Towards the sustainable production of lemons: native yeasts as biological control agents

The province of Tucumán is positioned as one of the main centers of production and processing of lemons. Among the problems associated with the production of lemons, the economic losses caused by postharvest fungal infections stand out. Chemical fungicides have traditionally been applied as control and preventive measures, but their use entails numerous problems such as environmental contamination, toxicity in humans and restrictions on international markets. However, efficient and sustainable alternatives to the use of such pesticides are not known so far. Thus, the aim of this research was to search for biological control alternatives based on native yeasts, understand the associated mechanisms of action, and formulate a sustainable biocontrol agent. Biocontrol yeasts were isolated from citrus plants and lemon packinghouses. The antagonism of the isolates against Penicillium digitatum in in vitro and in vivo assays as well as the possible mechanisms of action related to biological control were determined. In addition, both liquid and solid formulations were tested. Among the yeast isolates, Clavispora lusitaniae 146stood out as it was able to inhibit P. digitatum in vitro and also to control green mold onlemons with high efficiency, both in room temperature and cold storage. Yeast 146 was ableto resist stress factors associated with the packaging process and was compatible with carnauba wax. Among the mechanisms of action, the ability to colonize wounds and the competition for space and nutrients were evidenced. C. lusitaniae depicted a broad spectrum of action in controlling green mold on other citrus fruits, such as oranges, mandarins, and grapefruit. C. lusitaniae 146 did not negatively affect the aroma perception of fruits by consumers. Moreover, it was able to remove the mycotoxin patulin from a solution. Different liquid and solid formulations were tested; being the yeast dried by lyophilization in combination with sucrose and skimmed milk the most promising. The native yeast C. lusitaniae 146 is a promising biological control agent for the control of P. digitatum in lemons and other varieties of citrus fruits. A yeast-based formulation would replace the use of chemical fungicides and promote the organic production of lemons.Fil: Diaz, Mariana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Pereyra, Martina María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Rasuk, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Dib, Julian Rafael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Microbiología; ArgentinaXVIII Congreso de la Sociedad Argentina de Microbiología GeneralChapadmalalArgentinaSociedad Argentina de Microbiología Genera

Extreme-halophiles: their role in the arsenic biogeochemical cycle

Biofilms, mats and microbialites dwell under extreme environmental conditions (high salinity, extreme aridity, pH and arsenic concentration) in the Argentinean Puna and the Atacama Desert. Microbial communities inhabiting those ecosystems are poorly known. Arsenic metabolism is proposed to be an ancient mechanism in microbial life. Besides, some bacteria and archaea are not only able to use detoxification processes to grow under high arsenic concentration, but also, some of them are able to exploit arsenic as a bioenergetic substrate in either anaerobic arsenate respiration or chemolithotrophic growth on arsenite. Only four aioAB coding for arsenite oxidase and two arrA coding for arsenate reductase sequences from haloarchaea were previously deposited in the NCBI Database, but have not been reported in the literature. The arrA arsenate reductases are reliable indicators of anaerobic As (V) respiration and catalyze the electron transfer to the As (V) terminal acceptor in dissimilatory arsenatereducing prokaryotes (DARPs). In this work, we are presenting our first steps in the study of the arsenic biogeochemical cycle in these ecosystems. Thus, the aim of this study was to isolate and to study the arsenic metabolism genes of the isolated extreme halophile microorganisms as well as to test the growth in minimal medium using different carbon sources. Mats and microbialites samples were taken from the water’s edge of Laguna Tebenquiche, Laguna Brava (Salar de Atacama, Chile) during December 2012 and from gaylusite crystals (Laguna Diamante) in August 2014. Samples were enriched and plated in WS medium supplemented with arsenic (AsIII 0.5mM and AsV 20mM). Arsenite oxidase (aioB) and Arsenate reductase (arrA) primers specific for haloarchaea were designed using PrimerProspector software. Selected primers were aioB-1190F (5’-GCTCMTSACCGGCAGCGTCG-3’), aioB-1507R (5’-YGATCTCGTCGATGTCGGCG-3’), arrA-417F (5’CCCGAGTTCGAGCCSATCTC-3’) and arrA-614R (5’GCRCAGATCGMGCTGTGGGA-3’). In order to identify the isolates we used Archaea-specific primers for 16S rDNA gene amplification: 344F (5´- ACG GGG YGC AGC AGG CGC GA-3´) and 915R (5´- GTG CTC CCC CGC CAA TTC CT -3´). Fragments of 577 bp, 317pb and 197pb were obtained from 16S rDNA, aioB and arrA genes respectively. Universal primers 27F and 1492R were used to amplify 16S rDNA in bacterial isolates. 25 isolates belonging to Archaea and Bacteria Domain were obtained; they are related to the Phylum Euryarchaeota, Firmicutes and Proteobacteria. AioB and arrA genes were found in most of the isolates and DNA from the samples (mats, microbialites and biofilm). The best carbon source tested was pyruvate and acetate, being pyruvate better in all cases. Promising results were obtained in the search of organisms able to use arsenic in their bioenergetic metabolism. More studies are underway to try to better understand these very interesting systems.Fil: Rasuk, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Ordoñez, Omar Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Soria, Mariana Noelia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaXI Congreso Argentino de Microbiología GeneralCordobaArgentinaSociedad Argentina de Microbiología Genera

