PRODUCTION OF CAROTENOIDS BY

Size: px

Start display at page:

Download "PRODUCTION OF CAROTENOIDS BY"

Kimberly Pitts
6 years ago
Views:

PRODUCTION OF CAROTENOIDS BY Dunaliella tertiolecta USING CO 2 FROM ETHANOL FERMENTATION Chagas, A. L.¹, Rios, A.O. ¹, Jarenkow, A. ², Marcílio, N. R. ², Ayub, M. A. Z. ¹, Rech, R¹.

1 PRODUCTION OF CAROTENOIDS BY Dunaliella tertiolecta USING CO 2 FROM ETHANOL FERMENTATION Chagas, A. L.¹, Rios, A.O. ¹, Jarenkow, A. ², Marcílio, N. R. ², Ayub, M. A. Z. ¹, Rech, R¹. ¹ Food Science & Technology Institute, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil ( arteddie7@gmail.com; alessandro.rios@ufrgs.br; mazauyb@ufrgs.br; rrech@ufrgs.br) ² Chemical Engineering Department, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil ( andre.jarenkow@gmail.com; nilson@enq.ufrgs.br)

2 PRODUCTION OF CAROTENOIDS BY Dunaliella tertiolecta USING CO 2 FROM ETHANOL FERMENTATION Chagas, A. L.¹, Rios, A.O. ¹, Jarenkow, A. ², Marcílio, N. R. ², Ayub, M. A. Z. ¹, Rech, R¹. ¹ Food Science & Technology Institute, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil ( arteddie7@gmail.com; alessandro.rios@ufrgs.br; mazauyb@ufrgs.br; rrech@ufrgs.br) ² Chemical Engineering Department, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil ( andre.jarenkow@gmail.com; nilson@enq.ufrgs.br) ABSTRACT In this study, we evaluated the effect of growing Dunaliella tertiolecta microalgae using CO 2 from ethanol fermentation. An integrated system of microalgae photobioreactors and yeast fermenters was used, thus providing biological CO 2 continuously to the microalgae culture. Yeast cultures were carried out in fermenters using synthetic medium. The highest values obtained for microalgae cultures when using CO 2 from ethanol fermentation were 1.35 g L -1 of biomass, 0.22 g L -1 d -1 of biomass productivity, 0.39 d -1 specific growth rate, and 5.29 mg g -1 of total carotenoid content. These values are almost twice as high as the values observed for control cultivations where atmospheric CO 2 was used, showing that the integration system of yeast fermenters and microalgae photobioreactors is an interesting alternative to improve biomass formation. KEYWORDS Dunaliella tertiolecta; photobioreactors; carotenoids; carbon dioxide; biological CO 2 INTRODUCTION Carbon capture and storage technologies have been developed to reduce the CO 2 concentration in the atmosphere, but these techniques usually require the use of chemicals and high energy costs, and the captured CO 2 needs to be stored to prevent its return to atmosphere [1]. In this context, the use of microalgae to biofixation of CO 2 appears as an environmentally effective alternative to reduce this gas in the atmosphere through photochemical reactions. Microalgae biomass is rich in carbohydrates, lipids, and natural carotenoids, such as β-carotene and lutein [2]. The advantage integrated systems of photobioreactors and yeast fermenters is the reduction of costs by using the high purity CO 2 from the fermentation, eliminating the need for gas storage and processing [3]. Integrated systems using the CO 2 -enriched gas exit of aerobic cultures to aerate autotrophic microalgae cultures were successfully tested recently [4-6], and CO 2 from bioethanol produced from sugarcane fermentation was used for the continuous cultivation of Arthrospira platensis [7-9]. In this context, the aim of this research was to develop an integrated system in order to collect the CO 2 ethanol fermentation in microalgae photobioreactors (PBRs) to produce microalgae biomass. MATERIALS AND METHODS The marine microalgae Dunaliella tertiolecta BE 003 was obtained from the culture collection of the Department of Marine Biology, UFF (Niterói, Rio de Janeiro, Brazil). The microalgae cultures were performed using modified f/2 medium [10]. During the cultivations, 1 ml L -1 of phosphate solution and 1 ml L -1 of trace metals solution were daily added to the photobioreactors (PBR).

