Optimization of β-carotene production and fermentationparameters of Mortierella ramanniana

Carotenoids are lipid soluble pigments that have yellow to red colour. Also They have conjugated double bond in their backbonds forming tetraterpenes. Carotenoids are vital natural grade dyes that have wide range of areas used in as food, pharmaceutics, cosmetics, feed industry. The undersatnding of having beneficial effects of carotenoids on human and animal health have caused growing attention on carotenoids recently. Most of the carotenoid productions are synthesized chemically but a few of them are synthesized by natural ways as plants. However, the source scarcity results from season, climate, location dependent plant growing leads reseachers to obtain carotenoids from other sources as biotechnologically. Especially last decade, researcher have focused on production of β-carotene and its oxidized derivatives.It can be done that critical factors are determined during optimization study to increase in production rate of β-carotene. Thus, β-carotene production can be produced suffient amount in terms of industrial scale. So the utility of the compound with incresing rate can be involved in food, feed and pharmaceutical areas of industry. In this study, Mortierella ramanniana, one of a members of Mortierellacea family, is used in β-carotene production and optimization of the production is the main topic of this study. Prior to the first stage of optimization, two main compounds found in the medium were assessed. 9 different carbon sources and 6 different nitrogen sources were tried to produce maximum amount of β-carotene. First trial resulted in lactose, maltose and glucose selection as a best source of β-carotene production. After that six nitrogen sources were assayed with these three carbon sources. As a result of these trials lactose was selected as the best carbon source and KNO3 as nitrogen source. In the firt step of optimization Plackett-Burman design was used with 8 factors for optimizing the medium ingredients. Multiple regression and variance analysis of experimental data were assesed after Placket-Burman runs had been done. As a result, It was determined that nitrojen sources KNO3 and yeast extract were statistically important for Mortierella ramanniana while producing β-carotene. In the second stage of optimization, Box-Behnken design was used which is one of the response surface methods. In this step, effects of C:N ratio, lactose concentration and agitation rate on β-caroten production and biomass accumulation were studied. Following the runs proposed by the Box Behnken design were done, the models which are express that the effects of independent variable on responce were acquired. The selected model sufficiency was controlled by checking variance analysis (ANOVA) and multiple regression analysis results. After optimization process, the optimum contition were determined as lactose concentration of 32.42 g/L, C:N 20:1 and agitation rate 130 rpm. Under these conditions, β-carotene production was 1141 μg/L and biomass accumulation was 13.14 g/L. It is stated that β-carotene production was increased two times and biomass accumulation was increased 1.3 times as a compared to the control medium.