Characterizing proteases in an Antarctic Janthinobacterium sp. isolate: Evidence of a protease horizontal gene transfer event

Cecilia Martinez-Rosales1,2, Juan José Marizcurrena1, Andrés Iriarte3,4,5, Natalia Fullana1, Héctor Musto, Susana Castro-Sowinski1,2

Affiliations: 1 Sección Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de la República (UdelaR), Igua 4225, 11400, Montevideo, Uruguay 2 Microbiología Molecular, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE). Av Italia 3318, 11600, Montevideo, Uruguay 3 Dpto de Bioquímica y Genómica Microbiana and Dpto de Genómica (IIBCE) 4 Dpto de Desarrollo Biotecnológico, Instituto de Higiene, Facultad de Medicina, UdelaR 5 Laboratorio de Organización y Evolución del Genoma, Facultad de Ciencias, UdelaR


We report the isolation of a cold-adapted bacterium belonging to the genus Janthinobacterium (named AU11), from a water sample collected in Lake Uruguay (King George Island, South Shetlands). AU11 (growth between 4°C and 30°C) produces a single cold-active extracellular protease (ExPAU11), differentially expressed at low temperature. ExPAU11 was identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS) as an alkaline metallo-protease (70% coverage with an extracellular protease of Janthinobacterium sp. PI12), and by protease-inhibitor screening identified as a serine-protease. To the best of our knowledge this is the first experimental evidence of a cold-active extracellular protease produced by Janthinobacterium. Furthermore, we identified a serine-protease gene (named JSP8A) showing 60% identity (98% query coverage) to subtilisin peptidases belonging to the S8 family (S8A subfamily) of many cyanobacteria. A phylogenetic analysis of the JSP8A protease, along with related bacterial protein sequences, confirms that JSP8A clusters with S8A subtilisin sequences from different cyanobacteria, and is clearly separated from S8A bacterial sequences of other phyla (including its own).

An analysis of the genomic organization around JSP8A suggests that this protease gene was acquired in an event that duplicated a racemase gene involved in transforming L- to D-amino acids. Our results suggest that AU11 probably acquired this subtilisin-like protease gene by horizontal gene transfer (HGT) from a cyanobacterium. We discuss the relevance of a bacterial protease-HGT in the Antarctic environment in light of this hypothesis.


Keywords Antarctic, cold-active protease, horizontal gene transfer, Janthinobacterium, subtilisin

Citation Martinez-Rosales C, Marizcurrena J J, Iriarte A, et al. Characterizing proteases in an Antarctic Janthinobacterium sp. isolate: Evidence of a protease horizontal gene transfer event. Adv Polar Sci, 2015, 26:88-95, doi: 10.13679/j.advps.2015.1.00088 doi: 10.13


Five-year bio-monitoring of aquatic ecosystems near Artigas Antarctic Scientific Base, King George Island

María A. Morel 1, Victoria Braña1, Cecilia Martínez-Rosales1,2, Célica Cagide1, Susana Castro-Sowinski1,2

Affiliations: 1 Microbiología Molecular, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay 2 Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay

Received 27 May 2014; accepted 4 November 2014


Fildes Peninsula, in King George Island, Antarctica, has a great concentration of international facilities, and it has clearly been affected by human activities. The objective of this 5-year study was to assess the impact of anthropogenic activities on the bacterial abundance in water bodies close to Artigas Antarctic Scientific Base (BCAA, in Spanish Base Científica Antártica Artigas). Water samples from areas under different human influence (Uruguay Lake, nearby ponds, and meltwater from Collins Glacier) were aseptically collected and refrigerated until processed. The number of heterotrophic bacteria and Pseudomonas spp. was analyzed using a culture-dependent approach. Physico-chemical properties of the water samples (temperature, pH, and conductivity) were also determined. Results showed that water from the highly affected area, Uruguay Lake, where the pump that provides water to the BCAA is located, did not suffer significant fluctuations in heterotrophic bacterial abundance (104–105 CFU∙mL−1); however, Pseudomonas abundance increased until becoming the predominant population. In other water samples, the number of heterotrophic bacteria and Pseudomonas gradually increased during this 5-year study, by 2014 reaching similar values to those observed for Uruguay Lake. The implications of human activities on Antarctic bacterial abundance are discussed.

