Enhanced biodegradation of phenol by a microbial consortium in a solid?liquid two phase partitioning bioreactor

Abstract

Two phase partitioning bioreactors (TPPBs) operate by partitioning toxic substrates to or from an aqueous, cell-containing phase by means of second immiscible phase. Uptake of toxic substrates by the second phase effectively reduces their concentration within the aqueous phase to sub-inhibitory levels, and transfer of molecules between the phases to maintain equilibrium results in the continual feeding of substrate based on the metabolic demand of the microorganisms. Conventionally, a single pure species of microorganism, and a pure organic solvent, have been used in TPPBs. The present work has demonstrated the benefits of using a mixed microbial population for the degradation of phenol in a TPPB that uses solid polymer beads (comprised of ethylene vinyl acetate, or EVA) as the second phase. Polymer modification via an increase in vinyl acetate concentration was also shown to increase phenol uptake. Microbial consortia were isolated from three biological sources and, based on an evaluation of their kinetic performance, a superior consortium was chosen that offered improved degradation when compared to a pure strain of Pseudomonas putida ATCC 11172. The new microbial consortium used within a TPPB was capable of degrading high concentrations of phenol (approximately 2000 mg l(-1)), with decreased lag time (10 h) and increased specific rate of phenol degradation (0.71 g phenol g(1) cell h). Investigation of the four-member consortium showed that it consisted of two Pseudomonas sp., and two Acinetobacter sp., and tests conducted upon the individual isolates, as well as paired organisms, confirmed the synergistic benefit of their existence within the consortium. The enhanced effects of the use of a microbial consortium now offer improved degradation of phenol, and open the possibility of the degradation of multiple toxic substrates via a polymer-mediated TPPB system.

Kinetics of batch microbial degradation of phenols by indigenous Pseudomonas fluorescence

“…This increase may be due to the fact that the added phenol was converted to unknown intermediates that were later consumed. A similar observation has been reported for the isolates of Pseudomonas and Acinetobacter grown on phenol (Hao et al, 2002;Saez and Rittman, 1991;Prpich and Daugulis, 2005). As shown in Figs.…”

“…It is an organic, aromatic compound that occurs naturally in the environment (Prpich and Daugulis, 2005), but is more commonly produced artificially from industrial activities such as petroleum processing, plastic manufacturing, resin production, pesticide production, steel manufacturing and the production of paints and varnish (Mahadevaswamy et al, 1997;Bandyopadhyay et al, 1998). This aromatic compound is water-soluble and highly mobile (Collins and Daugulis, 1997) and as such waste waters generated from these industrial activities contain high concentrations of phenolic compounds (Chang et al, 1998) which eventually may reach down to streams, rivers, lakes, and soil, which represent a serious ecological problem due to their widespread use and occurrence throughout the environment (Fava et al, 1995).…”

“…Phenol is a listed priority pollutant by the U.S. Environmental Protection Agency (EPA, 1979) and is considered to be a toxic compound by the Agency for Toxic substances and Disease Registry (ATSDR, 2003). The adverse effects of phenol on health are well documented (Calabrese and Kenyon, 1991) and death among adults has been reported with ingestion of phenol ranging from 1 to 32 g (Prpich and Daugulis, 2005). The low volatility of phenol and its affinity for water make oral consumption of contaminated water the greatest risk to humans (Prpich and Daugulis, 2005).…”

“…The adverse effects of phenol on health are well documented (Calabrese and Kenyon, 1991) and death among adults has been reported with ingestion of phenol ranging from 1 to 32 g (Prpich and Daugulis, 2005). The low volatility of phenol and its affinity for water make oral consumption of contaminated water the greatest risk to humans (Prpich and Daugulis, 2005). A variety of techniques involving physical, chemical and biological methods have been used for the removal of phenol from industrial effluents and contaminated The meta-cleavage pathway for the biodegradation of phenol A= Phenol, B= Catechol, C= 2-Hydroxymuconic semialdehyde, D= 2-Hydroxymuconate, E= 2-Oxo-4-enoadipate, F= 2-Oxo-penta-4-enoate, G= Pyruvate, H= Acetaldehyde, I= Acetyl Co A, E1= Monooxygenase phenol hydroxylase, E2=Catechol-2, 3-dioxygenase, E3= Hydrolase, E4= Dehydrogenase, E5= Isomerase, E6= Decarboxylase, E7= Hydrotase, E8= Aldolase waters with bioremediation receiving the most attention due to its environmental friendliness, its, ability to completely mineralize toxic organic compounds and of low-cost (Kobayashi and Rittman, 1982;Prpich and Daugulis, 2005).…”

“…A variety of techniques involving physical, chemical and biological methods have been used for the removal of phenol from industrial effluents and contaminated The meta-cleavage pathway for the biodegradation of phenol A= Phenol, B= Catechol, C= 2-Hydroxymuconic semialdehyde, D= 2-Hydroxymuconate, E= 2-Oxo-4-enoadipate, F= 2-Oxo-penta-4-enoate, G= Pyruvate, H= Acetaldehyde, I= Acetyl Co A, E1= Monooxygenase phenol hydroxylase, E2=Catechol-2, 3-dioxygenase, E3= Hydrolase, E4= Dehydrogenase, E5= Isomerase, E6= Decarboxylase, E7= Hydrotase, E8= Aldolase waters with bioremediation receiving the most attention due to its environmental friendliness, its, ability to completely mineralize toxic organic compounds and of low-cost (Kobayashi and Rittman, 1982;Prpich and Daugulis, 2005). Microbial degradation of phenol with different initial concentrations ranging from 50-2000 mg/L have been actively studied using shake flask, fluidized-bed reactor, continuous stirred tank bioreactor, multistage bubble column reactor, air-lift fermenter and two phase partitioning bioreactor methods (Bettmann and Rehm, 1984;Sokol, 1988;Annadurai et al, 2000;Reardon et al, 2000;Ruiz-ordaz et al, 2001;Oboirien et al, 2005;Prpich and Daugulis, 2005;Saravanan et al, 2008) and these studies have shown that phenol can be aerobically degraded by wide variety of fungi and bacteria cultures such as Candida tropicalis (Ruiz-ordaz et al, 2001, Chang et al, 1998Ruiz-ordaz et al, 1998); Acinetobacter calcoaceticus (Paller et al, 1995); Alcaligenes eutrophus (Hughes et al, 1984;Leonard and Lindley, 1998); Pseudomonas putida (Hill and Robinson, 1975;Kotturi et al, 1991;Nikakhtari and Hill, 2006); and Burkholderia cepacia G4 (Folsom et al,1990, Solomon et al,1994. In microbial degradation of phenol under aerobic conditions, the degradation is initiated by oxygenation in which the aromatic ring is initially monohydroxylated by a mono oxygenase phenol hydroxylase at a position ortho to the pre-existing hydroxyl group to form catechol.…”