Juan Miguel González Grau


Dr. Juan Miguel González Grau

Investigador científico
Departamento Biogeoquímica, Ecología Vegetal y Microbiana
Instituto de Recursos Naturales y Agrobiología de Sevilla CSIC
Avenida Reina Mercedes 10
c.p. 41080 – Sevilla (Spain)
tel: +34 95 462 47 11 Ext. 146
fax: +34 95 462 40 02

e-mail: jmgrau<at>irnase.csic.es

The great majority of life on Earth is microscopic in size, and it is only visible through the microscope. Microbes are everywhere and they inhabit any environment, from very cold (below 0°C) to very hot (above 100°C) places, from very acidic to very alkaline sites, or high saline concentration, high pressure, or any other environment that might not look normal to humans. Microorganisms thriving under extreme conditions are the extremophiles.

This variable selection of systems is reflected by the huge diversity exiting in the microbial world. Currently, the level of microbial diversity on Earth is a topic of debate. While many microorganisms can easily be dispersed across the planet, the so called extreme environments present a selective factor for the living beings to develop in them. Thus, extreme environments can be considered as ideal model systems for studying ecological properties of microorganisms, their physiology, adaptative properties and many other characteristics related to microbial communities and specific microbial cells.

Due to the small size of microbes, working with them is not an easy task. Microscopic examination is required to see them. Classical microbiological studies required the ability to growth the microorganisms in the laboratory to be able to study their properties, such as growth conditions, nutrient sources, metabolic products, and so on. We now know that most microorganisms in the environment can not be brought into cultivation. So we have to design novel strategies to investigate their diversity, function, and potential applications. In order to understand our Planet, we are interested in the who, what, when, where, why and how questions about microbial life. The way to do it brings up an exciting experience to discover step by step the diverse microbial world.

It is too difficult (just to avoid to say impossible) to duplicate an organism’s host environment/ecosystem in a laboratory. However, some microbial processes or properties can be analyzed in the laboratory using isolated microorganisms. This apparent contradiction suggests a need for a variety of methodologies to be applied either in the laboratory or in the field.

With the advent of modern molecular techniques, we can understand the microbial environment in much greater detail. It is possible to use the information hold in the nucelic acids of microorganisms to detect those present in an environment. Thus, molecular methods based on DNA and RNA represent a very useful set of techniques to analyze microbial communities in situ. But nucleic acids can be used to both detect a microorganism and to look at its functional genes, and we can do similar research on microbial communities through metagenomic approaches. Of course, the amount of data to be processed increases exponentially with the number of different microorganisms in a sample and bioinformatic tools become an essential part of the research process. Detection of microorganisms and their functional genes are also complemented with an evaluation and analysis of the processes being carried out by those microbial communities in the environment.

Microorganisms are never alone. They work in communities, often composed by a large number of different types of cells. The study of microbial communities and their interaction with the environment are key aspects to understand the role and function of microorganisms in nature, and consequently the implications of microbial life at local and global scales in our planet.

Microorganisms thriving under extreme conditions generally present specific adaptations which allow them to develop in unique environments. The properties of their biomolecules are of interest in biotechnology due to their high stability which can be used in potential applications to industry or processes of commercial interest. The search for unique microorganisms and molecules also require the use of a variety of techniques.

Our group is keen in searching for novel methodologies and the application of a wide variety of strategies to answer specific questions. Methods involving a wide range of molecular techniques, the cultivation of microorganisms, biochemistry, physiology, ecology, biotechnology, genomics, bioinformatics, among others are some of the procedures commonly applied in our research. We pretend to further study microbial life from a multidisciplinary perspective and we will be glad to collaborate with other groups and individuals interested in related topics. For a list of our publications and projects, please, visit the corresponding page.

Thermophilic Isomerase Processes for Biotechnology. European Union. Horizon 2020. ERA-IB2 7th call. Industrial Biotechnology for Europe. An Integrated Approach; Ministerio de Economía y Productividad, Acciones de Programación Conjunta Internacional 2016. ERA-IB-16-049.

