María-José Bonete

University of Alicante | UA · Department of Agrochemistry and Biochemistry

Since the Industrial Revolution, nearly 700 Gt of carbon (GtC) have been emitted into the atmosphere as CO2 derived from human activities, of which 292 GtC remain uncontrolled. By the end of this century, the atmospheric CO2 concentration is predicted to surpass 700 ppm. The effects of this sudden carbon release on the worldwide biogeochemical cycl...

Since the Industrial Revolution, nearly 700 GtC of carbon have been emitted into the atmosphere as CO2 derived from human activities, of which 292 GtC remain uncontrolled. Furthermore, the emission rate is increasing yearly, with the latest value (2022) of 11 GtC. By the end of this century, the atmospheric CO2 concentration is predicted to surpass...

Phycocyanobilin (PCB) is a small chromophore found in certain phycobiliproteins, such as phycocyanins (PCs) and allophycocyanins (APCs). PCB, along with other phycobilins (PBs) and intermediates such as biliverdin (BV) or phycoerythrobilin (PEB), is attracting increasing biotechnological interest due to its fluorescent and medicinal properties that...

Tanning, crucial for leather production, relies heavily on chromium yet poses risks due to chromium’s oxidative conversion, leading to significant wastewater and solid waste generation. Physico-chemical methods are typically used for heavy metal removal, but they have drawbacks, prompting interest in eco-friendly biological remediation techniques l...

Tanning, crucial for leather production, relies heavily on chromium yet poses risks due to chromium's oxidative conversion, leading to significant wastewater and solid waste generation. Physico-chemical methods are typically used for heavy metal removal, but they have drawbacks, prompting interest in eco-friendly biological remediation techniques l...

Haloarchaea, like many other microorganisms, have developed defense mechanisms such as universal stress proteins (USPs) to cope with environmental stresses affecting microbial growth. Despite the wide distribution of these proteins in Archaea, their biochemical characteristics still need to be discovered, and there needs to be more knowledge about...

The Sm protein superfamily includes Sm, like-Sm (Lsm), and Hfq found in the Eukarya, Archaea, and Bacteria domains. Archaeal Lsm proteins have been shown to bind sRNAs and are probably involved in various cellular processes, suggesting a similar function in regulating sRNAs by Hfq in bacteria. Moreover, archaeal Lsm proteins probably represent the...

The Sm protein superfamily includes Sm, like-Sm (Lsm), and Hfq proteins. Sm and Lsm proteins are found in the Eukarya and Archaea domains, respectively, while Hfq proteins exist in the Bacteria domain. Even though Sm and Hfq proteins have been extensively studied, archaeal Lsm proteins still require further exploration. In this work, different bioi...

Archaea are microorganisms with great ability to colonize some of the most inhospitable environments in nature, managing to survive in places with extreme characteristics for most microorganisms. Its proteins and enzymes are stable and can act under extreme conditions in which other proteins and enzymes would degrade. These attributes make them ide...

The Archaea domain consists of a heterogeneous group of microorganisms with unique physiological properties that occupy a wide variety of niches in nature. Haloferax mediterranei is an extremely halophilic archaeon classified in the Phylum Euryarchaeota, which requires a high concentration of inorganic salts for optimal growth. In haloarchaea, tran...

Halophilic archaea represent a promising natural source of carotenoids. However, little information is available about these archaeal metabolites and their biological effects. In the present work, carotenoids of strains Haloferax sp. ME16, Halogeometricum sp. ME3 and Haloarcula sp. BT9, isolated from Algerian salt lakes, were produced, extracted an...

The genome of the halophilic archaea Haloferax mediterranei contains three ORFs that show homology with glutamine synthetase (GS) (glnA-1, glnA-2, and glnA-3). Previous studies have focused on the role of GlnA-1, suggesting that proteins GlnA-2 and GlnA-3 could play a different role to that of GS. Glutamine synthetase (EC 6.3.1.2) belongs to the cl...

Haloferax mediterranei is an extremely halophilic archaeon, able to live in hypersaline environments with versatile nutritional requirements, whose study represents an excellent basis in the field of biotechnology. The transcriptional machinery in Archaea combines the eukaryotic basal apparatus and the bacterial regulation mechanisms. However, litt...

Non-coding small RNAs (sRNAs) regulate a wide range of physiological processes in microorganisms that allow them to rapidly respond to changes in environmental conditions. sRNAs have predominantly been studied in a few model organisms, however it is becoming increasingly clear that sRNAs play a crucial role in environmentally relevant pathways. Sev...

The Sm, like-Sm, and Hfq proteins belonging to the Sm superfamily of proteins are represented in all domains of life. These proteins are involved in several RNA metabolism pathways. The functions of bacterial Hfq and eukaryotic Sm proteins have been described, but knowledge about the in vivo functions of archaeal Sm proteins remains limited. This s...

