Degradation of 2,4,6-tribromophenol by bacterial cells attached to chalk collected from a contaminated aquifer

Abstract

Aim: To investigate the factors governing the adhesion and activity of the 2,4,6-tribromophenol (TBP) degrading bacterium Achromobacter piechaudii TBPZ-N61 on chalk from a contaminated aquifer. Methods and Results: Adhesion kinetics of TBPZ-N61 to grey and white chalk from a polluted fractured chalk aquifer was tested in a batch system. Both grey and white chalk contain ca 80% CaCO 3 , while grey chalk contains more organic matter (2AE4%) than the white chalk (0AE3%) and also contains Dolmite and Clinoptilolite. Adhesion of the bacterial cells to the chalk particles (<0AE2 mm) occurred rapidly (96% of the cells within 15 min). Langmuirfitted adhesion isotherms suggest that cells in the stationary phase, which are more hydrophobic, adhere to both grey and white chalk more efficiently than cells in the logarithmic growth phase. Increasing the pH (from 6AE7 to 8AE1) caused a significant reduction in cell adhesion to the chalk. Activity of attached cells was evaluated in both batch and column experiments. Logarithmic cells adhering to white and grey chalk were more active in TBP degradation than cells in suspension. In column experiments, significant TBP degradation was retained up to 30 days after a single injection of TBPZ cells. Thereafter, activity was fully recovered by amendment of yeast extract. Chalk surfaces that were incubated in situ in contaminated groundwater for 20 days still allowed the adhesion and activity of TBPZ cells. Conclusions: Taken together, our results show that bacteria adhere efficiently to specific sites on the chalk surfaces, and that sustained bacterial activity of the attached cells can be achieved by adding a carbon source such as yeast extract which also overcome toxic constituents that may occur in some chalk types. Significance and Impact of the Study: Bioremediation of TBP-contaminated chalk aquifers is made possible by the injection of bacterial cultures.

Biodegradation of 2,4,6-Tribromophenol byOchrobactrumsp. Strain TB01

“…19) Cells adhering to chalk were more active in 2,4,6-TBP degradation than cells in suspension. 20) The bacterium, however, was not able to metabolize mono-or dibromophenols. 19,21) These results suggest that there are a number of bromophenoldegrading bacteria in various ecological niches, and that there is a diversity of dehalogenating enzymes with various substrate specificities.…”

Effect of flagella expression on adhesion ofAchromobacter piechaudiito chalk surfaces

“…In this pH range, the surface is electrically neutral, whereas at higher or lower pH, the surface is negatively or positively charged, respectively (Somasundaran and Agar 1967). Previously, we demonstrated that the adhesion of Achromobacter piechaudii TBPZ‐N61 to chalk follows a Langmuir isotherm and at saturation, cells in the stationary growth phase adhere more efficiently to chalk particles than cells in the logarithmic phase (Nejidat et al. 2004).…”

“…1999). As a part of our effort to design a practical scheme for the remediation of contaminated fractured chalk aquifers, we have been studying bacterial cell adhesion kinetics on a chalk matrix and the activity of the adhered cells (Nejidat et al. 2004).…”

“…Their activity was restored only after amendment with yeast extract. At saturation, it was calculated that the bacteria cover only 0·04% of the chalk surface, suggesting that bacteria adhere to specific sites on the chalk particles and that this limits the number of cells that can adhere (Nejidat et al. 2004).…”

Implications of Growth and Starvation Conditions in Bacterial Adhesion and Transport

“…Previous studies have reported mixed trends of hydrophobicity between the logarithmic and stationary growth phases. Higher hydrophobicity was observed for stationary growth phase as compared to the logarithmic phase cultures in a number of past studies [36,51,54,69,70]. Opposite trend, i.e., hydrophobicity decrease with cell age was reported in some other studies [28,35,52,53,71].…”