Papers by Concepcion Jimenez-lopez
Food Chemistry, 2021
Given the growing tendency of consumers to choose products with natural ingredients, food industr... more Given the growing tendency of consumers to choose products with natural ingredients, food industries have directed scientific research in this direction. In this regard, algae are an attractive option for the research, since they can synthesize a group of secondary metabolites, called phenolic compounds, associated with really promising properties and bioactivities. The objective of this work was to classify the major phenolic compounds, compare the effectiveness of the different extractive techniques used for their extraction, from traditional systems (like heat assisted extraction) to the most advance ones (such as ultrasound, microwave or supercritical fluid extraction); the available methods for identification and quantification; the stability of the enriched extract in phenolic compounds and the main bioactivities described for these secondary metabolites, to offer an overview of the situation to consider if it is possible and/or convenient an orientation of phenolic compounds from algae towards an industrial application.
Antibiotics, 2020
The search for food resources is a constant in human history. Nowadays, the search for natural an... more The search for food resources is a constant in human history. Nowadays, the search for natural and safe food supplies is of foremost importance. Accordingly, there is a renewed interest in eco-friendly and natural products for substitution of synthetic additives. In addition, microbial contamination of food products during their obtaining and distribution processes is still a sanitary issue, and an important target for the food industry is to avoid food contamination and its related foodborne illnesses. These diseases are fundamentally caused by certain microorganisms listed in this review and classified according to their Gram negative or positive character. Algae have proven to possess high nutritional value and a wide variety of biological properties due to their content in active compounds. Among these capabilities, macroalgae are recognized for having antimicrobial properties. Thus, the present paper revises the actual knowledge of microbial contaminants in the food industry an...
Antimicrobial Defenses of Table Eggs: Importance of Antibacterial Proteins in Egg White as a Function of Hen Age in an Extended Production Cycle
Social Science Research Network, 2022
MRS Proceedings, 1999
Ab initio calculations on water dimer, trimer, Pm11 polymer, I41md prototype structure, and ice V... more Ab initio calculations on water dimer, trimer, Pm11 polymer, I41md prototype structure, and ice VIII shows that the dependence of the 0-H bond length upon the intermolecular distance mostly depends upon environmental e8'ects due to non-H-bonded molecules. The hydrogen bonds are found to be weaker in ice VIII and Pm11 polymer than in the I4&md structure. This result is consistent with recent experiments on He-H20 and H2-H20 clathrates and emphasizes the role of interactions between nonbonded molecules. These effects can be qualitatively understood by a simple dipoledipole electrostatic model.
Size control of in vitro synthesized magnetite crystals by the MamC protein of Magnetococcus marinus strain MC-1
Applied Microbiology and Biotechnology, Jan 21, 2015
Magnetotactic bacteria are a diverse group of prokaryotes that share the unique ability of biomin... more Magnetotactic bacteria are a diverse group of prokaryotes that share the unique ability of biomineralizing magnetosomes, which are intracellular, membrane-bounded crystals of either magnetite (Fe3O4) or greigite (Fe3S4). Magnetosome biomineralization is mediated by a number of specific proteins, many of which are localized in the magnetosome membrane, and thus is under strict genetic control. Several studies have partially elucidated the effects of a number of these magnetosome-associated proteins in the control of the size of magnetosome magnetite crystals. However, the effect of MamC, one of the most abundant proteins in the magnetosome membrane, remains unclear. In this present study, magnetite nanoparticles were synthesized inorganically in free-drift experiments at 25 °C in the presence of different concentrations of the iron-binding recombinant proteins MamC and MamCnts (MamC without its first transmembrane segment) from the marine, magnetotactic bacterium Magnetococcus marinus strain MC-1 and three commercial proteins [α-lactalbumin (α-Lac), myoglobin (Myo), and lysozyme (Lyz)]. While no effect was observed on the size of magnetite crystals formed in the presence of the commercial proteins, biomimetic synthesis in the presence of MamC and MamCnts at concentrations of 10-60 μg/mL resulted in the production of larger and more well-developed magnetite crystals (~30-40 nm) compared to those of the control (~20-30 nm; magnetite crystals grown protein-free). Our results demonstrate that MamC plays an important role in the control of the size of magnetite crystals and could be utilized in biomimetic synthesis of magnetite nanocrystals.
