Development of metal tolerance in soil bacterial communities exposed to experimentally increased metal levels

• DOI: 10.1128/aem.62.8.2970-2977.1996
• Publication Date: 2020-01-06T18:18:45Z
• Authors: M Diaz-Ravina; E Baath
• Keywords: Incubation period; Dry weight; Bacterial growth

The development of metal tolerance in soil bacterial communities exposed to different heavy metals was examined under laboratory conditions. An agricultural amended with Zn concentrations studied most intensively, and measurements were made over a 28-month incubation period by means the thymidine incorporation technique. Tolerance levels not affected lower than 2 mmol kg (dry weight) soil(sup-1), but above this value, level increased exponentially logarithm concentration. detected after only days exposure. Thereafter, stable values observed at sampling times for up 8 weight)(sup-1), indicating no changes time. 32 weight)(sup-1) rapidly within second week incubation, then remained unchanged until end experiment. Bacterial from contaminated 16 showed an increase same magnitude, started later, 4 months took place much longer (more 1 year). Cd, Cu, Ni addition also resulted metal-tolerant communities, prolonged incubations soils. community exhibited pH optimum low osmotic potential. results suggest that adding can be attributed immediate effect due death sensitive species later competitive abilities adaptation surviving bacteria.