Use of response surface methodology to enhance carotenoid pigment production from Cellulosimicrobium strain AZ
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Use of response surface methodology to enhance carotenoid pigment production from Cellulosimicrobium strain AZ Atefeh Salehi Bakhtiyari1 · Zahra Etemadifar1 · Matia Sadat Borhani2 Received: 21 April 2020 / Accepted: 17 September 2020 © Springer Nature Switzerland AG 2020
Abstract In the present study, the response surface methodology based on a rotatable central composite design was applied to optimize the production of the carotenoid pigment using a strain of Cellulosimicrobium that has not been reported so far for this genus. The microbial biomass and pigment production of strain AZ were investigated in the presence of tricarboxylic acid cycle intermediates (citrate, malate, succinate), and glutamate. Besides, the influence of the pH of the fermentation medium was also evaluated. The design consisted of a total of 32 experiments at five levels for each factor. Optimum carotenoid production (28.86 mg/L) was observed in the fermentation medium (pH 8.04) containing citrate (11.18 mM), glutamate (12.48 mM), malate (14.19 mM), and succinate (13.38 mM). It was 1.65-fold more than that of the OFAT method (17.5 mg/L) and 12-fold more than the unoptimized conditions (2.4 mg/L). The results were fitted with a quadratic model that could predict the responses to new observations significantly (pred-R2 = 0.9686). Optimum microbial biomass (10.61 g/L) was observed in the presence of citrate (10.27 mM), glutamate (14.03 mM), malate (13.1 mM), and succinate (10.39 mM) as well as pH 8.36. In contrast to the results of one-factor-at-a-time, the carotenoid production had not a direct relationship with bacterial biomass. The established model could describe the variability of above 99.85% in the response based on the determination coefficient (R2). Keywords Carotenoid · Cellulosimicrobium · Optimization · Response surface methodology · Tricarboxylic acid cycle intermediates
1 Introduction Carotenoids are tetraterpenoid organic pigments that contain yellow, orange, and red colors. Lowering the risk of cancer, cataract, and cardiovascular diseases, as well as improvement of immune system function, are some of the benefits of carotenoids in human health attributed to their antioxidant potential [1]. In addition, carotenoids have vast applications in cosmetics, foods, and animal feeds industries [2].
Carotenoids are produced chemically or naturally by different organisms. However, the production of natural carotenoids by microbial fermentation has attracted more attention in recent years [3]. Various carotenogenic microbes and recombinant non-carotenogenic microbes have been reported for large-scale production of carotenoids [4]. The major advantage of microbial pigments is their cost-effective production [5]. The reason can be attributed to the rapid growth of microorganisms in the low-cost fermentation media that are
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s42452-020-03549-6) contains supplementary material, which is available to authorized users. * Zahra Etemadifar, z
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