Biodegradation of phenol and 4-chlorophenol by the yeast Candida tropicalis

Abstract

Biodegradation of phenol and 4-chlorophenol (4-cp) using a pure culture of Candida tropicalis was studied. The results showed that C. tropicalis could degrade 2,000 mg l(-1) phenol alone and 350 mg l(-1) 4-cp alone within 66 and 55 h, respectively. The capacity of the strain to degrade phenol was obviously higher than that to degrade 4-cp. In the dual-substrate system, 4-cp intensely inhibited phenol biodegradation. Phenol beyond 800 mg l(-1) could not be degraded in the presence of 350 mg l(-1) 4-cp. Comparatively, low-concentration phenol from 100 to 600 mg l(-1) supplied a sole carbon and energy source for C. tropicalis in the initial phase of biodegradation and accelerated the assimilation of 4-cp, which resulted in the fact that 4-cp biodegradation velocity was higher than that without phenol. And the capacity of C. tropicalis to degrade 4-cp was increased up to 420 mg l(-1) with the presence of 100-160 mg l(-1) phenol. In addition, the intrinsic kinetics of cell growth and substrate degradation were investigated with phenol and 4-cp as single and mixed substrates in batch cultures. The results illustrated that the models proposed adequately described the dynamic behaviors of biodegradation by C. tropicalis.

Evaluation of Nutritional and Environmental Conditions for Phenol Degradation by a Lebanese strain of Candida tropicalis

“…The maximum tolerable phenol concentration that Candida tropicalis H can degrade efficiently was 2000 mg/l. These findings are in good agreement with those found by Jiang et al (2007b), where Candida tropicalis was able to degrade up to 2000 mg/l of phenol. The toxicity threshold concentration of phenol against microbial strains is different from a strain to another.…”

Mutation of Candida tropicalis by Irradiation with a He-Ne Laser To Increase Its Ability To Degrade Phenol

“…It showed that the model regression agreed well with the experimental data. The values of kinetic parameters of mutant strain CTM 2 were bigger than those of its parent strain (12), which indicated that mutant strain CTM2 possessed a higher potential to degrade phenol.…”

“…Fialová et al (9) reported that the yeast Candida maltosa can degrade phenol at concentrations up to 1,700 mg liter Ϫ1 . A wild strain was isolated from acclimated activated sludge in our lab with the potential to degrade 2,000 mg liter Ϫ1 phenol within 66 h (12). To further promote phenol biodegradation potential, improvement of microorganisms is of great importance.…”

“…The objectives of these studies are to acquire a positive mutant strain with high phenol-degrading potential using a He-Ne laser to stimulate wild-type C. tropicalis, to investigate the variety of phenol hydroxylase activities and the sequences of phenol hydroxylase genes, and to investigate the cell growth and intrinsic phenol degradation kinetics of the mutant strain with a focus on those factors not influenced by transport processes but only on those factors concerning the concentration of reactants, temperature, and the character of the solvent by Haldane's equation (3,10,12). supplemented with ampicillin at 80 g ml Ϫ1 when necessary.…”

Stable isotope probing reveals Trichosporon yeast to be active in situ in soil phenol metabolism

“…The universal toxicity and ubiquitous nature of phenol make its biodegradation a topic of great interest (ATSDR, 2006). Although the earliest studies of phenol biodegradation focused on bacteria, there have been a growing number of fungi studied for their ability to degrade phenol, including members of the genera Trichosporon, Cryptococcus, Rhodotorula, Rhodococcus, Aspergillus, Penicillium, Cladosporium, Trichoderma, Phanerochaete, Candida and Fusarium (Harris and Ricketts, 1962;Dagley, 1967;Neujahr and Varga, 1970;Gaal and Neujahr, 1979;Rubin and Schmidt, 1985;Alexievaa et al, 2004;Atagana, 2004;Santos and Linardi, 2004;Bergauer et al, 2005;Margesin et al, 2005;Krallish et al, 2006;Singh, 2006;Stoilova et al, 2006;Jiang et al, 2007). Fungi are often able to thrive under environmentally stressed conditions (low nutrient availability, low moisture, low pH and low temperature) and unlike bacteria, they can extend their biomass through environmental matrices through hyphal growth, making their potential for metabolism of organic pollutants particularly promising (Buchan et al, 2003;Atagana, 2004;Margesin et al, 2005;de Boer et al, 2005).…”