Volume 19, No. 4, 2022
In Vitro Evaluation Of Mercury Tolerance By Endophytic Bacteria Título Breve: Endófitas Tolerancia A Mercúrio
Ramón Paternina-Hernández ; Alexander Pérez-Cordero ; Donicer Montes-Vergara
Abstract
The objective was to isolate endophytic bacteria from plant species present in soils contaminated with mercury in southern Bolivar, Colombia, and to evaluate in vitro their tolerance capacity to different concentrations of mercury. From each sampling site, roots, stems, leaves and flowers of the plants present were collected. The concentration of mercury in soil and plant tissues was determined using the instrumental technique of cold vapor atomic absorption spectrophotometry. The amount of endophytic bacteria per tissue was determined as CFU/g of soil. The tolerance of endophyte bacterial isolates to different concentrations of mercury was performed in liquid Tris-low phosphate buffer (TLP) medium. The average mercury concentration in soil was 5.9 ± 5.2 and in tissues 4.1 ± 2.2 mg/kg. The amount of endophytic bacteria found ranged from 5.0 107 ± 3.0 104 CFU/ g of tissues. The isolates identified as Bacillus cereus strain ML259; Bacillus mycoides O-1 and Bacillus cereus strain LB1016, showed in vitro tolerance capacity up to 500 and 400 mg/mL of HgCl2. The predominant plant species found in the soil corresponded to Melochia parvifolia, accumulating mercury in concentrations of 4.06 in the root, 3.83 in the stem, 3.6 in the leaf and 2.33 mg/kg in the flower. This plant species becomes a mercury indicator and accumulator plant and a possible alternative to remediate mercury-contaminated soils using the bioremediation technique assisted by endophytic bacteria for the management of soils contaminated with this metal.
Pages: 488-504
Keywords: Bacteria, soil, plant tissue, mercury.