Carbon fixation and rhodopsin systems in microbial mats from hypersaline lakes Brava and Tebenquiche, Salar de Atacama, Chile

In this work, molecular diversity of two hypersaline microbial mats was compared by Whole Genome Shotgun (WGS) sequencing of environmental DNA from the mats. Brava and Tebenquiche are lakes in the Salar de Atacama, Chile, where microbial communities are growing in extreme conditions, including high salinity, high solar irradiance, and high levels of toxic metals and metaloids. Evaporation creates hypersaline conditions in these lakes and mineral precipitation is a characteristic geomicrobiological feature of these benthic ecosystems. The mat from Brava was more rich and diverse, with a higher number of different taxa and with species more evenly distributed. At the phylum level, Proteobacteria, Cyanobacteria, Chloroflexi, Bacteroidetes and Firmicutes were the most abundant, including ~75% of total sequences. At the genus level, the most abundant sequences were affilitated to anoxygenic phototropic and cyanobacterial genera. In Tebenquiche mats, Proteobacteria and Bacteroidetes covered ~70% of the sequences, and 13% of the sequences were affiliated to Salinibacter genus, thus addressing the lower diversity. Regardless of the differences at the taxonomic level, functionally the two mats were similar. Thus, similar roles could be fulfilled by different organisms. Carbon fixation through the Wood-Ljungdahl pathway was well represented in these datasets, and also in other mats from Andean lakes. In spite of presenting less taxonomic diversity, Tebenquiche mats showed increased abundance and variety of rhodopsin genes. Comparison with other metagenomes allowed identifying xantorhodopsins as hallmark genes not only from Brava and Tebenquiche mats, but also for other mats developing at high altitudes in similar environmental conditions.Fil: Kurth, Daniel German. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Elias, Dario Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; ArgentinaFil: Rasuk, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Contreras, Emanuel. Centro de Ecología Aplicada (CEA); ChileFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentin

Impact of biocontrol yeast clavispora lusitaniae 146 on the lemon microbiome

The use of biocontrol agents has been proposed as an effective alternative to reduce citrus decays for promoting sustainable agriculture based on organic fruit production. Among the different microbial biocontrol agents, Clavispora lusitaniae 146 stands out as it is able of effectively controlling green mold in lemons. Although there is growing recognition of the role that the microbiome plays in the health and physiology of many plant species, to date, the composition of the lemon microbiome is unknown, nor is the effect of yeast 146 on it. Thus, the aim of this research was to study the impacts of biocontrol yeast Clavispora lusitaneae 146 on the composition of the lemon microbiome. Lemons were harvested, and then divided into two treatments: untreated and treated lemons with biocontrol yeast C. lusitaneae 146. Fruits were then stored at room temperature for 7 days. DNA was extracted from a pool of 3 pieces of peel per sample, and used for PCR that amplified the bacterial hypervariable V3-V4 region of the 16S rRNA gene. Paired-end sequencing of amplicons was done on an Illumina MiSeq sequencer. To assess the effects of postharvest treatment and storage on the diversity of the lemon microbiome, we used a series of ANOVA and adonis (~PERMANOVA) models with Shannon diversity and community composition as the response variables, respectively. There was no statistically significant difference (KruskalWallies, p > 0.05) in bacterial diversity between the treated and untreated fruits. In this sense, the application of Clavispora lusitaneae 146 did not produce significant changes on bacterial communities of lemons during storage, including alpha diversity, community composition and structure. The bacterial community was dominated by roteobacteria,followed by Firmicutes and Actinobacteria. Specific bacterial taxa were only identified for untreated lemons: Methylobacteriaceae (Alphaproteobacteria) and unclassified bacteria, however in a low abundance. Here, we presented the first lemon microbiome and we showed that the microbial abundance, diversity, and community structures were not significantly different for both treatments, revealing that Clavispora lusitaniae 146 didn´t modify the native bacterial population of the fruit microbiome. The present study is part of larger project whose objectives are to define the complete lemon microbiome, assess the effects of the postharvest biocontrol agents on the composition of the lemon microbiome to develop a science-based strategy for manipulating this microbiome to prevent postharvest decay and physiological disorders.Fil: Rasuk, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Pisa, José Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Chacón, Florencia Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Pereyra, Martina María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Dib, Julian Rafael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Microbiología; ArgentinaXVIII Congreso de la Sociedad Argentina de Microbiología GeneralChapadmalalArgentinaSociedad Argentina de Microbiología Genera

Bacteriorodhopsin or arsenite as energy source in the growth of haloarchaea

Laguna Diamante (S 26°1’50’’ O 67°2’32’’) ubicada en el cráter del volcán Galán en Catamarca, a 4750 m. s.n.m., presenta condiciones extremas como: elevado pH, salinidad, alta radiación ultravioleta (UV) y alto contenido de metales pesados y metaloides, principalmente arsénico (As) [1], el cuál es un compuesto altamente tóxico y muy distribuido en la corteza terrestre [2]. En este ambiente, han sido reportadas unas biopelículas rojas (BD) formadas en la parte inferior de microbialitos de tipo leiolitos, y los estudios metagenómicos demostraron que están constituidas por un 94% de haloarqueas [1]. Algunas haloarqueas presentan un mecanismo fotosintético que les permite producir ATP de una forma similar al realizado en la cadena transportadora, pero a diferencia de ésta, los protones expulsados no provienen de complejos proteicos sino de una bomba de protones fotoexitable, la “bacteriorrodopsina” (BR) [3]. Mecanismo que les permite enfrentar las bajas concentraciones de oxígeno de ambientes hipersalinos. Objetivo: estudiar la influencia de la luz en el crecimiento microbiano de haloarqueas aisladas de BD en presencia y ausencia de arsenito (As III). Para ello, se utilizaron cinco haloarqueas aisladas de BD del género Halorubrum (DM1, DM2, DM3, DM4 y DM5) para evaluar su crecimiento en medio mínimo (CDM con piruvato como fuente de carbono [5]) con y sin adición de AsIII (1 mM de concentración final); usando el medio de aislamiento WJK [4] como control. Los cultivos fueron incubados a 37 °C y agitados a 120 r.p.m. entre 7 – 10 días (dependiendo del tiempo de generación de la cepa) midiendo la densidad óptica (Do) a 600 nm cada 12 h. Se utilizaron dos condiciones: luz blanca fría (400 – 700 nm) y oscuridad (cubriendo los frascos con láminas de aluminio). Se observó que de las cepas estudiadas, DM2 presentó un mayor crecimiento en CDM con As III en oscuridad, mientras que en luz el mejor crecimiento fue observado en CDM sin la adición de As III, en el resto de las condiciones el crecimiento fue escaso. A partir de estos resultados obtenidos se sugiere que en presencia de luz DM2 utilizaría el sistema de la bacteriorodopsina para obtener energía y sostener su crecimiento, mientras que en oscuridad la obtención de energía sería a través del uso del As III como donador de electrones.Fil: Soria, Mariana Noelia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Rasuk, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Ordoñez, Omar Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaIII Reunión de Fotobiólogos Moleculares ArgentinosSan Miguel de TucumánArgentinaGrupo Argentino de Fotobiologí

