Degradation of chlorophenol mixtures in a fed-batch system by two soil bacteria

Abstract

This work was undertaken to investigate the effect of variations of the feed rate on a fed-batch set-up used to degrade xenobiotics. The mixture of substrates was composed of PCP, 2,4,6 TCP and 2,3,5,6 TeCP (pentachlorophenol, 2,4,6 trichlorophenol and 2,3,5,6 tetrachlorophenol respectively). Two acclimated bacteria isolated from soil were used: Pseudomonas aeruginosa and Achromobacter sp. nov. The different flow rates tested were: I: 0.5 mℓ•min . Our results show that during fed-batch operation the 2,4,6 TCP exhibits an earlier degradation than the other compounds, for all of the flow rates tested. This indicates that in this case the degradation of the most recalcitrant compounds (PCP and 2,3,5,6 TeCP) is benefited by the increase in biomass of bacteria, due to the metabolisation of a less recalcitrant compound (2,4,6 TCP). The defined parameter, specific degradation rate (SDR), was demonstrated to be very useful for comparing the degradation abilities at different flow rates of a fed-batch system. The degradation efficiencies were shown to be higher than 90% for all of the cases and to decrease as the feed rate increases. However, the SDR, a parameter that involves the rate of degradation and the biomass, increases as the flow rate increases. At a feed flow rate of 2 mℓ•min -1 SDR reaches a maximum of 12.476 x 10 -10 mgCP•h -1•CFU -1. Finally, among the feed flows tested, taking into account both the degradation efficiency and the SDR, 2 mℓ•min -1 is the most convenient flow rate for chlorophenol degradation in fed-batch systems. An even higher degradation efficiency (97%) can be achieved by using the feed rate of 2 mℓ•min -1 followed by an additional batch post-treatment of 2 h, with a SDR of 13.136 x 10 -10 mg CP•h -1•CFU -1.

Retracted: Acclimation of 2‐chlorophenol‐biodegrading activated sludge and microbial community analysis

“…Thus, in the present study, Bacillus may have been the primary degraders of 2‐chlorophenol. Pseudomonas , with low relative abundance (0.1%–1.3%), are also capable of using phenol and chlorophenols as carbon and energy sources (Durruty, Okada, González, & Murialdo, ; Kaczorek, Smułek, Zdarta, Sawczuk, & Zgoła‐Grześkowiak, ; Liu et al., ; Wang et al., ). On the whole, the abundance of known chlorophenol‐degrading bacteria was not high, nor did it increase with the concentration of 2‐chlorophenol.…”

Hydrocarbon biodegradation and dynamic laser speckle for detecting chemotactic responses at low bacterial concentration

“…Therefore, this research is focused on the biodegradation abilities and chemotactic responses of Pseudomonas strain H in the presence of some hydrocarbons which had not been previously studied with that strain. This strain was isolated from phenolcontaminated soil in Argentina, and is capable of using chlorophenols as its only carbon source (Murialdo et al, 2003;Wolski et al, 2006;Durruty et al, 2011aDurruty et al, , 2011b.…”

Dynamic laser speckle and fuzzy mathematical morphology applied to studies of chemotaxis towards hydrocarbons

“…used in this study was isolated from soil and capable of degrading chlorophenols (Murialdo et al, 2003;Wolski et al, 2006;Durruty et al, 2011aDurruty et al, , 2011b. Microorganisms were stored and grew as detailed in a previews work (Nisenbaum et al, 2013).…”