Mixed Acid Fermentation of Carbohydrate-Rich Dairy Manure Hydrolysate

Dairy manure (DM) is an abundant agricultural residue that is largely composed of lignocellulosic biomass. The aim of this study was to investigate if carbon derived from DM fibers can be recovered as medium-chain fatty acids (MCFAs), which are mixed culture fermentation products of economic interest. DM fibers were subjected to combinations of physical, enzymatic, chemical, and thermochemical pretreatments to evaluate the possibility of producing carbohydrate-rich hydrolysates suitable for microbial fermentation by mixed cultures. Among the pretreatments tested, decrystalization dilute acid pretreatment (DCDA) produced the highest concentrations of glucose and xylose, and was selected for further experiments. Bioreactors fed DCDA hydrolysate were operated. Acetic acid and butyric acid comprised the majority of end products during operation of the bioreactors. MCFAs were transiently produced at a maximum concentration of 0.17 mg CODMCFAs/mg CODTotal. Analyses of the microbial communities in the bioreactors suggest that lactic acid bacteria, Megasphaera, and Caproiciproducens were involved in MCFA and C4 production during DCDA hydrolysate metabolism.

Identification of Enzymatic Bottlenecks for the Aerobic Production of Malate from Glycerol by the Systematic Gene Overexpression of Anaplerotic Enzymes in Escherichia coli

The biotechnological production of dicarboxylic acids (C4) from renewable carbon sources represents an attractive approach for the provision of these valuable compounds by green chemistry means. Glycerol has become a waste product of the biodiesel industry that serves as a highly reduced carbon source for some microorganisms. Escherichia coli is capable of consuming glycerol to produce succinate under anaerobic fermentation, but with the deletion of some tricarboxylic acid (TCA) cycle genes, it is also able to produce succinate and malate in aerobiosis. In this study, we investigate possible rate-limiting enzymes by overexpressing the C-feeding anaplerotic enzymes Ppc, MaeA, MaeB, and Pck in a mutant that lacks the succinate dehydrogenase (Sdh) enzyme. The overexpression of the TCA enzyme Mdh and the activation of the glyoxylate shunt was also examined. Using this unbiased approach, we found that phosphoenol pyruvate carboxylase (Ppc) overexpression enhances an oxidative pathway that leads to increasing succinate, while phosphoenol pyruvate carboxykinase (Pck) favors a more efficient reductive branch that produces mainly malate, at 57.5% of the theoretical maximum molar yield. The optimization of the culture medium revealed the importance of bicarbonate and pH in the production of malate. An additional mutation of the ppc gene highlights its central role in growth and C4 production.

Amino acids and acylcarnitine production by Chlorella vulgaris and Chlorella sorokiniana microalgae from wastewater culture

Background Microalgae are a widely distributed group of prokaryotic and eukaryotic photosynthetic microorganisms that use a number of substances present in wastewater to produce a variety of biotechnological and nutritional biomolecules. Methods Production ofamino acids and acylcarnitine by Chlorella vulgaris and Chlorella sorokiniana was determined after 13 d of culture in wastewater, under various culture conditions. Wastewater was collected from “La Encantada” stream, located in Saltillo, Coahuila, Mexico. Microalgae was cultured at 23°C and natural day light, including the use of the following conditions: (1) extra light (12:12 light:dark cycles, 1,380 lumens), (2) agitation (130 rpm), and (3) both conditions, until exponential phase. Supernatant products were then analyzed by liquid chromatograph coupled to mass spectrometry. In addition, metabolomic profiles related to growing conditions were evaluated. Results Amino acids and acylcarnitine production by C. sorokiniana and C. vulgaris resulted in higher Ala and Leu concentrations by C. vulgaris compared with control, where control produced Gly and Pro in higher amounts compared with C. sorokiniana. Tyr, Phe, Val, and Cit were detected in lower amounts under light and shaking culture conditions. High concentrations of C0 acylcarnitines were produced by both microalgae compared with control, where C. sorokiniana production was independent of culture conditions, whereas C. vulgaris one was stimulated by shaking. C4 production was higher by C. sorokiniana compared with control. Furthermore, C4, C6DC, C14:1, C14:2, and C18:1OH production by microalga was low in all culture conditions. Conclusion Microalgae produced essential amino acids and nutritionally important carnitines from wastewater. In addition, C. sorokiniana biomass has higher potential as animal nutrient supplement, as compared with that of C. vulgaris.

(Re-)presenting the Paralympics: Affective Nationalism and the “Able-Disabled”

The relationship between media, sport, nations, and nationalism is well established; yet, there is an absence of these discussions at the intersection of communication, Paralympics, and disability studies. This omission is particularly significant considering the rapid commodification of the Paralympic spectacle, exacerbated by the entry of Channel 4 (C4) as the UK Paralympic rights holders, that has seen the games become an important site of disability (re-)presentation. In this article, we focus on the construction of national, normative, disabled bodies in Paralympic representation drawn from an analysis of three integrated data sets from C4’s broadcasting of the Rio 2016 Paralympics: interviews with C4 production and editorial staff, quantitative content analysis, and qualitative moving image analysis. We highlight the strategic approach taken by C4 to focus on successful medal-winning athletes, the implications this has on the sports and disability classifications given media coverage, and the role of affective high-value production practices. We also reveal the commercial tensions and editorial decisions that broadcasters face with respect to which disabilities/bodies are made hypervisible—and thereby those which are marginalized—as national disability sport icons that inculcate preferred notions of disability and the (re-)imagined nation.

Reperfusion induces 5-lipoxygenase translocation and leukotriene C4 production in ischemic brain

5-Lipoxygenase (5-LO) converts arachidonic acid, released from membrane phospholipids upon external stimulation, to leukotriene C4 (LTC4), which induces various kinds of cellular and molecular responses. We examined the effects of 5 min of ischemia on brain 5-LO and LTC4 during reperfusion using the gerbil model of transient forebrain ischemia that develops neuronal necrosis selectively in the hippocampus. Neurons exhibited dense 5-LO immunoreactivity; 5-LO was partially redistributed from cytosolic to particulate fractions 3 min during reperfusion. LTC4 was generated in neurons and was increased in all forebrain regions during reperfusion. Postischemic increases in LTC4 were inhomogeneous; a greater increase was observed in the hippocampus (13.37 +/- 0.24 pmol/g tissue) than in the other regions (cerebral cortex: 3.29 +/- 1.09 pmol/g). Superoxide dismutase and dimethylthiourea, oxygen radical scavengers, attenuated the production of LTC4 and damage to the neurons in the hippocampus during reperfusion. Our findings indicated that reperfusion, which was associated with translocation of cytosolic 5-LO to membranes and generation of oxygen radicals, induced the production of LTC4 and suggested that excess LTC4 production may mediate irreversible reperfusion injuries in the hippocampal neurons.