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Bart Van De Vijver - One of the best experts on this subject based on the ideXlab platform.

  • analysis of the type material of planothidium delicatulum bacillariophyta with the description of two new planothidium species from the sub Antarctic Region
    Fottea, 2018
    Co-Authors: Bart Van De Vijver, Carlos E Wetzel, Luc Ector
    Abstract:

    During a survey of the freshwater diatom flora on the sub-Antarctic islands of the southern Indian Ocean, two new Planothidium species were observed, showing some resemblance to Planothidium delicatulum. Therefore, the type material of Achnanthidium delicatulum Kutzing was analysed, a common species in northern hemisphere waterbodies that was later transferred to the genus Planothidium. Additionally the material of Types du Synopsis des Diatomees de Belgique n° 234, designated in 1980 as neotype for Achnanthes delicatula was investigated. This analysis showed that the population in Types n° 234 is not conspecific with Achnanthidium delicatulum but in fact is a population of Planothidium galaicum. Both Planothidium species in the investigated Antarctic material are described as new to science: P. lilianeanum Van de Vijver sp. nov. and P. australodelicatulum Van de Vijver, C.E.Wetzel et Ector sp. nov. The new species can be differentiated based on differences in valve outline, presence of ridges and silica outgrowths on the rapheless valve, the structure of the raphe and the shape and size of the central area. Notes on the ecology and distribution of the new Antarctic species are added. Achnanthidium delicatulum is formally lectotypified.

  • Ten new Bacillariophyta species from James Ross Island and the South Shetland Islands (Maritime Antarctic Region)
    Phytotaxa, 2016
    Co-Authors: Ralitsa Zidarova, Kateřina Kopalová, Bart Van De Vijver
    Abstract:

    The present paper describes 10 new diatom (Bacillariophyta) species from the Maritime Antarctic Region. Five of the newly described taxa: Caloneis australis sp . nov ., Mayamaea sweetloveana sp . nov ., Navicula romanedwardii sp . nov ., Sellaphora Antarctica sp . nov . and Sellaphora gracillima sp . nov . have been previously reported from the Antarctic Region but were force-fitted into incorrect names. Five other taxa: Chamaepinnularia elliptica sp . nov ., Cosmioneis regigeorgiensis sp . nov ., Mayamaea tytgatiana sp . nov ., Muelleria pimpireviana sp . nov . and Pinnularia pinseeliana sp . nov . are newly discovered taxa. The morphology of all new species is studied using both light and scanning electon microscope observations and compared with similar species from the Antarctic Region and worldwide. Data about the ecology and confirmed Antarctic distribution of the new species are added.

  • Two new Gomphonema species (Bacillariophyta) from the Maritime Antarctic Region
    Phytotaxa, 2016
    Co-Authors: Bart Van De Vijver, Kateřina Kopalová, Ralitsa Zidarova, J. Patrick Kociolek
    Abstract:

    Two new diatom taxa belonging to the genus Gomphonema were recorded during a survey of the Maritime Antarctic freshwater and limno-terrestrial diatom flora: Gomphonema jamesrossense sp . nov . and G . maritimo-Antarcticum sp . nov . Detailed light (LM) and scanning electron microscope (SEM) observations are used to characterize the morphology and ultrastructure of the two new Gomphonema taxa. Comparisons with similar taxa and the ecological preferences of each species are added. The revision of these species confirmed the endemic nature of the Antarctic diatom flora.

