Polyimide hollow fiber membranes for CO2 separation from wet gas mixtures

Matrimid®5218 hollow fiber membranes were prepared using the dry-wet spinning process. The transport properties were measured with pure gases (H2, CO2, N2, CH4 and O2) and with a mixture (30% CO2 and 70% N2) in dry and wet conditions at 25 ºC, 50 ºC, 60 ºC and 75 ºC and up to 600 kPa. Interesting values of single gas selectivity up to 60 ºC (between 31 and 28 for CO2/N2 and between 33 and 30 for CO2/CH4) in dry condition were obtained. The separation factor measured for the mixture was 20% lower compared to the single gas selectivity, in the whole temperature range analyzed. In saturation conditions the data showed that water influences the performance of the membranes, inducing a reduction of the permeance of all gases. Moreover, the presence of water caused a decrease of single gas selectivity and separation factor, although not so significant, highlighting the very high water resistance of hollow fiber membrane modules

Draft genome sequence of newly isolated agarolytic bacteria cellulophaga omnivescoria sp. nov. W5C carrying several gene loci for marine polysaccharide degradation

The continued research in the isolation of novel bacterial strains is inspired by the fact that native microorganisms possess certain desired phenotypes necessary for recombinant microorganisms in the biotech industry. Most studies have focused on the isolation and characterization of strains from marine ecosystems as they present a higher microbial diversity than other sources. In this study, a marine bacterium, W5C, was isolated from red seaweed collected from Yeosu, South Korea. The isolate can utilize several natural polysaccharides such as agar, alginate, carrageenan, and chitin. Genome sequence and comparative genomics analyses suggest that strain W5C belongs to a novel species of the Cellulophaga genus, from which the name Cellulophaga omnivescoria sp. nov. is proposed. Its genome harbors 3,083 coding sequences and 146 carbohydrate-active enzymes (CAZymes). Compared to other reported Cellulophaga species, the genome of W5C contained a higher proportion of CAZymes (4.7%). Polysaccharide utilization loci (PUL) for agar, alginate, and carrageenan were identified in the genome, along with other several putative PULs. These PULs are excellent sources for discovering novel hydrolytic enzymes and pathways with unique characteristics required for biorefinery applications, particularly in the utilization of marine renewable biomass. The type strain is JCM 32108T (= KCTC 13157BPT). © 2018, Springer Science+Business Media, LLC, part of Springer Nature

Substrate consumption, isoprene and biomass productions from different feeding modules^a.

a<p>Module 1, 2 and 3 used 10 g L⁻¹ glucose as substrate; module 4 and 5 used 10 g L⁻¹ D-xylose as substrate. Data reported were average values of duplicate cultivation runs.</p

Four glycolytic pathways present in <i>E. coli</i>.

<p>EMP, Embden-Meyerhof pathway; PPP, pentose phosphate pathway; EDP, Entner-Doudoroff pathway.</p

Pyruvate and G3P generation, energy and reducing equivalents production of different glycolytic pathways.

<p>Pyruvate and G3P generation, energy and reducing equivalents production of different glycolytic pathways.</p

Combination of Entner-Doudoroff Pathway with MEP Increases Isoprene Production in Engineered <i>Escherichia coli</i>

<div><p>Embden-Meyerhof pathway (EMP) in tandem with 2-<i>C</i>-methyl-D-erythritol 4-phosphate pathway (MEP) is commonly used for isoprenoid biosynthesis in <i>E. coli</i>. However, this combination has limitations as EMP generates an imbalanced distribution of pyruvate and glyceraldehyde-3-phosphate (G3P). Herein, four glycolytic pathways—EMP, Entner-Doudoroff Pathway (EDP), Pentose Phosphate Pathway (PPP) and Dahms pathway were tested as MEP feeding modules for isoprene production. Results revealed the highest isoprene production from EDP containing modules, wherein pyruvate and G3P were generated simultaneously; isoprene titer and yield were more than three and six times higher than those of the EMP module, respectively. Additionally, the PPP module that generates G3P prior to pyruvate was significantly more effective than the Dahms pathway, in which pyruvate production precedes G3P. In terms of precursor generation and energy/reducing-equivalent supply, EDP+PPP was found to be the ideal feeding module for MEP. These findings may launch a new direction for the optimization of MEP-dependent isoprenoid biosynthesis pathways.</p></div

Participation of MEP-dependent isoprene biosynthesis pathway into two modules.

<p>Gene symbols and the enzymes they encode (all genes were from <i>E. coli</i> except where noted): <i>dxs</i>, DXP synthase; <i>ispC</i>, DXP reductionisomerase; <i>ispD</i>, DXP-ME synthase; <i>ispE</i>, CDP-ME kinase; <i>ispF</i>, MECPP synthase; <i>ispG</i>, HMBPP synthase; <i>ispH</i>, HMBPP reductase; <i>idi</i>, IPP isomerase; <i>ispS</i>, isoprene synthase (<i>P. alba</i>). Pathway intermediates: G3P, glyceraldehyde-3-phosphate; DXP, 1-deoxy-D-xylulose 5-phosphate; MEP, 2-<i>C</i>-methyl-D-erythritol 4-phosphate; CDP-ME, 4-diphosphocytidyl-2-<i>C</i>-methyl-D-erythritol; CDP-MEP, 4-diphosphocytidyl-2-<i>C</i>-methyl-D-erythritol 2-phosphate; MECPP, 2-<i>C</i>-methyl-D-erythritol 2,4-cyclopyrophosphate; HMBPP, 1-hydroxy-2-methyl-2-(<i>E</i>)-butenyl 4-pyrophosphate; IPP, isopentenyl pyrophosphate; DMAPP, dimethylallyl pyrophosphate; DHAP, dihydroxyacetone 3-phosphate.</p

Isoprene titers and yields from different feeding modules.

<p>Module 1, EMP of strain FMIS 1; Module 2, EDP+PPP of strain FMIS 2; Module 3, EDP of strain FMIS 3, these three strains used glucose as carbon source. Module 4, PPP of strain FMIS 4; Module 5, Dahms pathway of strain FMIS 5, these two strains used D-xylose as carbon source. All strains are listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083290#pone.0083290.s003" target="_blank">Table S1</a> in File S1. A 160 mL serum bottle containing 40 mL of semi-defined medium, consisted of M9 salts, 5 g L⁻¹ yeast extract, 10 g L⁻¹ required carbon source and 1 mM thiamine pyrophosphate (TPP), was used for the cultivation of the strains for isoprene production.</p