RESUMEN
The potential of indigenously isolated bacteria from the Estância Velha stream to reduce Cr(VI) was evaluated and also the chromium contamination over the past ten years was verified in one of the most important industrial centers of Brazil, the "Brazilian Capital of Tanneries," Estância Velha municipality in the Rio Grande do Sul State, South Brazil. Samples were collected from the Estância Velha stream at the source (P1), as well as at upstream (P2) and downstream (P3) of the most demographically area. The bacterial strains reduced between 52.5 and 61.6% of 250 mg L-1 Cr(VI) in 48 h. The genus Acinetobacter was the most abundant and could efficiently reduce 500 mg L-1 of Cr(VI); for example, P2.8 and P2.9 strains of Acinetobacter ursingii reduced 21.3 and 24.5% of 500 mg L-1 of Cr(VI), respectively, after 48 h. Moreover, an analysis of Cr levels in the stream sediment reported up to 3594 mg. L-1 of total Cr and up to 138 mg. L-1 of Cr(VI) in 2009. Acinetobacter strains were identified as the most abundant and efficient in reducing Cr(VI), makes them an ideal candidate for cleaning environments contaminated with tannery effluents, an approach that is more cost-effective than the traditional methods.
Asunto(s)
Bacterias , Cromo/aislamiento & purificación , Contaminantes Ambientales/aislamiento & purificación , Residuos Industriales/análisis , Ríos , Bacterias/química , Bacterias/metabolismo , Biodegradación Ambiental , Brasil , Cromo/metabolismo , Contaminantes Ambientales/metabolismo , Sedimentos Geológicos/química , Sedimentos Geológicos/microbiología , Oxidación-Reducción , Ríos/química , Ríos/microbiología , CurtiembreRESUMEN
The bacterial strains SEMIA 587 and 5019 (Bradyrhizobium elkanii), 5079 (Bradyrhizobium japonicum), and 5080 (Bradyrhizobium diazoefficiens) are recommended for soybean inoculants in Brazil. In several countries, the current regulations are insufficient to induce companies for improving the quality of their products, leading to low performance and subsequent abandonment of inoculant use. From 2010 to 2014, 1086 samples coming mainly from Argentina and the southern region of Brazil were analyzed for viable cells counting, strains identification, and purity analysis according to the SDA/MAPA no. 30/2010 Normative Instruction. Most products were imported and formulated in liquid carriers with 5.0 × 109 colony-forming units (CFU)/mL. The strains most frequently used were SEMIA 5079/5080. Only 2.21% of samples had contaminants. The guaranteed concentration of viable cells in inoculants mostly ranged from 4.1 × 109 to 5.0 × 109 CFU/mL or CFU/g. The most frequently found concentration was above 1.1 × 1010 CFU/mL or CFU/g, which was higher than the product guarantee. The inoculants used for soybean crop in Brazil have excellent quality, leading the country to the leadership in taking advantage of the biological nitrogen fixation benefits for a productive and sustainable agriculture.