Isomers are molecules with identical atomic composition but with different structural characteristics. Different isomers can show very distinctive function. Isomerases are enzymes catalyzing the conversion between different types of isomers. Thermostable isomerases are desired because they possess high resistance and durability, are able to withstand harsh industrial process conditions, including heating and organic solvents. Elevated temperatures can also enhance substrate accessibility and solubility. The proposed project includes comparative bioinformatic analyses of sequence data to identify different classes of thermostable isomerases of industrial interest which will be cloned, over-expressed, functionally and structurally characterized and optimized towards their biotechnological application. Three types of isomerases will be targeted: sugar isomerases (to produce new desirable sugars for calorie-free sweeteners and as building blocks for drugs), disulfide isomerases (to improve protein folding and stability of industrial enzymes), and chalcone isomerases (involved in the transformation of flavonoids, secondary metabolites of importance as natural colorants, anti-oxidants, anti-microbial and anti-inflammatory agents). Durable isomerases will allow new opportunities for green, competitive and sustainable biotechnological processes that can replace conventional chemical synthesis.

Collaborators: IRNAS-CSIC (Spain), University of Bergen (Norway), Christian-Albrechts-Universitat Kiel (Germany), University of Exeter (United Kingdom), Bioavan SL (Spain)

Microbial life beyond optimal conditions. Ministry of Economy and Productivity. project CGL2014-58762-P.

Microorganisms are the base to support biogeochemical cycles and terrestrial ecosystems. However, the functioning of microorganisms in natural systems is remains to be deciphered, above all, under conditions considered as extreme or far from the optimum for those cells. It is known that a number of extremophilic microorganisms inhabit soils and sediments although their role has been barely studied. These extremophiles are an ideal target to tackle the role of microorganisms under conditions not included within their usual growth conditions. This proposal is built on the idea that microorganisms are able to perform some activities and maintenance growth at sites with, or during periods of, conditions beyond their usual growth range and the microorganisms in nature behave differently than in laboratory cultures. The actual growth and activity of microorganisms under those unique conditions remains unknown and so are the multiple potential consequences such as explaining high microbial diversity, microbial and enzymatic activities under extreme conditions, cell survival and the interest of applying the knowledge derived from understanding these processes to biotechnology. We propose the analysis of the microbial communities, their enzymatic activity, metabolism, and growth in terrestrial environments using extremophiles as target for this analysis. The use of extremophiles will facilitate the analysis by selecting a specific group of microorganisms from the vast microbial diversity existing in natural environments. Different environmental conditions will be analyzed, including those occurring during the extreme climate events along the year, including summer and winter extremest conditions. Methodologies will include new generation sequencing to characterize the structure of microbial communities under a variety of conditions and their genomic potential based on DNA genomic and amplicon analyses, the identification of metabolically active microbial taxa through their RNA, the determination of enzymatic extracellular activity and microbial metabolism by fluorescence assays and respiration measurements, quantification of growth/death rates through live/dead staining and microscopy and flow cytometer quantification, and evaluation of the potential of these processes and results to biotechnological applications. This study will bring up a significant advance on our understanding of the environmental role of microorganisms and their enzymes under marginalized conditions and it is expected that it will replace the current concept that those situations show minimal relevance. Understanding the behavior of microorganisms under unique conditions will establish a base to apply this knowledge to biotechnology and the sustainability, maintenance and efficient utilization of soils, including global climate changes and the C soil-atmosphere balance.

Effects of water content and temperature on microbial diversity and its activity in soils and sediments. Application to the degradation of halogenated pollutants. Andalusian Government, RNM2529.

