Limits...
Properties of a newly identified esterase from Bacillus sp. K91 and its novel function in diisobutyl phthalate degradation.

Ding J, Wang C, Xie Z, Li J, Yang Y, Mu Y, Tang X, Xu B, Zhou J, Huang Z - PLoS ONE (2015)

Bottom Line: In particular, genes involved in the hydrolysis of these compounds were not conclusively identified.Two intermediate products were identified, and a potential biodegradation pathway was proposed.Altogether, our findings present a novel DiBP degradation enzyme and indicate that the purified enzyme may be a promising candidate for DiBP detoxification and for environmental protection.

View Article: PubMed Central - PubMed

Affiliation: Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, Yunnan Normal University, Kunming 650500, Yunnan, China; Key Laboratory of Enzyme Engineering, Yunnan Normal University, Kunming 650500, Yunnan, China.

ABSTRACT
The widely used plasticizer phthalate esters (PAEs) have become a public concern because of their effects on environmental contamination and toxicity on mammals. However, the biodegradation of PAEs, especially diisobutyl phthalate (DiBP), remains poorly understood. In particular, genes involved in the hydrolysis of these compounds were not conclusively identified. In this study, the CarEW gene, which encodes an enzyme that is capable of hydrolyzing ρ-nitrophenyl esters of fatty acids, was cloned from a thermophilic bacterium Bacillus sp. K91 and heterologously expressed in Escherichia coli BL21 using the pEASY-E2 expression system. The enzyme showed a monomeric structure with a molecular mass of approximately 53.76 kDa and pI of 4.88. The enzyme exhibited maximal activity at pH 7.5 and 45 °C, with ρ-NP butyrate as the best substrate. The enzyme was fairly stable within the pH range from 7.0 to 8.5. High-pressure liquid chromatography (HPLC) and electrospray ionization mass spectrometry (ESI-MS) were employed to detect the catabolic pathway of DiBP. Two intermediate products were identified, and a potential biodegradation pathway was proposed. Altogether, our findings present a novel DiBP degradation enzyme and indicate that the purified enzyme may be a promising candidate for DiBP detoxification and for environmental protection.

No MeSH data available.


Related in: MedlinePlus

Effect of temperature and pH on CarEW activity and stability.Relative activity of purified CarEW was determined at different temperatures (A) or pH (C) using ρ-NP butyrate (ρ-NPC4) as the substrate at 405 nm. Remaining enzyme activity was measured at 45°C and pH 7.5 after incubating purified CarEW at different temperatures (B) or pH for 60 min. Error bars represent the mean±standard deviation (n = 3).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4352063&req=5

pone.0119216.g004: Effect of temperature and pH on CarEW activity and stability.Relative activity of purified CarEW was determined at different temperatures (A) or pH (C) using ρ-NP butyrate (ρ-NPC4) as the substrate at 405 nm. Remaining enzyme activity was measured at 45°C and pH 7.5 after incubating purified CarEW at different temperatures (B) or pH for 60 min. Error bars represent the mean±standard deviation (n = 3).

Mentions: The effect of pH on CarEW activity was determined using ρ-NPC4 as the substrate at 45°C with pH values ranging from 5.0 to 10.0. Maximal activity was observed at pH 7.5. The enzyme activity was below 10% of the maximum activity when the pH was lower than 5.0 or higher than 10.0 (Fig. 4A). The pH stability analysis revealed that the enzyme was very stable at pH 6.5 to 9.5, retaining more than 60% of the original activity after pre-incubation at the given pH range for 1 h. However, CarEW only maintained 23% and 19% of its activity at pH 5.0 and 10.0, respectively, after incubation for 1 h (Fig. 4B).


Properties of a newly identified esterase from Bacillus sp. K91 and its novel function in diisobutyl phthalate degradation.

Ding J, Wang C, Xie Z, Li J, Yang Y, Mu Y, Tang X, Xu B, Zhou J, Huang Z - PLoS ONE (2015)

Effect of temperature and pH on CarEW activity and stability.Relative activity of purified CarEW was determined at different temperatures (A) or pH (C) using ρ-NP butyrate (ρ-NPC4) as the substrate at 405 nm. Remaining enzyme activity was measured at 45°C and pH 7.5 after incubating purified CarEW at different temperatures (B) or pH for 60 min. Error bars represent the mean±standard deviation (n = 3).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4352063&req=5

pone.0119216.g004: Effect of temperature and pH on CarEW activity and stability.Relative activity of purified CarEW was determined at different temperatures (A) or pH (C) using ρ-NP butyrate (ρ-NPC4) as the substrate at 405 nm. Remaining enzyme activity was measured at 45°C and pH 7.5 after incubating purified CarEW at different temperatures (B) or pH for 60 min. Error bars represent the mean±standard deviation (n = 3).
Mentions: The effect of pH on CarEW activity was determined using ρ-NPC4 as the substrate at 45°C with pH values ranging from 5.0 to 10.0. Maximal activity was observed at pH 7.5. The enzyme activity was below 10% of the maximum activity when the pH was lower than 5.0 or higher than 10.0 (Fig. 4A). The pH stability analysis revealed that the enzyme was very stable at pH 6.5 to 9.5, retaining more than 60% of the original activity after pre-incubation at the given pH range for 1 h. However, CarEW only maintained 23% and 19% of its activity at pH 5.0 and 10.0, respectively, after incubation for 1 h (Fig. 4B).

Bottom Line: In particular, genes involved in the hydrolysis of these compounds were not conclusively identified.Two intermediate products were identified, and a potential biodegradation pathway was proposed.Altogether, our findings present a novel DiBP degradation enzyme and indicate that the purified enzyme may be a promising candidate for DiBP detoxification and for environmental protection.

View Article: PubMed Central - PubMed

Affiliation: Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, Yunnan Normal University, Kunming 650500, Yunnan, China; Key Laboratory of Enzyme Engineering, Yunnan Normal University, Kunming 650500, Yunnan, China.

ABSTRACT
The widely used plasticizer phthalate esters (PAEs) have become a public concern because of their effects on environmental contamination and toxicity on mammals. However, the biodegradation of PAEs, especially diisobutyl phthalate (DiBP), remains poorly understood. In particular, genes involved in the hydrolysis of these compounds were not conclusively identified. In this study, the CarEW gene, which encodes an enzyme that is capable of hydrolyzing ρ-nitrophenyl esters of fatty acids, was cloned from a thermophilic bacterium Bacillus sp. K91 and heterologously expressed in Escherichia coli BL21 using the pEASY-E2 expression system. The enzyme showed a monomeric structure with a molecular mass of approximately 53.76 kDa and pI of 4.88. The enzyme exhibited maximal activity at pH 7.5 and 45 °C, with ρ-NP butyrate as the best substrate. The enzyme was fairly stable within the pH range from 7.0 to 8.5. High-pressure liquid chromatography (HPLC) and electrospray ionization mass spectrometry (ESI-MS) were employed to detect the catabolic pathway of DiBP. Two intermediate products were identified, and a potential biodegradation pathway was proposed. Altogether, our findings present a novel DiBP degradation enzyme and indicate that the purified enzyme may be a promising candidate for DiBP detoxification and for environmental protection.

No MeSH data available.


Related in: MedlinePlus