3 The yeast used in the fermentations was the commercial Saccharomyces cerevisiae CAT-1 strain obtained from the BiotecLab culture collection (Food Science & Technology Institute, UFRGS). The fermentations were performed using modified YPD medium containing 10 g L -1 of yeast extract, 20 g L -1 of bacteriological peptone, and different glucose concentrations (10 g L -1, 20 g L -1, 30 g L -1, 40 g L -1, 50 g L -1 or 60 g L -1 ). The yeast fermentations were performed in jacketed Duran bottles (2.0 L working volume), at 28 C, homogenized by a magnetic stirrer. Microalgae was cultured in flat-panel airlift PBRs filled with 2.4 L working volume [11]. PBRs were illuminated at the riser side at 18.0 klx, using a panel of electronic lamps (12 13 W cool light). The temperature was kept at 28 C, and airflow rate at 1 L min -1 of filtered compressed air (0.22 µm). The fermenters gas exits were connected to the PBRs, so the CO 2 produced by fermentations was bubbled into the bottom of the PBRs. Each fermenter remained connected for 24 h to the PBR. A control culture without CO 2 injection was always performed along with the assays. Glucose and ethanol concentrations were determined by HPLC [12]. Biomass was measured by optical density at 750 nm and correlated with dry cell weight. The ph was measured using a ph indicator strip and the light intensity was monitored using digital light meter. Daily samples of the PBRs were collected and centrifuged (16,000 g; 5 min), the supernatant and the pellet were stored separately (-18 C). Nitrate concentration was determined in the supernatant according to Cataldo et al [13]. The total carotenoid content was determined spectrophotometrically by extracting cell pellets with acetone [14]. Table 1: Integrated system between ethanol fermentation and photobioreactor. Time start and glucose concentration of the YPD culture medium. Time of PBR Glucose concentration of yeast culture (g L -1 ) culture (h) YPD 30 /72 YPD 60/72 YPD 30/24 YPD (10-60)/24 24 h g L g L h g L g L h 30 g L g L g L g L h 30 g L g L g L g L h 30 g L g L g L g L h 30 g L g L g L g L -1 RESULTS AND DISCUSSION In all microalgae cultures enriched with CO 2 from YPD fermentation (Figure 2), higher biomasses, carotenoids concentration, and faster nitrogen consumption were observed in relation to the controls (Figure 1). Initially, the integration between PBRs and YPD fermentation was started after 72 h of microalgae cultivation, allowing time to increase the microalgae biomass capable of fixing the incoming CO 2 (Figure 2 YPD 30/72 and YPD 60/72). The ph of CO 2 -enriched cultures oscillated between 7.0 and 9.0. In the control cultivation, however, the ph tended to alkalinize the medium, starting at 8.0 and stabilizing at 9.0 after 72 h of cultivation. As the ph of CO 2 - enriched cultures did not fall below 7.0, new integrated cultures were performed starting the yeast fermentation at the 24 h point of the microalgae cultivation (Figure 2 YPD 30/24 and YPD (10-60)/24). The ph of these microalga cultures fell to 6.5 after the two first yeast bioreactors were coupled to the PBRs (24 h and 48 h), indicating an excess of CO 2 production by yeast compared to CO 2 uptake by microalgae.

4 Figure 1: Kinetics of control cultivations of Dunaliella tertiolecta in photobioreactors without the addition of CO 2 from yeast fermentations. Figure 2: Cultivation of Dunaliella tertiolecta in photobioreactor enriched with CO 2 from YPD 30/72, YPD 60/72, YPD 30/24 and YPD (10-60)/24 cultures. The arrows indicate the time at which the fermenters were coupled to the photobioreactors. In the integrated systems, nitrogen was consumed faster when compared to the control culture, matching the increased availability of carbon source and biomass production. The carotenoid content of the biomass increased until nitrogen depletion. At the beginning of the cultivation, the cell concentration was low and the light fully penetrated the culture, enabling photosynthesis. As biomass concentration increased, the cells started shading each other, hence carotenoid production increased to maintain high cellular light uptake. After nitrogen depletion, carotenoid mass fraction tended to stabilize, or even decrease, whereas biomass concentration continued to increase, possibly by synthesizing lipids and carbohydrates, reaching its