Microorganisms in soils and sediments are essential for maintaining these systems. Predictions of global climatic changes and the existence of periods of high temperatures and droughts in our region suggest the importance of knowing the variations in diversity and activity induced on microbial communities in order to achieve an efficient use of resources. These phenomena are critical, for instance, to obtain an appropriate use of soils and sediments for agriculture and the recovery of polluted sites. Microorganisms are the only link able to carry out a high number of processes such as closing the biogeochemical cycles of elements, which are related to the fertilization of terrestrial environments, the degradation of recalcitrant pollutants, and global phenomena. This study will analyze the influence of high temperatures (>40°C) and periods of desiccation on microbial communities, their diversity and activity, in relationship to the decomposition of organic matter and recycling of nutrients in terrestrial environments. This includes their use within a sustainable scheme and the degradation of pollutants under those extreme conditions. To this aim different methods will be used; such as molecular techniques including new generation sequencing to detect the huge microbial diversity existing in soils and sediments, including metagenomics of these natural microbial communities. These methods will be combined with enzyme activity assays that will be designed specifically for these conditions. Experiments will include the analysis of a broad range of temperatures and desiccation conditions both in nature as in the laboratory aiming to understand the functioning and dynamics of microbial communities as a response to changes in water content and temperature, as well as applications to the sustainability of soils and sediments and the recovery of these environments. As an added value, this investigation will search for novel enzymes or biocatalysts which will be characterized. This project represents a collaboration between a research center (IRNAS-CSIC) and a technology-based enterprise (Bioavan SL) which shares a common interest to reach the necessary knowledge to maintain our environment and economic development through sustainability.

Integrative analysis of extremophiles in search for new biotechnological solutions. NILS Science and Sustainability programme, EEA Grants, 003-ABEL-CM-2013.

A sustainable bioindustrial economy requires replacing chemical processes by green, renewable bio-based alternatives. Microorganisms represent the best potential target for biotechnology. Among them, the extremophiles (microorganisms living, for example, under extreme temperature and pH) include the most resistant cells and enzymes required to support the hardiest industrial processes. This action focuses on searching for new hydrolytic biocatalysts, a first step in biotransforming complex residues into assimilable molecules. The strategy includes the major stages: cells, genomes, enzymes and mathematics as an integral approach to model, design and discover novel biocatalysts such as highly resistant enzymes or novel functionality for existing genes. This project involves four research groups, one Norwegian (University of Bergen) and three Spanish teams (IRNAS-CSIC, Center of Astrobiology-CSIC, University of Sevilla). The aim is to join multidisciplinary views to generate biotechnological solutions and advancement into the hydrolysis of cellular materials and residues.

Comparative Microbial Genomics. MICROGEN. Ministry of Science and Innovation, project CSD2009-00006.

Microorganisms are still the main cause of death in the world, they are the main source of genetic biodiversity and the main players in ecosystem functioning. However, the way bacterial populations are structured, the way they evolve or interact with other biotic components or the way they adapt to the environment and evolve are still poorly known. This is partly due to the need for pure culture in order to perform experiments and to the application of an evolutionary model imported from eukaryotic systems. With the advent of genomics and the new high-throughput sequencing techniques of low cost, a new era has emerged in which bacteria can be studied through their genomes, obviating the need for culturing the microorganisms and allowing a holistic study of ecosystems. In addition, the study of this vast genetic reservoir may provide access to a wealth of new bioactive compounds previously unreachable by standard techniques. Some important changes in our way of understanding microbes are starting to emerge, a crucial one being the existence of a gigantic pool of genes within each bacterial species, in such a way that this gene pool (the “pan-genome”) is much larger than the genome of each individual strain. This is vital to understand bacterial biology and has important consequences from an applied point of view.

The present project aims to study microorganisms by a combination of genomics, bioinformatics, molecular biology, metagenomics and next generation sequencing. This will be achieved by the creation of a multidisciplinary team combining all those skills in an ambitious proposal that would not be possible by standard funding. The consortium will use many different bacterial species as models of pathogenicity and symbiosis in human, animal and plant hosts, as well as studying different natural and human-related ecosystems to unravel the population genomics and genome fluidity of bacteria. This will shed light on the species concept, the structure of bacterial populations, its interaction with viruses and the environment, their adaptation and their evolution, as well as opening new avenues for treating infectious diseases. In addition, a web-based server will be created to study, annotate and analyze bacterial genomes, and new scripts and computer programs will be developed that will be of great use for the scientific community. It is anticipated that the group will serve as a nucleating agent that will permit Spanish Microbiology to remain in the mainstream of international Microbiology and to continue being a support to the future of Spanish Biotechnology and Biomedicine.

