Simultaneous removal of zinc, copper and cobalt from contaminated soils by biosurfactant [electronic resource].

Includes references.

A biosurfactant-producing bacterium isolated from clay soils was investigated for its effects on the plant growth characteristics and heavy metal removal. A pot experiment was conducted for investigating the capability of the biosurfactant-producing bacterial strain Rhodococcus sp. to improve the plant growth and zinc, copper and cobalt uptake of tomato in soil artificially contaminated with different levels of Zn, Cu and Co (50 ppm kg⁻¹, for each element). Data revealed that bacilli gave a highly percentage of the bacterial isolates (38.7%) followed by micrococci group (34.4%). While, short rods Gram negative presented 16.1% of the total isolates. Moreover, both of the long rods Gram positive and filaments bacteria presented 5.4%, respectively. The morphological characteristics of pure isolates indicated that Gram positive presented 84.2% of the total isolates. While, the Gram negative represented (15.8%) from the total isolates. Thirty three isolates were tested for biosurfactant production. Only 6 isolates had potential to degrade the diesel oil after 3 to 5 days with a different degree of degradation. The percentage of the height of emulsified layer (cm) after 3 and 5 days of incubation period of the selected six isolates showed that isolate Sm2-4 gave the highest emulsification percentage (91%) after 3 days of incubation period. While isolates Sm 1-1, Sm2-3 and Sm2-8 gave the lowest emulsification % reached 71% after 3 days. Both of the two isolates number Sm2-12 and Sm2-9 recorded the second category of emulsification percentage and reached 88% after 3 days of incubation period.

Summary in Arabic.

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