pH-dependent and whole-cell catalytic decolorization of dyes using recombinant dye-decolorizing peroxidase from Rhodococcus jostii.

Dyes in wastewater have adverse effects on the environment and human health. Dye-decolorizing peroxidase (DyP) is a promising biocatalyst to dyes degradation, but the decolorization rates varied greatly which influencing factors and mechanisms remain to be fully disclosed. To explore an effective decolorizing approach, we have studied a DyP from Rhodococcus jostii (RhDyPB) which was overexpressed in Escherichia coli to decolorize four kinds of dyes, Reactive blue 19, Eosin Y, Indigo carmine, and Malachite green. We found the decolorization rates of the dyes by purified RhDyPB were all pH-dependent and the highest one was 94.4% of Malachite green at pH 6.0. ESI-MS analysis of intermediates in the decolorization process of Reactive blue 19 proved the degradation was due to peroxidase catalysis. Molecular docking predicated the interaction of RhDyPB with dyes, and a radical transfer reaction. In addition, we performed decolorization of dyes with whole E. coli cell with and without expressing RhDyPB. It was found that decolorization of dyes by E. coli cell was due to both cell absorption and degradation, and RhDyPB expression improved the degradation rates towards Reactive blue 19, Indigo carmine and Malachite green. The effective decolorization of Malachite green and the successful application of whole DyP-overexpressed cells in dye decolorization is conducive to the bioremediation of dye-containing wastewaters by DyPs.

Breastfeeding competency and its influencing factors among pregnant women in third trimester pregnancy: a cross-sectional study.

Competency is closely related to the occurrence of the behavior. Breastfeeding competence is the mastery of different breastfeeding factors which intervene in breastfeeding behavior. Breastfeeding competence could improve the breastfeeding behavior. However, few studies have paid attention to the status and the influencing factors of breastfeeding competency. The breastfeeding competency of pregnant women in third trimester pregnancy has the greatest impact on breastfeeding behavior after childbirth. Therefore, the objective of this study were to investigate the breastfeeding competency level and independent risk factors for breastfeeding competency among pregnant women in third trimester pregnancy. A cross-sectional survey method and convenience sampling method was used in the study. The general information questionnaire including age, gestational week, educational background, and so on were used to investigate the general information of pregnant women and their husbands. A breastfeeding competency scale (BCS) was used to investigate the breastfeeding competency of pregnant women. The total score of the BCS ranges from 38 to 190, with higher scores indicating greater breastfeeding competency. Lower level, medium level and higher level are 38-89, 90-140 and 141-190 respectively. Type-D Scale-14 (DS14) was used to investigate the type D personality of pregnant women. A multivariable linear regression was used to examine the independent predictors of breastfeeding competency. A total of 550 questionnaires were collected and finally 525 effective questionnaires were collected. The age of 525 pregnant women is (30.24 ± 3.954) years old. The breastfeeding competency score of pregnant women was (134 ± 19.741). Multivariable linear regression analysis showed that higher breastfeeding competency in pregnant women were reported among pregnant women who gestational age ≥ 256 days (37 weeks) (B = 8.494, p < 0.001), the previous breastfeeding experience were exclusive breastfeeding (B = 17.384, p < 0.001) and partial breastfeeding (B = 16.878, p < 0.001), participating in pregnant women school 2-3 times (B = 10.968, p = 0.013) and ≥ 5 times (B = 13.731, p = 0.034). Pregnant women with lower breastfeeding competency were found in women who were judged to have type D personality (B = - 6.358, p < 0.001). The result can explain 25.8% of the variation in the total breastfeeding competency score. This should be considered an important issue by maternal and child health care in the medical system that the moderate level of breastfeeding capacity among pregnant women. Differentiated and targeted breastfeeding support and services for pregnant women should be carried out based on influencing factors of breastfeeding competency.

Transformation of Reactive Blue 19 by a recombinant peroxidase DyP.

Wastewater containing recalcitrant dyes causes environmental problems. A new superfamily of heme-containing peroxidases, dye-decolorizing peroxidases (DyPs), has been found to decolorize different kinds of dyes, especial anthraquinone dyes efficiently. However, the mechanism of dyes degradation by DyPs has not been fully understood and the toxicity of dye degradation intermediates by DyPs catalysis to microbes is unclear. In this study, a purified recombinant Thermobifida fusca DyP (TfuDyP) in E. coli BL21(DE3) was used to treat Reactive Blue 19 (RB19), an anthraquinone dye. The reaction intermediates analyzed by ultra performance liquid chromatography/mass spectroscopy (UPLC-MS) indicated the initial site of TfuDyP attack on RB19. In addition, it was found that both RB19 and its incomplete degradation products inhibited the growth of Bacillus subtilis. These findings provided a novel understanding of DyPs catalysis to anthraquinone dyes.

Spin crossover in hydrogen-bonded frameworks of FeII complexes with organodisulfonate anions.