  • the genus luticola d g mann bacillariophyta from the mcmurdo sound Region Antarctica with the description of four new species
    Phytotaxa, 2015
    Co-Authors: Tyler J Kohler, Bart Van De Vijver, Kateřina Kopalová, Patrick J Kociolek
    Abstract:

    A revision of the freshwater diatom genus Luticola from the McMurdo Sound Region, including the McMurdo Dry Valleys and Cape Royds, Antarctica, was made to contribute to a consistent flora for the entire Antarctic Region. Detailed light and scanning electron microscopic observations, review of pertinent literature, and examination of historical and type material lead to the identification of 12 Luticola species. Four new species and one new combination are proposed, including L . bradyi sp . nov ., L . spainiae , sp . nov ., L . macknightiae , sp . nov ., L . transAntarctica , sp . nov ., and L . elegans , comb . nov . stat . nov . Several of these taxa were previously identified as part of the L . muticopsis (Van Heurck) D.G.Mann complex; Navicula muticopsis f. evoluta W. & G.S. West, L . muticopsis f. reducta (W. & G.S. West) Spaulding, and N . muticopsis f. capitata Carlson, or mistaken for the similar L . mutica (Kutzing) D.G.Mann and L . cohnii (Hilse) D.G.Mann. Morphological features of all new species were compared to the closest morphologically similar taxa, and their ecology and biogeography are discussed. All Luticola species considered here show restricted Antarctic distributions, and 8 of the 12 reported species are known only from the Antarctic continent.

  • five new species of the genus humidophila bacillariophyta from the maritime Antarctic Region
    Diatom Research, 2015
    Co-Authors: Kateřina Kopalová, Ralitsa Zidarova, Patrick J Kociolek, Rex L Lowe, Bart Van De Vijver
    Abstract:

    Five unknown taxa belonging to the newly established genus Humidophila were found during ongoing taxonomic revision of the freshwater and limno-terrestrial diatom flora of the Maritime Antarctic Region. These taxa were previously identified as Diadesmis arcuata, D. biscutella, D. comperei and D. ingeae, but detailed light and scanning electron microscopy observations allowed their clear separation from the already known taxa, and resulted in the description of five new species: Humidophila sceppacuerciae Kopalova sp. nov., H. australoshetlandica Kopalova, Zidarova & Van de Vijver sp. nov., H. keiliorum Kopalova sp. nov., H. deceptionensis Kopalova, Zidarova & Van de Vijver sp. nov. and H. vojtajarosikii Kopalova sp. nov. All five new taxa are compared with the morphologically most similar taxa, and their ecology and biogeography are discussed. Although the genus Humidophila is present worldwide, a large number of Humidophila taxa have a restricted distribution within the (sub-)Antarctic Region, showing a ...

Kateřina Kopalová - One of the best experts on this subject based on the ideXlab platform.

  • Ten new Bacillariophyta species from James Ross Island and the South Shetland Islands (Maritime Antarctic Region)
    Phytotaxa, 2016
    Co-Authors: Ralitsa Zidarova, Kateřina Kopalová, Bart Van De Vijver
    Abstract:

    The present paper describes 10 new diatom (Bacillariophyta) species from the Maritime Antarctic Region. Five of the newly described taxa: Caloneis australis sp . nov ., Mayamaea sweetloveana sp . nov ., Navicula romanedwardii sp . nov ., Sellaphora Antarctica sp . nov . and Sellaphora gracillima sp . nov . have been previously reported from the Antarctic Region but were force-fitted into incorrect names. Five other taxa: Chamaepinnularia elliptica sp . nov ., Cosmioneis regigeorgiensis sp . nov ., Mayamaea tytgatiana sp . nov ., Muelleria pimpireviana sp . nov . and Pinnularia pinseeliana sp . nov . are newly discovered taxa. The morphology of all new species is studied using both light and scanning electon microscope observations and compared with similar species from the Antarctic Region and worldwide. Data about the ecology and confirmed Antarctic distribution of the new species are added.

  • Two new Gomphonema species (Bacillariophyta) from the Maritime Antarctic Region
    Phytotaxa, 2016
    Co-Authors: Bart Van De Vijver, Kateřina Kopalová, Ralitsa Zidarova, J. Patrick Kociolek
    Abstract:

    Two new diatom taxa belonging to the genus Gomphonema were recorded during a survey of the Maritime Antarctic freshwater and limno-terrestrial diatom flora: Gomphonema jamesrossense sp . nov . and G . maritimo-Antarcticum sp . nov . Detailed light (LM) and scanning electron microscope (SEM) observations are used to characterize the morphology and ultrastructure of the two new Gomphonema taxa. Comparisons with similar taxa and the ecological preferences of each species are added. The revision of these species confirmed the endemic nature of the Antarctic diatom flora.

