Loading...
Research Project
Yeast and Microalgae Symbiotic System for Brewery Wastewater Treatment, Biofuels and Bioproducts
Funder
Authors
Publications
Rhodosporidium toruloides and Tetradesmus obliquus Populations Dynamics in Symbiotic Cultures, Developed in Brewery Wastewater, for Lipid Production
Publication . Dias, Carla; Gouveia, Luisa; Santos, J. A. L.; Reis, Alberto; Silva, Teresa Lopes da
ABSTRACT: In this work, primary brewery wastewater (PBWW) and secondary brewery wastewater (SBWW) separately, or mixed at the ratios of 1:1 (PBWW:SBWW) and 1:7 (PBWW:SBWW), with or without supplementation with sugarcane molasses (SCM), were used as culture media for lipid production by a mixed culture of the oleaginous yeast Rhodosporidium toruloides NCYC 921 and the microalgae Tetradesmus obliquus (ACOI 204/07). Flow cytometry was used to understand the dynamics of the two micro-organisms during the mixed cultures evolution, as well as to evaluate the physiological states of each microorganism, in order to assess the impact of the different brewery effluent media composition on the microbial consortium performance. Both brewery wastewaters (primary and secondary) without supplementation did not allow R. toruloides heterotrophic growth. Nevertheless, all brewery wastewater media, with and without SCM supplementation, allowed the microalgae growth, although the yeast was the dominant population. The maximum total biomass concentration of 2.17 g L-1 was achieved in the PBWW mixed cultivation with 10 g L-1 of SCM. The maximum lipid content (14.86% (w/w DCW)) was obtained for the mixed culture developed on SBWW supplemented with 10 g L-1 of SCM. This work demonstrated the potential of using brewery wastewater supplemented with SCM as a low-cost culture medium to grow R. toruloides and T. obliquus in a mixed culture for brewery wastewater treatment with concomitant lipid production.
Concomitant wastewater treatment with lipid and carotenoid production by the oleaginous yeast Rhodosporidium toruloides grown on brewery effluent enriched with sugarcane molasses and urea
Publication . Dias, Carla; Reis, Alberto; Santos, J. A. L.; Silva, Teresa Lopes da
ABSTRACT: In this study, secondary brewery wastewater (SBWW) supplemented with sugarcane molasses (SCM) was used for SBWW treatment with concomitant lipid and carotenoid production by the yeast Rhodosporidium toruloides NCYC 921. In order to improve the biomass production, ammonium sulfate, yeast extract and urea were tested as nitrogen sources. Urea was chosen as the best low-cost nitrogen source. A fed-batch cultivation was carried out with SBWW supplemented with 10 g L−1 of sugarcane molasses as carbon source, and 2 g L−1 of urea as nitrogen source. A maximum biomass concentration of 42.5 g L−1 was obtained at t=126.5 h and the maximum biomass productivity was 0.55 g L−1 h−1 at t=48.25 h. The maximum lipid content was 29.9 % w/w (DCW) at t=94 h of cultivation and the maximum carotenoid content was 0.23 mg g−1 at 120 h of cultivation. Relatively to the SBWW treatment, after the batch phase, 45.8 % of total Kjeldahl nitrogen removal, 81.7 % of COD removal and 100 % of sugar consumption were observed. Flow cytometry analysis revealed that 27.27 % of the cells had injured membrane after the inoculation. This proportion was reduced to 10.37 % at the end of the cultivation, indicating that cells adapted to the growth conditions.
