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Yadira Rodríguez Silvia García Raquel Lebrero Raúl Muñoz 《Biotechnology and bioengineering》2023,120(11):3224-3233
Biogas biorefineries have opened up new horizons beyond heat and electricity production in the anaerobic digestion sector. Added-value products such as polyhydroxyalkanoates (PHAs), which are environmentally benign and potential candidates to replace conventional plastics, can be generated from biogas. This work investigated the potential of an innovative two-stage growth-accumulation system for the continuous production of biogas-based polyhydroxybutyrate (PHB) using Methylocystis hirsuta CSC1 as cell factory. The system comprised two turbulent bioreactors in series to enhance methane and oxygen mass transfer: a continuous stirred tank reactor (CSTR) and a bubble column bioreactor (BCB) with internal gas recirculation. The CSTR was devoted to methanotrophic growth under nitrogen balanced growth conditions and the BCB targeted PHB production under nitrogen limiting conditions. Two different operational approaches under different nitrogen loading rates and dilution rates were investigated. A balanced nitrogen loading rate along with a dilution rate (D) of 0.3 day−1 resulted in the most stable operating conditions and a PHB productivity of ~53 g PHB m−3 day−1. However, higher PHB productivities (~127 g PHB m−3 day−1) were achieved using nitrogen excess at a D = 0.2 day−1. Overall, the high PHB contents (up to 48% w/w) obtained in the CSTR under theoretically nutrient balanced conditions and the poor process stability challenged the hypothetical advantages conferred by multistage vs single-stage process configurations for long-term PHB production. 相似文献
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ABSTRACT:?The market for microbial biopolymers is currently expanding to include several emerging biomedical applications. Specifically, these applications are drug delivery and wound healing. A fundamental understanding of the key fermentation parameters is necessary in order to optimize the production of these biopolymers. Considering that most microbial biopolymer systems exhibit non-Newtonian rheology, oxygen mass transfer can be an important parameter to optimize and control. In this article, we present a critical review of recent advances in rheological and mass transfer characteristics of selected biopolymers of commercial interest in biomedical applications. 相似文献
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Marcos R. Betancourt 《Biopolymers》2016,105(6):312-323
Bond‐orientational correlations for finite‐length homopolypeptides and a selected group of denatured proteins are obtained by numerical simulations using a polypeptide model with a potential of mean force. These correlations characterize the stiffness of the polypeptide backbone and are generally described by either an exponential or a power‐law decay in the asymptotic limit. However, for finite length polypeptides and unfolded proteins the correlations significantly deviate from either single exponential or power‐law behavior. A heuristic model is developed to analyze the correlations of homopolypeptides, which depends on the chain length and the side‐chain properties. The model contains power‐law and multi‐exponential terms, the latter which could be interpreted as local persistence lengths. In the asymptotic limit, the model reduces to the expected power‐law behavior. Simulations of denatured proteins show that the power‐law behavior of the correlations is significantly suppressed and only the multi‐exponential term is needed to model the correlations. In addition, average persistence lengths (ranging from 2.0 to 2.5 nm) are obtained from the correlations by fitting single exponentials and shown to be in general agreement with experiments, which also assume single exponential decay. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 312–323, 2016. 相似文献
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The evolution of petroleum‐derived polymers is one of the crowning accomplishments of the past century. Although the significant economic gains from this industrial model of resource utilization are achieved, the environmental impacts are fatal. One of the principles of sustainable development is to replace such polymers with potential alternatives derived from renewable materials. Biopolymers derived from natural resources afford a new, versatile, environmentally benign feedstock that could exhibit closed‐loop life cycles as part of a future material's industrial ecology. However, the solubility and processability of biopolymer materials provoke a serious bottleneck owing to their dense networks of inter ‐ and intramolecular bondings and structural heterogeneity. Recently, ionic liquids (ILs) have emerged as promising green solvents and acquired augmented appreciation for their peerless power of biopolymer processing. Among the fourteen principle of green chemistry, the two key elements encourage the exploitation of renewable raw materials by using environmentally benign solvents that cover in dissolution of biopolymers using ILs. This mini review represents a brief overview of the comprehensive ILs assisted extraction and processing of various biopolymeric materials for value‐added applications. 相似文献
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Silvia Barbi Massimo Messori Tiziano Manfredini Martina Pini Monia Montorsi 《Biopolymers》2019,110(5):e23250
In this study proteins extracted from prepupae of Hermetia illucens, also known as black soldier fly, are investigated as promising base for a new type of bioplastics for agricultural purposes. Design of experiments techniques are employed to perform a rational study on the effects of different combination of glycerol as plasticizer, citric acid as cross-linking agent and distilled water as solvent on the capability of proteins to form a free-standing film through casting technique, keeping as fixed the quantity of proteins. Glycerol shows interesting properties as plasticizer contributing to the formation of homogenous and free-standing film. Moreover, mechanical and thermal characterizations are performed to estimate the effect of increasing amounts of proteins on the final properties and thickness of the specimens. Proteins derived from H. illucens can be successfully employed as base for bioplastics to be employed for agricultural purposes. 相似文献
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Mazza CB Rege K Breneman CM Sukumar N Dordick JS Cramer SM 《Biotechnology and bioengineering》2002,78(1):60-72
The stability and structure of protein-containing water-in-oil (w/o) microemulsions were investigated by using the large protein immunoglobulin G (IgG, MW 155,000) in a mixture comprised of brine, sulfosuccinic acid bis [2-ethylhexyl]ester (sodium salt), and isooctane. We explored factors affecting the initial uptake of IgG into the w/o microemulsion and its subsequent release to a solid (precipitate) phase, and the kinetics of the latter process. Influences of such parameters as pH, ionic strength, and protein concentration on the solubilization and precipitation of bovine IgG in the organic phase are described. The structure and dynamics in microemulsions containing bovine IgG were probed by using dynamic light scattering, and it was found that the presence of IgG in the microemulsion induced strong attractive forces between the droplets. Based on results obtained by using these various experimental approaches, a model for protein solubilization and release is proposed. In this model, we propose the formation of clusters within which bovine IgG resides and which substantially slow the kinetics of protein release from the droplets to the precipitate phase. 相似文献
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Belicová Anna Krajčovič Juraj Križková Lìvia Ebringer Libor Košíková Božena 《World journal of microbiology & biotechnology》2000,16(1):91-93
Sulphur-free lignin biopolymer and its oxidized and reduced derivatives have been prepared and their inhibitory activity against u.v.-induced mutagenesis in Euglena gracilis was evaluated. The structure- and dose-dependent anti-u.v. activity of lignins was observed at concentrations higher than 250gml–1. The oxidized lignin showed the most antimutagenic activity, followed by the reduced lignin and the unmodified lignin had the least antimutagenic activity. 相似文献
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S. Janette Williams Qun Wang Ronal R. MacGregor Teruna J. Siahaan Lisa Stehno‐Bittel Cory Berkland 《Biopolymers》2009,91(8):676-685
Dramatic reversal of Type 1 diabetes in patients receiving pancreatic islet transplants continues to prompt vigorous research concerning the basic mechanisms underlying patient turnaround. At the most fundamental level, transplanted islets must maintain viability and function in vitro and in vivo and should be protected from host immune rejection. Our previous reports showed enhancement of islet viability and insulin secretion per tissue mass for small islets (<125 μm) as compared with large islets (>125 μm), thus, demonstrating the effect of enhancing the mass transport of islets (i.e. increasing tissue surface area to volume ratio). Here, we report the facile dispersion of rat islets into individual cells that are layered onto the surface of a biopolymer film towards the ultimate goal of improving mass transport in islet tissue. The tightly packed structure of intact islets was disrupted by incubating in calcium‐free media resulting in fragmented islets, which were further dispersed into individual or small groups of cells by using a low concentration of papain. The dispersed cells were screened for adhesion to a range of biopolymers and the nature of cell adhesion was characterized for selected groups by quantifying adherent cells, measuring the surface area coverage of the cells, and immunolabeling cells for adhesion proteins interacting with selected biopolymers. Finally, beta cells in suspension were centrifuged to form controlled numbers of cell layers on films for future work determining the mass transport limitations in the adhered tissue constructs. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 676–685, 2009. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com 相似文献
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