The presence and role of low abundance microorganisms could explain the huge microbial diversity of natural systems. A case study in the Doñana National Park. Ministry of Science and Innovation, project CGL2009-12328/BOS.

Microbial diversity in natural environments is huge and difficult to determine. These microbial communities can be considered as formed by a low number of highly abundant microorganisms and a very high number of rare, low abundant, microorganisms. We present the hypothesis that the microorganisms representing that minority are important in natural ecosystems. The study of the rare microorganisms is essential for understanding the functional role of microbial communities in an spatial and temporal environment, as well as to comprehend why exist a so large microbial diversity. The selection of microorganisms adapted to thrive under extreme conditions (high temperature, low or high pH) from moderate environments is proposed. The selected environment is the sediment from the natural ponds at Doñana National Park. Environmental variables will be determined and changes in the microbial communities will be monitored during the selecting process. Molecular methods will be used for the detection of microorganisms based on both fingerprinting techniques and sequencing, and in situ detection methods. Cultures of selected microorganisms will be approached. Microorganisms, Bacteria and Archaea, will be identified and their physiological properties evaluated. Also, their spatial distribution will be analyzed and will contribute to decipher the potential function within their ecosystem. The possibility that those extreme conditions could represent natural situations will be studied. The analyzed processes will represent a model of the dynamic of microbial communities as a consecuence of environmental changes and their potential response both in the ecosystem and global biogeochemical cycles.

Microbial diversity and microbiology of extreme environments. Andalusian Government, BIO288.

Microbial diversity is a broad term that can be approached from very different perspectives. This includes not only the phylogenetic diversity but also includes molecular, functional, and mechanistics points of view. To achieve this broad assessment of the whole microbial world we use a wide and radically different methodologies which point towards a common objective, decipher the functioning of the microbial world. The focus on extremophiles allows to center on a specific type of microorganisms and communities which are of great interest for their potential biotechnological applications as well as model systesms for the study of natural communities.


Santana, M.M., J.M. González, M.I. Clara. 2016. Inferring pathways leading to organic-sulfur mineralization in the Bacillales. Critical Reviews in Microbiology 42: 31-45. doi:10.3109/1040841X.2013.877869.

Cuecas, A., J. Cruces, J.F. Galisteo-López, X. Peng, J.M. González. 2016. Cellular viscosity in prokaryotes and thermal stability of low-molecular weight biomolecules. Biophysical Journal 111(4): 875-882. doi: 10.1016/j.bpj.2016.07.024.

Kanoksilapatham, W., P. Pasomsup, P. Keawram, A. Cuecas, M.C. Portillo, J.M. González. 2016. Fervidobacterium thailandense sp. nov., a novel extreme thermophilic bacterium isolated from a hot spring in Northern Thailand. International Journal of Systematics and Environmental Microbiology.

Gaspar, H., R. Ferreira, J.M. González, M.I. da Clara, M.M. Santana. 2016. Influence of temperature and copper on Oxalobacteraceae in soil enrichments. Current Microbiology 72: 370-376.

Villahermosa, D., A. Corzo, E. Garcia-Robledo, J.M. González, S. Papaspyrou. 2016. Kinetics of indigenous nitrate reducing sulfide oxidizing activity in microaerophilic wastewater biofilms. PLoS ONE 11(2): e0149096. doi: 10.1371/journal.pone.0149096


González, J.M., M.C. Portillo, M. Piñeiro-Vidal. 2015. Latitude-dependent underestimation of microbial extracellular enzyme activity in soils. International Journal of Environmental Science and Technology 12: 2427-2434. doi:10.1007/s13762-014-0635-7

Lucena-Padrós, H., J.M. González, B. Caballero-Guerrero, J.L. Ruiz-Barba, A. Maldonado-Barragán. 2015. Vibrio olivae sp. nov., isolated from Spanish-style green olive fermentations. International Journal of Systematics and Environmental Microbiology 65: 1895-1901. It can also be found here.