Impact of brewery wastewater inhibitors in pure and mixed cultures of the yeast Rhodosporidium toruloides NCYC 921 and the microalga Tetradesmus obliquus ACOI 204/07
Publication . Dias, Carla; Santos, J. A. L.; Reis, Alberto; Silva, Teresa Lopes da
ABSTRACT: Brewery wastewater (BWW) is an appealing low-cost substrate for the production of single cell oils by oleaginous microorganisms. However, it may contain inhibitor compounds that may affect the microbial metabolism. This work investigated, for the first time, the presence of potential inhibitor compounds in primary brewery wastewater (PBWW) and secondary brewery wastewater (SBWW) for the pure and mixed cultivation of the yeast Rhodosporidium toruloides NCYC 921 and the microalga Tetradesmus obliquus ACOI 204/07. Three organic acids (OrgAc) were identified in the brewery effluents (acetic, propionic and butyric acids). Yeast and microalga pure and mixed cultivations were performed in PBWW and SBWW in order to understand the behaviour of the microorganisms, individually and together. Flow cytometry (FC) was used to monitor each microbial population during the mixed cultivations, and to study the yeast and microalga cell viability throughout all cultivations. The yeast cells in pure cultures grown in both effluents were severely affected by the OrgAc presence confirmed by the cell stress results obtained by FC. However, in the mixed cultures, the yeast cells were able to develop, and the levels of stress conditions were considerably lower. Only in microalga pure and mixed cultures efficient OrgAc removal was observed.
Lipid and carotenoid production by a Rhodosporidium toruloides and Tetradesmus obliquus mixed culture using primary brewery wastewater supplemented with sugarcane molasses and urea
Publication . Dias, Carla; Nobre, B. P.; Santos, J. A. L.; Reis, Alberto; Silva, Teresa Lopes da
ABSTRACT: In this study, Rhodosporidium toruloides and Tetradesmus obliquus were used for lipid and carotenoid production in mixed cultures using primary brewery wastewater (PBWW) as a culture medium, supplemented with sugarcane molasses (SCM) as a carbon source and urea as a nitrogen source. To improve biomass, lipid, and carotenoid production by R. toruloides and T obliquus mixed cultures, initial SCM concentrations ranging from 10 to 280 g L-1 were tested. The medium that allowed higher lipid content (26.2% w/w dry cell weight (DCW)) and higher carotenoid productivity (10.47 mu g L-1 h(-1)) was the PBWW medium supplemented with 100 g L-1 of SCM and 2 g L-1 of urea, which was further used in the fed-batch mixed cultivation performed in a 7-L bioreactor. A maximum biomass concentration of 58.6 g L-1 and maximum lipid content of 31.2% w/w DCW were obtained in the fed-batch cultivation. PBWW supplemented with SCM was successfully used as a low-cost medium to produce lipids and carotenoids in a R. toruloides and T obliquus mixed culture, with higher productivities than in pure cultures, which can significantly reduce the cost of the biofuels obtained.
Effect of brewery effluent inhibitors on Rhodotorula toruloides NCYC 921 cells grown in pure and mixed cultures at pH 4 and 6
Publication . Dias, Carla; Santos, J. A. L.; Reis, Alberto; Silva, Teresa Lopes da
ABSTRACT: The presence of inhibitor compounds in the culture medium can cause severe effects on the microorganisms cells. Brewery wastewaters present organic acids (acetic, propionic and butyric acids) which can severely affect yeast cells metabolism, when grown in pure cultures, although in mixed cultures they are able to develop. To understand the physiological changes on Rhodotorula toruloides (formerly Rhodosporidium toruloides) cells when fermenting in the presence of the organic acids present in brewery wastewater, pure and mixed cultures with the microalga Tetradesmus obliquus were performed in a synthetic medium containing the same organic acids concentrations that are present in brewery wastewater at pH 4 and 6. It was concluded that, at pH 4, the organic acids effects in the yeast cells were much more toxic than at pH 6. Moreover, mixed cultures can be an advantage over heterotrophic pure cultures as the microalga is able to contribute for the consumption of potential inhibitors for the yeast.
Organizational Units
Description
Keywords
Contributors
Funders
Funding agency
Fundação para a Ciência e a Tecnologia
Funding programme
Funding Award Number
SFRH/BD/117355/2016