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

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.info:eu-repo/semantics/publishedVersio

The Use of Oleaginous Yeasts and Microalgae Grown in Brewery Wastewater for Lipid Production and Nutrient Removal: A Review

ABSTRACT: Brewery wastewater has been proposed as an attractive low-cost substrate for microbial lipid production for oleaginous yeast and microalga with promising results. For each liter of beer produced, from 3 to 10 L of wastewater are generated which can be used as culture medium for autotrophic or heterotrophic metabolism. This strategy allows reducing the culture medium cost, as well as obtaining high lipid contents and other high value compounds which can make the process profitable. Additionally, the use of industrial effluents/wastes as substrates for microbial growth can be a strategy to treat them based on the circular economy rules. This review presents the different brewery wastewater treatment strategies using oleaginous yeast and microalga pure and mixed cultures for the concomitant wastewater treatment and lipids/carotenoids production so far reported, highlighting the benefits/disadvantages of such strategies and comparing their performance in terms of wastewater treatment, lipids and carotenoids production between pure and mixed cultures performance.info:eu-repo/semantics/publishedVersio

Concomitant wastewater treatment with lipid and carotenoid production by the oleaginous yeast Rhodosporidium toruloides grown on brewery effluent enriched with sugarcane molasses and urea

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.info:eu-repo/semantics/publishedVersio

Effect of brewery effluent inhibitors on Rhodotorula toruloides NCYC 921 cells grown in pure and mixed cultures at pH 4 and 6

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.info:eu-repo/semantics/publishedVersio

Mutual diffusivity in n-Heptane + n-Hexane isomers

A preliminary study of the effect of branching in the binary diffusion of hexane isomer + n-heptane systems is presented. Measurements have been performed with an instrument modeled for the Taylor dispersion technique, at several compositions, at 297 K, for the n-hexane + n-heptane and 2,2-dimethylbutane + n-heptane binary mixtures. The accuracy is estimated to be 1%. The influence of branching is discussed. It was found that the rough hard sphere model for binary diffusion can reproduce the experimental data within 6%. This model was used to predict the binary diffusion coefficients in the 2-methylpentane + n-heptane and 3-methylpentane + n-heptane mixtures, with an estimated accuracy of 5%

Rhodosporidium toruloides and Tetradesmus obliquus populations dynamics in symbiotic cultures, developed in brewery wastewater, for lipid production

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.info:eu-repo/semantics/publishedVersio

In vitro tests of suitability of bacteriocin-producing lactic acid bacteria, as potential biopreservation cultures in vacuum-packaged cold-smoked salmon

The objectives of this study were to ascertain the in vitro potential of nine bacteriocin-producing lactic acid bacteria (LAB) strains, isolated from vacuum-packaged cold-smoked salmon (CSS), for possible use as biopreservative cultures against Listeria monocytogenes. The antilisterial activity of cultures’ supernatants was assessed at 0.5%, 3.0% and 5.0% w/v of salt, at 5ºC, 10ºC and 25ºC both in aerobic and anaerobic atmospheres, simulating the conditions pertaining in vacuum-packaged CSS. The kinetics of growth, bacteriocin biosynthesis, the minimum inhibitory concentrations (MICs) of ten antibiotics, histamine and tyramine production of LAB strains, were determined jointly with the haemolytic activity for the enterococci. Only five strains were able to secrete active bacteriocins into the culture medium, at high salt concentrations and low temperatures, both in aerobic and anaerobic atmospheres. Enterococci showed neither haemolyt ic activity nor vancomycin resistance. The production of histamine was not observed for any of the bacteriocin-producing strains

Lipid and carotenoid production by a Rhodosporidium toruloides and Tetradesmus obliquus mixed culture using primary brewery wastewater supplemented with sugarcane molasses and urea

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.info:eu-repo/semantics/publishedVersio

Gellan gum-based hydrogels support the recreation of the dermal papilla microenvironment

The dermal papilla (DP), a specialized compartment within the hair follicle, regulates hair growth. However, human DP cells rapidly lose their inductivity in 2D-culture given the loss of positional and microenvironmental cues. Spheroids have been capable of recreating the 3D intercellular organization of DP cells, however, DP cell-matrix interactions are poorly represented. Considering the specific nature of the DP's extracellular matrix (ECM), we functionalized gellan gum (GG) with collagen IV-(HepIII) or fibronectin-(cRGDfC) derived peptide sequences to generate a 3D environment in which the phenotype and physiological functions of DP cells are restored. We further tuned the stiffness of the microenvironments by varying GG amount. Biomimetic peptides in stiffer hydrogels promoted the adhesion of DP cells, while each peptide and amount of polymer independently influenced the type and quantity of ECM proteins deposited. Furthermore, although peptides did not seem to have an influence, stiffer hydrogels improved the inductive capacity of DP cells after short term culture. Interestingly, independently of the peptide, these hydrogels supported the recapitulation of basic hair morphogenesis-like events when incorporated in an organotypic human skin in vitro model. Our work demonstrates that tailored GG hydrogels support the generation of a microenvironment in which both cell-ECM and cell-cell interactions positively influence DP cells towards the creation of an artificial DP.Authors would like to acknowledge the financial support from the Consolidator Grant “ECM_INK” (ERC-2016-COG-726061) and from FCT/MCTES (Fundação para a Ciência e a Tecnologia/Ministério da Ciência, Tecnologia e Ensino Superior) through the PD/59/2013, PD/BD/113800/2015 (Carla Abreu), PD/169/2013 (Manuela Lago) and IF/00945/2014 (Alexandra Marques) grants. The authors also appreciate the support given by the FSE/POCH (Fundo Social Europeu through the Programa Operacional do Capital Humano) under the scope of the NORTE-08-5369-FSE-000037 grant (Manuela Lago)