Reina, M., M.C. Portillo, L. Serrano, E.C.H.E.T. Lucassen, J.G.M. Roelofs, A. Romero, J.M. González. 2015. The interplay of hydrological, chemical and microbial processes in the formation of floating surface iron-rich films in aquatic environments at a circumneutral pH. Limnetica 34: 365-380.

Kanoksilapatham, W., P. Keawram, J.M. González, F. Robb. 2015. Isolation, characterization and survival strategies of Thermotoga sp. strain PD524, a hyperthermophile from a hot spring in Northern Thailand. Extremophiles 19(4): 853-861 doi: 10.1007/s00792-015-0761-2

Ferreira, R., H. Gaspar, J.M. González, M.I. Clara, M.M. Santana. 2015. Copper and temperature modify microbial communities, ammonium and sulfate release in soil. Journal of Plant Nutrition and Soil Science 178: 953-962. doi: 10.1002/jpln.201500318

Santana, M.M., J.M. González. 2015. High temperature microbial activity in upper soil layers. FEMS Microbiology Letters 362: 1-4. doi: http://dx.doi.org/10.1093/femsle/fnv182

Sant’Anna, F.H., A. Slovodkin, T. Sokolova, F.T. Robb, J.M. González. 2015. Genome analysis of three genomes within the thermophilic hydrogenogenic bacterial species Caldanaerobacter subterraneus with a focus on carbon monoxide dehydrogenase evolution and hydrolase diversity. BMC Genomics 16: 757. doi: 10.1186/s12864-015-1955-9


Lucena-Padrós, H., J.M. González, B. Caballero-Guerrero, J.L. Ruiz-Barba, A. Maldonado-Barragán. 2014. Propionibacterium olivae sp. nov., and Propionibacterium damnosus sp. nov., isolated from spoiled packaged Spanish-style green olives. International Journal of Systematics and Environmental Microbiology 64: 2980-2985. It can also be found here.

Lucena-Padrós, H., J.M. González, B. Caballero-Guerrero, J.L. Ruiz-Barba, A. Maldonado-Barragán. 2014. Enterococcus olivae sp. nov., isolated from Spanish-style green olive fermentation. International Journal of Systematics and Environmental Microbiology 64: 2534-2539. It can also be found here.

Cuecas, A., M.C. Portillo, W. Kanoksilapatham, J.M. González. 2014. Bacterial distribution along a 50ºC temperature gradient reveals a parcelled out hot spring environment. Microbil Ecology 68: 729-739.

González, J.M. 2014. Evaluating putative chimeric sequences from PCR-amplified products. In, K. Nelson et al. (eds.). Encyclopedia of Metagenomics, Springer. doi: 10.1007/978-1-4614-6418-1_791-1

Gazulla, M.F., E. Sánchez, J.M. González, M. Orduña. 2014. Comportamiento de tejas de differente color (rojo y paja) frente al deterioro. Bolletin de la Sciedad Española de Cerámica y Vidrio 53: 227-234.


Villahermosa, D., A. Corzo, J.M. González, M.C. Portillo, E. Garcia-Robledo, S. Papaspyrou. 2013. Reduction of Net Sulfide Production Rate by Nitrate in Wastewater Bioreactors. Kinetics and Changes in the Microbial Community. Water, Air & Soil Pollution 224: 1738.

Santana, M.M, M.C. Portillo, J.M. González, M.I.E. Clara. 2013. Characterization of new soil thermophilic bacteria potentially involved in soil fertilization. Journal of Plant Nutrition and Soil Science 176: 47-56.

Sánchez-Porro, C., R. de la Haba, N. Cruz-Hernández, J.M. González, C. Reyes-Guirao, L. Navarro-Sampedro, M. Carballo, A. Ventosa. 2013. Draft Genome of the Marine Gammaproteobacterium Halomonas titanicae. Genome Announcements 1(2): e00083-13.