Keywords anthropogenic activities, water bodies, bacterial abundance

Citation Morel M A, Braña V, Martínez-Rosales C, et al. Five-year bio-monitoring of aquatic ecosystems near Artigas Antarctic Scientific Base, King George Island. Adv Polar Sci, 2015, 26: 102-106, doi: 10.13679/j.advps.2015.1.00102


Characterization and comparison of potential denitrifiers
in microbial mats from King George Island, Maritime Antarctica

Rocio J. Alcántara-Hernández • Carla M. Centeno • Alejandro Ponce-Mendoza • Silvia Batista • Martin Merino-Ibarra • Julio Campo • Luisa I. Falcón
Received: 28 May 2013 / Revised: 16 December 2013 / Accepted: 16 December 2013
Springer-Verlag Berlin Heidelberg 2013


Cyanobacterial microbial mats are highly structured communities commonly found in Antarctic inland waters including melt streams. These benthic microbial associations comprise a large number of microorganisms with different metabolic capacities, impacting nutrient dynamics where established. The denitrification process is a feasible nitrogen loss pathway and a biological source of nitrous oxide, a potent greenhouse gas that also promotes ozone depletion. Potential denitrifiers from five microbial mats were characterized using a PCR-DGGE (denaturing gradient gel electrophoresis) approach. Molecular markers encoding for key enzymes in the denitrification process (nirK, nirS and nosZ) were used. Fingerprints were obtained for the five sampled mats and compared for two successive years. Distance analysis showed that despite the sampled year, the denitrifying genetic potential was similar between most of the sites when represented in Euclidean space. The number of dominant denitrifiers detected for each sample ranged between 6 and 18 for nirK, 4–10 for nirS and 6–17 for nosZ. The seventy-two sequenced phylotypes showed 80–98 %identity to previously reported environmental sequences from water column, sediments and soil samples. These results suggest that Antarctic microbial mats have a large denitrification potential, previously uncharacterized and composed by both site-specific and common phylotypes belonging mainly to Alpha-, Beta- and Gammaproteobacteria.

Keywords Cyanobacterial microbial mat – Denitrifiers – PCR-DGGE – Maritime Antarctica


Antarctic bacterial isolates that produce cold-active extracellular proteases at low temperature but are active and stable at high temperature

Cecilia Martínez-Rosales, Susana Castro-Sowinski


We report the isolation and identification of bacteria that produce extracellular cold-active proteases, obtained from water samples collected near the Uruguayan Antarctic Base on King George Island, South Shetlands. The bacteria belonged to the genera Pseudomonas (growth between 4 and 30°C) and Flavobacterium (growth between 4 and 18°C). In all cases, extracellular protease production was evident when reaching the stationary phase at 18 and 4ºC, but was not detected at 30ºC. The zymogram revealed the secretion of one extracellular protease per isolate, each with different relative electrophoretic mobility. The extracellular proteases produced at 4ºC showed thermal activity and stability at 30ºC. Both activity and stability at temperature higher that 10ºC have no physiological meaning because the isolates do not experience such temperatures in the Antarctic environment; however, the possible ecological value of cold-active and -stable extracellular proteases is discussed.

Keywords Antarctic, cold-active enzymes, protease
(Published: 22 April 2011)
Citation Polar Research 2011, 30, 7123, DOI: 10.3402/polar.v30i0.7123



Antarctic DNA moving forward: genomic plasticity and biotechnological potential.

Martinez-Rosales C, Fullana N, Musto H, Castro-Sowinski

Sección Bioquímica, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay.

FEMS Microbiol Lett. 2012 Jun;331(1):1-9. doi: 10.1111/j.1574-6968.2012.02531.x. Epub 2012 Mar 12.


Antarctica is the coldest, driest, and windiest continent, where only cold-adapted organisms survive. It has been frequently cited as a pristine place, but it has a highly diverse microbial community that is continually seeded by nonindigenous microorganisms. In addition to the intromission of ‘alien’ microorganisms, global warming strongly affects microbial Antarctic communities, changing the genes (qualitatively and quantitatively) potentially available for horizontal gene transfer. Several mobile genetic elements have been described in Antarctic bacteria (including plasmids, transposons, integrons, and genomic islands), and the data support that they are actively involved in bacterial evolution in the Antarctic environment. In addition, this environment is a genomic source for the identification of novel molecules, and many investigators have used culture-dependent and culture-independent approaches to identify cold-adapted proteins. Some of them are described in this review. We also describe studies for the design of new recombinant technologies for the production of ‘difficult’ proteins.