Chemical Purity of<i>Shewanella oneidensis</i>-Induced Magnetites
Geomicrobiology Journal, Sep 14, 2013
ABSTRACT Magnetite is a common iron oxide produced both inorganically and biogenically. Biologica... more ABSTRACT Magnetite is a common iron oxide produced both inorganically and biogenically. Biologically-induced magnetite is often originated, under appropriate conditions, as a result of the Fe3+ reduction by dissimilatory iron reducing bacteria, which are usually found in anoxic environments or at the oxic-anoxic interface. Such a Fe3+ bioreduction occurs upon this cation acting as an electron acceptor of an anaerobic respiration, thus creating favorable conditions for magnetite precipitation. This biologically-induced magnetite is an important biomineral in the environments inhabited by iron reducing bacteria. The presence of a variety of cations may influence both the biomineralization process and the resulting biomineral, however this phenomenon has not been investigated extensively. In the present study, we study the effect on the magnetite biomineralization process of the presence of calcium, magnesium and manganese in the culture medium where Shewanella oneidensis lives. We also test the incorporation of these cations into the crystalline structure of inorganic and biogenic magnetite induced by S. oneidensis. According to our findings, manganese ions likely become incorporated into the crystal structure of biologically produced magnetites, while magnesium ions are incorporated in inorganic magnetites, and calcium ions are excluded from the crystal structure of both inorganic and biotic magnetites. We hypothesize that the incorporation of cations into magnetite depends not only on the relative cation radii, but also on the mechanisms of magnetite formation.
Crystal Growth & Design, Jan 8, 2020
Magnetite nanoparticles (MNPs) are being used in a number of nanotechnological applications, 35 e... more Magnetite nanoparticles (MNPs) are being used in a number of nanotechnological applications, 35 especially biomedical, both in diagnosis and therapeutics such as hyperthermia agents and as drug 36 nanocarriers for targeted chemotherapy. However, the development of efficient methodologies to 37 produce novel MNPs with the specific requirements needed for biomedical applications is still 38 challenging. In this context, biomimetic approaches taking use of magnetosome proteins expressed 39 as recombinant and/or polyaminoacids are becoming of great interest. In fact, these protocols give 40 rise to magnetite nanoparticles of adequate size, magnetic properties and surface functionalization 41 Page 2 of 39 ACS Paragon Plus Environment Crystal Growth & Design that make them compatible for biomedical applications. In this respect, herein we show for the 42 first time that Lysine (Lys), unless other aminoacids like Arginine (Arg), is able to exert a control 43 over the size of MNPs produced in water and at room temperature. This control occurs through 44 the stabilization of the magnetite nuclei by the lateral ammonium group of Lys. The strength of 45 such stabilization allows a further release of these previously bonded nuclei to allow the further 46 growth of the larger ones, thus resulting in larger crystals compared to those obtained by using 47 48 (30 nm) while being superparamagnetic at room temperature. They present an isoelectric point of 49 4, which may allow the coupling/release of these MNPs to other molecules based on electrostatic 50 interaction, a large magnetic moment per particle and high magnetization saturation. This study 51 highlights the effects that biological additives have in the process of magnetite biomineralization 52 and goes in the line of previous reports using magnetosome proteins and polyaminoacids.
Bioprotection
Encyclopedia of earth sciences, 2011
Journal of Materials Chemistry B, 2020
Geochimica et Cosmochimica Acta, Jun 1, 2012
It has never been demonstrated whether magnetite synthesized through the heat-dependent decomposi... more It has never been demonstrated whether magnetite synthesized through the heat-dependent decomposition of carbonate precursors retains the chemical and structural features of the carbonates. In this study, synthetic (Ca,Mg,Fe)CO 3 was thermally decomposed by heating from 25 to 700°C under 1 atm CO 2 , and by in situ exposure under vacuum to the electron beam of a transmission electron microscope. In both cases, the decomposition of the carbonate was topotactic and resulted in porous pseudomorphs composed of oriented aggregates of magnetite nanocrystals. Both calcium and magnesium were incorporated into nanophase magnetite, forming (Ca,Mg)-magnetites and (Ca,Mg)-ferrites when these elements were present in the parent material, thus preserving the chemical signature of the precursor. These results show that magnetites synthesized in this way acquire a chemical and structural inheritance from their carbonate precursor that indicates how they were produced. These results are not only important in the determination of the origin of chemically-impure, oriented nanophase magnetite crystals in general, but they also provide important insights into the origin of the large, euhedral, chemically-pure, [111]elongated magnetites found within Ca-, Mg-and Fe-rich carbonates of the Martian meteorite ALH84001. Based on our experimental results, the chemically-pure magnetites within ALH84001 cannot be genetically related to the Ca-, Mg-and Fe-rich carbonate matrix within which they are embedded, and an alternative explanation for their occurrence is warranted.