Analysing bacterial communities from microbial mats and sediments located in the Atacama desert

The Atacama Desert has more than 100 basins with interior drainage and most of them contain salt flats. These ecosystemshave extreme environmental conditions that allow the development of unique microbial communities. The objetctive of this wasto study the bacterial diversity using independent culture tools of microbial mats and sediments from salt flats in the AtacamaDesert. Some physicochemical conditions of the water surrounding these samples were analysed to discover if anyphysicochemical characteristic could be influencing in its taxonomic composition. Five samples were collected, three of themwere microbial mats and two were sediments. The mat samples were taken from Laguna Llamara (samples named LL1 andLL2) and Laguna Cejar (Cej). Sediments were taken from Laguna Jachucoposa (Cop) and Laguna Pujsa (Puj) where microbialmats are not present. Total metagenomic DNA extraction was performed on each sample and the V4 hypervariable region of thebacterial 16S rRNA gene was amplified by pyrosequencing using the Ribosomal Database Project (RDP)-suggested universalprimers. Diversity of the microbial community was assessed using the QIIME software package. Lakes that harbor microbialmats have a higher salinity and a lower dissolved oxygen concentration and proportion of organic matter and total phosphorousthan lakes where mats are absent. All the samples have important concentrations of arsenic, with an extremely high amount inPuj. Proteobacteria and/or Bacteroidetes are the major phyla represented in all samples. Also, other phyla as Spirochaetes,Chloroflexi or Verrucomicrobia are found. However, cyanobacterial sequences are only observed in LL2 and Puj. On the otherhand, we have found a higher diversity in sediment than in mat samples. The sediments samples contain phyla not observed inmat samples. 16S rRNA gene sequences classified within Actinobacteria and Gracilibacteria are only found in Puj and related toTenericutes, Gemmatimonadetes and Acidobacteria are only observed in Cop. Finally, an important fraction of the sequencescould not be classified at phylum level. The high diversity found in sediment samples may be explained by the physicochemicalconditions in the environment. For example, they have a lower conductivity than mat samples. It is known hypersalineenvironments have a low diversity, where halophilic microorganisms are able to survive to these extreme conditions becausethey have specific strategies to balance the osmotic pressure. Besides, we found a low proportion or absence of Cyanobacteriain the ecosystems studied, suggesting the possibility that other groups may be playing an essential role as primary producers inthese extreme environments. Additionally, the large proportion of 16S rRNA gene sequences that could not be affiliated to anyknown bacterial phyla suggesting that in these ecosystems there are potential novel representatives of bacterial phyla not yetdescribed.Fil: Fernández, Ana Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Rasuk, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Kurth, Daniel German. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Contreras, M.. No especifíca;Fil: Novoa, F.. No especifíca;Fil: Poire, D.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; ArgentinaFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaXI Congreso Argentino de Microbiología GeneralCórdobaArgentinaSociedad Argentina de Microbiología Genera

Prokaryotic diversity in ecosystems associated to minerals from the hypersaline lake Tebenquiche in the Atacama desert

