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DOI 10.3390/biology12081142
Harnessing Diesel-Degrading Potential of an Antarctic Microalga from Greenwich Island and Its Physiological Adaptation
2023-08
Lim, Zheng Syuen
;
Wong, Chiew-Yen
;
Ahmad, Siti Aqlima
;
Puasa, Nurul Aini
;
Phang, Lai Yee
;
Shaharuddin, Noor Azmi
;
Merican, Faradina
;
Convey, Peter
;
Zulkharnain, Azham
;
Shaari, Hasrizal
Phytoremediation is a plant-based approach to extract, stabilise, eliminate, or render pollutants into less harmful form. The study highlights the use of a native polar microalga as a means of phytoremediation in Antarctica where imported microbes are prohibited. Since 1959, Antarctica has been a protected region to preserve its dynamic ecosystems, but it is increasingly vulnerable to climate change and pollution. One of the anthropogenic disturbances in the continent is diesel spillage. Due to the extreme polar environment, natural attenuation of spilled diesel is severely hindered; hence, the problem calls for an effective and sustainable solution. This laboratory study proved that Antarctic microalga was capable of removing diesel (57.6%) through biodegradation and biosorption in the span of nine days. Meanwhile, mixotrophic cultivation triggered the vacuolar activities and potentially stimulated lipid assimilation in the cells. The microalgal-based process offers a cheap alternative in water decontamination while bearing the economic potential through the secretion of valuable products, such as biolipids. Abstract: Microalgae are well known for their metal sorption capacities, but their potential in the remediation of hydrophobic organic compounds has received little attention in polar regions. We evaluated in the laboratory the ability of an Antarctic microalga to remediate diesel hydrocarbons and also investigated physiological changes consequent upon diesel exposure. Using a polyphasic taxonomic approach, the microalgal isolate, WCY_AQ5_1, originally sampled from Greenwich Island (South Shetland Islands, maritime Antarctica) was identified as Tritostichococcus sp. (OQ225631), a recently erected lineage within the redefined Stichococcus clade. Over a nine-day experimental incubation, 57.6% of diesel (similar to 3.47 g/L) was removed via biosorption and biodegradation, demonstrating the strain's potential for phytoremediation. Fourier transform infrared spectroscopy confirmed the adsorption of oil in accordance with its hydrophobic characteristics. Overall, degradation predominated over sorption of diesel. Chromatographic analysis confirmed that the strain efficiently metabolised medium-chain length n-alkanes (C-7 to C-21), particularly n-heneicosane. Mixotrophic cultivation using diesel as the organic carbon source under a constant light regime altered the car/chl-a ratio and triggered vacuolar activities. A small number of intracellular lipid droplets were observed on the seventh day of cultivation in transmission electron microscopic imaging. This is the first confirmation of diesel remediation ability in an Antarctic green microalga.
