Bioaugmentation with Arthrobacter sp. strain AAC22 for atrazine attenuation in agricultural soils of Córdoba, Argentina

URSELER, N; BACHETTI R; MORGANTE V; MILOC E; AGOSTINI E; MORGANTE; CA

Santiago

Congreso; XXIV Congreso Latinoamericano de Microbiología; 2018

ALAM

Bioremediation is an important technology for removal of persistent pollutants from the environment. Atrazine (AT) is a s-triazine herbicide widely used in Córdoba (Argentina) for the control of broad-leaved weeds in corn, sorghum, alfalfa among other crops. Our research group isolated an efficient s-triazine degrading strain identified as Arthrobacter sp. AAC22 (GenBank accession number KT591504) from surface contaminated water. The aims of this work were: i) to study the AT bioremediation potential of AAC22 in soils; ii) to compare the AT degradation under bioaugmentation conditions vs. natural attenuation capacity. The experiments were performed in microcosm using a surface soil (typical Natracualf) that had >15 years of AT application. To evaluate the AT soil removal, four treatments (three replications) were established: A) soil + AT + AAC22; B) sterile soil + AT + AAC22; C) soil + AT; C) sterile soil + AT. Each microcosm contained 200 g of soil was added with AT (100 mg.kg-1) and inoculated with AAC22 bacterial (1x105 CFU.g-1) in the corresponding treatments. The water content was adjusted to 50% of the field capacity with sterile distilled water. The parameters assessed were: 1) residual AT concentration by Micellar elektrokinetic chromatography; 2) AAC22 enumeration by surface plate count; 3) atrazine-degrading microorganisms (ADM) enumeration using the respiration indicator (TTC) and the most-probable-number (MPN) enumeration. At 2 days of trial, was observed a marked decrease in the initial AT concentration in A (89%) and B (85%) treatments, and the total AT removal (100%) after 8 days. However, in non-inoculated control (C) and abiotic control (D) the AT concentration remained constant. Therefore, the AT degradation can be attributed exclusively to the biodegradation by AAC22. After 48 h, the AAC22 recount was increment of two orders of magnitude, coinciding with a high metabolic activity. The recount of ADM decrease in respiratory activity, probably native microbiota may have been affected by presence of AT or by competition with strain AAC22, resulting in a decrease in total respiratory activity. Bioremediation with strain AAC22 was successful for the removal of AT at microcosms scale. The native communities in the soil were influenced as a result of bioaugmentation.