The assimilatory pathway of the nitrogen cycle in the haloarchaeon Haloferax mediterranei has been well described and characterized in previous studies. However, the regulatory mechanisms involved in the gene expression of this pathway remain unknown in haloarchaea. This work focuses on elucidating the regulation at the transcriptional level of the...

Haloarchaea can survive and thrive under exposure to a wide range of extreme environmental factors, which represents a potential interest to biotechnology. Growth responses to different stressful conditions were examined in the haloarchaeon Haloferax mediterranei R4. It has been demonstrated that this halophilic archaeon is able to grow between 10...

Over the years, in order to survive in their natural environment, microbial communities have acquired adaptations to nonoptimal growth conditions. These shifts are usually related to stress conditions such as low/high solar radiation, extreme temperatures, oxidative stress, pH variations, changes in salinity, or a high concentration of heavy metals...

The regulatory networks involved in the uptake and metabolism of different nitrogen sources in response to their availability are crucial in all organisms. Nitrogen metabolism pathways have been studied in detail in archaea such as the extreme halophilic archaeon Haloferax mediterranei. However, knowledge about nitrogen metabolism regulation in hal...

Glutamine synthetase is an essential enzyme in ammonium assimilation and glutamine biosynthesis. The Haloferax mediterranei genome has two other glnA-type genes (glnA2 and glnA3) in addition to the glutamine synthetase gene glnA. To determine whether the glnA2 and glnA3 genes can replace glnA in nitrogen metabolism, we generated deletion mutants of...

A set of 110 extremely halophilic archaeal strains were isolated from seven distinct saline habitats located in different regions of Algeria. The physicochemical characterization of the samples showed that these habitats were thalassohaline. The carotenoid production from isolated strains varied from 0.1 to 3.68 µg/ml. Based on their physiological...

Several amylolytic activities have been isolated from a controlled growing media containing starch and nitrate or ammonium acetate as a carbon and energy source, excreted by the halophilic archaeon Haloferax mediterranei. These enzymes produced in nitrate-containing medium were different from those produced by the organism when cultured in ammonium...

Small RNAs have been studied in detail in domains Bacteria and Eukarya but, in the case of the domain Archaea, the knowledge is scarce and the physiological function of these small RNAs (sRNAs) is still uncertain. To extend the knowledge of sRNAs in the domain Archaea and their possible role in the regulation of the nitrogen assimilation metabolism...

Biotechnological processes, and in general industrial processes, require in many cases the use of catalysers able to work at extreme conditions in terms of temperature, ionic strength, pressure, extreme pHs or even in the presence of toxic/heavy metals. Several approaches have been explored so far involving the use of mesophilic enzymes isolated ma...

Denitrification is one of the most studied respiratory pathways because of its ecological importance, since it allows the return of fixed nitrogen to the atmosphere through the reduction of nitrates / nitrites of soils and water. However, the knowledge about this route is little in the case of environments considered extreme, which are characterise...

Microorganisms, including Bacteria and Archaea, play a key role in denitrification, which is the major mechanism by which fixed nitrogen returns to the atmosphere from soil and water. Whilst the enzymology of denitrification is well understood in Bacteria, the details of the last two reactions in this pathway, which catalyse the reduction of nitric...

Denitrification is the major mechanism by which fixed nitrogen returns to the atmosphere from soil and water and microorganisms play an important role in it. Denitrifying ability has been found in both domains Bacteria and Archaea, however, the last two reactions of this pathway have not been yet explored into detail in archaea in general, and in h...

Halophilic archaea belong to the third domain of life, which live and survive in a highly salty environment. Nitrate assimilation is one of the main processes of the N-cycle, allowing the use of NO3−, NO2− and/or NH4+ as N source for growth. This pathway in general termed “Assimilatory nitrate pathway or assimilatory nitrate reduction” includes not...

A number of species of Haloferax genus (halophilic archaea) are able to grow microaerobically or even anaerobically using different alternative electron acceptors such as fumarate, nitrate, chlorate, dimethyl sulphoxide, sulphide and/or trimethylamine. This metabolic capability is also shown by other species of the Halobacteriaceae and Haloferacace...

Stegophorus macronectes (Johnston & Mawson, 1942) is a gastrointestinal parasite found in Antarctic seabirds. The original description of the species, which was based only on females, is poor and fragmented with some unclear diagnostic characters. This study provides new morphometric and molecular data on this previously poorly described parasite....

The extreme conditions under which haloarchaea survive make them good bioremediation agents in water treatment processes and in saline and hypersaline environments contaminated with toxic compounds such as nitrate, nitrite and ammonia, chlorine compounds such as perchlorate and chlorate, heavy metals, and aromatic compounds. New advances in the und...

