Ciencias Agropecuarias

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Subject: search.filters.subject.BACTERIAS ASOCIADAS

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    Evaluación de la capacidad de fijación del nitrógeno atmosférico de las bacterias asociadas con la rizosfera de plantas de Solanum tuberosum L. Var. Superchola en la provincia de Tungurahua
    (2023-09) Altamirano Diaz, Vanessa Carolina; Leiva Mora, Michel
    The present study was developed with the purpose of isolating, quantifying, characterizing, evaluating and conserving free-living bacteria associated with the potato rhizosphere with atmospheric nitrogen fixation capacity, from soil samples from four localities in the province of Tungurahua. First, soil samples were collected from the potato crop and placed in plastic containers of 6 L capacity, where tubers of the Superchola variety were planted. After 60 days, samples of rhizospheric soil (area near the roots) were extracted. For isolation, the pour plate method was used in Jensen culture medium free of nitrogen sources. To quantify viable bacteria per gram of soil from each locality, serial solutions were prepared where 100 µl were deposited in solid medium, incubated for 72 hours at 30 ºC in inverted position and the plate count was performed. The locality of Santa Rita in the canton of Pillaro had the highest number of CFU/g of soil. A total of 72 isolates were obtained from the potato rhizosphere, of which only 38 isolates produced a positive reaction with the color change of the medium modified with bromothymol blue from green to blue, these were subjected to morphological and cultural characterization. In relation to morphology, 84% were predominantly Gram (-) bacteria, bacilli (95%) and their grouping was mostly in the form of diplobacilli (37%). In the cultural characterization, the following shapes predominated: circular (42%), entire margin (84%), smooth texture (87%), flat surface (42%), smooth consistency (82%) and 95% showed brightness. The bacterial isolate with the greatest capacity to fix atmospheric nitrogen was (T1-FCAGP-BFN1) from the El Placer sector of the Quero canton, which had no statistically significant difference with respect to isolates T3-FCAGP-BFN14, T3-FCAGP-BFN16 and T4- FCAGP-BFN24. The purified isolates were deposited in eppendorf tubes with 15% glycerol and BHI liquid medium + 20% glycerol and stored at -20 ºC. The bacterial isolates with the highest nitrogen-fixing capacity obtained could be used to determine their plant growth-promoting activity in greenhouses prior to their possible use as biofertilizers under field conditions.
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    Aislamiento de bacterias asociadas con la rizosfera de Solanum tuberosum L. var. Superchola en dos localidades de la provincia de Tungurahua
    (2023-03) Altamirano Mayorga, Christian Alejandro; Leiva Mora, Michel
    The purpose of this research was to isolate and characterize the cultivable bacteria present in the roots (rhizobacteria) of the potato of the Superchola variety in two locations in the province of Tungurahua. In the first phase, the examination of soils where potatoes are grown was carried out, to later place them in plastic bottles with a capacity of 6000 ml; where the tubers of the Superchola variety were planted. In this way, 50 days elapsed, root samples were taken at each of the depths (8, 16 and 24 cm) to carry out the isolation by 3 methods (Inclusion of 10 mm long root fragments, Washing planting and by root dissemination, and Maceration of root fragments in NaCl saline buffer and dissemination), for which the nutrient agar culture medium was obtained. It was possible to obtain the number of 82 isolated bacteria obtained in their predominant cultural characterization in 84% with a circular shape, 85% with an entire border, 93% colonies with shine, 67% with a flat elevation and 88% with a smooth texture. In relation to its morphological characterization, Gram (+) bacteria predominated in 58%, bacilli 97%. To determine the amount of CFU/g of root, serial solutions of each location and depth were made, leaving them to incubate for 48 hours at 28°C and thus proceed to count. In order to measure the diversity of cultivable bacteria in the soil, 250 g of the sample from each location were taken, which were sent to the IDgen laboratory, where the metagenomic analysis was carried out, in which the report mentions the prevalence of 7856 cultivable bacteria in the soil. the town of Santa Rita in the canton of Píllaro and 1307 in the town of Llangahua in the canton of Ambato. Based on the results obtained, it could be said that in the Santa Rita locality of the Píllaro canton there is a greater bacterial biodiversity. It would be very interesting if each of the isolates obtained is used for research that seeks the creation of bio-inputs for this type of staple crop in the diet of the population.