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  • Artículo
    Acceso Abierto
    Age, growth, maturity and extinction risk of an exploited and endangered skate, Atlantoraja castelnaui, from off Uruguay and northern Argentina
    (2021) Barbini, Santiago Aldo; Sabadin, David Ezequiel; Román, Jorge Martín; Scarabotti, Pablo Augusto; Lucifora, Luis Omar
    The spotback skate Atlantoraja castelnaui (Arhynchobatidae) is a large and threatened skate species subjected to fishing pressure, endemic to the Southwest Atlantic that occurs from Rio de Janeiro, Brazil, to San Jorge Gulf, Argentina. The age, growth, age at maturity and the maximum intrinsic rate of population increase rmax of A. castelnaui were studied using 152 specimens collected from off Uruguay and north Argentina (35°–42° S), between June 2013 and February 2020. Vertebrae from 143 individuals were used for ageing (females: n = 83, size range 404–1300 mm total length, TL; males: n = 60, size range 400–1270 mm TL). Maximum ages determined for females and males were 30 and 28 years, respectively. To fit growth models, non-linear and Bayesian estimation approaches were considered. For the first approach, a set of four candidate growth (size-at-age) models were fitted: three-parameter von Bertalanffy, two-parameter von Bertalanffy with fixed L0, Gompertz and Logistic. In the second approach, von Bertalanffy, Gompertz and Logistic were fitted. For non-linear estimation, model selection indicated that the entire set of candidate growth models were supported by the data. The von Bertalanffy was selected as the best model for Bayesian estimation. There were no differences in growth between sexes. For the sexes combined, the von Bertalanffy growth model by Bayesian method was considered the most adequate to describe the growth of A. castelnaui (growth mean parameters ± S.D.: L∞ = 1210.29 ± 40.68 mm; k = 0.12 ± 0.01 years−1; L0 = 179.20 ± 11.62 mm). The age at maturity was estimated at 16.21 and 14.04 years for females and males, respectively. The maximum intrinsic rate of population increase rmax was estimated as 0.252 years−1. Life-history traits and rmax provided in the present study suggest that this species has a relatively low productivity and may be vulnerable to an intense fishing pressure.
  • Artículo
    Acceso Abierto
    The ichthyofaunistic colonization and complex biogeographic history of the southern portion of the Southwest Atlantic Ocean
    (2023) Figueroa, Daniel Enrique; Barbini, Santiago Aldo; Belleggia, Mauro; Sabadin, David Ezequiel; Román, Jorge Martín; De Wysiecki, Agustín María
    Here, we highlight the geological processes that resulted in the current conformation of the southern Southwest Atlantic Ocean, and explore the heterogeneous composition of the marine ichthyofauna found between 33° and 56° from a paleobiological perspective. During the early Cretaceous (140 Mya), the South Atlantic was still not formed, and Gondwana was probably a set of united plates with shallow continental waters. In the middle Cretaceous (112 Mya), the major Gondwanan plates started diverging from each other, allowing shallow marine intrusions and the diversification of an endemic fish fauna. By the end of the Mesozoic (66 Mya), the proto-South Atlantic connected with the North Atlantic, which was still part of the Tethys Sea, allowing its ichthyofauna to colonize the south and reach the Antarctic region. The opening of the Drake Passage in the Oligocene (33 Mya) enabled the cold waters of the Pacific Ocean to reach the South Atlantic, causing drastic effects on the thermophilic fauna and favoring the dispersion of cold-water species. Successive glaciations during the Quaternary (2 Myr to 10,000 years ago) resulted in the prevalence of Antarctic climatic conditions in the southern Southwest Atlantic. The long history of changing scenarios in the constitution of the southern Southwest Atlantic is reflected in the heterogeneous composition of the marine ichthyofauna between 33° and 56°S, which is characterized by a mixture of cosmopolitan, Tethyan, Pacific, Gondwanan, Antarctic, and endemic origins.
  • Comunicacion
    Acceso Abierto
    Egg capsules of the multispine skate, Bathyraja multispinis: the largest of the genus recorded in South American waters
    (2022) Román, Jorge Martín; Mabragaña, Ezequiel; Sabadin, David Ezequiel; Lucifora, Luis Omar; Figueroa, Daniel Enrique; Barbini, Santiago Aldo
    Egg capsules of the multispine skate, Bathyraja multispinis (Norman, 1937), described here for the first time, are larger (180 mm in length without horns) than those of any Bathyraja species from the South-west Atlantic Ocean (SWA). The capsule’s surface texture is relatively smooth by the presence of woven-like fibres. However, below the fibres, it is rough to the touch by the presence of longitudinal ridges and prickles of different shapes and sizes, ending in two or more digitiform projections. An identification key to all described Bathyraja egg capsules occurring in the SWA from 34° to 55°S is provided.
  • Artículo
    Acceso Abierto
    Feeding habits of the cockfish, Callorhinchus callorynchus (Holocephali: Callorhinchidae) from off northern Argentina
    (2020) Román, Jorge Martín; Chierichetti, Melisa Antonela; Barbini, Santiago Aldo; Scenna, Lorena Beatriz
    The feeding habits of Callorhinchus callorynchus were investigated in coastal waters off northern Argentina. The effect of body size, seasons and regions was evaluated on female diet composition using a multiple-hypothesis modelling approach. Callorhinchus callorynchus fed mainly on bivalves (55.61% PSIRI), followed by brachyuran crabs (10.62% PSIRI) and isopods (10.13% PSIRI). Callorhinchus callorynchus females showed changes in the diet composition with increasing body size and also between seasons and regions. Further, this species is able to consume larger bivalves as it grows. Trophic level was 3.15, characterizing it as a secondary consumer. We conclude that C. callorynchus showed a behavior of crushing hard prey, mainly on bivalves, brachyuran, gastropods and anomuran crabs. Females of this species shift their diet with increasing body size and in response to seasonal and regional changes in prey abundance or distribution.
  • Artículo
    Acceso Abierto
    Soil survey reveals a positive relationship between aggregate stability and anaerobically mineralizable nitrogen
    (2020) García, Gisela Vanesa; Wyngaard, Nicolás; Reussi Calvo, Nahuel Ignacio; San Martino, Silvina; Covacevich, Fernanda; Studdert, Guillermo Alberto
    Soil health status should be monitored to allow planning sustainable management, but indicators available do not encourage frequent soil health evaluation because of the complexity, time-consumption, and expensiveness of the methodologies. Aggregate stability (AS) is a good soil physical health indicator associated with soil (SOC) and particulate (POC) organic carbon but is difficult to monitor. Anaerobically mineralizable nitrogen (AN) has been proposed as soil health indicator because is cheap, simple, and safe to measure, is sensitive to soil-use changes, is also related to soil (SOC) and particulate (POC) organic carbon, and is frequently determined by farmers in Mollisols of the Southeastern Argentinean Pampas to support soil fertility diagnosis. We hypothesize that AN is positively related to and can be used as indicator of AS. Soil samples were taken at 0–5 and 5–20 cm depths from 46 sites throughout the southeastern Buenos Aires province, Argentinean Pampas. In each site, we sampled Mollisols under continuous cropping (CC) and others that had not been disturbed for many years (pseudo-pristine, PRIS). We determined texture, SOC, mineral-associated organic C, POC, AS and AN. We also calculated variable values for 0–20 cm. Soil organic carbon, POC, AN and AS were reduced by continuous cropping. Anaerobically mineralizable N was positively related to SOC (R2 = 0.74, 0.46, and 0.62 at 0–5, 5–20, and 0–20 cm) and POC (R2 = 0.73, 0.33, and 0.60, respectively). An important proportion of the total variability in AS was explained by SOC (R2 = 0.77, 0.65, and 0.73 at 0–5, 5–20, and 0–20 cm, respectively), POC (R2 = 0.75, 0.63, and 0.73, respectively), and AN (R2 = 0.78, 0.69, and 0.81, respectively). The AS increased with the increase of SOC, POC, and AN at all three depths, with slopes that did not differ between CC and PRIS, but with intercepts that differed. Neither sand nor clay contents significantly contributed to explain the variations in AS as a function of SOC, POC, and AN. An independent validation of the regression model relating AS and AN at 0–20 cm was done and the output was very good (RPIQ (ratio of performance to interquartile distance) = 2.20). Results support our hypothesis because AN was positively related to AS. Consequently, AN would be a good indicator of AS, SOC, and POC. Based on our results, we consider that a simple and cheap soil analysis as AN can not only be used to diagnose soil fertility, but to monitor soil physical and biochemical health status.
  • Artículo
    Acceso Abierto
    Anaerobically mineralized nitrogen within macroaggregates as a soil health indicator
    (2021) García, Gisela Vanesa; Campos, María E.; Wyngaard, Nicolás; Reussi Calvo, Nahuel I.; San Martino, Silvina; Covacevich, Fernanda; Studdert, Guillermo Alberto
    Anaerobically mineralized nitrogen (AN) in bulk soil (ANBS) has been described as a soil health indicator. Considering that large macroaggregates (2000–8000 μm, MA) are more sensitive to management practices than the bulk soil (i.e. whole soil), AN within MA (ANMA) would be a better soil health indicator than ANBS. The aim of this study was to evaluate if ANMA is a better indicator of: i) soil organic carbon (SOC) and particulate organic carbon (POC) in bulk soil (SOCBS and POCBS, respectively) and ii) aggregate stability (AS) than ANBS. Soil samples were taken at 0–5 and 5–20 cm from 46 continuously cultivated plots (CC) and a reference plot for each CC (pseudo-pristine, PRIS). These soils, located in the Argentinean Pampas, were classified as Mollisols with contrasting surface textural classes. The AS, SOCBS, POCBS, ANBS, SOC (SOCMA), and POC (POCMA) within MA and ANMA were determined separately at 0–5 and 5–20 cm soil depths and estimated at the 0–20 cm layer. The ANMA was a good indicator of SOCBS (R2 0.75, 0.48, and 0.61 at 0–5, 5–20 and 0–20 cm depths, respectively), POCBS (R2 0.66, 0.31, and 0.49, respectively), and AS (R2 0.80, 0.68, and 0.76, respectively). The ANMA performed similarly to predict SOCBS, POCBS, and AS as compared to ANBS, because ANMA was closely correlated to ANBS (r 0.90 at 0–20 cm). Since ANMA determination is more time-consuming than ANBS determination, its use as a soil health indicator would not be convenient. Therefore, the use of ANBS would be recommended over ANMA as a variable to monitor soil health.
  • Artículo
    Acceso Abierto
    Simplifying the Determination of Aggregate Stability Indicators of Mollisols
    (2020) García, Gisela Vanesa; Tourn, Santiago Néstor; Roldán, María Florencia; Mandiola, Mariana; Studdert, Guillermo Alberto
    Aggregate stability (AS) is a very sensitive soil physical health indicator. The complexity of its determination discourages frequent monitoring. We hypothesized that a reduction of steps to determine AS would yield good AS indicators. We evaluated 196 samples from a range of Mollisols from sandy- to clay-loam surface texture from the southeastern Buenos Aires province, Argentina. Six AS indicators were evaluated: aggregate mean weight diameter (MWD) after capillary wetting (CW) (MWDCW), MWD after sudden immersion in water (VW) (MWDVW), change of MWD (ΔMWD), remnant mass of macroaggregates (MAm) after CW (MAmCW), MAm after VW (MAmVW), and change of MAm between VW and CW (ΔMAmVW-CW). Determining ΔMWD requires six sievings, MWD requires three, ΔMAmVW-CW requires two, and MAm requires only one. Indicators after CW (MWDCW and MAmCW) were not good AS indicators. Likewise, those determined as a difference between CW and VW (ΔMWD and ΔMAmVW-CW) failed to distinguish contrasting AS situations making them unfeasible as universal AS indicators. However, MAmVW explained 99% of MWDVW variability and adequately distinguished among AS situations. With only one sieving, a good indicator of AS could be obtained, and this would encourage the adoption by soil testing laboratories and frequent soil physical health monitoring by farmers.
  • Artículo
    Restringido
    Nitrogen mineralized in anaerobiosis as indicator of soil aggregate stability
    (2020) Guillermo Studdert; Rivero, Camila; Tourn, Santiago N.; García, Gisela Vanesa; Videla, Cecilia; Domínguez, Germán; Studdert, Guillermo Alberto
    Monitoring soil health status is imperative to pursue sustainable agriculture. Aggregate stability (AS) is fundamental to define several soil functions and, therefore, physical soil health. The objectives of thisworkwere to (i) evaluate the effect of contrasting cropping systems on AS, soil (SOC) and particulate (POC) organic carbon, and anaerobic nitrogen (AN) both in bulk soil and in macroaggregates (MA), and (ii) assess the relationship between AS and AN both in bulk soil and in MA to facilitate soil physical health monitoring. Aggregate stability, AN, SOC and POC were evaluated at three depths (0–5, 5–20, and 0–20 cm) in a Mollisol of the Southeastern Argentinean Pampas under a long-term experiment of cropping systems (crop-pasture rotations under conventional tillage [CT] and no-tillage [NT]). Bulk-soil SOC and POC contents and AN showed the effect of cropping systems, especially the effect of crop-pasture rotation and at 0–5 cm depth. However, NT did not lead to SOC sequestration except at 0–5 cm depth. In turn, pastures in the rotation and NT improved AS. Bulk-soil AN explained 75, 41, and 71% of AS at 0–5, 5–20, and 0–20 cm depths, respectively, and provides an indication of AS status. Instead, AN in MA did not explain bulk-soil AS changes as much as bulk-soil AN, except at 0–5 cm depth. Therefore, it is not worth determining AN in MA. However, routine bulk-soil AN determination at 0–20 cm depth by producers to diagnose nitrogen soil fertility would also provide an additional valuable indication of AS status.
  • Artículo
    Acceso Abierto
    Carbono extraíble en agua caliente como indicador de salud de molisoles del sudeste bonaerense
    (2020) Rodríguez, Silvia; Baeza, María Cecilia; García, Gisela Vanesa; Domínguez, Germán Franco; Clemente, Natalia Liliana; Studdert, Guillermo Alberto
    Una agricultura sustentable requiere indicadores tempranos del estado de salud edáfica (ISE). Se necesitan variables fácilmente medibles como el carbono extraíble en agua caliente (CAC) para favorecer su uso. El objetivo fue evaluar el CAC como ISE analizando: i) la magnitud de los cambios en CAC producidos por el uso agrícola, en comparación con los producidos en el COT y en el COP, y ii) la relación entre CAC, COP, COT, nitrógeno de amonio producido durante incubaciones anaeróbicas cortas (NAN) con estabilidad de los agregados. Se analizaron muestras de suelo (0-5 y 5-20 cm) de 32 lotes de producción (LP) y situaciones seudoprístinas (SP) localizados en el sudeste bonaerense. Se determinó: densidad aparente (DA), cambio en el diámetro medio ponderado de los agregados (CDMP), COT, COP, NAN y CAC. En 0-20 cm, el CAC varió entre 0,69 y 1,41 g kg-1 para los LP y entre 0,75 y 2,36 g kg-1 para las SP, representando, en promedio, 3,23% y 3,57% del COT, respectivamente. Se relacionó negativamente con la DA y el CDMP, y positivamente con COT y COP expresados como stock referidos a una masa equivalente (COTME y COPME, respectivamente) y con NAN. Además, el CAC en los LP cayó 35%, respecto a las SP, y COPME y COTME cayeron 62% y 25%, respectivamente. El CAC podría utilizarse como ISE, ya que fue sensible a los cambios por el uso agrícola del suelo y se relacionó con otras propiedades edáficas utilizadas como ISE. Su determinación es sencilla, rápida y económica, favoreciendo su adopción por los laboratorios de análisis.
  • Resumen
    Acceso Abierto
    Actividad estacional y de forrajeo de hormigas podadoras (Hymenoptera: Formicidae) en Balcarce, Buenos Aires
    (2019) Stoessel, Melisa Nicole; Tulli, María Celia; Martiarena, Diego; Divita, Ignacio; Mateos Inschauspe, Facundo; Camona, Dora Mabel
    Las hormigas podadoras de hojas (HPH) (Hymenoptera: Formicidae) son insectos sociales que viven en colonias. Se caracterizan por forrajear (cortar, seleccionar y acarrear) una gran variedad de especies vegetales para el cultivo de un hongo simbionte que utilizan, principalmente, para alimentar a sus larvas. Debido a ello, ocasionan daños en áreas agrícolas, forestales, y parques urbanos cercanos a sus nidos. El objetivo de este trabajo fue determinar la actividad y patrón de forrajeo estacional de las HPH.
  • Artículo
    Acceso Abierto
    Video processing analysis for the determination and evaluation of the chemotactic response in bacterial populations
    (2016) Nisenbaum, Melina; Maldonado, Emilio; Martinez Arca, Jorge; Gonzalez, Jorge Froilan; Passoni, Lucía I.; Murialdo, Silvia Elena
    The aim of the present work was to design a methodology based on video processing to obtain indicators of bacterial population motility that allow the quantitative and qualitative analysis and comparison of the chemotactic phenomenon with different attractants in the agarose-in plug bridge method. Video image sequences were processed applying Shannon's entropy to the intensity time series of each pixel, which conducted to a final pseudo colored image resembling a map of the dynamic bacterial clusters. Processed images could discriminate perfectly between positive and negative attractant responses at different periods of time from the beginning of the assay. An index of spatial and temporal motility was proposed to quantify the bacterial response. With this index, this video processing method allowed obtaining quantitative information of the dynamic changes in space and time from a traditional qualitative assay. We conclude that this computational technique, applied to the traditional agarose-in plug assay, has demonstrated good sensitivity for identifying chemotactic regions with a broad range of motility.
  • Artículo
    Acceso Abierto
    Tow-components system: a molecular dialogue between ruminal bacteria and feed particles (forage plants)
    (2017) Galicia Jiménez, Mónica Marcela; López Garrido, Serafín Jacobo; Ávila-Serrano, Narciso Ysac; Murialdo, Silvia Elena
    The ability to adapt rapidly to changes in the environment is one of the main characteristics of the bacterial cell. The rumen is a highly dynamic environment, and none of the changes are permanent due to the various microbial species found in the rumen. Signal transduction networks are information processing pathways that recognize various physical and chemical stimuli, amplification, signal processing, and trigger responses of the bacterial cell. The aim of the present review is to show the importance of these two component systems in rumen bacteria, because it is based on the knowledge of the principles governing the bacterial population communication, its main interactions and products of metabolism, we can approach the manipulation of Ruminal fermentation to improve animal health, productivity and food safety.
  • Artículo
    Acceso Abierto
    Bacillus subtilis as a bioindicator to estimate pentachlorophenol toxicity and concentration
    (2009) Ayude, M. A.; Okada, E.; González, J. F.; Haure, P. M.; Murialdo, Silvia Elena
    Pentachlorophenol (PCP) and its sodium salt (Na-PCP) are extremely toxic chemicals responsible for important soil and groundwater pollution, mainly caused by wastes from wood-treatment plants, because chlorinated phenols are widely used as wood preservatives. The methods most commonly used for routine analysis of pesticides such as PCP and Na-PCP are high-performance liquid chromatography (HPLC) and gas chromatography– mass spectroscopy (GC–MS). A variety of rapid biological screening tests using marine organisms, bioluminescent bacteria, and enzymes have also been reported. In this study, rapid biological screening analysis using Bacillus subtilis was developed, to assess the biodegradation of PCP and its by-products in liquid samples. An empirical model is proposed for spectrophotometric analysis of Na-PCP concentration after growth of Bacillus subtilis.
  • Artículo
    Acceso Abierto
    New Findings on Aromatic Compounds’ Degradation and Their Metabolic Pathways, the Biosurfactant Production and Motility of the Halophilic Bacterium Halomonas sp. KHS3
    (2018) Corti Monzón, G.; Nisenbaum, M.; Seitz, K.H.; Murialdo, Silvia Elena
    The study of the aromatic compounds’ degrading ability by halophilic bacteria became an interesting research topic, because of the increasing use of halophiles in bioremediation of saline habitats and effluents. In this work, we focused on the study of aromatic compounds’ degradation potential of Halomonas sp. KHS3, a moderately halophilic bacterium isolated from hydrocarbon-contaminated seawater of the Mar del Plata harbour. We demonstrated that H. sp. KHS3 is able to grow using different monoaromatic (salicylic acid, benzoic acid, 4-hydroxybenzoic acid, phthalate) and polyaromatic (naphthalene, fluorene, and phenanthrene) substrates. The ability to degrade benzoic acid and 4-hydroxybenzoic acid was analytically corroborated, and Monod kinetic parameters and yield coefficients for degradation were estimated. Strategies that may enhance substrate bioavailability such as surfactant production and chemotactic responses toward aromatic compounds were confirmed. Genomic sequence analysis of this strain allowed us to identify several genes putatively related to the metabolism of aromatic compounds, being the catechol and protocatechuate branches of β-ketoadipate pathway completely represented. These features suggest that the broad-spectrum xenobiotic degrader H. sp. KHS3 could be employed as a useful biotechnological tool for the cleanup of aromatic compounds-polluted saline habitats or effluents.
  • Artículo
    Acceso Abierto
    Enrichment and key features of a robust and consistent indigenous marine-cognate microbial consortium growing on oily bilge wastewaters
    (91-108, 2020) Nisenbaum, Melina; Corti-Monzón, Georgina; Villegas-Plazas, Marcela; Junca, Howard; Mangani, Adriana; Patat, María L.; Gonzalez, Jorge Froilan; Murialdo, Silvia Elena
    Oily bilge wastewater (OBW) is a hazardous hydrocarbon-waste generated by ships worldwide. In this research, we enriched, characterized and study the hydrocarbon biodegradation potential of a microbial consortium from the bilges of maritime ships. The consortium cZ presented a biodegradation efficiency of 66.65% for total petroleum hydrocarbons, 72.33% for aromatics and 97.76% removal of n-alkanes. This consortium showed the ability to grow in OBWs of diverse origin and concentration. A 67-fold increase in biomass was achieved using a Sequential Batch Reactor with OBW as the only carbon and energy source. The bacterial community composition of the enriched OBW bacterial consortium at the final stable stage was characterized by 16S amplicon Illumina sequencing showing that 25 out of 915 of the emerged predominant bacterial types detected summed up for 84% of total composition. Out of the 140 taxa detected, 13 alone accumulated 94.9% of the reads and were classified as Marinobacter, Alcanivorax, Parvibaculum, Flavobacteriaceae, Gammaproteobacteria PYR10d3, Novispirillum and Xanthomonadaceae among the most predominant, followed by Thalassospira, Shewanella, Rhodospirillaceae, Gammaprotobacteria, Rhodobacteriaceae and Achromobacter. The microbial community from OBW bioreactor enrichments is intrinsically diverse with clear selection of predominant types and remarkably exhibiting consistent and efficient biodegradation achieved without any nutrient or surfactant addition. Due to there is very little information available in the OBW biodegradation field, this work contributes to the body of knowledge surrounding the treatment improvement of this toxic waste and its potential application in wastewater management.
  • Artículo
    Acceso Abierto
    Monitoring the characteristics of cultivable halophilic microbial community during salted-ripened anchovy (Engraulis anchoita) production
    (2018) Silvina, Perez; Pérez, Silvina; Czerner, Marina; Patat, María Laura; Zaritzky, Noemi Elisabet; Murialdo, Silvia Elena; Yeannes, María Isabel
    The halophilic microbial community of the salted-ripened anchovy process was studied. Samples from raw materials (salt and fresh anchovies) and from the stages of brining and ripening were collected and analyzed for their bacterial counts at 15 and 20% NaCl. No halophilic colonies were found in fresh anchovy and counts of about 103 CFU/g were determined in salt samples. A fluctuation of bacterial counts during the process was found. At the end of brining, ~104 CFU/g were determined in anchovy samples and this value was reduced to not detectable counts at the beginning of the ripening stage. After one month, counts increased to ~104 CFU/g and remained stable until the end of the process. From each sample, colonies having different morphotypes were isolated and submitted to a macro and microscopic characterization, a study of salt requirement for growth, and biochemical and phenotypic tests. The results were submitted to Univariate, Bivariate and Multiple Correspondence Factorial Analysis (MCFA). A total of 79 colonies were isolated during the salting-ripening anchovy process. Among the isolates, about 40–50% was positive for indole production and lipolytic activity and a 25% showed ability to produce H2S and proteolytic capacity. Proteolytic and lipolytic activities were well balanced along the process and resulted independent from the isolation stage, which is a desirable condition due to the contribution of microbial proteolysis and lipolysis to the development of texture and final aroma, respectively. H2S and indole producers practically were not detected during ripening. This fact is important because indole and H2S are associated with the development of off-flavors and spoilage in salted fish products. MFCA and Cluster Analyses complemented the Bivariate Analyses. The factor map showed proximity between the isolates from salt samples and from ripening. Isolates were statistically clustered in two groups. Cluster 1 grouped non-desirable activities (H2S and indole production) with cultures proceeding from brining whereas Cluster 2 related isolates mainly from salt samples and during ripening with some desirable microbial capacities (Cytochrome oxidase activity and non-H2S and non-indole production). These results would indicate that during the ripening process of salted anchovies, a natural selection of beneficial microorganisms for the development of the typical product sensory attributes occurred.
  • Artículo
    Acceso Abierto
    Enrichment and characterization of a bilge microbial consortium with oil in water-emulsions breaking ability for oily wastewater treatment
    (2020) Corti-Monzón, Georgina; Nisenbaum, Melina; Villegas-Plazas, Marcela; Junca, Howard; Murialdo, Silvia Elena
    Oily bilge wastewater is one of the main sources of hydrocarbons pollution in marine environments due to accidental or clandestine discharges. The main technical challenge for its effective treatment is the presence of stable oil-in-water (O/W) emulsions. In this work we are reporting an enriched microbial consortium from bilge wastewater with remarkable ability to demulsify oil in water emulsions. The consortium showed emulsion-breaking ratios up to 72.6% in the exponential growth phase, while the values range from 11.9 to 8.5% in stationary phase. A positive association was observed between demulsifying ability and microbial adhesion to hydrocarbons, as well as between cell concentration and demulsifying ability. Also, an interesting ability to demulsify under different temperatures, conditions of agitation, and bilge emulsions from different vessels was observed. The Bacterial and Archaeal composition was analyzed by 16S rRNA gene amplicon lllumina sequencing analyses, revealing an assemblage composed of bacterial types highly related to well characterized bacterial isolates and also to non-yet cultured bacterial types previously detected in marine and sediment samples. Hydrocarbonoclastic microbial types such as Marinobacter, Flavobacteriaceae, Alcanivorax and Gammaproteobacteria PYR10d3 were found in high relative abundance (27.0%– 11.1%) and types of marine oligotrophs and surfactant degraders such as Thallasospira, Parvibaculum, Novospirillum, Shewanella algae, and Opitutae were in a group of middle predominance (1.7–3.5%). The microbial consortium reported has promising potential for the biological demulsification of bilge wastewater and other oily wastewaters.
  • Artículo
    Acceso Abierto
    Analysis Of Bacterial Chemotactic Response Using Dynamic Laser Speckle
    (2009) Murialdo, Silvia Elena; Sendra, Gonzalo Hernán; Passoni, Lucía I.; Arizaga, Ricardo; Gonzalez, Jorge Froilan; Rabal, Héctor J.; Trivi, Marcelo Ricardo
    Chemotaxis has a meaningful role in several fields, such as microbial physiology, medicine and biotechnology. We present a new application of dynamic laser speckle or biospeckle to detect different degrees of bacterial motility during chemotactic response experiments. Encouraging results showed different bacterial dynamic responses due to differences in the hardness of the support in the swarming plates. We compare this method to a conventional technique that uses white light. Both methods showed to be analogous and, in some cases, complementary. The results suggest that biospeckle processed images can be used as an alternative method to evaluate bacterial chemotactic response and can supply additional information about the bacterial motility in different areas of the swarm plate assay that might be useful for biological analysis.
  • Artículo
    Acceso Abierto
    Diversity of fungi in bottled water in Jeddah, Saudi Arabia
    (2017) Ameen, Fuad; Albejad, Alhanouf; Gashgari, Rukaia; Murialdo, Silvia Elena; Al-Sabri, A.
    The occurrence of fungi in drinking water systems has received increased attention over recent decades and fungi are now generally accepted as drinking water system contaminants. However, fungal contamination of bottled water has received little attention. Forty unopened bottled water samples, of different trademarks, were collected from various localities in Jeddah city, Saudi Arabia and analyzed for fungal contamination: 1) immediately after opening the bottles; and 2) after closing and storing them for 180 and 365 days. The fungal species were identified under a compound microscope followed by molecular sequencing. At least one fungal species were found in 58% of the bottles. In total, 18 fungal species belonging to 11 fungal genera were identified. Rhizopus nigricans and seven different species of Aspergillus were found to frequently contaminate the bottled water samples. Penicillium sp. were found in one sample. The 180 days storage of opened and reclosed bottles did not substantially affect the abundance of fungi or the species found. Some of the fungi identified may be pathogenic and the contamination of fungi in bottled water should be considered during the processing of water.
  • Artículo
    Acceso Abierto
    Chemotaxis detection towards chlorophenols using video processing analysis
    (2017) Okada, E.; Nisenbaum, M.; Martínez Arca, J.; Murialdo, Silvia Elena
    To our knowledge, this communication is the first report of chemotaxis towards chlorophenols by any bacteria. We used a recently published method based on the agarose in-plug assay combined with video processing analysis and we also present a new index of bacterial mean speed for these assays.