© 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

PMID: 22360528 [PubMed – in process]


Phylotype diversity in a benthic cyanobacterial mat community on King George Island, maritime Antarctica

Callejas, Cecilia1; Gill, Paul2; Catalán, Ana1; Azziz, Gastón1; Castro-Sowinski, Susana1; Batista, Silvia1


1: Unidad de Microbiología Molecular, Instituto de Investigaciones Biológicas Clemente Estable (MEC), Unidad Asociada a Facultad de Ciencias, Ministerio de Educación y Cultura, Av. Italia 3318, 11600, Montevideo, Uruguay 2: Unidad de Microbiología Molecular, Instituto de Investigaciones Biológicas Clemente Estable (MEC), Unidad Asociada a Facultad de Ciencias, Ministerio de Educación y Cultura, Av. Italia 3318, 11600, Montevideo, Uruguay, Email: Publication date: 2011-06-01

Source: World Journal of Microbiology and Biotechnology, Volume 27, Number 6, June 2011 , pp. 1507-1512(6) – Publisher: Springer


Cyanobacterial 16S ribosomal RNA gene diversity was examined in a benthic mat on Fildes Peninsula of King George Island (62º09′54.4′′S, 58º57′20.9′′W), maritime Antarctica. Environmental DNA was isolated from the mat, a clone library of PCR-amplified 16S rRNA gene fragments was prepared, and amplified ribosomal DNA restriction analysis (ARDRA) was done to assign clones to seven groups. Low cyanobacterial diversity in the mat was suggested in that 83% of the clones were represented by one ARDRA group. DNA sequences from this group had high similarity with 16S rRNA genes of Tychonema bourrellyi and T. bornetii isolates, whose geographic origins were southern Norway and Northern Ireland. Cyanobacterial morphotypes corresponding to Tychonema have not been reported in Antarctica, however, this morphotype was previously found at Ward Hunt Lake (83ºN), and in western Europe (52ºN). DNA sequences of three of the ARDRA groups had highest similarity with 16S rDNA sequences of the Tychonema group accounting for 9.4% of the clones. Sequences of the remaining three groups (7.6%) had highest similarity with 16S rRNA genes of uncultured cyanobacteria clones from benthic mats of Lake Fryxell and fresh meltwater on the McMurdo Ice Shelf.

Keywords Antarctic environmental gradient; 16S rRNA gene; ARDRAs; Fildes Peninsula; Tychonema; Oscillatoriales




Verónica Piñeiro3 , Gabriela Eguren1 , Iris Pereira 2 y Natalia Zaldúa3

1 Instituto de Ecología y Ciencias Ambientales, Facultad de Ciencias, UdelaR, Uruguay. 2 Instituto de Biología Vegetal y Biotecnología, Universidad de Talca, Talca, Chile. 3Caubá Flora Nativa, Facultad de Ciencias, UdelaR, Uruguay.

Correo electrónico:


Tesis de Doctorado en Biología de la M. Sc. Odile Volonterio

“La conexión Antártico-Magallánico: Diversidad y biogeografía de microturbelorios intersticiales del Arco de Escocia” de la M. Sc. Odile Volonterio del Programa de Desarrollo de las Ciencias Básicas de la Universidad de la República (PEDECIBA).

Por mayor información consultar al mail:

Laboratorio de Zoología Invertebrados,

Facultad de Ciencias, Iguá 4225 (Piso 8-Sur) – C.P. 11400

Montevideo, Uruguay.


Publicaciones sobre investigaciones del Área de Biología Humana

Artículo de difusión en inglés: “Taking the pulse of Antarctica” escrito por la Lic. Angela Quartarolo

Artículo de difusión en italiano: “Studio psicosociale delle basi Antartiche Uruguayane“. por Angela Quartarolo y Antonio Peri publicado en Giornale di Medicina Militare.


Radiative Heat Loss in Gentoo Penguin (Pygoscelis papua) – Adults and Chicks and the Importance of Warm Feet

ABSTRACT: Adult penguins and their chicks differ considerably in their apparent body insulation. The chicks are covered in down, whereas the adults have the short, hard body feathers characteristic of the family, so mechanisms of heat loss may vary considerably between the two groups. We examined radiative heat loss by measuring body surface temperatures of gentoo penguins (Pygoscdis papua) in Antárctica. At the time the birds were considered to be in their thermoneutral zone, and there was little or no wind. Measurements of infrared emission were made on breeding adults and in large downy, and thermally independent, chicks in relation to environmental temperature. All 28 external body surface sites measured were positively correlated with ambient temperature, although there was considerable intersite variability in the relationship between site temperature and ambient temperature. Foot temperature increased most rapidly per degree ambient temperature increase, followed by the flippers, followed by the trunk. This pattern was particularly pronounced in the chicks, indicating that the exceptional heat-loss capacities of the feet may counteract for the reduced capacity of the flippers. Net heat transfer by radiation was examined using Stefan-Boltzmann’s law and preliminary data on the surface area of a gentoo penguin body. This showed that between ground temperatures of 5° and 15°C overall heat transfer remains essentially constant, although radiative heat loss from the trunk decreases, this being counteracted by increasing heat transfer from the flippers and feet. Over the same temperature range the specific radiation heat transfer of the feet increased approximately 100 times faster  per degree ambient temperature increase than did that of the flippers. This and the bimodality in foot temperature found in the study birds even under constant ambient temperatures indicate that within the thermoneutral zone heat loss by radiation in gentoo penguins is primarily executed using the feet, through which the blood circulates in pulses. Rory P. Wilson1,* Dieter Adelung1, Leonardo Latorre 2 ‘Institut für Meereskunde, Düsternbrooker Weg 20, D-24105 Kiel, Germany; 2Instituto Antárctico Uruguayo, 8 de Octubre 2958, Montevideo, Uruguay – Accepted 4/16/98


