Degradation of formaldehyde at high concentrations by phenol-adaptedRalstonia eutrophaclosely 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.

Fast Biodegradation of Diesel Hydrocarbons at High Concentration by the Sophorolipid-Producing Yeast <b><i>Candida catenulata</i></b> KP324968

“…Originally, the concentrations of aliphatic fractions are higher than those of aromatic fractions in diesel, and thus an increase in initial diesel concentration in the contaminated effluent results in inhibition of the enzymatic systems involved in the biodegradation of the aliphatic hydrocarbons at high concentrations [Nakhla et al, 2006]. In order to determine the mathematical modeling of the biodegradation rate (Y 2 ), the Michaelis-Menten (equation 4) and Haldane (equation 5) models were used [Nakhla et al, 2006;Habibi and Vahabzadeh, 2013]. ) are the halfsaturation and self-inhibition constants, respectively.…”

Formaldehyde degradation in Corynebacterium glutamicum involves acetaldehyde dehydrogenase and mycothiol-dependent formaldehyde dehydrogenase

“…1), however, this bacterium can withstand relatively high formaldehyde concentrations as compared to, for example, fibroblasts (IC 50 of approximately 263 mM; Lovschall et al, 2002) or Ralstonia eutropha (IC 50 of about 1.6 mM; Habibi & Vahabzadeh, 2013). One potential candidate for an enzyme oxidizing formaldehyde to formate in C. glutamicum is the acetaldehyde dehydrogenase Ald, which is essential for utilization of ethanol (Auchter et al, 2009).…”

Formaldehyde degradation byRalstonia eutrophain an immobilized cell bioreactor

“…Adaptation of the test bacterium to FA had been carried out as described in details in a separate study. [14] Immobilization of R. eutropha in the LICB The setup shown in Fig. 1 consisted of a FA glass feed vessel of 500 mL capacity, equipped with magnetic stirrer, air condenser and air filter (Millipore).…”

“…[14] Fifty milliliters of the FA-adapted bacterial culture solution containing a biomass concentration at the level of 150 mg L −1 equal to approximately 7.5 mg of dried cell weight was transferred to the FA feed vessel having test solution with 200 mg L −1 of FA as the initial concentration of FA. Table 1 shows the composition of the test solution in the FA feed vessel.…”

“…[12,13] FA degradation by the phenol-adapted R. eutropha has also recently been reported. [14] Various fermentation processes are carried out with the use of the immobilized cells and immobilization in several ways is advantageous such as efficient utilization of substrates in bio-treatment of wastewater. Although a number of immobilization supports have been studied in detail, natural supports such as loofa sponge had been successfully used for fuel ethanol production from sugar beet juice in a bubble column bioreactor because of the availability of support at low cost and also possibility of keeping cells viable for longer time.…”