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Free cyanide and thiocyanate biodegradation by Pseudomonas aeruginosa STK 03 capable of heterotrophic nitrification under alkaline conditions

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ABSTRACT

An alkali-tolerant bacterium, Pseudomonas aeruginosa STK 03 (accession number KR011154), isolated from an oil spill site, was evaluated for the biodegradation of free cyanide and thiocyanate under alkaline conditions. The organism had a free cyanide degradation efficiency of 80 and 32 % from an initial concentration of 250 and 450 mg CN−/L, respectively. Additionally, the organism was able to degrade thiocyanate, achieving a degradation efficiency of 78 and 98 % from non- and free cyanide spiked cultures, respectively. The organism was capable of heterotrophic nitrification but was unable to denitrify aerobically. The organism was unable to degrade free cyanide in the absence of a carbon source, but it was able to degrade thiocyanate heterotrophically, achieving a degradation efficiency of 79 % from an initial concentration of 250 mg SCN−/L. Further increases in thiocyanate degradation efficiency were only observed when the cultures were spiked with free cyanide (50 mg CN−/L), achieving a degradation efficiency of 98 % from an initial concentration of 250 mg SCN−/L. This is the first study to report free cyanide and thiocyanate degradation by Pseudomonas aeruginosa. The higher free cyanide and thiocyanate tolerance of the isolate STK 03, which surpasses the stipulated tolerance threshold of 200 mg CN−/L for most organisms, could be valuable in microbial consortia for the degradation of cyanides in an industrial setting.

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Free cyanide degradation profile at different concentrations and growth profile of Pseudomonas aeruginosa STK 03 (a) and growth patterns of the organism (b). Error bars represent deviations
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Fig1: Free cyanide degradation profile at different concentrations and growth profile of Pseudomonas aeruginosa STK 03 (a) and growth patterns of the organism (b). Error bars represent deviations

Mentions: In this study, a free cyanide and thiocyanate tolerant bacterium was isolated and identified as Pseudomonas aeruginosa STK 03. Free cyanide biodegradation by Pseudomonas aeruginosa STK 03 and growth patterns in MM is shown in Fig. 1a, b, respectively. The organism was able to degrade 250 and 450 mg CN−/L, achieving a BRE of 80 and 32 % within 150 h, respectively. Recently, it has been reported that an active aerobic degradation process has a maximum cyanide threshold concentration of 200 mg CN−/L (Kuyucak and Akcil 2013). However, in this study, Pseudomonas aeruginosa STK 03 was able to degrade free cyanide in cultures containing cyanide concentrations above 200 mg CN−/L. Free cyanide degradation was accompanied by growth of the organism, with the initial cyanide having a negative impact on the growth of the organism. The cultures that had low cyanide concentrations showed a shorter lag phase while the cultures with a higher concentration demonstrated a prolonged lag phase. This phenomenon was observed elsewhere (Mekuto et al. 2013), where a Bacillus consortia showed varying lag phases with respect to different initial cyanide concentrations, with cultures with the higher concentrations showing a prolonged lag phase. The prolonged lag phase with an increase in free cyanide concentration was a result of cyanide inhibition on microbial growth.Fig. 1


Free cyanide and thiocyanate biodegradation by Pseudomonas aeruginosa STK 03 capable of heterotrophic nitrification under alkaline conditions
Free cyanide degradation profile at different concentrations and growth profile of Pseudomonas aeruginosa STK 03 (a) and growth patterns of the organism (b). Error bars represent deviations
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4697911&req=5

Fig1: Free cyanide degradation profile at different concentrations and growth profile of Pseudomonas aeruginosa STK 03 (a) and growth patterns of the organism (b). Error bars represent deviations
Mentions: In this study, a free cyanide and thiocyanate tolerant bacterium was isolated and identified as Pseudomonas aeruginosa STK 03. Free cyanide biodegradation by Pseudomonas aeruginosa STK 03 and growth patterns in MM is shown in Fig. 1a, b, respectively. The organism was able to degrade 250 and 450 mg CN−/L, achieving a BRE of 80 and 32 % within 150 h, respectively. Recently, it has been reported that an active aerobic degradation process has a maximum cyanide threshold concentration of 200 mg CN−/L (Kuyucak and Akcil 2013). However, in this study, Pseudomonas aeruginosa STK 03 was able to degrade free cyanide in cultures containing cyanide concentrations above 200 mg CN−/L. Free cyanide degradation was accompanied by growth of the organism, with the initial cyanide having a negative impact on the growth of the organism. The cultures that had low cyanide concentrations showed a shorter lag phase while the cultures with a higher concentration demonstrated a prolonged lag phase. This phenomenon was observed elsewhere (Mekuto et al. 2013), where a Bacillus consortia showed varying lag phases with respect to different initial cyanide concentrations, with cultures with the higher concentrations showing a prolonged lag phase. The prolonged lag phase with an increase in free cyanide concentration was a result of cyanide inhibition on microbial growth.Fig. 1

View Article: PubMed Central - PubMed

ABSTRACT

An alkali-tolerant bacterium, Pseudomonas aeruginosa STK 03 (accession number KR011154), isolated from an oil spill site, was evaluated for the biodegradation of free cyanide and thiocyanate under alkaline conditions. The organism had a free cyanide degradation efficiency of 80 and 32 % from an initial concentration of 250 and 450 mg CN−/L, respectively. Additionally, the organism was able to degrade thiocyanate, achieving a degradation efficiency of 78 and 98 % from non- and free cyanide spiked cultures, respectively. The organism was capable of heterotrophic nitrification but was unable to denitrify aerobically. The organism was unable to degrade free cyanide in the absence of a carbon source, but it was able to degrade thiocyanate heterotrophically, achieving a degradation efficiency of 79 % from an initial concentration of 250 mg SCN−/L. Further increases in thiocyanate degradation efficiency were only observed when the cultures were spiked with free cyanide (50 mg CN−/L), achieving a degradation efficiency of 98 % from an initial concentration of 250 mg SCN−/L. This is the first study to report free cyanide and thiocyanate degradation by Pseudomonas aeruginosa. The higher free cyanide and thiocyanate tolerance of the isolate STK 03, which surpasses the stipulated tolerance threshold of 200 mg CN−/L for most organisms, could be valuable in microbial consortia for the degradation of cyanides in an industrial setting.

No MeSH data available.


Related in: MedlinePlus