Magnetite Mineralization inside Cross-Linked Protein Crystals
Crystal Growth & Design, Apr 28, 2023
Antibacterial directed chemotherapy using AS-48 peptide immobilized on biomimetic magnetic nanoparticles combined with magnetic hyperthermia
International Journal of Biological Macromolecules, Oct 1, 2021
The design of new strategies to increase the effectiveness of the antibacterial treatments is a m... more The design of new strategies to increase the effectiveness of the antibacterial treatments is a main goal in public health. So, the aim of the study was to achieve a local antibacterial directed therapy as novel alternative allowing both, the delivery of the drug at the target, while minimizing undesirable side effects, thus anticipating an enhanced effectiveness. Hence, we have developed an innovative nanoformulation composed by biomimetic magnetic nanoparticles functionalized with the antimicrobial peptide AS-48 and its potential against Gram-positive and Gram-negative bacteria, either by itself or combined with magnetic hyperthermia has been investigated. Besides, the physical properties, binding efficiency, stability and mechanism of action of this nanoassembly are analyzed. Remarkably, the nanoassembly has a strong bactericidal effect on Gram-positive bacteria, but surprisingly also on E. coli and, finally, when combined with magnetic hyperthermia, on P. aeruginosa and K. pneumoniae. The results obtained represent a breakthrough since it allows a local treatment of infections, reducing and concentrating the dose of antimicrobial compounds, avoiding secondary effects, including the resistance generation and particularly because the combination with magnetic hyperthermia helps sensitizing resistant bacteria to the bactericidal effect of AS-48. Thus, this new formulation should be considered a promising tool in the antibacterial fight.
Development and characterization of magnetic eggshell membranes for lead removal from wastewater
Ecotoxicology and Environmental Safety, Apr 1, 2020
An increasing concern for natural resources preservation and environmental safety is the removal ... more An increasing concern for natural resources preservation and environmental safety is the removal of heavy metals from contaminated water. It is essential to develop simple procedures that use ecofriendly materials with high removal capacities. In this context, we have synthesized a new hybrid material in which eggshell membranes (ESMs) act as nucleation sites for magnetite nanoparticles (MNPs) precipitation in the presence of an external magnetic field. As a result, ESM was transformed into a magnetic biomaterial (MESM) in order to combine the Pb adsorption abilities of both MNPs and ESM and to facilitate collection of the bioadsorbant using an external magnetic field. This green co-precipitation method produced long strands of bead-like 50 nm superparamagnetic MNPs decorating the ESM fibers. When MESM were incubated in Pb(NO3)2 solutions, the hybrid material displayed a 2.5-fold increase in binding constant with respect to that of ESM alone, and a 10-fold increased capacity to remove Pb ions from aqueous solution. The manufactured MESMs present a maximum loading capacity of 0.066 ± 0.009 mg Pb/mg MNPs at 25 °C, which is increased up to 0.15 ± 0.05 mg Pb/mg MNPs at 45 °C. Moreover, the MESM system is very stable, since incubation in 1% HCl solution resulted in rapid Pb desorption, while MNP release from the MESM during the same period was negligible. Altogether, these results suggest that MESM could be utilized as an efficient nanoremediation agent for separation/removal of heavy metal ions or other charged pollutants from contaminated waters, with facile recovery for recycling.
