Oxidation of polycyclic aromatic hydrocarbons using Bacillus subtilis CotA with high laccase activity and copper independence

Zeng, Jun; Zhu, Qihong; Wu, Yucheng; Lin, Xiangui

doi:10.1016/j.chemosphere.2016.01.019

Cited by 86 publications

(37 citation statements)

References 49 publications

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“…Unlike the free laccase, the immobilized laccase achieved complete decolorization of MG as expected, without accumulation of tetradesmethyl MG at 60 °C. The significance of improved laccase stability certainly goes beyond laccase-catalyzed malachite green decolorization and is appreciated in many processes that may require higher temperatures, such as denim bleaching 31 , delignification 32 , pulp bleaching 33 , organic synthesis 34 , 35 , bioremediation 36 , etc. Nonetheless, the comparison of malachite green decolorization behavior of the free and immobilized laccases intuitively illustrated the significance of enhanced operational stability of the immobilized enzyme.…”

Section: Resultsmentioning

confidence: 99%

Immobilized Cerrena sp. laccase: preparation, thermal inactivation, and operational stability in malachite green decolorization

Yang

Wang

Lin

et al. 2017

Sci Rep

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Laccases are polyphenol oxidases with widespread applications in various industries. In the present study, the laccase from Cerrena sp. HYB07 was immobilized with four methods, namely entrapment in alginate, covalently binding to chitosan as well as formation of cross-linked enzyme aggregates (CLEAs) and magnetic CLEAs (M-CLEAs). The activity recovery rates of the immobilized laccases ranged from 29% to 68%. Immobilization elevated the reaction temperature optimum and reduced substrate specificity, but not necessarily the turnover rate. pH stability of immobilized laccases was improved compared with that of the free laccase, especially at acidic pH values. Thermal inactivation of all laccases followed a simple first-order exponential decay model, and immobilized laccases displayed higher thermostability, as manifested by lower thermal inactivation rate constants and longer enzyme half-life time. Operational stability of the immobilized laccase was demonstrated by decolorization of the triphenylmethane dye malachite green (MG) at 60 °C. MG decolorization with free laccase was accompanied by a shift of the absorption peak and accumulation of a stable, colored intermediate tetradesmethyl MG, probably due to lower thermostability of the free laccase and premature termination of the degradation pathway. In contrast, complete decolorization of MG was achieved with laccase CLEAs at 60 °C.

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Section: Resultsmentioning

confidence: 99%

Immobilized Cerrena sp. laccase: preparation, thermal inactivation, and operational stability in malachite green decolorization

Yang

Wang

Lin

et al. 2017

Sci Rep

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“…The ability of the CueO protein and its mutants to degrade benzo[α]pyrene, a mutagenic and highly carcinogenic environmental polycyclic aromatic hydrocarbon (PAH), was evaluated (Zhao et al 2013). The results indicate that the cloned cueO mutants could catalyze transformation of PAHs, similar to the function of fungal laccase from Trametes versicolor (Zeng et al 2011(Zeng et al , 2016Hullo et al 2001;Roberts et al 2002). Therefore, useful mutants can be identified from the metagenome, increasing our understanding of the genetic diversity of the functional gene.…”

Section: Open Accessmentioning

confidence: 89%

Identification of bacterial laccase cueO mutation from the metagenome of chemical plant sludge

Yue

Yang

Zhao

et al. 2017

Bioresour. Bioprocess.

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Background:The metagenome contains plenty of genetic resources and can be used to search for the novel gene or mutant. Results:In this study, the bacterial laccase gene (cueO) with single or multiple mutations was directly cloned based on the metagenome of a chemical plant sludge. An interesting mutation (G276R) was identified from those cloned mutants. The other mutants (G276N, G276Y, and G276K) with improved catalytic efficiency were identified by the saturation mutagenesis on residue G276. The optimal temperature for wild-type CueO enzyme activity was about 70 °C, compared to 60 °C, 50 °C, 50 °C, and 30 °C for the G276R, G276N, G276Y, and G276K mutant enzymes, respectively. The catalytic efficiency (k cat /K m ) with 8 mmol Cu 2+ of the G276R, G276N, G276Y, and G276K mutants was 1.2-, 2.7-, 1.3-, and 2.7-fold, respectively, compared to the wild-type enzyme. In addition, the mutants G276R, G276N, G276Y, and G276K oxidized the carcinogen benzo[α]pyrene more efficiently compared to the wild-type enzyme. Conclusion:All of the results indicate that G276 of CueO plays an important role in enzyme activity, and the useful mutants can be identified based on the metagenome.

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“…Bacillus could produce highly dormant endospores in response to the environmental stress 39 . Besides, its ability of resisting heavy metal and degrading organic pollutants has been reported 40,41 .…”

Section: Discussionmentioning

confidence: 99%

The influence of e-waste recycling on the molecular ecological network of soil microbial communities in Pakistan and China

Jiang

Cheng

Zhang

et al. 2017

Environmental Pollution

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Primitive electronic waste (e-waste) recycling releases large amounts of organic pollutants and heavy metals into the environment. As crucial moderators of geochemical cycling processes and pollutant remediation, soil microbes may be affected by these contaminants. We collected soil samples heavily contaminated by e-waste recycling in China and Pakistan, and analyzed the indigenous microbial communities. The results of this work revealed that the microbial community composition and diversity, at both whole and core community levels, were affected significantly by polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs) and heavy metals (e.g., Cu, Zn, and Pb). The geographical distance showed limited impacts on microbial communities compared with geochemical factors. The constructed ecological network of soil microbial communities illustrated microbial co-occurrence, competition and antagonism across soils, revealing the response of microbes to soil properties and pollutants. Two of the three main modules constructed with core operational taxonomic units (OTUs) were sensitive to nutrition (total organic carbon and total nitrogen) and pollutants. Five key OTUs assigned to Acidobacteria, Proteobacteria, and Nitrospirae in ecological network were identified. This is the first study to report the effects of e-waste pollutants on soil microbial network, providing a deeper understanding of the ecological influence of crude e-waste recycling activities on soil ecological functions.

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Oxidation of polycyclic aromatic hydrocarbons using Bacillus subtilis CotA with high laccase activity and copper independence

Cited by 86 publications

References 49 publications

Immobilized Cerrena sp. laccase: preparation, thermal inactivation, and operational stability in malachite green decolorization

Immobilized Cerrena sp. laccase: preparation, thermal inactivation, and operational stability in malachite green decolorization

Identification of bacterial laccase cueO mutation from the metagenome of chemical plant sludge

The influence of e-waste recycling on the molecular ecological network of soil microbial communities in Pakistan and China

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