title: Degradation of formaldehyde at high concentrations by phenol-adapted Ralstonia eutropha closely related to pink-pigmented facultative methylotrophs.
abstract: The ability of the phenol-adapted Ralstonia eutropha to utilize formaldehyde (FD) as the sole source of carbon and energy was studied. Adaptation to FD was accomplished by substituting FD for glucose in a stepwise manner. The bacterium in the liquid test culture could tolerate concentrations of FD up to 900 mg L(-1). Degradation of FD was complete in 528 h at 30°C with shaking at 150 rpm (r = 1.67 mg L(-1) h(-1)), q = 0.035 g(FD) g(cell) (-1) h(-1). Substrate inhibition kinetics (Haldane and Luong equations) are used to describe the experimental data. At non-inhibitory concentrations of FD, the Monod equation was used. According to the Luong model, the values of the maximum specific growth rate (μ(max)), half-saturation coefficient (k(S)), the maximum allowable formaldehyde concentration (S(m)), and the shape factor (n) were 0.117 h(-1), 47.6 mg L(-1), 900 mg L(-1), and 2.2, respectively. The growth response of the test bacterium to consecutive FD feedings was examined, and the FD-adapted R. eutropha cells were able to degrade 1000 mg L(-1) FD in 150 h through 4 cycles of FD feeds. During FD degradation, formic acid metabolite was formed. Assimilation of FD, methanol, formic acid, and oxalate by the test bacterium was accompanied by the formation of a pink pigment. The carotenoid nature of the cellular pigment has been confirmed and the test bacterium appeared to be closely related to pink-pigmented facultative methylotrophs (PPFM). The extent of harm to soil exposed to biotreated wastewaters containing FD may be moderated due to the association between methylotrophic/oxalotrophic bacteria and plants.
authors.affiliation: Chemical Engineering Department, Amirkabir University of Technology, Tehran, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Habibi
authors.forename: Farzaneh
authors.initials: F
authors.lastname: Vahabzadeh
mesh_terms: D000064:Acclimatization; D001673:Biodegradation, Environmental; D020118:Cupriavidus necator / Q000254:growth & development / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004785:Environmental Pollutants / Q000378:metabolism*; D005557:Formaldehyde / Q000378:metabolism*; D005561:Formates / Q000378:metabolism; D008954:Models, Biological; D019800:Phenol / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D004785:Environmental Pollutants; D005561:Formates; C030544:formic acid; D005557:Formaldehyde; D019800:Phenol