Development and Characterization of Electrospun Biopapers of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Derived from Cheese Whey with Varying 3-Hydroxyvalerate Contents

[EN] In the present study, three different newly developed copolymers of poly(3-hydroxybutyrate-co-3-hydroxyval-erate) (PHBV) with 20, 40, and 60 mol % contents in 3-hydroxyvalerate (3HV) were produced by the biotechnological process of mixed microbial cultures (MMCs) using cheese whey (CW), a by-product from the dairy industry, as feedstock. The CW-derived PHBV copolyesters were first purified and then processed by solution electrospinning, yielding fibers of approximately 2 mu m in cross-section in all cases. The resultant electrospun PHBV mats were, thereafter, post-processed by annealing at different temperatures, below their maximum of melting, selected according to their 3HV content in order to obtain continuous films based on coalesced fibers, so-called biopapers. The resultant PHBV films were characterized in terms of their morphology, crystallinity, and mechanical and barrier properties to assess their potential application in food packaging. The CW-derived PHBV biopapers showed high contact transparency but a slightly yellow color. The fibers of the 20 mol % 3HV copolymer were seen to contain mostly poly(3-hydroxybutyrate) (PHB) crystals, the fibers of the 40 mol % 3HV copolymer a mixture of PHB and poly(3-hydroxyvalerate) (PHV) crystals and lowest crystallinity, and the fibers of the 60 mol % 3HV sample were mostly made of PHV crystals. To understand the interfiber coalesce process undergone by the materials during annealing, the crystalline morphology was also assessed by variable-temperature both combined small-angle and wide-angle X-ray scattering synchrotron and Fourier transform infrared experiments. From these experiments and, different from previously reported biopapers with lower 3HV contents, all samples were inferred to have a surface energy reduction mechanism for interfiber coalescence during annealing, which is thought to be activated by a temperature-induced decrease in molecular order. Due to their reduced crystallinity and molecular order, the CW-derived PHBV biopapers, especially the 40 mol % 3HV sample, were found to be more ductile and tougher. In terms of barrier properties, the three copolymers performed similarly to water and limonene, but to oxygen, the 40 mol % sample showed the highest relative permeability. Overall, the materials developed, which are compatible with the Circular Bioeconomy organic recycling strategy, can have an excellent potential as barrier interlayers or coatings of application interest in food packaging.This research work was funded by the H2020 EU project YPACK (reference number 773872) and by the Spanish Ministry of Science and Innovation (MICI) project RTI2018-097249-B-C21. B.M.-R. would like to acknowledge the MICI for her FPI fellowship (BES-2016-077972) and S.T.-G. for his MICI Juan de la Cierva-Incorporacion contract (IJCI-2016-29675). The ALBA Synchrotron is also acknowledged for the funding received through the project "Time-resolved Combined Wide-and Small-angle X-ray Scattering Characterization as a Function of Temperature of Electrospun Polyhydroxyalkanoates Derived from Biowaste" (2018022619). The authors would also like to thank the Unidad Asociada IATA(CSIC)-UJI in "Plastics Technology".Meléndez-Rodríguez, B.; Reis, MAM.; Carvalheira, M.; Sammon, C.; Cabedo, L.; Torres-Giner, S.; Lagaron, JM. (2021). Development and Characterization of Electrospun Biopapers of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Derived from Cheese Whey with Varying 3-Hydroxyvalerate Contents. Biomacromolecules. 22(7):2935-2953. https://doi.org/10.1021/acs.biomac.1c00353S2935295322

The effect of substrate competition on the metabolism of polyphosphate accumulating organisms (PAOs)

The type of carbon source present in the wastewater is one factor that affects the competition between polyphosphate accumulating organisms (PAO) and glycogen accumulating organisms (GAO) and therefore, the efficiency of the enhanced biological phosphorus removal (EBPR) process. This study investigated the impact of the carbon source composition on the anaerobic and aerobic kinetics of PAOs and the EBPR performance of an 85% PAO enrichment. When both acetate (HAc) and propionate (HPr) were present, propionate was depleted more quickly, with a constant uptake rate of 0.18±0.02C-mol/(C-mol biomass·h), while the acetate uptake rate decreased with an increase in propionate concentration, due to the substrate competition between acetate and propionate. The metabolic model for PAOs was modified to incorporate the anaerobic substrate competition effect. The aerobic rates for phosphorus (P) uptake, glycogen production and polyhydroxyalkanoates (PHA) degradation were within the same range for all tests, indicating that these rates are essentially independent of the acetate and propionate concentration, simplifying the calibration procedure for metabolic models. The metabolic model applied to describe the anaerobic and aerobic activity agreed well with the experimental data of HAc, HPr, P, PHA and biomass growth. The low glycogen consumption observed suggest that some reducing equivalents were generated anaerobically through the TCA cycle. The results of this work suggest that the propionate uptake kinetics by PAOs can provide them an advantage over GAOs in EBPR systems, even when the propionate fraction of the influent is relatively low

The impact of aeration on the competition between polyphosphate accumulating organisms and glycogen accumulating organisms