We present here the syntheses, crystal structures, and thermal and magnetic properties of a series of mononuclear Fe2+ spin crossover (SCO) complexes of the formula [Fe(bamp)2]·Anion·Solv (Anion = NDS2-, Solv = 2H2O, 1NDS; Anion = BPDS2-, Solv = 4.4H2O, 2BPDS; Anion = ABDS2-, Solv = Et2O and H2O, 3ABDS; Anion = DNDS2-, Solv = MeCN, 4DNDS; bamp = 2,6-pyridinedimethanamine, H2NDS = 1,5-naphthalenedisulphonic acid, H2BPDS = 4,4'-biphenyldisulphonic acid, H2ABDS = 4,4'-azobenzenedisulfonic acid, H2DNDS = 4,4'-dinitrostilbene-2,2'-disulfonic acid). The structures and SCO properties of these complexes can be finely modified by organodisulfonate couteranions. Single-crystal X-ray analyses revealed that all these compounds are hydrogen-bonded three-dimensional frameworks constructed from the charge-assisted hydrogen bonds between bamp donors, organodisulfonate acceptors, and/or crystallized solvent molecules. SCO behavior was observed in all four complexes and has been evidenced by detailed structural and magnetic investigations. While 1NDS exhibits a sharp cooperative SCO transition with a transition temperature T1/2 of 247 K, 2BPDS, 3ABDS, and 4DNDS undergo more gradual SCO transitions with T1/2 values of 176, 171 and 158 K, respectively. Magneto-structural relationship studies revealed that the tunable SCO properties, including the trend of the transition temperatures and the cooperativity of the SCO transition, are mainly attributable to the size of the organodisulfonate anions. This study shows that in order to exhibit cooperative SCO properties, "efficient" hydrogen bonds directly connecting the SCO centers, rather than those between the SCO centers and the innocent neighboring groups, are preferred.

Syntheses, structures, and magnetic properties of three new MnII-[MoIII(CN)7]4- molecular magnets.

By reaction of K4[MoIII(CN)7]·2H2O, Mn(ClO4)2·6H2O and bidentate chelating ligands, three new cyano-bridged compounds, namely Mn2(3-pypz)(H2O)(CH3CN)[Mo(CN)7] (1), Mn2(1-pypz)(H2O)(CH3CN)[Mo(CN)7] (2) and Mn2(pyim)(H2O)(CH3CN)[Mo(CN)7] (3) (3-pypz = 2-(1H-pyrazol-3-yl)pyridine, 1-pypz = 2-(1H-pyrazol-1-yl)pyridine, pyim = 2-(1H-imidazol-2-yl)pyridine), have been synthesized and characterized structurally and magnetically. Single crystal X-ray analyses revealed that although the chelating ligands are different, compounds 1 to 3 are isomorphous and crystallize in the same monoclinic space group C2/m. Connected by the bridging cyano groups, one crystallographically unique [Mo(CN)7]4- unit and three crystallographically unique MnII ions of different coordination environments form similar three-dimensional frameworks, which have a four-nodal 3,4,4,7-connecting topological net with a vertex symbol of {43}{44·62}2{410·611}. Magnetic measurements revealed that compounds 1-3 display long-range magnetic ordering with critical temperatures of 64, 66 and 62 K, respectively. These compounds are rare examples of a small number of chelating co-ligand coordinated [Mo(CN)7]4--based magnetic materials. Specifically, the bidentate chelating ligands were successfully introduced into the heptacyanomolybdate system for the first time.

Two-dimensional frameworks formed by pentagonal bipyramidal cobalt(ii) ions and hexacyanometallates: antiferromagnetic ordering, metamagnetism and slow magnetic relaxation.

We herein report the syntheses, structures, and magnetic properties of two isostructural two-dimensional (2D) coordination polymers based on a pentagonal bipyramidal CoII unit [Co(TODA)]2+ and two hexacyanometallates, namely [MIII(CN)6]2[CoII(TODA)]3·9H2O (M = Cr (1), Co (2), TODA = 1,4,10-trioxa-7,13-diazacyclopentadecane). Structure analyses show that both complexes have 2D honeycomb structures where the [Co(TODA)]2+ units are bridged by the [MIII(CN)6]3- groups through three cyano groups in the facial positions. Magnetic investigation reveals ferromagnetic coupling between the CrIII and CoII centres through cyanides in 1. Due to the antiferromagnetic interaction between the layers, compound 1 exhibits an antiferromagnetic ordering below 11.4 K, and shows a metamagnetic phase transition under an external dc field. Due to the disorder of the TODA ligands, compound 1 shows a spin glass behavior, which leads to slow magnetic relaxation in 1. A butterfly-shaped hysteresis loop at 1.8 K can be observed with a coercive field of 720 Oe, which is quite large for cyano-bridged Cr-Co molecular magnets. For compound 2 containing the diamagnetic [CoIII(CN)6]3- unit, field-induced slow magnetic relaxation was also verified, which makes compound 2 a rare example of an SIM assembled in a 2D network. An easy-plane magnetic anisotropy with a positive D value (29.9 cm-1 by PHI and 26.5 cm-1 by Anisofit2.0) was deduced for hepta-coordinated CoII centers. These results show the efficiency of the strategy of combining cyanometallates and pentagonal bipyramidal precursors for novel molecular magnetic materials.