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DOI 10.3390/biology12081142
Harnessing Diesel-Degrading Potential of an Antarctic Microalga from Greenwich Island and Its Physiological Adaptation
2023-08
Lim, Zheng Syuen
;
Wong, Chiew-Yen
;
Ahmad, Siti Aqlima
;
Puasa, Nurul Aini
;
Phang, Lai Yee
;
Shaharuddin, Noor Azmi
;
Merican, Faradina
;
Convey, Peter
;
Zulkharnain, Azham
;
Shaari, Hasrizal
Phytoremediation is a plant-based approach to extract, stabilise, eliminate, or render pollutants into less harmful form. The study highlights the use of a native polar microalga as a means of phytoremediation in Antarctica where imported microbes are prohibited. Since 1959, Antarctica has been a protected region to preserve its dynamic ecosystems, but it is increasingly vulnerable to climate change and pollution. One of the anthropogenic disturbances in the continent is diesel spillage. Due to the extreme polar environment, natural attenuation of spilled diesel is severely hindered; hence, the problem calls for an effective and sustainable solution. This laboratory study proved that Antarctic microalga was capable of removing diesel (57.6%) through biodegradation and biosorption in the span of nine days. Meanwhile, mixotrophic cultivation triggered the vacuolar activities and potentially stimulated lipid assimilation in the cells. The microalgal-based process offers a cheap alternative in water decontamination while bearing the economic potential through the secretion of valuable products, such as biolipids. Abstract: Microalgae are well known for their metal sorption capacities, but their potential in the remediation of hydrophobic organic compounds has received little attention in polar regions. We evaluated in the laboratory the ability of an Antarctic microalga to remediate diesel hydrocarbons and also investigated physiological changes consequent upon diesel exposure. Using a polyphasic taxonomic approach, the microalgal isolate, WCY_AQ5_1, originally sampled from Greenwich Island (South Shetland Islands, maritime Antarctica) was identified as Tritostichococcus sp. (OQ225631), a recently erected lineage within the redefined Stichococcus clade. Over a nine-day experimental incubation, 57.6% of diesel (similar to 3.47 g/L) was removed via biosorption and biodegradation, demonstrating the strain's potential for phytoremediation. Fourier transform infrared spectroscopy confirmed the adsorption of oil in accordance with its hydrophobic characteristics. Overall, degradation predominated over sorption of diesel. Chromatographic analysis confirmed that the strain efficiently metabolised medium-chain length n-alkanes (C-7 to C-21), particularly n-heneicosane. Mixotrophic cultivation using diesel as the organic carbon source under a constant light regime altered the car/chl-a ratio and triggered vacuolar activities. A small number of intracellular lipid droplets were observed on the seventh day of cultivation in transmission electron microscopic imaging. This is the first confirmation of diesel remediation ability in an Antarctic green microalga.
Scopus© Citations 6 3
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DOI 10.1016/j.carbon.2022.02.048
Edge type effect in the gasification mechanism of graphene clusters with H2O and/or CO2: armchair vs. zigzag
2022-06-30
Oyarzún Aravena, Andrea María
;
Gottschalk-Ojeda, Catalina
;
Moya-Barria, Ivan
;
Vallejos-Burgos, Fernando
Reactions of carbon and oxygen containing molecules, such as O-2, NO, H2O and CO2, are ubiquitous on earth and the universe. Through ab initio calculations, we study the reactions of H2O and CO(2)with small graphene clusters containing armchair edges, both H- and non-H terminated, and compare with studies of zigzag carbon edges interacting with oxygen-containing molecules. Our results highlight the differences between armchair and zigzag sites and our mechanistic comparisons regarding carbon reactions with H2O and CO2, identify similarities and differences on their reactivity. In the case of H2O, adsorption is favored over armchair sites exhibiting no rotational process and the H-2 desorption step is favored over zigzag sites. Regarding the CO2 reaction, chemisorption is favored on zigzag sites. Several adsorption mechanisms lead to the formation of lactone groups as the most stable structures. A specific armchair CO desorption path for stable functional groups exists, agreeing with experimental reports, and thus completing our explanations for this reaction, previously limited to zigzag sites. Finally, the reaction over armchair sites leads to direct formation of pentagonal rings, without an active site deactivation process and with low activation energies. This deeper understanding provides further possibilities for improving the control of carbon-oxygen reactions.