Journal of Structural Biology, Nov 1, 2016
the role of magnetosome associated proteins on the in vitro synthesis of magnetite nanoparticles ... more the role of magnetosome associated proteins on the in vitro synthesis of magnetite nanoparticles has gained interest, both to obtain a better understanding of the magnetosome biomineralization process and to be able to produce novel magnetosome-like biomimetic nanoparticles. Up to now, only one recombinant protein has been used at the time to in vitro form biomimetic magnetite precipitates, being that a scenario far enough from what probably occurs in the magnetosome. In the present study, both Mms6 and MamC from Magnetococcus marinus MC-1 have been used to in vitro form biomimetic magnetites. Our results show that MamC and Mms6 have different, but complementary, effects on in vitro magnetite nucleation and growth. MamC seems to control the kinetics of magnetite nucleation while Mms6 seems to preferably control the kinetics for crystal growth. Our results from the present study also indicate that it is possible to combine both proteins to tune the properties of the resulting biomimetic magnetites. In particular, by changing the relative ratio of these proteins, better faceted and/or larger magnetite crystals with, consequently, different magnetic moment per particle could be obtained. this study provides with tools to obtain new biomimetic nanoparticles with a potential utility for biotechnological applications.
Subcellular localization of the magnetosome protein MamC in the marine magnetotactic bacterium Magnetococcus marinus strain MC-1 using immunoelectron microscopy
Archives of Microbiology, Apr 24, 2014
Magnetite as a prokaryotic biomarker: A review
Journal of Geophysical Research, Apr 22, 2010
Geochimica et Cosmochimica Acta, Mar 1, 2007
Myxococcus xanthus, a common soil bacterium, plays an active role in the formation of spheroidal ... more Myxococcus xanthus, a common soil bacterium, plays an active role in the formation of spheroidal vaterite. Bacterial production of CO 2 and NH 3 and the transformation of the NH 3 to NH 4 þ and OH À , thus increasing solution pH and carbonate alkalinity, set the physicochemical conditions (high supersaturation) leading to vaterite precipitation in the microenvironment around cells, and directly onto the surface of bacterial cells. In the latter case, fossilization of bacteria occurs. Vaterite crystals formed by aggregation of oriented nanocrystals with c-axis normal to the bacterial cell-wall, or to the core of the spherulite when bacteria were not encapsulated. While preferred orientation of vaterite c-axis appears to be determined by electrostatic affinity (ionotropic effect) between vaterite crystal (0001) planes and the negatively charged functional groups of organic molecules on the bacterium cell-wall or on extracellular polymeric substances (EPS), analysis of the changes in the culture medium chemistry as well as high resolution transmission electron microscopy (HRTEM) observations point to polymorph selection by physicochemical (kinetic) factors (high supersaturation) and stabilization by organics, both connected with bacterial activity. The latter is in agreement with inorganic precipitation of vaterite induced by NH 3 and CO 2 addition in the protein-rich sterile culture medium. Our results as well as recent studies on vaterite precipitation in the presence of different types of bacteria suggest that bacterially mediated vaterite precipitation is not strain-specific, and could be more common than previously thought.
MBP-MamC magnetite-interaction component mutant-D70A
Física de la tierra, Nov 30, 2016
The suggestion in 1996 that the Martian meteorite ALH84001 could contain proof of possible biolog... more The suggestion in 1996 that the Martian meteorite ALH84001 could contain proof of possible biologic activity in the past have generated a huge controversy that last until today. One of the most discussed evidence is the presence of magnetite crystals that resemble those produced by a particular group of bacteria, the so called magnetotactic bacteria (MTB). These microorganisms are the only known example of biologically controlled biomineralization among the prokaryotes and exert an exquisite control over the biomineralization process of intracellular magnetite that result in crystals with very unique features that, so far, cannot be replicated by inorganic means. These unique features have been used to recognize the biological origin of natural terrestrial magnetites, but the problem arises when those same biogenecity criteria are applied to extraterrestrial magnetites. Most of the problems are caused by the fact that it is not clear whether or not some of those characteristics can be reproduced inorganically. Magnetosome protein mediated magnetite synthesis seems to be the best approach to obtain magnetosome-like magnetites, and such strategy may help clarify what is the specific biosignature of magnetotactic bacteria.
Crystals, Jul 28, 2021
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
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Papers by Concepcion Jimenez-lopez