Optimization of growth media components for polyhydroxyalkanoate (PHA) production from organic acids by Ralstonia eutropha

We employed systematic mixture analysis to determine optimal levels of acetate, propionate, and butyrate for cell growth and polyhydroxyalkanoate (PHA) production by Ralstonia eutropha H16. Butyrate was the preferred acid for robust cell growth and high PHA production. The 3-hydroxyvalerate content in the resulting PHA depended on the proportion of propionate initially present in the growth medium. The proportion of acetate dramatically affected the final pH of the growth medium. A model was constructed using our data that predicts the effects of these acids, individually and in combination, on cell dry weight (CDW), PHA content (%CDW), PHA production, 3HV in the polymer, and final culture pH. Cell growth and PHA production improved approximately 1.5-fold over initial conditions when the proportion of butyrate was increased. Optimization of the phosphate buffer content in medium containing higher amounts of butyrate improved cell growth and PHA production more than 4-fold. The validated organic acid mixture analysis model can be used to optimize R. eutropha culture conditions, in order to meet targets for PHA production and/or polymer HV content. By modifying the growth medium made from treated industrial waste, such as palm oil mill effluent, more PHA can be produced.Malaysia. Ministry of Science, Technology and Innovation (MOSTI

Mischformen und Überlappung des Typ-1- und des Typ-2-Diabetes. Limitationen individueller Therapieoptionen durch die bestehende Disease-Management-Programm-Systematik.  

Bei einem 67-jährigen Patienten mit Typ-2-Diabetes und Facetten des metabolischen Syndroms wurden niedrigtitrige GAD-Autoantikörper (GAD: Glutamatdekarboxylase) bei gleichzeitig negativen Befunden für die anderen Inselantikörper nachgewiesen und deshalb die Diagnose geändert auf Typ-1-Diabetes. In der Folge kam es unter einer intensivierten Insulintherapie mit maximal 137 Einheiten Insulin/Tag trotz Beibehaltung des Metformins zu einer ausgeprägten Gewichtszunahme von 18 kg in 3 Jahren. Es handelt sich hier am ehesten um einen Typ-2-Diabetes mit LADA-Phänotyp (LADA: „latent autoimmune diabetes in adults“) als Mischbild oder aber bei den niedrigtitrigen GADA (GAD-Autoantikörper) um nicht mit Diabetes assoziierte unspezifische Autoantikörper. Die DMP-Systematik (DMP: Disease-Management-Programm) kann diesen Phänotyp aber nicht abbilden, da lediglich das DMP Diabetes mellitus Typ 1 und das DMP Diabetes mellitus Typ 2 zur Verfügung stehen. Aus diesem Grund wurde der Patient erneut in das DMP Diabetes mellitus Typ 2 eingeschrieben. Zumindest für Patienten, die phänotypisch einem Typ-2-Diabetes entsprechen und niedrigtitrige Single-GADA aufweisen, wäre eine Diagnose „Typ-2-Diabetes mit β‑Zell-Autoimmunität“ zutreffender als Typ-1-Diabetes/LADA. Nach zusätzlicher Gabe von Liraglutid 1,8 mg s. c. (subkutan) nahm der Patient in kurzer Zeit 9 kg ab und konnte die Insulindosis auf zuletzt 38 Einheiten/Tag senken

Risk stratification in women with gestational diabetes according to and beyond current WHO criteria.

The pregnancy outcomes in women with gestational diabetes mellitus (GDM) and 'overt diabetes in pregnancy' were compared and the need for further subclassification was investigated with respect to postpartum outcome risk. Data from 944 women who had been uniformly diagnosed as having GDM in Munich, Germany, between 1998 and 2010, were re-classified into GDM and 'overt diabetes in pregnancy'. Pregnancy related outcomes in the offspring were derived from Bavarian birth registry data. Classification and regression trees were used to identify further GDM sub-phenotypes. In total, 88 women (9.3%) were re-classified as having 'overt diabetes in pregnancy'. Compared to women with GDM, women with 'overt diabetes in pregnancy' used insulin more frequently, and were at increased risk for large for gestational age infants [odds ratio 2.50 (95% confidence interval 1.02, 6.13)], preterm delivery [odds ratio 3.28 (1.02, 10.50)], and low APGAR-score at 5 min [odds ratio 12.70 (1.58, 102.2)]. In the 856 women with GDM, classification and regression tree analyses provided further risk stratification in that a combination of fasting glucose>5.3 mmol/l and 1-h glucose>11.1 mmol/l at GDM diagnosis predicted insulin requirement [OR 5.57 (3.75, 8.27) compared to the rest], and maternal body mass index (BMI)≥35 kg/m(2) predicted large for gestational age status. The new differentiation between GDM and 'overt diabetes in pregnancy' is a first step towards refining classification relevant to fetal and maternal postpartum risk. A combination of glucose levels and maternal BMI at diagnosis of GDM may provide further improvement

Role of Fatty Acid De Novo Biosynthesis in Polyhydroxyalkanoic Acid (PHA) and Rhamnolipid Synthesis by Pseudomonads: Establishment of the Transacylase (PhaG)-Mediated Pathway for PHA Biosynthesis in Escherichia coli

Since Pseudomonas aeruginosa is capable of biosynthesis of polyhydroxyalkanoic acid (PHA) and rhamnolipids, which contain lipid moieties that are derived from fatty acid biosynthesis, we investigated various fab mutants from P. aeruginosa with respect to biosynthesis of PHAs and rhamnolipids. All isogenic fabA, fabB, fabI, rhlG, and phaG mutants from P. aeruginosa showed decreased PHA accumulation and rhamnolipid production. In the phaG (encoding transacylase) mutant rhamnolipid production was only slightly decreased. Expression of phaG from Pseudomonas putida and expression of the β-ketoacyl reductase gene rhlG from P. aeruginosa in these mutants indicated that PhaG catalyzes diversion of intermediates of fatty acid de novo biosynthesis towards PHA biosynthesis, whereas RhlG catalyzes diversion towards rhamnolipid biosynthesis. These data suggested that both biosynthesis pathways are competitive. In order to investigate whether PhaG is the only linking enzyme between fatty acid de novo biosynthesis and PHA biosynthesis, we generated five Tn5 mutants of P. putida strongly impaired in PHA production from gluconate. All mutants were complemented by the phaG gene from P. putida, indicating that the transacylase-mediated PHA biosynthesis route represents the only metabolic link between fatty acid de novo biosynthesis and PHA biosynthesis in this bacterium. The transacylase-mediated PHA biosynthesis route from gluconate was established in recombinant E. coli, coexpressing the class II PHA synthase gene phaC1 together with the phaG gene from P. putida, only when fatty acid de novo biosynthesis was partially inhibited by triclosan. The accumulated PHA contributed to 2 to 3% of cellular dry weight