  • the genus luticola d g mann bacillariophyta from the mcmurdo sound Region Antarctica with the description of four new species
    Phytotaxa, 2015
    Co-Authors: Tyler J Kohler, Bart Van De Vijver, Kateřina Kopalová, Patrick J Kociolek
    Abstract:

    A revision of the freshwater diatom genus Luticola from the McMurdo Sound Region, including the McMurdo Dry Valleys and Cape Royds, Antarctica, was made to contribute to a consistent flora for the entire Antarctic Region. Detailed light and scanning electron microscopic observations, review of pertinent literature, and examination of historical and type material lead to the identification of 12 Luticola species. Four new species and one new combination are proposed, including L . bradyi sp . nov ., L . spainiae , sp . nov ., L . macknightiae , sp . nov ., L . transAntarctica , sp . nov ., and L . elegans , comb . nov . stat . nov . Several of these taxa were previously identified as part of the L . muticopsis (Van Heurck) D.G.Mann complex; Navicula muticopsis f. evoluta W. & G.S. West, L . muticopsis f. reducta (W. & G.S. West) Spaulding, and N . muticopsis f. capitata Carlson, or mistaken for the similar L . mutica (Kutzing) D.G.Mann and L . cohnii (Hilse) D.G.Mann. Morphological features of all new species were compared to the closest morphologically similar taxa, and their ecology and biogeography are discussed. All Luticola species considered here show restricted Antarctic distributions, and 8 of the 12 reported species are known only from the Antarctic continent.

  • five new species of the genus humidophila bacillariophyta from the maritime Antarctic Region
    Diatom Research, 2015
    Co-Authors: Kateřina Kopalová, Ralitsa Zidarova, Patrick J Kociolek, Rex L Lowe, Bart Van De Vijver
    Abstract:

    Five unknown taxa belonging to the newly established genus Humidophila were found during ongoing taxonomic revision of the freshwater and limno-terrestrial diatom flora of the Maritime Antarctic Region. These taxa were previously identified as Diadesmis arcuata, D. biscutella, D. comperei and D. ingeae, but detailed light and scanning electron microscopy observations allowed their clear separation from the already known taxa, and resulted in the description of five new species: Humidophila sceppacuerciae Kopalova sp. nov., H. australoshetlandica Kopalova, Zidarova & Van de Vijver sp. nov., H. keiliorum Kopalova sp. nov., H. deceptionensis Kopalova, Zidarova & Van de Vijver sp. nov. and H. vojtajarosikii Kopalova sp. nov. All five new taxa are compared with the morphologically most similar taxa, and their ecology and biogeography are discussed. Although the genus Humidophila is present worldwide, a large number of Humidophila taxa have a restricted distribution within the (sub-)Antarctic Region, showing a ...

  • new species in the genus muelleria bacillariophyta from the maritime Antarctic Region
    Fottea, 2014
    Co-Authors: Bart Van De Vijver, Ralitsa Zidarova, Kateřina Kopalová
    Abstract:

    During a survey of the freshwater aquatic and limno-terrestrial diatom flora of the Maritime Antarctic Region, six taxa belonging to the genus Muelleria that could not be identified were observed. Based on detailed LM and SEM observations, these six taxa have been described as new taxa: Muelleria desseiniana sp. nov., M. levkoviana sp. nov., M. nogae sp. nov., M. spauldingiana sp. nov., M. subsabbei sp. nov. and M. undulatoides sp. nov. Comments are made on their taxonomic position and how they can be distinguished from other species in this genus. Brief notes on the ecology and distribution of the six taxa are added. A compiled list of all Muelleria taxa described worldwide is included in this paper.