The Salar de Atacama is located in the Chilean central Andes and it is a huge evaporitic system with a large number of saline water bodies in its interior. Lake Tebenquiche is one of the largest and prokaryotic microorganisms inhabiting this lake are subjected to severe conditions as high solar radiation due to a lower barometric pressure at high altitude, extreme daily temperature fluctuations, intense changes in salinity caused by net evaporation and high arsenic concentrations in the water due to volcanic events. Therefore, we decided to analyse the prokaryotic diversity of microbial mats, microbialites and one evaporite by pyrosequencing of the V4 hypervariable region of the 16S rRNA gene. In addition, the total metagenomic DNA of a microbial mat was sequenced to study the genetic and metabolic diversity for understanding the microbial processes associated to minerals in a system at high altitude. Methods: Five different samples were collected from lake Tebenquiche: two microbial mats, TebMa1 and TebMa2; two microbialites, TebMi1 and TebMi2; and one evaporite, TebEv1. The total metagenomic DNA of each sample was extracted and pyrosequenced the V4 hypervariable region of the prokaryotic 16S rRNA gene. The prokaryotic 16S rRNA amplicons were analysed using the QIIME software package. The total metagenomic DNA from microbial mat, TebMa1, was sequenced using paired-end Hi-Seq 1500 Illumina Technology and the raw reads obtained were filtered, assembled into contigs and annotated. Results: Euryarchaeota is one of the most abundant phyla in all samples studied, especially in TebEv1 with 97 % of 16S rRNA sequences. Most of the euryarchaeal OTUs are classified within the class Halobacteria or anaerobic and methanogenic archaea. Specific genes as indicators of particular biogeochemical cycles were searched in the assembled contigs of TebMa1. Nitrogenase gene sequences are found in a high amount and these sequences were aligned with a range of 70%-89% identity to known nitrogenase sequences. Phosphate is mainly obtained by two mechanisms when there is a reduced availability of phosphorous: polyphosphate metabolism and phosphate recycling. Cytoplasmic arsenate reduction and arsenite oxidation are clearly present in the arsenic-rich habitat TebMa1. Conclusions: The high conductivity measured in TebMa2 and TebEv1 must be promoting the growth of members belonging to the class Halobacteria due to the dominance of this taxon in both samples. In TebMa1, we suggest could be carried out an active biological nitrogen fixation by bacteria and archaea and due to the low percentage identity to the closest relative an important part could be novel diazotrophic microorganisms. This ecosystem is rich in arsenic and its inhabitants use arsenic resistance strategies as cytoplasmic arsenate reduction and arsenite oxidation but a possible mechanism employed by these microorganisms could be through quelation of this metalloid using polyphosphates.Fil: Fernandez, Ana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Rasuk, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Contreras, Manuel. Centro de Ecologia Aplicada; ChileFil: Novoa, Fernando. Centro de Ecologia Aplicada; ChileFil: Poire, Daniel Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; ArgentinaFil: Visscher, Pieter T.. University of Connecticut; Estados UnidosFil: Ventosa, Antonio. Universidad de Sevilla; EspañaFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaXI Congreso Argentino de Microbiologia GeneralCórdobaArgentinaSociedad Argentina de Microbiología Genera

Diet and feeding selectivity of the Andean Flamingo Phoenicoparrus andinus and Chilean Flamingo Phoenicopterus chilensis in lowland wintering areas

Flamingos Phoenicopteridae sp. are gregarious birds that travel long distances between breeding and feeding sites. Here we describe the diet and feeding selectivity of two flamingo species, the Andean Flamingo Phoenicoparrus andinus and Chilean Flamingo Phoenicopterus chilensis, which coexist in a lowland area of Argentina. Environmental characteristics and available food resources were assessed at twelve lakes where feeding flocks of both species of flamingos occurred. Food items found in faeces (16S rRNA for bacteria and archaea) and microscopic analyses (for Cyanobacteria, microalgae and microinvertebrates) were analysed, and the birds? feeding selectivity and niche overlap were estimated. Results showed that the lakes were of eutrophic to hypereutrophic status, and with hypohaline to mesohaline salinity levels. Predominant microorganisms belonged to the Planctomycetes, Verrucomicrobia, Chloroflexi, Euryarchaeota, Cyanobacteria, Bacillariophyta and Copepoda phyla. Euryarchaeota and Firmicutes were the main phyla found in the faeces, with Chloroflexi and Planctomycetes also present in smaller quantities. Proteobacteria were well represented in Andean Flamingo faeces, but Verrucomicrobia were scarce in both species. Cyanobacteria, Bacillariophyta, Copepoda, Cladocera, and Rotifera were abundant in Chilean Flamingo faeces, and larger organisms belonging to Ostracoda, Nematoda, and Diptera were also found. The most consumed taxa were in the intermediate to large size range (104 to 2×105 μm3, and 108 to 2×108 μm3). Andean Flamingo faeces were composed mainly of microalgae, especially diatoms. Cladocera and Copepoda species were found to a lesser extent, showing the flamingos? preference for intermediate prey sizes (104 to 2×105 μm3). Food selection was probably dependent on the spatial variability in prey availability, as both positive selectivity (for Bacillariophyceae) and avoidance (for Copepoda) were observed in Chilean Flamingos. In contrast, Andean Flamingos showed a high positive selection for diatoms, and strong negative selection for microinvertebrates. Both flamingo species can apparently coexist whilst feeding on a wide spectrum of microorganisms, but trophic niches differed in the amounts of Cyanobacteria, microalgae and microinvertebrates taken. Such a low niche overlap probably contributes to the coexistence of both sympatric species in similar waters.Fil: Polla, Wanda. Universidad Nacional del Litoral; ArgentinaFil: Di Pasquale, Vanesa Anabel. Universidad Nacional del Litoral; ArgentinaFil: Rasuk, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Barberis, Ignacio Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; ArgentinaFil: Romano, Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones para el Descubrimiento de Fármacos de Rosario. Universidad Nacional de Rosario. Instituto de Investigaciones para el Descubrimiento de Fármacos de Rosario; ArgentinaFil: Manzo, Ramiro Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Paggi, Juan Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Contreras, Manuel. Centro de Ecologí­a Aplicada (cea),; ChileFil: Devercelli, Melina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentin

Microbial Diversity in Sediment Ecosystems (Evaporites Domes, Microbial Mats, and Crusts) of Hypersaline Laguna Tebenquiche, Salar de Atacama, Chile

We combined nucleic acid-based molecular methods, biogeochemical measurements, and physicochemical characteristics to investigate microbial sedimentary ecosystems of Laguna Tebenquiche, Atacama Desert, Chile. Molecular diversity, and biogeochemistry of hypersaline microbial mats, rhizome-associated concretions, and an endoevaporite were compared with: The V4 hypervariable region of the 16S rRNA gene was amplified by pyrosequencing to analyze the total microbial diversity (i.e., bacteria and archaea) in bulk samples, and in addition, in detail on a millimeter scale in one microbial mat and in one evaporite. Archaea were more abundant than bacteria. Euryarchaeota was one of the most abundant phyla in all samples, and particularly dominant (97% of total diversity) in the most lithified ecosystem, the evaporite. Most of the euryarchaeal OTUs could be assigned to the class Halobacteria or anaerobic and methanogenic archaea

Haloarchaea from the Andean Puna: Biological Role in the Energy Metabolism of Arsenic

Biofilms, microbial mats, and microbialites dwell under highly limiting conditions (high salinity, extreme aridity, pH, and elevated arsenic concentration) in the Andean Puna. Only recent pioneering studies have described the microbial diversity of different Altiplano lakes and revealed their unexpectedly diverse microbial communities. Arsenic metabolism is proposed to be an ancient mechanism to obtain energy by microorganisms. Members of Bacteria and Archaea are able to exploit arsenic as a bioenergetic substrate in either anaerobic arsenate respiration or chemolithotrophic growth on arsenite. Only six aioAB sequences coding for arsenite oxidase and three arrA sequences coding for arsenate reductase from haloarchaea were previously deposited in the NCBI database. However, no experimental data on their expression and function has been reported. Recently, our working group revealed the prevalence of haloarchaea in a red biofilm from Diamante Lake and microbial mat from Tebenquiche Lake using a metagenomics approach. Also, a surprisingly high abundance of genes used for anaerobic arsenate respiration (arr) and arsenite oxidation (aio) was detected in the Diamante’s metagenome. In order to study in depth the role of arsenic in these haloarchaeal communities, in this work, we obtained 18 haloarchaea belonging to the Halorubrum genus, tolerant to arsenic. Furthermore, the identification and expression analysis of genes involved in obtaining energy from arsenic compounds (aio and arr) showed that aio and arr partial genes were detected in 11 isolates, and their expression was verified in two selected strains. Better growth of two isolates was obtained in presence of arsenic compared to control. Moreover, one of the isolates was able to oxidize As[III]. The confirmation of the oxidation of arsenic and the transcriptional expression of these genes by RT-PCR strongly support the hypothesis that the arsenic can be used in bioenergetics processes by the microorganisms flourishing in these environments.Fil: Ordoñez, Omar Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Rasuk, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Soria, Mariana Noelia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Contreras, Manuel. Centro de Ecología Aplicada; ChileFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentin