Grupo UTN GISTAQ - Difusión Científica - Trabajos Presentados en Congresos
Permanent URI for this collectionhttp://48.217.138.120/handle/20.500.12272/3709
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Item Aislamiento de bacterias autóctonas de suelos de cultivos de arroz con aplicaciones periódicas de agroquímicos(2022-06) Cuadra, Pablo Nicolás; Fontana, Gimena Lilián; Farías, Alejandro Rubén; Jorge, Nelly Lidia; Vullo, Diana LiaLa expansión de la actividad agrícola ha impulsado el uso de agroquímicos, cuya permanencia en los suelos puede provocar serios problemas de contaminación. Su infiltración hacia las aguas subterráneas o escurrimientos hacia cursos de agua superficiales, como también la deposición de éstos en las cadenas tróficas implican un riesgo latente para el equilibrio de los ecosistemas. El presente trabajo posee como objetivos aislar bacterias autóctonas a partir de suelos agrícolas en presencia de una mezcla de agroquímicos (glifosato, clomazone e imazapir-imazapic) para utilizarlas potencialmente en ensayos de recuperación de suelos contaminados. Las muestras de suelo fueron tomadas de tres zonas de un campo destinado al cultivo de arroz: 1. zona virgen sin aplicaciones registradas de plaguicidas (ZA), 2. zona sin aplicaciones desde hace 1 década (ZB), y 3. zona de cultivos con aplicación continua de agroquímicos (ZC). Primeramente, para explorar la población microbiana cultivable resistente a los plaguicidas mencionados, se realizó un recuento en placa por siembra en superficie sobre dos medios de cultivo: medio nutritivo (Agar para recuento=APC) y medio oliogotrófico simulando el entorno natural (Agar Suelo=AS) tanto en presencia como en ausencia de agroquímicos (CP y SP respectivamente). Se obtuvieron diferencias tanto en los recuentos como en la diversidad de colonias acorde a la zona de muestreo, a la composición del medio y a la presencia de plaguicidas. Se observó una mayor disminución en UFC/g correspondiente a ZA en los medios suplementados con agroquímicos, consistente con sus antecedentes de no exposición, no así con ZB y ZC. Ante la diversidad de colonias desarrolladas en AS-CP y APC-CP; se aislaron y purificaron en tres pasos 15 cepas. Estos aislamientos serán utilizados en ensayos de biodegradación de plaguicidas para utilizarlas potencialmente en procesos de biorremediación a futuro.Item Ensayos de resistencia en medios de cultivo sólidos de colonias bacterianas autóctonas en presencia del herbicida Kifix®(2023-09-01) Viera, María Florencia; Delgado, Lautaro; Sánchez Irigoyen, María Florencia; Ayala Bengler, Paula; Cuadra, Pablo NicolásEl presente trabajo tiene como objeto evaluar la resistencia de un grupo de 30 bacterias al herbicida Kifix, aisladas previamente en trabajos anteriores a partir de diferentes muestras de suelo de un cultivo arrocero ubicado en la localidad de Las Palmas, Chaco, con la finalidad de identificar aquellas que presenten mayor potencial de biodegradación para ser utilizadas en posteriores ensayos. Para ello, se realizó la inoculación de estos microorganismos mediante la técnica de estriado en placa de Petri, utilizando medios de cultivo nutritivos y oligotróficos, dosificados con concentraciones crecientes del contaminante. La evaluación del crecimiento bacteriano se llevó a cabo mediante observaciones macroscópicas de las siembras realizadas durante periodos de tiempo específicos. Los resultados obtenidos demostraron que 15 cepas son capaces de desarrollarse en un medio nutritivo tradicional y 12 en medios oligotróficos con concentraciones considerables del plaguicida, por lo que se pretende continuar con los ensayos a concentraciones más elevadas del agroquímico.Item Furfural removal from a polluted effluent by using a fluidized bed reactor(2023-10-02) Echeverría, Macarena Celeste; Cuadra, Pablo Nicolás; Sandoval, Evangelina; Benimeli, Claudia SusanaFurfural is a heterocyclic aromatic aldehyde and wastewaters derived from its production can contain around 800 mg l-1, which can cause toxic effects on living systems if released into the environment without proper treatment. In the present work, the furfural removal from a simulated effluent by a fluidized bed bioreactor filled with an actinobacteria biofilm on vegetable sponge (Luffa aegyptiaca) support was studied. For this, a suspension of a mixed culture of Nocardiopsis sp. L9, Streptomyces sp. A12 and M7, in TSB medium (D.O540nm=1) was prepared. The luffa support was cut in cubes of approximately 0.1 g, which were washed and sterilized. The bacterial biofilm production on luffa cubes was carried out in 250 ml Erlenmeyer flasks, which contained 0.5 g of the support and 60 ml of the bacterial suspension. After 96 h of incubation at 30 °C and 100 rpm, the colonized sponge cubes were introduced into the reactor for the bioremediation treatment. A laboratory-scale fluidized bed reactor was used, which had an inlet for the effluent to be treated in the lower side and an outlet for the treated effluent in the upper part. The furfural residual concentration in the treated effluent was evaluated by HPLC, every 24 h for 4 days. Ecotoxicity tests were carried out using Raphanus sativus seeds (radish, Punta Blanca variety). Bacterial colonization on vegetal sponge was also evaluated by scanning electron microscopy, before and after treatment. The analysis by HPLC showed a complete depletion of furfural in the effluent after 24 h of treatment. Microphotographs by scanning electron microscopy showed an increase in the presence of possible polymeric substances in luffa cubes at the end of treatment regarding to the initial time, as result of biofilm production by the actinobacterial consortium. The ecotoxicity tests with radish seeds showed significant increases (p<0.05) in the vegetable biomarkers of seedlings obtained in the treated effluent, indicating that the toxic effects caused by furfural were reversed, confirming the effectiveness of the bioremediation process.Item Growth kinetics of soil bacteria in presence of pesticides applied for rice crop production(2023-10-05) Cuadra, Pablo Nicolás; Farías, Alejandro Rubén; Utgés, Enid Marta; Jorge, Nelly Lidia; Vullo, Diana LiaThe expansion of agricultural activity promoted the use of agrochemicals, whose permanence in the soil can cause serious contamination problems. Its infiltration into groundwater or runoff into surface watercourses, as well as their deposition in trophic chains, imply a latent risk to the balance of ecosystems. The present work objective is to analyze the growth kinetics of bacteria isolated from soils destined for rice cultivation in Las Palmas, Chaco, Argentina, in the presence of glyphosate, imazapic-imazapyr and clomazone, pesticides of current application. Two of 24 isolated bacteria named H5 and I2 were specially selected for this study because of their resistant to high agrochemical concentrations. Growth kinetics tests were carried out applying two methods to monitor biomass increase. One of these methods was based on biomass determination by dry weight (BPS) and the other by colony forming units/ml (CFU/ml) count using the drop technique (RMG). Initial inoculums were prepared in minimal saline medium (M9) with glucose 0,5%p/V and incubated at 30°C at 200 or 300 rpm for 24 h. Then, 5 ml of each were transferred to 50 ml of M9 with 1% V/V of the mixture of agrochemicals as the only carbon source to evaluate growth kinetics under these restrictive conditions. The formation of bacterial aggregates at the lowest agitation level was observed, interfering with biomass determinations. For this reason, the subsequent tests were carried out at 300 rpm to prevent the floc formation. To apply the BPS method, 1 ml culture samples were centrifuged 30 minutes, and the pellet obtained was dried for 10 h at 60°C to be subsequently weighed. For the RMG method, culture samples were taken and 10 µl drops of serial dilutions in NaCl 150 mM, were seeded in triplicates in Plate Count Agar (PCA). The growth kinetics was also analyzed by RMG with glucose as sole carbon source. The emulsification of clomazone formulation derived in turbidity in culture medium, generating interferences in the biomass estimation by the BPS method. Therefore, the only way to evaluate kinetic parameters was by the CFU/ml counting method by RMG at 300 rpm. In this way, growth curves for the two tested bacteria revealed generation times (tg) of 1.48 h and 7.46 h with division rates () of 0.68 h-1 and 0.15 h-1 for I2 and H5 respectively. Results obtained with glucose showed higher division rates and shorter generation times (I2=1,4 h-1,H5= 0,48 h-1, tgI2=0,73 h, tgH5=2.34 h) demonstrating a slowdown in bacterial growth by pesticide formulation consume. Further studies will be focused on the identification of degradation products to proceed with the application of mixed cultures in rice crop soil bioremediation microcosms experiments.Item Selection of native bacteria from rice soils resistant to glyphosate, clomazone and Kifix, to be used as biodegrading agents(2022-10-28) Cuadra, Pablo Nicolás; Fontana, Gimena Lilián; Farías, Alejandro Rubén; Jorge, Nelly Lidia; Vullo, Diana LiaRice is the main crop worldwide, covering about 11% of the planet’s arable land and constitutes a strategic component of the diet adopted for more than half of the world population. In Argentina, 3% of its production is in the Province of Chaco. Glyphosate, clomazone and kifix, are herbicides commonly used in rice crops for weed control, generating alterations in the soil ecosystem, and affecting the trophic chain. In this province, several studies reported poisoning cases in humans by herbicide applications, particularly in La Leonesa. Consequently, local producers requested assistance to find a prompt solution for this environmental concern. As demonstrated, the ability of certain soil bacteria to degrade these types of pollutants ensures an onsite detoxification process. For this reason, the objective of this work was to isolate native bacteria from soils of rice crops, resistant to a mixture of agrochemicals composed by the commercial formulates of glyphosate, clomazone and kifix, to be applied in biodegradation tests. The soils samples were taken from 3 areas of a field intended for rice cultivation, located in La Leonesa: 1. Virgin area without registered pesticide applications (ZA), 2. Area without applications for a decade (ZB), and 3. Crop area with continuous application of agrochemicals (ZC). As a first approach, counts of cultivable microorganisms were carried out in a traditional nutrient medium (PCA) and an oligotrophic medium (AS= soil agar) with and without pesticides (CP and SP respectively). Differences were detected both in number and in the diversity according to the sampling area, the composition of the medium and the presence of pesticides. In parallel, mixed cultures were obtained from soil suspensions in a saline broth (M9) with 0.5% m/v glucose and 1% v/v of the same herbicides, obtaining new isolates in M9 agar (AM9). As a result, 24 strains were selected and purified from AS-CP, PCA-CP and AM9. Toxicity was evaluated by exposing these isolates to increasing concentrations of herbicides in agar cultures, registering a greater growth inhibition in AS-CP with respect to PCA and AM9, probably related to pesticide interactions with medium components lowering the bioavailability. From these tests, 16 strains were selected according to their resistance to the highest concentrations of the mixture (from 0.25% in AS-CP to 15% in PCA-CP). Finally, resistance assays were performed in M9 broth supplemented with increasing concentrations of herbicides (1-20% v/v), detecting 9 strains capable of developing up to 15% v/v. In further studies, pesticide biodegradation by-products will be screened in cultures supernatants. Regarding that the agrochemical applications in crops will eventually not be discontinued, this work represents the first step to develop an alternative based on native bacteria bioinoculants for the future quality recovery of Chaco rice production soils.