Enzymatic degradation of nitriles by Klebsiella oxytoca

Abstract

Klebsiella oxytoca, isolated from cyanide-containing wastewater, was able to utilize many nitriles as sole source of nitrogen. The major objective of this study was to explore the ability of K. oxytoca to utilize some nitriles and then further evaluate the pathways of transformation of cyanide compounds by K. oxytoca. Results from this study indicate that succinonitrile and valeronitrile were the most optimal sources of nitrogen for the growth of K. oxytoca. The biodegradation of acetonitrile proceeded with the formation of acetamide followed by acetic acid. The production of ammonia was also detected in this biodegradation experiment. Similar results were observed in the propionitrile biodegradation experiments. Collectively, this study suggests that the breakdown of acetonitrile or propionitrile by this bacterium was via a two-step enzymatic hydrolysis with amides as the intermediates and organic acids plus with ammonia as the end products.

Biodegradation of organonitriles by adapted activated sludge consortium with acetonitrile-degrading microorganisms

“…A similar pathway for the formation of amide, and then carboxylic acid and ammonia from microbial transformation of nitrile compounds was also reported by others (Kao et al, 2006;Rezende et al, 2003). For example, Kao et al (2006) reported the biodegradation of acetonitrile and propionitrile by Klebsiella oxytoca involving a two-step enzymatic degradation mechanism (no information on the degradation pathway of benzonitrile was given). In contrast, the biodegradation performance and metabolic products of benzonitrile shown in Fig.…”

“…C5 (Yamamoto et al, 1992), Cryptococcus sp. UFMG-Y28 (Rezende et al, 2000), Klebsiella oxytoca (Kao et al, 2006), Kluyveromyces thermotolerans MGBY 37 (Prasad et al, 2005), Nocardia rhodochrous (DiGeronimo and Antoine, 1976), Paracoccus thiophilus , Pseudomonas marginalis (Babu et al, 1995), Pseudomonas putida (Nawaz et al, 1989), Rhodococcus erythropolis A10 (Acharya and Desai, 1997), R. erythropolis BL1 (Langdanhl et al, 1996), Rhodococcus rhodochrous PA-34 (Bhalla et al, 1992) and Rhodococcus sp. N 774 (Endo and Watanabe, 1989).…”

“…Typical examples of these compounds include acetonitrile, acrylonitrile and benzonitrile that are widely used in laboratories and industries as solvents and extractants, or used as an ingredient in pharmaceuticals, plastics, synthetic rubbers, drug intermediates (chiral synthons), herbicides and pesticides (e.g., dichlobenil, bromoxynil, ioxynil, buctril), etc. (Henahan and Idon, 1971;Banerjee et al, 2002;Kao et al, 2006). As a consequence, organonitrile compounds are often contained in the effluents from these applications and thus present a challenge in the decomposition/ detoxification of these compounds in wastewater treatment.…”

“…The pH in the culture medium showed similar small changes as in those cases for acetonitrile and acrylonitrile. In the literature, Kao et al (2006) reported that a 2 mM (206 mg L…”

Bioremediation of soil and water polluted by cyanide: A review

“…Another disadvantage is that it is relatively expensive due to the quantity of chlorine required. Further reason, the addition of excess chlorine increases the total solids content of water, making it undesirable for recycling and reuses purposes and leaves a residue with a high chlorine content which is toxic to aquatic life (Kao et al, , 2006. In addition, various chlorinated organics may be produced if the wastewater contains organic substances (Dash et al, 2009).…”