Abstract:BACKGROUND
Acrylamide is an important monomer for the synthesis of polyacrylamide, which has wide applications in industries. This molecule can be produced by the hydration of acrylonitrile, catalyzed by the enzyme nitrile hydratase (NHase) secreted by microorganisms. Herein, synthesis of acrylamide was carried out by soil isolate Rhodococcus rhodochrous (RS‐6) contains NHase. The critical parameters affecting the bioconversion process such as pH, temperature, substrate concentration, resting cell concentratio… Show more
“…The effect of substrate concentration on acrylonitrile bioconversion by immobilized R. rhodochrous (RS‐6) cells was investigated by changing the substrate concentrations from 250 mM to 2500 mM in the reaction mixture (Sahu et al, 2021).…”
Aims
The efficiency of acrylamide production was examined with immobilized cells of Rhodococcus rhodochrous (RS‐6) containing NHase.
Methods and Results
Different entrapment matrices such as agar, alginate and polyacrylamide were used. Various immobilization parameters like agar concentration, cell concentration and reaction conditions affecting the bioconversion process using suitable matrices were determined. The cells immobilized with agar matrix were found to be most effective for acrylonitrile conversion. The bioconversion was more efficient in beads prepared with 2% agar and 5% (v/v) cell concentration. The entire conversion of acrylonitrile to acrylamide with agar entrapped cells was achieved in 120 min at 15°C. The agar entrapped R. rhodochrous (RS‐6) cells exhibited 8% (w/v) tolerance to acrylonitrile and 35% tolerance to acrylamide. The immobilized cells also retained 50% of its conversion ability up to seven cycles. The laboratory‐scale (1 L) production resulted in 466 g L−1 accumulation of acrylamide in 16 h.
Conclusions
The cells immobilized in agar showed better stability and biocatalytic properties and increased reusability potential.
Significance and Impact of the study
The agar‐immobilized Rhodococcus rhodochrous (RS‐6) cells showed enhanced tolerance for both the substrate and product and is economical for the large‐scale production of acrylamide.
“…The effect of substrate concentration on acrylonitrile bioconversion by immobilized R. rhodochrous (RS‐6) cells was investigated by changing the substrate concentrations from 250 mM to 2500 mM in the reaction mixture (Sahu et al, 2021).…”
Aims
The efficiency of acrylamide production was examined with immobilized cells of Rhodococcus rhodochrous (RS‐6) containing NHase.
Methods and Results
Different entrapment matrices such as agar, alginate and polyacrylamide were used. Various immobilization parameters like agar concentration, cell concentration and reaction conditions affecting the bioconversion process using suitable matrices were determined. The cells immobilized with agar matrix were found to be most effective for acrylonitrile conversion. The bioconversion was more efficient in beads prepared with 2% agar and 5% (v/v) cell concentration. The entire conversion of acrylonitrile to acrylamide with agar entrapped cells was achieved in 120 min at 15°C. The agar entrapped R. rhodochrous (RS‐6) cells exhibited 8% (w/v) tolerance to acrylonitrile and 35% tolerance to acrylamide. The immobilized cells also retained 50% of its conversion ability up to seven cycles. The laboratory‐scale (1 L) production resulted in 466 g L−1 accumulation of acrylamide in 16 h.
Conclusions
The cells immobilized in agar showed better stability and biocatalytic properties and increased reusability potential.
Significance and Impact of the study
The agar‐immobilized Rhodococcus rhodochrous (RS‐6) cells showed enhanced tolerance for both the substrate and product and is economical for the large‐scale production of acrylamide.
“…NHase (EC 4.2.1.84), which can catalyze the hydration of nitriles into amides, plays a crucial role in enzymatic processes in the chemical industry. 6 For example, the industrial enzymatic synthesis of acrylamide has reached several hundred thousand tons per year 7 and already replaced chemical synthesis owing to its environmental friendliness and easy product recovery with high purity. 8 However, the poor thermostability of NHase and the exothermic hydration reaction (68.99 kJ heat per mol acrylamide generated) 9,10 result in the rapid inactivation of the unstable NHase, which requires additional cooling equipment to control the reaction temperature at below 25 °C and leads to large energy consumption costs in industrial processes.…”
Nitrile hydratase (NHase), an excellent biocatalyst, has been widely used for amide production, but the exothermic hydration reaction leads to the rapid inactivation of NHase, hindering its industrial applications, which...
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