The movements of gentoo penguins Pygoscelis papua from Ardley Island, Antarctica

Abstract: The movements of gentoo penguins (Pygoscelis papua) in Antarctica were studied by equipping a total of 37 birds captured at Ardley Island, South Shetlands between December 1991 and May 1996 with position-determining devices. Information on area usage was derived from 20 of’ these devices and covered the incubation period (N = 3 birds), the chick-rearing period (N = 14 birds) and the over-wintering period (N = 3 birds). During incubation birds only ventured further than 50 km from the colony 20% of the time and no individual ranged further than 200 km from the colony. In contrast, no individuals attending chicks ranged further than 16 km from the colony. During winter the maximum distance ranged from the colony was 268 km. Mean distances between the birds and the colony were 80, 81 and 127 km.  Individual birds tended to associate with one spot, making short (10 day) forays away before returning to nodal areas. The ranging capacity of gentoo penguins appears considerably less than that of sympatric congeners and may reflect the ability of gentoo penguins to dive deeper and thus exploit prey not accessible to congeners.   R.P. Wilson, · B. Alvarrez, · L.Latorre,· D. Adelung, B. Culik · R. Bannasch Received: 1 October 1997 /Accepted: 3 February 1998




Proyecto GLACKMA:
Adolfo Eraso,  Carmen Domínguez


El glaciar Collins (isla Rey Jorge – Shetland del Sur) como sensor natural del calentamiento global en la Antártida

Implementación de una Cuenca Piloto Experimental, con registro continuo plurianual de la descarga hídrica glaciar (Expediciones “Antártida 2000” y “Antártida 2002”)

  1. Eraso1,  C. Domínguez2 , A. Lluberas3

1 Dpto. Ingeniería Geológica, E.T.S. Ingenieros de Minas. Universidad Politécnica de Madrid. C/ Ríos Rosas 21, 28003  Madrid. España

2 Dpto. Matemática Aplicada. Universidad de Salamanca. Plaza de los Caídos,     37008   Salamanca. España. E-mail:

3 Instituto Antártico Uruguayo. Uruguay


Determination of glacier velocities on King George Island (Antarctica) by DInSAR

Albert Moll(1), Matthias Braun(1), and Albert Lluberas(2)

(1) Center for Remote Sensing of Land Surfaces (ZFL), University of Bonn, Walter-Flex-Str.3, 53113 Bonn, Germany, Phone: +49-228-734925, Fax: +49-228-736857,    (2) Instituto Antártico Uruguayo (IAU), Av. 8 de Octubre 2958, Montevideo, Uruguay


Glaciology of the South Shetlands Programme (GLASS)

Newsletter 2002

compiled by Jefferson Cardia Simões


A clean protocol for determining ultralow heavy metal concentrations: its application to the analysis of Pb, Cd, Cu, Zn and Mn in Antarctic snow

Sungmin Hong1*, Albert Lluberas2, Fernando Rodriguez2

1 Polar Research Center, Korea Ocean Research and Development Institute, Ansan, P.O. Box 29, Seoul 425-600, Korea

2 Instituto Antartico Uruguayo, Avenida 8 de Octubre 2958, PO Box 6051, Montevideo CP 11600, Uruguay

Corresponding author. Tel.: + 82 345 4006432; fax: + 82 345 4085825; e-mail:

Corresponding coauthor   Tel: + 598 2  4878341; fax:  + 598 2 4876004; e-mail:

Submitted to “Korean Journal of Polar Research”, June 14, 2000


Natural and anthropogenic heavy metal deposition to the snow in King George Island, Antarctic Peninsula

Sungmin Hong1*, Albert Lluberas2, Gangwoong Lee3, Jun Kun Park1

1Polar Sciences Laboratory, Korea Ocean Research and Development Institute, Ansan P.O. Box 29, 425-600 Seoul, Korea; 2Instituto Antartico Uruguayo, Avenida 8 de Octubre 2958, P.O. Box 6051, Montevideo CP 11600, Uruguay; 3Department of Environmental Sciences, Hankook University of Foreign Studies, 89, Wangsan-ri Mohyeon-myon, Yongin-shi, Kyongki-do, Korea;

* Corresponding author; Tel.: + 82 31 4006432; fax: + 82 31 4085825;