Rincón, B., M.C. Portillo, J.M. González, R. Borja. 2013. Microbial communities analyses in a two-stage anaerobic digestion process treating two-phase olive mill solid residue. Journal of Environmental Science and Technology (in press).


Kanoksilapatham, W., P. Pasomsup, M.C. Portillo, P. Keawram, J.M. González. 2012. Identification and characterization of a freshwater Pyrococcus sp. strain PK 5017 and identification of pfu-like IS elements in Thermococcus sibiricus MM 739. International Journal of Biology 4: 11-22.

Santana, M., M.C. Portillo, J.M. González. 2012. Mutualistic growth of the sulfate-reducer Desulfovibrio vulgaris Hildenborough with different carbohydrates. Microbiology 81(6): 663-668.

Santana, M.M., M.C. Portillo, J.M. González, I. Clara. 2012. Characterization of new soil thermophilic bacteria potentially involved in soil fertilization. Journal of Plant Nutrition and Soil Science (in press).

González, J.M., M.C. Portillo, P. Belda-Ferre, A. Mira. 2012. Amplification by PCR artificially reduces the proportion of the rare biosphere in microbial communities. Plos One 7(1): e29973.

Portillo, M.C., M. Santana, J.M. González. 2012. Presence and potential role of thermophilic bacteria in temperate terrestrial environments. Naturwissenschaften 99: 43-53.

Zimmermann, J., M.C. Portillo, L. Serrano, W. Ludwig, J.M. González. 2012. Acidobacteria in freshwater ponds at Doñana National Park, Spain. Microbial Ecology 63: 844-855.

Sanchez-Moral, S., M.C. Portillo, I. Janices, S. Cuezva, A. Fernandez-Cortes, J.C. Cañaveras, J.M. González. 2012. The role of microorganisms in the formation of calcitic moonmilk deposits and speleothems in Altamira Cave. Geomorphology 139-140: 285-292.


Rincón, B., M.C. Portillo, J.M. González, V. Fernandez-Cegri, M.A. De La Rubia, R. Borja. 2011. Feasibility of sunflower oil cake degradation with three different anaerobic consortia. Journal of Environmental Science and Health, Part A 46: 1412-1416.

Gazulla, M.F., E. Sánchez, J.M. González, M.C. Portillo, M. Orduña. 2011. Relationship between certain ceramic roofing tile characteristics and biodegradation. Journal of the European Ceramic Society 31: 2753-2761.

Portillo, M.C., J.M. González. 2011. Moonmilk deposits originate from specific bacterial communities in Altamira Cave (Spain). Microbial Ecology 61: 182-189.

Portillo, M.C., M.F. Gazulla, E. Sánchez, J.M. González. 2011. A procedure to evaluate the resistance to biological colonization as a characteristic for product quality of ceramic roofing tiles. Journal of the European Ceramic Society 31: 351-359.

Portillo, M.C., D. Villahermosa, A. Corzo, J.M. González. 2011. Microbial community fingerprints by differential display denaturing gradient gel electrophoresis (DD-DGGE). Applied and Environmental Microbiology 77: 351-354.


Sahin, N., J.M. González, T. Iizuka, J.E. Hill. 2010. Characterization of two aerobic ultramicrobacteria isolated from urban soil and description of Oxalicibacterium solurbis sp. nov. FEMS Microbiology Letters 307: 25-29.

Santana, M., M.C. Portillo, J.M. González. 2010. Cloning strategy to obtain recombinant proteins identical to the native forms. Journal of Biotechnology 149: 21-23.

González, J.M., M.C. Portillo. 2010. Spider fibers and the apparent fungal colonization of rock-art caves. Naturwissenschaften 97: 115-116.

Portillo, M.C., J.M. González. 2010. Differential effects of distinct bacterial biofilms in a cave environment. Current Microbiology 60: 435-438.