5 highest concentration between 144 h and 168 h of cultivation. The highest biomass concentration and carotenoid content were, respectively, 1.35 g L -1 and 5.29 mg g -1 in YPD (10-60)/24 culture. In this culture, the CO 2 was added gradually, in parallel with the glucose concentration in YPD medium, which increased by 10 g L -1 every 24 h. CONCLUSIONS The integrated culture system between yeast fermentation and microalgae photobioreactors proved to be an interesting and environmentally-attractive process, because the CO 2 released during ethanol production is recycled by the microalgae, increasing their biomass and carotenoid content. The CO 2 profile offered to the PBRs affected the culture ph, with CO 2 excess, mainly at the beginning of microalgae culture, causing ph to drop, negatively affecting the specific growth rate of the microalgae biomass. However, adequate CO 2 -enrichment earlier in the PBRs allowed for higher carotenoids contents in the biomass. ACKNOLEDGMENTS The authors wish to thank CNPq, FAPERGS, and CAPES (Brazil) for their financial support and scholarships for this project. REFERENCES Bilanovic D, Andargatchew A, Kroeger T, Shelef G. Freshwater and marine microalgae sequestering of CO2 at different C and N concentrations Response surface methodology analysis. Energy Conversion and Management 2009;50:262. Dewapriya P, Kim S-k. Marine microorganisms: An emerging avenue in modern nutraceuticals and functional foods. Food Research International 2014;56:115. Molina Grima E, Belarbi EH, Acién Fernández FG, Robles Medina A, Chisti Y. Recovery of microalgal biomass and metabolites: process options and economics. Biotechnology Advances 2003;20:491. Puangbut M, Leesing R. Integrated Cultivation Technique for Microbial Lipid Production by Photosynthetic Microalgae and Locally Oleaginous Yeast. 2012;6:1169. Santos CA, Ferreira ME, da Silva TL, Gouveia L, Novais JM, Reis A. A symbiotic gas exchange between bioreactors enhances microalgal biomass and lipid productivities: taking advantage of complementary nutritional modes. Journal of Industrial Microbiology & Biotechnology 2011;38:909. Santos CA, Caldeira ML, Lopes da Silva T, Novais JM, Reis A. Enhanced lipidic algae biomass production using gas transfer from a fermentative Rhodosporidium toruloides culture to an autotrophic Chlorella protothecoides culture. Bioresource Technology 2013;138:48. Matsudo MC, Bezerra RP, Converti A, Sato S, Carvalho JCM. CO2 from Alcoholic Fermentation for Continuous Cultivation of Arthrospira (Spirulina) platensis in Tubular Photobioreactor Using Urea as Nitrogen Source. Biotechnology Progress 2011;27:650. Bezerra RP, Matsudo MC, Sato S, Converti A, Carvalho JCM. Fed-Batch Cultivation of Arthrospira platensis Using Carbon Dioxide from Alcoholic Fermentation and Urea as Carbon and Nitrogen Sources. BioEnergy Research 2013;6:1118. Ferreira LS, Rodrigues MS, Converti A, Sato S, Carvalho JCM. Arthrospira (Spirulina) platensis cultivation in tubular photobioreactor: Use of no-cost CO2 from ethanol fermentation. Applied Energy 2012;92:379. DA FRÉ NC. et al. Influência da Temperatura e da Salinidade no Cultivo da Microalga Dunaliella tertiolecta em Fotobiorreator Airlift. X Oktoberfórum Kochem LH, Da Fré NC, Redaelli C, Rech R, Marcílio NR. Characterization of a Novel Flat-Panel Airlift Photobioreactor With an Internal Heat Exchanger. Chemical Engineering & Technology 2014;37:59. Gabardo S, Rech R, Rosa CA, Ayub MAZ. Dynamics of ethanol production from whey and whey permeate by immobilized strains of Kluyveromyces marxianus in batch and continuous bioreactors. Renewable Energy 2014;69:89. Cataldo DA, Maroon M, Schrader LE, Youngs VL. Rapid colorimetric determination of nitrate in plant tissue by nitration of salicylic acid 1. Communications in Soil Science and Plant Analysis 1975;6:71.

6 Lichtenthaler HK, Buschmann C. Chlorophylls and Carotenoids: Measurement and Characterization by UV-VIS Spectroscopy. Current Protocols in Food Analytical Chemistry: John Wiley & Sons, Inc.; 2001.

EFFECT OF TEMPERATURE AND SALT CONCENTRATION ON GROWTH, LIPID AND CAROTENOID PRODUCTION BY

EFFECT OF TEMPERATURE AND SALT CONCENTRATION ON GROWTH, LIPID AND CAROTENOID PRODUCTION BY Chlorella minutissima Cristiane Redaelli 1,2, Rosane Rech 1, Alessandro O. Rios 1 and Nilson R. Marcilio 2 1 Food