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Toxicity and biodegradation of ibuprofen by Bacillus thuringiensis B1(2015b)

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ABSTRACT

In recent years, the increased intake of ibuprofen has resulted in the presence of the drug in the environment. This work presents results of a study on degradation of ibuprofen at 25 mg L−1 in the presence of glucose, as an additional carbon source by Bacillus thuringiensis B1(2015b). In the cometabolic system, the maximum specific growth rate of the bacterial strain was 0.07 ± 0.01 mg mL−1 h−1 and Ksμ 0.27 ± 0.15 mg L−1. The maximum specific ibuprofen removal rate and the value of the half-saturation constant were qmax = 0.24 ± 0.02 mg mL−1 h−1 and Ks = 2.12 ± 0.56 mg L−1, respectively. It has been suggested that monooxygenase and catechol 1,2-dioxygenase are involved in ibuprofen degradation by B. thuringiensis B1(2015b). Toxicity studies showed that B. thuringiensis B1(2015b) is more resistant to ibuprofen than other tested organisms. The EC50 of ibuprofen on the B1 strain is 809.3 mg L−1, and it is 1.5 times higher than the value of the microbial toxic concentration (MTCavg). The obtained results indicate that B. thuringiensis B1(2015b) could be a useful tool in biodegradation/bioremediation processes.

No MeSH data available.


Biodegradation of ibuprofen by Bacillus thuringiensis B1(2015b) in monosubstrate (a) and cometabolic systems with glucose (b), phenol (c) and benzoate (d) as growth substrates
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Fig1: Biodegradation of ibuprofen by Bacillus thuringiensis B1(2015b) in monosubstrate (a) and cometabolic systems with glucose (b), phenol (c) and benzoate (d) as growth substrates

Mentions: Bacillus species belong to Gram-positive bacteria, which are known for their tolerance to various toxic compounds. This results mainly from the structure of their cellular membranes as well as from their ability to synthesise surface-active agents and specific enzymes (Satchanska et al. 2006; Solyanikova et al. 2014; Swaathy et al. 2014; Trivedi et al. 2011). For this study, B. thuringiensis B1(2015b) isolated from the soil at the Chemical Factory “Organika-Azot” in Jaworzno and able to degrade ibuprofen and naproxen was used (Marchlewicz et al. 2016). The adaptation of B. thuringiensis B1(2015b) strain to increasing concentrations of ibuprofen showed its ability to degrade up to 5 mg L−1 of this drug. However, in the presence of ibuprofen as a sole carbon and energy source, growth of the culture was not observed, and consequently, the B1(2015b) strain lost its degradation activity (Fig. 1a). It is generally known that the introduction of an additional carbon source to the culture may enhance the metabolism of xenobiotics. For example, Quintana et al. (2005) showed that the degradation of 5 mg L−1 ibuprofen by activated sludge lasted for over 28 days, while in the presence of powder milk as an additional carbon source, complete degradation of the introduced dose of ibuprofen was observed after 22 days. In the studies on the cometabolic degradation of ibuprofen, glucose was chosen as an easily assimilated growth substrate. Simultaneously, as growth substrates, phenol, benzoate and 4-hydroxybenzoate were used. These aromatic compounds are substrates of similar structure to ibuprofen and are known to induce synthesis of the enzymes engaged in aromatic ring fission (Wojcieszyńska et al. 2014). The highest rate of ibuprofen degradation was observed in the presence glucose as the growth substrate. Under these conditions, B1(2015b) was able to degrade completely up to 25 mg L−1 of ibuprofen (Fig. 1b). In turn, the addition of aromatic compounds as growth substrates resulted in the decreased ability of strain B1(2015b) to degrade ibuprofen. In the presence of these compounds, B1(2015b) degraded only up to 5 mg L−1 of ibuprofen (Fig. 1c, d). This may result from the competition between aromatic growth substrates and ibuprofen for the active site of enzymes involved in aromatic ring degradation (Wang et al. 2015). Particularly, in the presence of benzoate or 4-hydroxybenzoate as a carbon source, degradation of ibuprofen was ineffective. In the presence of benzoate, complete degradation of 5 mg L−1 of ibuprofen was observed after 14 days of incubation (Fig. 1d). In the presence of 4-hydroxybenzoate after 4 days of incubation, darkening of the culture was observed. At the same time, a 40.8% loss of ibuprofen and a 100% loss of 4-hydroxybenzoate were determined (data not shown). This may suggest condensation of ibuprofen and 4-hydroxybenzoate, as carboxylic acids are known to initiate this kind of reaction (Stebbins et al. 2015; Wasiniak and Lukaszewicz 2010). Additionally, the presence of the hydroxy group in the para position of 4-hydroxybenzoate facilitates the condensation of these compounds.Fig. 1


