L design and style, model construction, model validation and approach optimization [16-19]. As it is unknown no matter whether the conditions made use of for adaptive evolution are optimal for lutein production in D. salina HI 001. Using the aid of RSM, we have set out to study the robustness and flexibility of adaptive evolution for optimizing lutein production in D. salina at the same time as cell adaptability beneath varied environmental stimuli. The framework on the study design and style is shown schematically in Figure 1.ResultsResponse surface experimental designNitrogen availability (as indicated by the amount of KNO3 within the medium), osmotic strain (as indicated by the NaCl level in the medium) and light top quality (as indicated by the percentage of the blue LEDs of your total LEDs), had been selected as three components influencing Dunaliella development and associated pigment accumulation. These components had been utilized as experimental variables in a Box ehnken form experimental design and style [20] and the software Style Expert (Stat-Ease Inc., Minneapolis, U.S.A.) was employed to analyze the data. A fixed photon flux of 170 E/m2/s was supplied towards the PBRs in each of the RSM experiments along with the center point from the design was selected as 1.5 M NaCl, 31.two mM KNO3 and 25 blue LEDs. The NaCl concentration was based on preceding studies [21,22]. A KNO3 concentration of 31.two mM was previously located to support biomass capacity of five gDCW/L [7], and 25 blue LEDs was adopted from our prior study [7]. These development conditions were previously applied to D. salina HI 001 for enhancing growth and carotenoid accumulation by means of adaptive evolution [7]. Facts of your experimental design and style, like both coded and actual values from the variables are offered in Table 1.848821-76-1 Formula Effects of abiotic stressors on growth and lutein productionThe final results of the experiments are shown in Tables two and Further file 1: Table S1. Clear differences in biomass and lutein productivities as well as chlorophylls and lutein content material in cells were observed among the diverse development conditions.1256355-53-9 site Additionally, lutein accumulation was in very good agreement together with the chlorophyll a and chlorophyll b content in D.PMID:24982871 salina (Figure 2). These outcomes recommended that lutein accumulation in D. salina was regulated in the identical manner as chlorophyll synthesis [7]. The correlation in between lutein productivity and biomass productivity further confirmed that lutein was a growth-coupled primary metabolite (More file 1: Figure S2).Fu et al. Microbial Cell Factories 2014, 13:three http://microbialcellfactories/content/13/1/Page three ofFigure 1 A schematic style with the study for the optimization of lutein production in D. salina.The following quadratic model was obtained just after averaging the triplicate measurements (resulting in 15 information points out there for model estimation).Table 1 Coded and actual values of variables in experiments of Box ehnken designExperiment number 1 two 3 4 five 6 7 8 9 10 11 12 13 14aY ??:9112 ?0:0639X 1 ?0:0676X two ?4:5330X 3 ?0:000087X 1 XbCoded and actual values of variables X1 ( ) 0 (-1) 50 (1) 0 (-1) 50 (1) 0 (-1) 50 (1) 0 (-1) 50 (1) 25 (0) 25 (0) 25 (0) 25 (0) 25 (0) 25 (0) 25 (0) X2 (mM) 0.two (-1) 0.2 (-1) 62.two (1) 62.two (1) 31.2 (0) 31.2 (0) 31.2 (0) 31.2 (0) 0.2 (-1) 62.two (1) 0.two (-1) 62.2 (1) 31.2 (0) 31.2 (0) 31.2 (0)a?:0048X 1 X three ?:0065X two X three ?:0012X 1 2 ?:0011X 2 two ?:3682X 3X3 (M) 1.five (0) 1.5 (0) 1.5 (0) 1.5 (0) 0.five (-1) 0.5 (-1) 2.five (1) 2.five (1) 0.5 (-1) 0.five (-1) two.five (1) 2.five (1) 1.5 (0) 1.5 (0) 1.five (0)??where Y could be the daily lutein productivity (mg/L/day).