The production of pigments by halophilic archaea has been analysed during the last half a century. The main reasons that sustains this research are: (i) many haloarchaeal species possess high carotenoids production availability; (ii) downstream processes related to carotenoid isolation from haloarchaea is relatively quick, easy and cheap; (iii) car...

Wastewater treatments (WWT) rely on microorganisms to perform the breakdown of sewage influent. Modern biological treatments of wastewater involve not only carbon removal, but also elimination of other nutrients such as nitrogen. Although the importance of eukaryotic and bacterial organisms in these processes has long been recognized, the role play...

Microorganisms belonging to the Archaea Domain constitute a major part of microbial populations in many types of very hostile environments. As a result, they play a crucial role in regulating global budgets of atmospheric gases in such environments. Archaeal methane production and consumption have received substantial investigation, however, knowle...

Objectives: 1) to propose a new classification of the trace elements based on a study of the recently reported research; 2) to offer detailed and actualized information about trace elements. Results: the analysis of the research results recently reported reveals that the advances of the molecular analysis techniques point out the importance of cert...

Unlabelled: To obtain insights into archaeal nitrogen signaling and haloadaptation of the nitrogen/carbon/energy-signaling protein PII, we determined crystal structures of recombinantly produced GlnK2 from the extreme halophilic archaeon Haloferax mediterranei, complexed with AMP or with the PII effectors ADP or ATP, at respective resolutions of 1...

Glutamate synthase (GOGAT) is one of the two important enzymes involved in the ammonium assimilation pathway glutamine synthetase (GS)/GOGAT, which enables Hfx. mediterranei to thrive in media with low ammonium concentration or containing just nitrate as single nitrogen source. The gene coding for this enzyme, gltS, has been sequenced, analysed and...

The haloarchaeon Haloferax mediterranei is able to grow in a defined culture media not only in the presence of inorganic nitrogen salt but also with amino acid as the sole nitrogen source. Assimilatory nitrate and nitrite reductases respectively catalyze the first and second reactions,. The genes involved in this process are: nasA, which encodes ni...

Gene homologs of GlnK PII regulators and AmtB-type ammonium transporters are often paired on prokaryotic genomes, suggesting these proteins share an ancient functional relationship. Here, we demonstrate for the first time in Archaea that GlnK associates with AmtB in membrane fractions after ammonium shock, thus, providing a further insight into Gln...

In this work we report for the first time a post-translational modification of PII homologues from the Archaea Domain. Haloferax mediterranei is the first haloarchaea whose PII proteins have been studied, it possesses two of them (GlnK(1) and GlnK(2) ), both encoded adjacent to a gene for the ammonia transporter Amt. An approach based on two-dimens...

The green Cu-NirK from Haloferax mediterranei (Cu-NirK) has been expressed, refolded and retrieved as a trimeric enzyme using an expression method developed for halophilic Archaea. This method utilizes Haloferax volcanii as a halophilic host and an expression vector with a constitutive and strong promoter. The enzymatic activity of recombinant Cu-N...

RESUMEN (ABSTRACT) El objetivo de este estudio es analizar el grado de aprovechamiento académico y satisfacción de los alumnos del grupo de Alto Rendimiento Académico (en adelante ARA) en la asignatura Bioquímica I del primer curso del Grado en Biología, título que se encuentra adscrito a la Facultad de Ciencias de la Universidad de Alicante. Esta...

GlnK proteins belong to the PII superfamily of signal transduction proteins and are involved in the regulation of nitrogen metabolism. These proteins are normally encoded in an operon together with the structural gene for the ammonium transporter AmtB. Haloferax mediterranei possesses two genes encoding for GlnK, specifically, glnK(1) and glnK(2)....

The past decade has seen a rekindling of interest in extreme microorganisms isolated from ancient evaporates and salty environments such as multipond salterns (which are usually semi-artificial coastal or inland systems), marshes or salted lakes. From a practical point of view, there is concern that viable microbial communities in salt deposits cou...

Haloferax mediterranei is a denitrifying halophilic archaeon able to reduce nitrate and nitrite under oxic and anoxic conditions. In the presence of oxygen, nitrate and nitrite are used as nitrogen sources for growth. Under oxygen scarcity, this haloarchaeon uses both ions as electron acceptors via a denitrification pathway. In the present work, th...

A cyclodextrin glycosyltransferase (CGTase, EC 2.4.1.19) was successfully isolated and characterized from the halophilic archaeon Haloferax mediterranei. The enzyme is a monomer with a molecular mass of 77 kDa and optimum activity at 55°C, pH 7.5 and 1.5 M NaCl. The enzyme displayed many activities related to the degradation and transformation of s...