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DOI 10.1016/j.carbon.2022.02.048
Edge type effect in the gasification mechanism of graphene clusters with H2O and/or CO2: armchair vs. zigzag
2022-06-30
Oyarzún Aravena, Andrea María
;
Gottschalk-Ojeda, Catalina
;
Moya-Barria, Ivan
;
Vallejos-Burgos, Fernando
Reactions of carbon and oxygen containing molecules, such as O-2, NO, H2O and CO2, are ubiquitous on earth and the universe. Through ab initio calculations, we study the reactions of H2O and CO(2)with small graphene clusters containing armchair edges, both H- and non-H terminated, and compare with studies of zigzag carbon edges interacting with oxygen-containing molecules. Our results highlight the differences between armchair and zigzag sites and our mechanistic comparisons regarding carbon reactions with H2O and CO2, identify similarities and differences on their reactivity. In the case of H2O, adsorption is favored over armchair sites exhibiting no rotational process and the H-2 desorption step is favored over zigzag sites. Regarding the CO2 reaction, chemisorption is favored on zigzag sites. Several adsorption mechanisms lead to the formation of lactone groups as the most stable structures. A specific armchair CO desorption path for stable functional groups exists, agreeing with experimental reports, and thus completing our explanations for this reaction, previously limited to zigzag sites. Finally, the reaction over armchair sites leads to direct formation of pentagonal rings, without an active site deactivation process and with low activation energies. This deeper understanding provides further possibilities for improving the control of carbon-oxygen reactions.
Scopus© Citations 16 1
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DOI 10.4067/s0718-50062022000200103
Training in computational chemistry and its applications through a research project developed in the Chilean Patagonia Formación en química computacional y sus aplicaciones a través de un proyecto de investigación desarrollado en la Patagonia chilena
2022-04-01
Oyarzún Aravena, Andrea María
;
Moya-Barría, Iván I.
;
Navarro Pérez, Daniela Josefina
This study assesses the pedagogical benefits obtained by students, teachers, and a sponsor through the development of a computational chemistry research project on interactions between carbon materials and gases. Achievements, challenges, and opportunities are identified, emphasizing the mastery of transferable and technical skills throughout the four-year-long project. Engineering thesis students formed the teamwork. We highlight the implementation of the servers and software which are necessary to apply computational chemistry as a methodological tool. The subject of air pollution is also examined by performing a multidisciplinary analysis that determines potential areas for future applications and the impact of the computational analyses performed. It is concluded that there is development of training abilities in complex scientific-technological areas for both undergraduate and graduate students in a geographically isolated context that may limit performance.
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DOI 10.4067/s0718-50062022000200103
Training in computational chemistry and its applications through a research project developed in the Chilean Patagonia Formación en química computacional y sus aplicaciones a través de un proyecto de investigación desarrollado en la Patagonia chilena
2022-04-01
Oyarzún Aravena, Andrea María
;
Moya-Barría, Iván I.
;
Navarro Pérez, Daniela Josefina
This study assesses the pedagogical benefits obtained by students, teachers, and a sponsor through the development of a computational chemistry research project on interactions between carbon materials and gases. Achievements, challenges, and opportunities are identified, emphasizing the mastery of transferable and technical skills throughout the four-year-long project. Engineering thesis students formed the teamwork. We highlight the implementation of the servers and software which are necessary to apply computational chemistry as a methodological tool. The subject of air pollution is also examined by performing a multidisciplinary analysis that determines potential areas for future applications and the impact of the computational analyses performed. It is concluded that there is development of training abilities in complex scientific-technological areas for both undergraduate and graduate students in a geographically isolated context that may limit performance.
Scopus© Citations 1 1
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DOI 10.22352/aip202250002
Identificación de bacterias antárticas con actividad antimicrobiana aisladas de la rizósfera de Deschampsia antarctica Desv.