Ralitsa Zidarova - One of the best experts on this subject based on the ideXlab platform.

  • Ten new Bacillariophyta species from James Ross Island and the South Shetland Islands (Maritime Antarctic Region)
    Phytotaxa, 2016
    Co-Authors: Ralitsa Zidarova, Kateřina Kopalová, Bart Van De Vijver
    Abstract:

    The present paper describes 10 new diatom (Bacillariophyta) species from the Maritime Antarctic Region. Five of the newly described taxa: Caloneis australis sp . nov ., Mayamaea sweetloveana sp . nov ., Navicula romanedwardii sp . nov ., Sellaphora Antarctica sp . nov . and Sellaphora gracillima sp . nov . have been previously reported from the Antarctic Region but were force-fitted into incorrect names. Five other taxa: Chamaepinnularia elliptica sp . nov ., Cosmioneis regigeorgiensis sp . nov ., Mayamaea tytgatiana sp . nov ., Muelleria pimpireviana sp . nov . and Pinnularia pinseeliana sp . nov . are newly discovered taxa. The morphology of all new species is studied using both light and scanning electon microscope observations and compared with similar species from the Antarctic Region and worldwide. Data about the ecology and confirmed Antarctic distribution of the new species are added.

  • Two new Gomphonema species (Bacillariophyta) from the Maritime Antarctic Region
    Phytotaxa, 2016
    Co-Authors: Bart Van De Vijver, Kateřina Kopalová, Ralitsa Zidarova, J. Patrick Kociolek
    Abstract:

    Two new diatom taxa belonging to the genus Gomphonema were recorded during a survey of the Maritime Antarctic freshwater and limno-terrestrial diatom flora: Gomphonema jamesrossense sp . nov . and G . maritimo-Antarcticum sp . nov . Detailed light (LM) and scanning electron microscope (SEM) observations are used to characterize the morphology and ultrastructure of the two new Gomphonema taxa. Comparisons with similar taxa and the ecological preferences of each species are added. The revision of these species confirmed the endemic nature of the Antarctic diatom flora.

  • five new species of the genus humidophila bacillariophyta from the maritime Antarctic Region
    Diatom Research, 2015
    Co-Authors: Kateřina Kopalová, Ralitsa Zidarova, Patrick J Kociolek, Rex L Lowe, Bart Van De Vijver
    Abstract:

    Five unknown taxa belonging to the newly established genus Humidophila were found during ongoing taxonomic revision of the freshwater and limno-terrestrial diatom flora of the Maritime Antarctic Region. These taxa were previously identified as Diadesmis arcuata, D. biscutella, D. comperei and D. ingeae, but detailed light and scanning electron microscopy observations allowed their clear separation from the already known taxa, and resulted in the description of five new species: Humidophila sceppacuerciae Kopalova sp. nov., H. australoshetlandica Kopalova, Zidarova & Van de Vijver sp. nov., H. keiliorum Kopalova sp. nov., H. deceptionensis Kopalova, Zidarova & Van de Vijver sp. nov. and H. vojtajarosikii Kopalova sp. nov. All five new taxa are compared with the morphologically most similar taxa, and their ecology and biogeography are discussed. Although the genus Humidophila is present worldwide, a large number of Humidophila taxa have a restricted distribution within the (sub-)Antarctic Region, showing a ...

  • new species in the genus muelleria bacillariophyta from the maritime Antarctic Region
    Fottea, 2014
    Co-Authors: Bart Van De Vijver, Ralitsa Zidarova, Kateřina Kopalová
    Abstract:

    During a survey of the freshwater aquatic and limno-terrestrial diatom flora of the Maritime Antarctic Region, six taxa belonging to the genus Muelleria that could not be identified were observed. Based on detailed LM and SEM observations, these six taxa have been described as new taxa: Muelleria desseiniana sp. nov., M. levkoviana sp. nov., M. nogae sp. nov., M. spauldingiana sp. nov., M. subsabbei sp. nov. and M. undulatoides sp. nov. Comments are made on their taxonomic position and how they can be distinguished from other species in this genus. Brief notes on the ecology and distribution of the six taxa are added. A compiled list of all Muelleria taxa described worldwide is included in this paper.

  • analysis of the type material of achnanthidium lanceolatum brebisson ex kutzing bacillariophyta with the description of two new planothidium species from the Antarctic Region
    Fottea, 2013
    Co-Authors: Bart Van De Vijver, Kateřina Kopalová, Ralitsa Zidarova, Carlos E Wetzel, Luc Ector
    Abstract:

    The type material of Achnanthidium lanceolatum (transferred in 1999 to the genus Planothidium) is investigated to reveal the identity of several Planothidium populations from the Antarctic Region. The morphology and the ultrastructure was analysed using light and scanning electron microscopy. The results of this analysis revealed the presence of two so far undescribed Planothidium species in the investigated Antarctic material. Both species are described as new to science: P. rost- rolanceolatum Van de VijVer, KopaloVa et zidaroVa sp. nov. and P. subAntarcticum Van de VijVer et c.e.Wetzel sp. nov. The new species can be differentiated based on differences in valve outline and the shape and size of the central area. Planothidium lanceolatum is formally lectotypified. Notes on the ecology and distribution of the new Antarctic species are added.

Marcelo Baeza - One of the best experts on this subject based on the ideXlab platform.

  • Characterization of gelatinase produced by Antarctic Mrakia sp.
    Journal of Basic Microbiology, 2019
    Co-Authors: Yassef Yuivar, Jennifer Alcaíno, Víctor Cifuentes, Marcelo Baeza
    Abstract:

    : In the present study, 20 psychrotolerant yeast species isolated from the soils of King George Island in the sub-Antarctic Region were evaluated for the production of extracellular gelatinase, an enzyme with high potential for applications in diverse areas, such as food and medicine. The production of extracellular gelatinase was confirmed in the yeasts Metschnikowia sp., Leucosporidium fragarium, and Mrakia sp., the last one being the yeast in which the highest gelatinase activity was detected. The enzyme was purified from cultures of Mrakia sp., and the effect of different physical-chemical factors on its activity was determined. The gelatinase produced by Mrakia sp. would correspond to a protein of relative molecular weight (rMW) 37,000, which displayed the highest activity at 36°C, pH 7.0, 10 mM CaCl 2 , and 5 mM ZnSO 4 .

  • Diversity and extracellular enzymatic activities of yeasts isolated from King George Island, the sub-Antarctic Region
    BMC Microbiology, 2012
    Co-Authors: Mario Carrasco, Salvador Barahona, Jennifer Alcaíno, Víctor Cifuentes, Juan Manuel Rozas, Marcelo Baeza
    Abstract:

    Background Antarctica has been successfully colonized by microorganisms despite presenting adverse conditions for life such as low temperatures, high solar radiation, low nutrient availability and dryness. Although these “cold-loving” microorganisms are recognized as primarily responsible for nutrient and organic matter recycling/mineralization, the yeasts, in particular, remain poorly characterized and understood. The aim of this work was to study the yeast microbiota in soil and water samples collected on King George Island. Results A high number of yeast isolates was obtained from 34 soil and 14 water samples. Molecular analyses based on rDNA sequences revealed 22 yeast species belonging to 12 genera, with Mrakia and Cryptococcus genera containing the highest species diversity . The species Sporidiobolus salmonicolor was by far the most ubiquitous, being identified in 24 isolates from 13 different samples. Most of the yeasts were psychrotolerant and ranged widely in their ability to assimilate carbon sources (consuming from 1 to 27 of the 29 carbon sources tested). All species displayed at least 1 of the 8 extracellular enzyme activities tested. Lipase, amylase and esterase activity dominated, while chitinase and xylanase were less common. Two yeasts identified as Leuconeurospora sp. and Dioszegia fristingensis displayed 6 enzyme activities. Conclusions A high diversity of yeasts was isolated in this work including undescribed species and species not previously isolated from the Antarctic Region, including Wickerhamomyces anomalus , which has not been isolated from cold Regions in general. The diversity of extracellular enzyme activities, and hence the variety of compounds that the yeasts may degrade or transform, suggests an important nutrient recycling role of microorganisms in this Region. These yeasts are of potential use in industrial applications requiring high enzyme activities at low temperatures.