In the absence of ammonium, many organisms, including the halophilic archaeon Haloferax volcanii DS2 (DM3757), may assimilate inorganic nitrogen from nitrate or nitrite, using a ferredoxin-dependent assimilatory NO₃⁻/NO₂⁻ reductase pathway. The small acidic ferredoxin Hv-Fd plays an essential role in the electron transfer cascade required for assim...

During the past few decades, the microbial communities inhabiting extreme environments have become a focus on scientific interest owing to the unique properties of the biocatalysts they produce (extremozymes). These extremozymes can cope with industrial process conditions (high temperatures, high salt concentrations, low water availability, etc.) d...

Haloferax mediterranei is an extreme halophilic micro-organism belonging to the Archaea domain that was isolated from the Santa Pola solar salterns (Alicante, Spain) in 1983. The biochemistry of the proteins involved in nitrogen metabolism is being studied, but the knowledge of their regulation is very scarce at present. The PII superfamily is cons...

The extraction of salt from seawater by means of coastal solar salterns is a very well-described process. Moreover, the characterization of these environments from ecological, biochemical and microbiological perspectives has become a key focus for many research groups all over the world over the last 20 years. In countries such as Spain, there are...

La presente memoria de investigación recoge los resultados del grupo de trabajo de la Red Elaboración de la guía docente de la asignatura Iniciación a la Investigación por todos los departamentos con docencia en la misma, del Proyecto Redes de Investigación en Docencia Universitaria 2010, presentado en la Modalidad I: Redes de Investigación en Doce...

Haloferax mediterranei is a denitrifier haloarchaeon able to reduce nitrate under anoxic conditions. The first reaction of this pathway is catalyzed by the respiratory nitrate reductase (Nar), a membranebound protein recently described as a respiratory nitrate reductase belonging to the pNar group. ‘Bacterial’ Nar system is oriented such that nitra...

Structural analysis of glucose dehydrogenase from Haloferax mediterranei revealed that the adenosine 2′-phosphate of NADP+ was stabilized by the side chains of Arg207 and Arg208. To investigate the structural determinants for coenzyme specificity, several mutants involving residues Gly206, Arg207 and Arg208 were engineered and kinetically character...

The haloarchaeon Haloferax mediterranei is able to assimilate nitrate or nitrite using the assimilatory nitrate pathway. An assimilatory nitrate reductase (Nas) and an assimilatory nitrite reductase (NiR) catalyze the first and second reactions, respectively. The genes involved in this process are transcribed as two messengers, one polycistronic (n...

Haloferax mediterranei is a denitrifying halophilic archaeon, able to assimilate nitrate or nitrite in the presence of oxygen by the assimilatory nitrate pathway. It can also grow in the presence of high nitrate or nitrite concentrations under anoxic conditions, using both nitrogen species as electron acceptors. In this study, the ability of H. med...

The kinetic mechanism of NADP-glutamate dehydrogenase (EC 1.4.1.4) from the Archaeon Haloferax mediterranei was studied in 3 M KC1 and in glycerol. Haloferax mediterranei is a halophilic organism requiring 20-25% NaCl for optimal growth, so its enzymes are stabilised by high salt concentrations. We have replaced the salt by 20% (v/v) glycerol in or...

Reverse micelles were used as a cytoplasmic model to study the kinetics of an extreme halophilic enzyme such as the recombinant glucose dehydrogenase from the Archaeon Haloferax mediterranei. This enzyme was solubilized in reverse micelles of hexadecyltrimethylammoniumbromide in cyclohexane, with 1-butanol as co-surfactant. Glucose dehydrogenase re...

Fig. 1 Supplemental Thin layer chromatography for the degradation reaction of AMY2 and AMY3 on starch, maltotriose and maltohexose. S, G, M, T y H: starch, glucose, maltose, maltotriose and maltohexaose standars. S2 and H2: degradation of starch and maltohexaose by AMY2. S3 and H3: degradation of starch and maltohexaose by AMY3. S3a, S3b, S3c, S3d:...

Three different amylolytic activities, designated AMY1, AMY2, and AMY3 were detected in the cytoplasm of the extreme halophilic archaeon Haloferax mediterranei grown in a starch containing medium. This organism had also been reported to excrete an alpha-amylase into the external medium in such conditions. The presence of these different enzymes whi...

Despite being the subject of intensive investigations, many aspects of the mechanism of the zinc-dependent medium chain alcohol dehydrogenase (MDR) superfamily remain contentious. We have determined the high-resolution structures of a series of binary and ternary complexes of glucose dehydrogenase, an MDR enzyme from Haloferax mediterranei. In star...

Avances en el metabolismo de nitrógeno: De la genómica y la proteómica a las aplicaciones agronómicas, industriales y medioambientales