2022
ORELLANA, PAZ
;
PAVÓN, ALEQUIS
;
Calisto Ulloa, Nancy Cristina
;
WIESE, GUILLERMO
;
NAVARRO, LAURA
;
CORTÉS-CORTÉS, PIEDAD
;
GIDEKEL, MANUEL
;
GUTIÉRREZ-MORAGA, ANA
;
CORSINI, GINO
RESUMEN: La disminución sostenida de la disponibilidad de nuevas moléculas antimicrobianas para el uso terapéutico en las últimas décadas y el gran aumento de microorganismos resistentes a estos compuestos hace necesario buscar nuevas sustancias con propiedades antimicrobianas. Los ambientes extremos, donde hay poca disponibilidad de nutrientes, son escenarios propicios para buscar este tipo de compuestos, ya que las bacterias compiten entre sí y con otros organismos por posicionarse en el nicho ecológico y secretan, asociado a su metabolismo secundario, una serie de moléculas que inhiben o matan a otros microorga nismos, evitando su multiplicación. Nuestro grupo posee una colección de bacterias aisladas de la rizósfera de suelo del con tinente antártico, que logran crecer en condiciones de deprivación de nutrientes y a 4°C. Debido al hábitat extremo donde se desarrollan, las bacterias de los suelos de la Antártica están en una constante competencia por los recursos nutricionales, desarrollando distintas estrategias para colonizar su nicho ecológico y competir con otros microorganismos de la microbiota antártica. El objetivo de este trabajo consistió en identificar bacterias aisladas de la rizósfera de Deschampsia antarctica Desv. que inhiben el crecimiento de bacterias y hongos patógenos para humanos. A partir de una colección de 55 aislados de la rizósfera de la planta D. antarctica Desv. se identificaron 11 aislados con capacidad de matar o inhibir bacterias patógenas humanas, pero ningún aislado inhibió el crecimiento del hongo Candida albicans. Los resultados mos traron que las 11 bacterias antárticas con actividad antibacteriana corresponden a bacilos aerobios estrictos, Gram negativo, psicrófilos que pertenecen al género Pseudomonas.
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DOI 10.22352/aip202250005
La comunidad macrobentónica intermareal de bahía Chile (isla Greenwich, Antártica) y su relación entre parámetros fisicoquímicos y granulométricos
2022
Pérez, Daniel
;
Gomez Fuentes, Claudio German
;
Aravena, Daniel
;
Calisto Ulloa, Nancy Cristina
Resumen: La actividad humana ha ido aumentando en el continente antártico, lo que se traduce un impacto directo en áreas litorales por medio de las aguas residuos, los cuales afectan a las comunidades bentónicas intermareales. Además, estas comunidades han sido poco estudiadas debido a la escasez de áreas intermareales libres de hielo en el continente blanco. El presente estudio tiene como objetivo determinar los parámetros comunitario de los macroinvertebrados bentónicos en el intermareal de bahía Chile/ Discovery (Isla Greenwich) y su relación con variables fisicoquímicas (materia orgánica, hidrocarburos totales del petróleo, fósforo libre y nitrógeno total) en las proximidades del emisario de la base naval Arturo Prat. Para ello, se tomaron muestras de sedimento en dos transectos paralelos a la línea de costa a ambos lados del emisario a 25, 50, 200 y 300 metros de distancia. Se identificaron un total de 10 taxones de los cuales Harpacticoidea y Oligochaeta fueron los más abundante. Los valores de abundancia por muestra variaron entre 256 y 12.176 (Ind*m-2). Mientras que el promedio del índice de Shannon-Wiener (H') varió entre 0,57 (± 0,53) y 1,32 (± 1,26) y la uniformidad promedio (J) varió entre 0,32 (± 0,29) y 0,63 (± 0,60). El análisis de componentes principales mostró una relación directa entre la abundancia y la concentración de las variables fisicoquímicas. Por otro lado, los resultados obtenidos muestran que las variables fisicoquímicas, composición taxonómica, equidad y valores de diversidad eran similares a las obtenidas para otras áreas de la Isla Rey Jorge.
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DOI 10.22352/aip202250002
Identificación de bacterias antárticas con actividad antimicrobiana aisladas de la rizósfera de Deschampsia antarctica Desv.
