They constitute a group of more than 750 molecules responsible for the color of vegetables, microorganisms, and animals. Carotenoids are precursors of vitamin A [1] and different hormones [2], and show immunostimulating [3], photoprotective [2,4] and putative antitumor activities [5]. They contribute to the pool of low molecular weight non-enzymatic compounds that detoxify oxidizing species, and display antioxidant properties [1,6,7]. Β-carotene and other carotenoids induce ROS production, depolarize mitochondrial membrane in a dose dependent manner [15], and cause membrane stress [16]. Above a certain concentration, may become toxic for the cell and the induction of multidrug transporters may be necessary for the secretion of β-carotene [17]

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