Comamonas sp. 3ah48 is a dibenz[a,h]anthracene-degrading bacterium that is tolerant to heavy metals
LETTERS IN APPLIED MICROBIOLOGY
Authors: Okai, M.; Ohki, Y.; Yamamoto, S.; Takashio, M.; Ishida, M.; Urano, N.
Abstract
Industrialization often causes polycyclic aromatic hydrocarbon (PAH) and heavy metal contamination of soil and water. In this study, we isolated a bacterium from bottom mud water around a park of Kawasaki Port, Japan, that degrades the 5-ring PAH dibenz[a,h]anthracene (DBA). The strain, Comamonas sp. 3ah48, degraded 29% of DBA (30 mu g ml(-1)) in 7 days, and the degradation level increased drastically, to 59%, by the addition of glutamate to the medium. The strain also degraded 40, 14, 15 and 19% of pyrene (Pyr), benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF) and benzo[g,h,i]perylene (BghiP) respectively. Benzo[a]pyrene (BaP) was degraded only when glutamate was added to the medium. Strain 3ah48 retained its degradation levels in the presence of 2 mmol l(-1) Co2+, Zn2+ or Cr2+, at almost the same level as that without metal, and increased the DBA degradation level to 57% in the presence of 2 mmol l(-1) Cu2+, suggesting the possibility of the presence of laccase.
Mechanism of hydrolyzable metal ions effect on the zeta potential of fine quartz particles
JOURNAL OF DISPERSION SCIENCE AND TECHNOLOGY
Authors: Liu, Chunfu; Min, Fanfei; Liu, Lingyun; Chen, Jun; Du, Jia
Abstract
The effects of ion species, cation valence, ionic strength, and hydrated ionic radius on the zeta potential of quartz have been systematically studied through the measurement of zeta potential, sedimentation rate, and aggregation observation. The results show that the interaction between hydrolysis components and quartz particles results in three critical points - CR1, CR2, and CR3. The results of sedimentation and aggregation observation are in good agreement with the changes of the zeta potential in 0.1 M MgCl2, the maximum sedimentation rate being 99.26% at pH 10.85. When the pH is around 6.25 or 10.00, the sedimentation rate is relatively lower and the size of aggregation smaller. The adsorption of hydrolyzable multivalent metal ions on the quartz surface is a combination of three adsorption forms, namely electrostatic adsorption, hydroxyl complex adsorption, and hydroxide precipitation adsorption. Then the hydrolysis properties of metal ions and the surrounding environment determine the action of the hydrolysis components and the main form of adsorption. [GRAPHICS] .