  • diversity and extracellular enzymatic activities of yeasts isolated from king george island the sub Antarctic Region
    BMC Microbiology, 2012
    Co-Authors: Mario Carrasco, Salvador Barahona, Jennifer Alcaíno, Víctor Cifuentes, Juan Manuel Rozas, Marcelo Baeza
    Abstract:

    Background Antarctica has been successfully colonized by microorganisms despite presenting adverse conditions for life such as low temperatures, high solar radiation, low nutrient availability and dryness. Although these “cold-loving” microorganisms are recognized as primarily responsible for nutrient and organic matter recycling/mineralization, the yeasts, in particular, remain poorly characterized and understood. The aim of this work was to study the yeast microbiota in soil and water samples collected on King George Island.

Mario Carrasco - One of the best experts on this subject based on the ideXlab platform.

  • Diversity and extracellular enzymatic activities of yeasts isolated from King George Island, the sub-Antarctic Region
    BMC Microbiology, 2012
    Co-Authors: Mario Carrasco, Salvador Barahona, Jennifer Alcaíno, Víctor Cifuentes, Juan Manuel Rozas, Marcelo Baeza
    Abstract:

    Background Antarctica has been successfully colonized by microorganisms despite presenting adverse conditions for life such as low temperatures, high solar radiation, low nutrient availability and dryness. Although these “cold-loving” microorganisms are recognized as primarily responsible for nutrient and organic matter recycling/mineralization, the yeasts, in particular, remain poorly characterized and understood. The aim of this work was to study the yeast microbiota in soil and water samples collected on King George Island. Results A high number of yeast isolates was obtained from 34 soil and 14 water samples. Molecular analyses based on rDNA sequences revealed 22 yeast species belonging to 12 genera, with Mrakia and Cryptococcus genera containing the highest species diversity . The species Sporidiobolus salmonicolor was by far the most ubiquitous, being identified in 24 isolates from 13 different samples. Most of the yeasts were psychrotolerant and ranged widely in their ability to assimilate carbon sources (consuming from 1 to 27 of the 29 carbon sources tested). All species displayed at least 1 of the 8 extracellular enzyme activities tested. Lipase, amylase and esterase activity dominated, while chitinase and xylanase were less common. Two yeasts identified as Leuconeurospora sp. and Dioszegia fristingensis displayed 6 enzyme activities. Conclusions A high diversity of yeasts was isolated in this work including undescribed species and species not previously isolated from the Antarctic Region, including Wickerhamomyces anomalus , which has not been isolated from cold Regions in general. The diversity of extracellular enzyme activities, and hence the variety of compounds that the yeasts may degrade or transform, suggests an important nutrient recycling role of microorganisms in this Region. These yeasts are of potential use in industrial applications requiring high enzyme activities at low temperatures.

  • diversity and extracellular enzymatic activities of yeasts isolated from king george island the sub Antarctic Region
    BMC Microbiology, 2012
    Co-Authors: Mario Carrasco, Salvador Barahona, Jennifer Alcaíno, Víctor Cifuentes, Juan Manuel Rozas, Marcelo Baeza
    Abstract:

    Background Antarctica has been successfully colonized by microorganisms despite presenting adverse conditions for life such as low temperatures, high solar radiation, low nutrient availability and dryness. Although these “cold-loving” microorganisms are recognized as primarily responsible for nutrient and organic matter recycling/mineralization, the yeasts, in particular, remain poorly characterized and understood. The aim of this work was to study the yeast microbiota in soil and water samples collected on King George Island.