2022
ORELLANA, PAZ
;
PAVÓN, ALEQUIS
;
Calisto Ulloa, Nancy Cristina
;
WIESE, GUILLERMO
;
NAVARRO, LAURA
;
CORTÉS-CORTÉS, PIEDAD
;
GIDEKEL, MANUEL
;
GUTIÉRREZ-MORAGA, ANA
;
CORSINI, GINO
RESUMEN: La disminución sostenida de la disponibilidad de nuevas moléculas antimicrobianas para el uso terapéutico en las últimas décadas y el gran aumento de microorganismos resistentes a estos compuestos hace necesario buscar nuevas sustancias con propiedades antimicrobianas. Los ambientes extremos, donde hay poca disponibilidad de nutrientes, son escenarios propicios para buscar este tipo de compuestos, ya que las bacterias compiten entre sí y con otros organismos por posicionarse en el nicho ecológico y secretan, asociado a su metabolismo secundario, una serie de moléculas que inhiben o matan a otros microorga nismos, evitando su multiplicación. Nuestro grupo posee una colección de bacterias aisladas de la rizósfera de suelo del con tinente antártico, que logran crecer en condiciones de deprivación de nutrientes y a 4°C. Debido al hábitat extremo donde se desarrollan, las bacterias de los suelos de la Antártica están en una constante competencia por los recursos nutricionales, desarrollando distintas estrategias para colonizar su nicho ecológico y competir con otros microorganismos de la microbiota antártica. El objetivo de este trabajo consistió en identificar bacterias aisladas de la rizósfera de Deschampsia antarctica Desv. que inhiben el crecimiento de bacterias y hongos patógenos para humanos. A partir de una colección de 55 aislados de la rizósfera de la planta D. antarctica Desv. se identificaron 11 aislados con capacidad de matar o inhibir bacterias patógenas humanas, pero ningún aislado inhibió el crecimiento del hongo Candida albicans. Los resultados mos traron que las 11 bacterias antárticas con actividad antibacteriana corresponden a bacilos aerobios estrictos, Gram negativo, psicrófilos que pertenecen al género Pseudomonas.
1
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DOI 10.22352/aip202250005
La comunidad macrobentónica intermareal de bahía Chile (isla Greenwich, Antártica) y su relación entre parámetros fisicoquímicos y granulométricos
2022
Pérez, Daniel
;
Gomez Fuentes, Claudio German
;
Aravena, Daniel
;
Calisto Ulloa, Nancy Cristina
Resumen: La actividad humana ha ido aumentando en el continente antártico, lo que se traduce un impacto directo en áreas litorales por medio de las aguas residuos, los cuales afectan a las comunidades bentónicas intermareales. Además, estas comunidades han sido poco estudiadas debido a la escasez de áreas intermareales libres de hielo en el continente blanco. El presente estudio tiene como objetivo determinar los parámetros comunitario de los macroinvertebrados bentónicos en el intermareal de bahía Chile/ Discovery (Isla Greenwich) y su relación con variables fisicoquímicas (materia orgánica, hidrocarburos totales del petróleo, fósforo libre y nitrógeno total) en las proximidades del emisario de la base naval Arturo Prat. Para ello, se tomaron muestras de sedimento en dos transectos paralelos a la línea de costa a ambos lados del emisario a 25, 50, 200 y 300 metros de distancia. Se identificaron un total de 10 taxones de los cuales Harpacticoidea y Oligochaeta fueron los más abundante. Los valores de abundancia por muestra variaron entre 256 y 12.176 (Ind*m-2). Mientras que el promedio del índice de Shannon-Wiener (H') varió entre 0,57 (± 0,53) y 1,32 (± 1,26) y la uniformidad promedio (J) varió entre 0,32 (± 0,29) y 0,63 (± 0,60). El análisis de componentes principales mostró una relación directa entre la abundancia y la concentración de las variables fisicoquímicas. Por otro lado, los resultados obtenidos muestran que las variables fisicoquímicas, composición taxonómica, equidad y valores de diversidad eran similares a las obtenidas para otras áreas de la Isla Rey Jorge.
1

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