Toxicity and biodegradation of ibuprofen by Bacillus thuringiensis B1(2015b)
Biodegradation of ibuprofen by Bacillus thuringiensis B1(2015b) in monosubstrate (a) and cometabolic systems with glucose (b), phenol (c) and benzoate (d) as growth substrates
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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Fig1: Biodegradation of ibuprofen by Bacillus thuringiensis B1(2015b) in monosubstrate (a) and cometabolic systems with glucose (b), phenol (c) and benzoate (d) as growth substrates
Mentions: Bacillus species belong to Gram-positive bacteria, which are known for their tolerance to various toxic compounds. This results mainly from the structure of their cellular membranes as well as from their ability to synthesise surface-active agents and specific enzymes (Satchanska et al. 2006; Solyanikova et al. 2014; Swaathy et al. 2014; Trivedi et al. 2011). For this study, B. thuringiensis B1(2015b) isolated from the soil at the Chemical Factory “Organika-Azot” in Jaworzno and able to degrade ibuprofen and naproxen was used (Marchlewicz et al. 2016). The adaptation of B. thuringiensis B1(2015b) strain to increasing concentrations of ibuprofen showed its ability to degrade up to 5 mg L−1 of this drug. However, in the presence of ibuprofen as a sole carbon and energy source, growth of the culture was not observed, and consequently, the B1(2015b) strain lost its degradation activity (Fig. 1a). It is generally known that the introduction of an additional carbon source to the culture may enhance the metabolism of xenobiotics. For example, Quintana et al. (2005) showed that the degradation of 5 mg L−1 ibuprofen by activated sludge lasted for over 28 days, while in the presence of powder milk as an additional carbon source, complete degradation of the introduced dose of ibuprofen was observed after 22 days. In the studies on the cometabolic degradation of ibuprofen, glucose was chosen as an easily assimilated growth substrate. Simultaneously, as growth substrates, phenol, benzoate and 4-hydroxybenzoate were used. These aromatic compounds are substrates of similar structure to ibuprofen and are known to induce synthesis of the enzymes engaged in aromatic ring fission (Wojcieszyńska et al. 2014). The highest rate of ibuprofen degradation was observed in the presence glucose as the growth substrate. Under these conditions, B1(2015b) was able to degrade completely up to 25 mg L−1 of ibuprofen (Fig. 1b). In turn, the addition of aromatic compounds as growth substrates resulted in the decreased ability of strain B1(2015b) to degrade ibuprofen. In the presence of these compounds, B1(2015b) degraded only up to 5 mg L−1 of ibuprofen (Fig. 1c, d). This may result from the competition between aromatic growth substrates and ibuprofen for the active site of enzymes involved in aromatic ring degradation (Wang et al. 2015). Particularly, in the presence of benzoate or 4-hydroxybenzoate as a carbon source, degradation of ibuprofen was ineffective. In the presence of benzoate, complete degradation of 5 mg L−1 of ibuprofen was observed after 14 days of incubation (Fig. 1d). In the presence of 4-hydroxybenzoate after 4 days of incubation, darkening of the culture was observed. At the same time, a 40.8% loss of ibuprofen and a 100% loss of 4-hydroxybenzoate were determined (data not shown). This may suggest condensation of ibuprofen and 4-hydroxybenzoate, as carboxylic acids are known to initiate this kind of reaction (Stebbins et al. 2015; Wasiniak and Lukaszewicz 2010). Additionally, the presence of the hydroxy group in the para position of 4-hydroxybenzoate facilitates the condensation of these compounds.Fig. 1

View Article: PubMed Central - PubMed

ABSTRACT

In recent years, the increased intake of ibuprofen has resulted in the presence of the drug in the environment. This work presents results of a study on degradation of ibuprofen at 25 mg L−1 in the presence of glucose, as an additional carbon source by Bacillus thuringiensis B1(2015b). In the cometabolic system, the maximum specific growth rate of the bacterial strain was 0.07 ± 0.01 mg mL−1 h−1 and Ksμ 0.27 ± 0.15 mg L−1. The maximum specific ibuprofen removal rate and the value of the half-saturation constant were qmax = 0.24 ± 0.02 mg mL−1 h−1 and Ks = 2.12 ± 0.56 mg L−1, respectively. It has been suggested that monooxygenase and catechol 1,2-dioxygenase are involved in ibuprofen degradation by B. thuringiensis B1(2015b). Toxicity studies showed that B. thuringiensis B1(2015b) is more resistant to ibuprofen than other tested organisms. The EC50 of ibuprofen on the B1 strain is 809.3 mg L−1, and it is 1.5 times higher than the value of the microbial toxic concentration (MTCavg). The obtained results indicate that B. thuringiensis B1(2015b) could be a useful tool in biodegradation/bioremediation processes.

No MeSH data available.