In wastewater treatment plants (WWTPs), aeration is the major energetic cost, thus its minimisation will improve the cost-effectiveness of the process. This study shows that both the dissolved oxygen (DO) concentration and aerobic hydraulic retention time (HRT) affect the competition between polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs). At low DO levels, Accumulibacter PAOs were shown to have an advantage over Competibacter GAOs, as PAOs had a higher oxygen affinity and thus largely maintained their aerobic activity at low DO levels, while GAO activity decreased. Bioreactor operation at low DO levels was found to increase the PAO fraction of the sludge. Furthermore, an increase in aerobic HRT (at a DO level of 2 mg O-2/L), promoted the proliferation of GAOs over PAOs, decreasing the EBPR efficiency. Overall, this study shows that low aeration can be beneficial for EBPR performance through selecting for PAOs over GAOs, which should be incorporated into WWTP models in order to minimise energetic costs and improve WWTP sustainability. (C) 2014 Elsevier Ltd. All rights reserved

Distinctive denitrifying capabilities lead to differences in N2O production by denitrifying polyphosphate accumulating organisms and denitrifying glycogen accumulating organisms

This study aims at investigating the denitrification kinetics in two separate enriched cultures of denitrifying polyphosphate accumulating organisms (dPAO) and denitrifying glycogen accumulating organisms (dGAO) and compare their N2O accumulation potential under different conditions. Two sequencing batch reactors were inoculated to develop dPAO and dGAO enriched microbial communities separately. Seven batch tests with different combinations of electron acceptors (nitrate, nitrite and/or nitrous oxide) were carried out with the enriched biomass from both reactors. Results indicate that in almost all batch tests, N2O accumulated for both cultures, however dPAOs showed a higher denitrification capacity compared to dGAOs due to their higher nitrogen oxides reduction rates. Additionally, the effect of the simultaneous presence of several electron acceptors in the reduction rates of the different nitrogen oxides was also assessed in dPAOs and dGAOsThis study was funded by the Spanish Government (MINECO) (CTM 2011-27163 and CTM 2015-66892-R), the European Commission (FP7-PEOPLE-2011-CIG 303946) and the Portuguese Fundação para a Ciência e Tecnologia (PTDC/AACAMB/12058/2010, UID/Multi/04378/2013 , PhD grant SFRH/BD/74515/2010). Spanish and Portuguese Governments are acknowledged for Acciones Integradas (PRIAIBPT- 2011-1232) and Luso-Espanhola action E-61/12. The European Commission is also acknowledged through COST action ES1202 (Water 2020). M. Pijuan and A. Ribera-Guardia acknowledge the Ramon y Cajal research fellowship (RYC-2009-04959) and the FPIPhD grant (BES-2012-052753) respectively provided by the Spanish Governmen

Deletion of 17p13 and LIS1 gene mutation in isolated lissencephaly sequence

Classical lissencephaly is a neuroblast migration disorder that occurs either as isolated lissencephaly sequence or in association with malformation syndromes, such as the Miller-Dieker syndrome. in this work, alterations of the LIS1 gene in patients diagnosed as having isolated lissencephaly sequence were investigated. Ten patients were evaluated for the following aspects: classical cytogenetics by karyotyping using solid staining and G-banding; molecular cytogenetics using fluorescent in situ hybridization with a specific probe for the critical region of isolated lissencephaly sequence; and molecular analysis using deoxyribonucleic acid sequencing. Classical cytogenetic analysis indicated apparently normal karyotypes in all patients, but fluorescent in situ hybridization revealed a 17p13.3 microdeletion in one. in another patient, deoxyribonucleic acid sequencing disclosed a 1 base pair insertion in exon 4 within a sequence of eight consecutive adenine residues (162-163insA), a mutation that predicts a truncated protein. Two different polymorphisms were also detected: a T > C substitution in intron 6 (c.568 + 27bp T > C) and a C > T substitution in the nontranslated region of exon 11 (1250 C > T). These results indicate that cytogenetic analysis and molecular investigation of the LIS1 gene are not always sufficient to determine the disease etiology. These findings are consistent with previous studies and suggest the involvement of other genes in cortical malformation. (c) 2006 by Elsevier Inc. All rights reserved.Universidade Federal de São Paulo, Dept Morfol, Disciplina Genet, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Diagnost Imagen, BR-04023900 São Paulo, BrazilUniv Cuiaba, Fac Med, Disciplina Embriol, Cuiaba, BrazilUniversidade Federal de São Paulo, Dept Morfol, Disciplina Genet, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Diagnost Imagen, BR-04023900 São Paulo, BrazilWeb of Scienc

Determination of the extraction kinetics for the quantification of polyhydroxyalkanoate monomers in mixed microbial systems

For the first time, a systematic approach was conducted to determine the key factors influencing the kinetics of hydroxyalkanote (HA) extraction in biological systems. Six mixed microbial systems where polyhydroxyalkanoate (PHA) is produced were evaluated. Experiments were carried out for full-scale and lab-scale activated sludge systems using different configurations (containing floccular or granular sludge), as well as specific PHA accumulating cultures that contain high or low intracellular PHA fractions. The overall reaction was limited by the kinetics of the PHA hydrolysis in floccular cultures, whereas in granular cultures, it was limited by the cell lysis step. The monomeric composition of the polymer also had an impact on the HA extraction rate: higher acid concentration and a longer digestion time should be employed when cells accumulate monomers with more substituents, such as hydroxy-2-methylbutyrate (H2MB) and hydroxy-2-methylvalerate (H2MV). This study optimised the method for HA extraction, which impacts the assessment of the quantity and quality of PHA biopolymers