Engineering yield and rate of reductive biotransformation in Escherichia coli by partial cyclization of the pentose phosphate pathway and PTS-independent glucose transport

Optimization of yields and productivities in reductive whole-cell biotransformations is an important issue for the industrial application of such processes. In a recent study with Escherichia coli, we analyzed the reduction of the prochiral β-ketoester methyl acetoacetate by an R-specific alcohol dehydrogenase (ADH) to the chiral hydroxy ester (R)-methyl 3-hydroxybutyrate (MHB) using glucose as substrate for the generation of NADPH. Deletion of the phosphofructokinase gene pfkA almost doubled the yield to 4.8 mol MHB per mole of glucose, and it was assumed that this effect was due to a partial cyclization of the pentose phosphate pathway (PPP). Here, this partial cyclization was confirmed by 13C metabolic flux analysis, which revealed a negative net flux from glucose 6-phosphate to fructose 6-phosphate catalyzed by phosphoglucose isomerase. For further process optimization, the genes encoding the glucose facilitator (glf) and glucokinase (glk) of Zymomonas mobilis were overexpressed in recombinant E. coli strains carrying ADH and deletions of either pgi (phosphoglucose isomerase), or pfkA, or pfkA plus pfkB. In all cases, the glucose uptake rate was increased (30–47%), and for strains Δpgi and ΔpfkA also, the specific MHB production rate was increased by 15% and 20%, respectively. The yield of the latter two strains slightly dropped by 11% and 6%, but was still 73% and 132% higher compared to the reference strain with intact pgi and pfkA genes and expressing glf and glk. Thus, metabolic engineering strategies are presented for improving yield and rate of reductive redox biocatalysis by partial cyclization of the PPP and by increasing glucose uptake, respectively

Dietary practices in isovaleric acidemia:A European survey

Background: In Europe, dietary management of isovaleric acidemia (IVA) may vary widely. There is limited collective information about dietetic management. Aim: To describe European practice regarding the dietary management of IVA, prior to the availability of the E-IMD IVA guidelines (E-IMD 2014). Methods: A cross-sectional questionnaire was sent to all European dietitians who were either members of the Society for the Study of Inborn Errors of Metabolism Dietitians Group (SSIEM-DG) or whom had responded to previous questionnaires on dietetic practice (n=53). The questionnaire comprised 27 questions about the dietary management of IVA. Results: Information on 140 patients with IVA from 39 centres was reported. 133 patients (38 centres) were given a protein restricted diet. Leucine-free amino acid supplements (LFAA) were routinely used to supplement protein intake in 58% of centres. The median total protein intake prescribed achieved the WHO/FAO/UNU [2007] safe levels of protein intake in all age groups. Centres that prescribed LFAA had lower natural protein intakes in most age groups except 1 to 10 y. In contrast, when centres were not using LFAA, the median natural protein intake met WHO/FAO/UNU [2007] safe levels of protein intake in all age groups. Enteral tube feeding was rarely prescribed. Conclusions: This survey demonstrates wide differences in dietary practice in the management of IVA across European centres. It provides unique dietary data collectively representing European practices in IVA which can be used as a foundation to compare dietary management changes as a consequence of the first E-IMD IVA guidelines availability. (C) 2017 The Authors. Published by Elsevier Inc

