Phenol biodegradation by the thermoacidophilic archaeon Sulfolobus solfataricus 98/2 in a fed-batch bioreactor

Abstract

Toxic at low concentrations, phenol is one of the most common organic pollutants in air and water. In this work, phenol biodegradation was studied in extreme conditions (80°C, pH = 3.2) in a 2.7 l bioreactor with the thermoacidophilic archaeon Sulfolobus solfataricus 98/2. The strain was first acclimatized to phenol on a mixture of glucose (2000 mg l(-1)) and phenol (94 mg l(-1)) at a constant dissolved oxygen concentration of 1.5 mg l(-1). After a short lag-phase, only glucose was consumed. Phenol degradation then began while glucose was still present in the reactor. When glucose was exhausted, phenol was used for respiration and then for biomass build-up. After several batch runs (phenol < 365 mg l(-1)), specific growth rate (μ(X)) was 0.034 ± 0.001 h(-1), specific phenol degradation rate (q(P)) was 57.5 ± 2 mg g(-1) h(-1), biomass yield (Y(X/P)) was 52.2 ± 1.1 g mol(-1), and oxygen yield factor (Y(X/O2)) was 9.2 ± 0.2 g mol(-1). A carbon recovery close to 100% suggested that phenol was exclusively transformed into biomass (35%) and CO(2) (65%). Molar phenol oxidation constant (Y(O2/P)) was calculated from stoichiometry of phenol oxidation and introducing experimental biomass and CO(2) conversion yields on phenol, leading to values varying between 4.78 and 5.22 mol mol(-1). Respiratory quotient was about 0.84 mol mol(-1), very close to theoretical value (0.87 mol mol(-1)). Carbon dioxide production, oxygen demand and redox potential, monitored on-line, were good indicators of growth, substrate consumption and exhaustion, and can therefore be usefully employed for industrial phenol bioremediation in extreme environments.

Genome-Scale Reconstruction and Analysis of the Metabolic Network in the Hyperthermophilic Archaeon Sulfolobus Solfataricus

“…Other possible explanations for the low biomass yield in comparison to E. coli could be the inefficiency of metabolism at high temperatures due to the instability of metabolites [36] and the possibility that S. solfataricus does not use all of the imported glucose for biomass formation and respiration. Recent literature studies described a carbon recovery between 72% and 83% [37], [38], where only 25% of the imported carbon atoms are used for biomass formation. One possible explanation for this discrepancy is that S. solfataricus is known to produce exopolysaccharides (EPS) [39], [40].…”

“…S. solfataricus is known to grow on phenol as sole carbon source [16], [37]. To make phenol bioavailable (in S. solfataricus ), phenol is converted to catechol by phenol 2-monooxygenase (Figure 6: (49)).…”

Extreme thermophiles: moving beyond single-enzyme biocatalysis

“…For example, the degradation of toxic pollutants has been demonstrated; S. solfataricus 98/2 could utilize phenol for growth in a fed-batch bioreactor [83]. The recovery of base, precious and strategic metals through whole cell bio-oxidation processes has been a long-term goal for extreme thermoacidophiles and recent efforts have focused on identifying process bottlenecks and improved processing strategies.…”

Estimación y control de procesos biotecnológicos multivariables

“…Muchos de los modelos que describen este efecto se basan en expresiones obtenidas originalmente para la cinética de inhibición de enzimas. Un modelo muy utilizado para representar la inhibición de µ con s es el denominado modelo de Haldane 12) donde k i se denomina constante de inhibición y µ o…”

“…Algunos metabolitos como los carotenoides, las lipasas y la biomasa de microalgas tienen una gran variedad de aplicaciones industriales [8,9,10]. También se los considera para el tratamiento de desechos orgánicos, la biodegradación de sustancias peligrosas [11,12] y la producción de combustibles alternativos (hidrógeno, metano, butano, entre otros) [13,14]. Existe a su vez una variedad de microorganismos capaces de generar biopolímeros los cuales, además de ser biodegradables, exhiben interesantes propiedades físicas [15].…”