Valorization of lubricant-based wastewater for bacterial neutral lipids production: growth-linked biosynthesis

Available online 24 May 2016Lipids produced by microorganisms are currently of great interest as raw material for either biofuels or oleochemicals production. Significant biosynthesis of neutral lipids, such as triacylglycerol (TAG) and wax esters (WE) are thought to be limited to a few strains. Hydrocarbonoclastic bacteria (HCB), key players in bioremediation of hydrocarbon contaminated ecosystems, are among this group of strains. Hydrocarbon rich wastewaters have been overlooked concerning their potential as raw material for microbial lipids production. In this study, lubricant-based wastewater was fed, as sole carbon source, to two HCB representative wild strains: Alcanivorax borkumensis SK2, and Rhodococcus opacus PD630. Neutral lipid production was observed with both strains cultivated under uncontrolled conditions of pH and dissolved oxygen. A. borkumensis SK2 was further investigated in a pH- and OD-controlled fermenter. Different phases were assessed separately in terms of lipids production and alkanes removal. The maximum TAG production rate occurred during stationary phase (4 mg-TAG/L h). The maximum production rate of WE-like compounds was 15 mg/L h, and was observed during exponential growth phase. Hydrocarbons removal was 97% of the gas chromatography (GC) resolved straight-chain alkanes. The maximum removal rate was observed during exponential growth phase (6 mg-alkanes/L h). This investigation proposes a novel approach for the management of lubricant waste oil, aiming at its conversion into valuable lipids. The feasibility of the concept is demonstrated under low salt (0.3%) and saline (3.3%) conditions, and presents clues for its technological development, since growth associated oil production opens the possibility for establishing continuous fermentation processes.The authors thank the FCT Strategic Project of UID/BIO/04469/ 2013 unit, the project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124- FEDER-027462) and the Project “BioEnv - Biotechnology and Bioengineering for a sustainable world”, REF. NORTE-07-0124- FEDER-000048, co-funded by the Programa Operacional Regional do Norte (ON.2 e O Novo Norte), QREN, FEDER

Effect of Solution Composition on the Energy Production by Capacitive Mixing in Membrane-Electrode Assembly

The final edited version of the paper can be found at: http://pubs.acs.org/articlesonrequest/AOR-c9UMxSzGY3eiU5SENNgT The complete citation is: Ahualli, S.; et al. Effect of Solution Composition on the Energy Production by Capacitive Mixing in Membrane-Electrode Assembly. Journal of Physical Chemistry, 118(29): 15590-15599 (2014). DOI:10.1021/jp504461mOpen access in the Journal on May 26, 2015In this work we consider the extent to which the presence of multi-valent ions in solution modifies the equilibrium and dynamics of the energy production in a capacitive cell built with ion-exchange membranes in contact with high surface area electrodes. The cell potential in open circuit (OCV) is controlled by the difference between both membrane potentials, simulated as constant volume charge regions. A theoretical model is elaborated for steady state OCV, first in the case of monovalent solutions, as a reference. This is compared to the results in multi-ionic systems, containing divalent cations in concentrations similar to those in real sea water. It is found that the OCV is reduced by about 25 % (as compared to the results in pure NaCl solutions) due to the presence of the divalent ions, even in low concentrations. Interestingly, this can be related to the “uphill” transport of such ions against their concentration gradients. On the contrary, their effect on the dynamics of the cell potential is negligible in the case of highly charged membranes. The comparison between model predictions and experimental results shows a very satisfactory agreement, and gives clues for the practical application of these recently introduced energy production methods.The research leading to these results received funding from the European Union 7th Framework Programme (FP7/2007-2013) under agreement No. 256868. Further financial support from Junta de Andalucia, Spain (PE2012-FQM 694) is also acknowledged. One of us, M.M.F., received financial support throughan FPU grant from the Universityof Granada

Experiences of parents to children with congenital heart defects : A literature study