Dietary practices in propionic acidemia:A European survey

Background: The definitive dietary management of propionic acidaemia (PA) is unknown although natural protein restriction with adequate energy provision is of key importance. Aim: To describe European dietary practices in the management of patients with PA prior to the publication of the European PA guidelines. Methods: This was a cross-sectional survey consisting of 27 questions about the dietary practices in PA patients circulated to European IMD dietitians and health professionals in 2014. Results: Information on protein restricted diets of 186 PA patients from 47 centres, representing 14 European countries was collected. Total protein intake [PA precursor-free L-amino acid supplements (PFAA) and natural protein] met WHO/FAO/UNU (2007) safe protein requirements for age in 36 centres (77%). PFAA were used to supplement natural protein intake in 81% (n = 38) of centres, providing a median of 44% (14-83%) of total protein requirement. Seventy-four per cent of patients were prescribed natural protein intakes below WHO/ FAO/UNU (2007) safe levels in one or more of the following age groups: 0-6 m, 7-12 m, 1-10 y, 11-16 y and > 16 y. Sixty-three per cent (n = 117) of patients were tube fed (74% gastrostomy), but only 22% received nocturnal feeds. Conclusions: There was high use of PFAA with intakes of natural protein commonly below WHO/FAO/UNU (2007) safe levels. Optimal dietary management can only be determined by longitudinal, multi-centre, prospective case controlled studies. The metabolic instability of PA and small patient cohorts in each centre ensure that this is a challenging undertaking

La veille

Chapitre dans ouvrage coordonné par Jacky Akoka et Isabelle Comyn-WattiauNational audienceCe chapitre propose d'apporter une clarification et une structuration du champ de la veille en replaçant dans un schéma de synthèse les différentes formes de veille dans l'entreprise comme par exemple la veille technologique, l'intelligence économique, la veille concurrentielle ou encore la Veille Anticipative Stratégique - Intelligence Collective (VAS-IC). Adoptant une définition processuelle, il détaille les différentes phases de la veille en s'attachant à montrer les différentes acceptations existantes dans les entreprises. Enfin, il propose une réflexion sur les résultats de la veille au regard des missions, de l'utilité et des finalités attendues par les manager

Diet macronutrient composition reported before treatment predicts BMI change in obese children: the role of lipids.

In this study, we tested the hypothesis that diet composition reported by children before the beginning of an obesity treatment program could be a predicting factor of the clinical outcome. A sample of 138 obese 6-16-year-old children and adolescents were recruited. Anthropometry and dietary habits were recorded. Each patient participated in a multidimensional treatment program in an outpatient obesity public service clinic. Therapy was based on a 6-month educational program on nutrition, lifestyle and physical activity. Children with a lipid intake above 34.7\% of total energy had a 2.5 times higher chance of reducing at least 1.5 units of BMI with treatment than children with lower lipid intake. These results suggest that the assessment of habitual diet, in particular diet composition before starting treatment, may help to identify obese children who are more sensitive to intervention and those who need more specific nutritional assistance.European Journal of Clinical Nutrition advance online publication, 25 July 2012; doi:10.1038/ejcn.2012.97

Breakfast skipping in prepubertal obese children: hormonal, metabolic and cognitive consequences.

Background and Aims:Skipping breakfast influences cognitive performance. The aim of our study was to investigate the relationship between the variation of hormonal and metabolic postprandial parameters induced by breakfast consumption or fasting and cognitive performance in obese children.Methods:Cross-sectional study for repeated measures. Memory and attention assessment tests, hormones and nutrient oxidation were measured before and after consuming breakfast vs fasting in 10 prepubertal obese children.Results:Fasting induced a significant (P<0.05) increase of the Overall Index of the Continuous Performance Test II (a global index of inattention) and the Test of Memory and Learning Word Selective Reminding (a test of verbal memory), whereas no changes were found after breakfast. Fasting was associated with a reduction of insulin and an increase in glucagon, with no changes in glucose. The increase in inattention was associated with a reduction of carbohydrate oxidation (\u3c1=-0.66, P<0.05). We found no difference in the area under the curve of peptide YY and glucagon-like peptide-1 after breakfast or fasting, whereas Ghrelin was significantly lower. No association between postprandial hormone variation and cognitive performance was found.Conclusions:Attention and visual memory performance in the morning were reduced when the children skipped breakfast. No association was found with hormones or metabolic changes, but we did find an association with a reduction of carbohydrate oxidation. Nevertheless, these preliminary findings need confirmation in larger sample siz