Bakgrund: Varje år föds 1 % av alla barn i Sverige med medfött hjärtfel. Barnet med denna diagnos och dess föräldrar är i stort behov av omvårdnad. Viktiga komponenter i denna omvårdnad är stöd och uppmuntran, information på rätt nivå för mottagaren och att frågor blir besvarade. Föräldrar till barn med medfött hjärtfel lider i större mån än andra föräldrar av någon form av psykosocial stress eller ångest relaterat till barnets diagnos. Syfte: Syftet var att beskriva föräldrars upplevelser av att ha barn med medfödda hjärtfel. Metod: En litteraturstudie baserad på kvalitativa vetenskapliga artiklar. Artiklarna hittades via sökningar i CINAHL Complete, MEDLINE, Academic Search Elite och CINAHL with Full Text där tio artiklar inkluderades efter kvalitetsgranskning. Resultat: I studiens analys av artiklarna framkom fyra teman som präglade föräldrarnas upplevelser under barnens uppväxt. Dessa var; känslan av otillräcklighet och osäkerhet, en ny komplex situation, stress samt stöd och tillit. Slutsats: När ett barn får diagnosen medfött hjärtfel står hela familjen inför en ny situation som innebär stora omställningar i vardagen. Stress var en konstant börda och föräldrarna upplevde att de kände sig otillräckliga och osäkra i föräldrarollen. Behovet av stöd och tillit, från både vårdpersonal, släkt och vänner, var stort för att orka med situationen. Klinisk betydelse: Resultatet i denna litteraturstudie kan bidra med kunskap om föräldrars upplevelser av att ha ett barn med medfött hjärtfel. Studien kan medvetandegöra behoven hos denna grupp föräldrar, vilket kan vara till hjälp för utformning av riktlinjer inom denna ram för omvårdnad.Background: Each year, 1% of all children born in Sweden are diagnosed at birth with congenital heart defects. The child with this diagnosis and its parents are in great need of care. Key components of this care are support and encouragement, information given at the right level for the receiver, and making sure that questions are answered. Parents of children with congenital heart disease suffer to a greater extent than other parents from some form of psychosocial stress or anxiety related to their child's diagnosis. Aim: The aim of this study was to describe parents' experiences of having children with congenital heart defects. Method: A literature study based on qualitative scientific articles. The articles were found through the databases CINAHL Complete, MEDLINE, Academic Search Elite and CINAHL with Full Text and ten articles were included after quality control. Findings: The study's analysis of the articles revealed four themes that characterized the parents' experiences as the children grew. These were; feeling of inadequacy and insecurity, new complex situation, stress, and also support and trust. Conclusion: In the new situation in which a child where diagnosed with congenital heart defect, the whole family underwent major changes in everyday life. Stress was a constant burden and parents experienced inadequacy and insecurity in the parental role. The need for support and trust from both health care workers, friends and, family was great when dealing with the situation. Relevance to clinical practice: The results of this study will hopefully contribute knowledge about parents' experiences of having a child with congenital heart defects. The study may sensitize the needs of this group of parents, which can be helpful for the development of guidelines within this framework of nursing care

Effect of Methanethiol Concentration on Sulfur Production in Biological Desulfurization Systems under Haloalkaline Conditions

Bioremoval of H₂S from gas streams became popular in recent years because of high process efficiency and low operational costs. To expand the scope of these processes to gas streams containing volatile organic sulfur compounds, like thiols, it is necessary to provide new insights into their impact on overall biodesulfurization process. Published data on the effect of thiols on biodesulfurization processes are scarce. In this study, we investigated the effect of methanethiol on the selectivity for sulfur production in a bioreactor integrated with a gas absorber. This is the first time that the inhibition of biological sulfur formation by methanethiol is investigated. In our reactor system, inhibition of sulfur production started to occur at a methanethiol loading rate of 0.3 mmol L^–1 d^–1. The experimental results were also described by a mathematical model that includes recent findings on the mode of biomass inhibition by methanethiol. We also found that the negative effect of methanethiol can be mitigated by lowering the salinity of the bioreactor medium. Furthermore, we developed a novel approach to measure the biological activity by sulfide measurements using UV-spectrophotometry. On the basis of this measurement method, it is possible to accurately estimate the unknown kinetic parameters in the mathematical model

Inhibition of a biological sulfide oxidation under haloalkaline conditions by thiols and diorgano polysulfanes

A novel approach has been developed for the simultaneous description of reaction kinetics to describe the formation of polysulfide and sulfate anions from the biological oxidation of hydrogen sulfide (H2S) using a quick, sulfide-dependent respiration test. Next to H2S, thiols are commonly present in sour gas streams. We investigated the inhibition mode and the corresponding inhibition constants of six thiols and the corresponding diorgano polysulfanes on the biological oxidation of H2S. A linear relationship was found between the calculated IC50 values and the lipophilicity of the inhibitors. Moreover, a mathematical model was proposed to estimate the biomass activity in the absence and presence of sulfurous inhibitors. The biomass used in the respiration tests originated from a full-scale biodesulfurization reactor. A microbial community analysis of this biomass revealed that two groups of microorganism are abundant, viz. Ectothiorhodospiraceae and Piscirickettsiaceae.Accepted Author ManuscriptBT/Environmental Biotechnolog