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Functionalization of whole-cell bacterial reporters with magnetic nanoparticle.

Zhang D, Fakhrullin RF, Özmen M, Wang H, Wang J, Paunov VN, Li G, Huang WE - Microb Biotechnol (2011)

Bottom Line: The MFBs were all viable and functional as good as the native cells in terms of sensitivity, specificity and quantitative response.More importantly, we demonstrated that salicylate sensing MFBs can be applied to sediments and garden soils, and semiquantitatively detect salicylate in those samples by discriminably recovering MFBs with a permanent magnet.The magnetically functionalized cells are especially useful to complex environments in which the indigenous cells, particles and impurities may interfere with direct measurement of bioreporter cells and conventional filtration is not applicable to distinguish and harvest bioreporters.

View Article: PubMed Central - PubMed

Affiliation: Kroto Research Institute, University of Sheffield, Broad Lane, Sheffield S3 7HQ, UK.

ABSTRACT
We developed a biocompatible and highly efficient approach for functionalization of bacterial cell wall with magnetic nanoparticles (MNPs). Three Acinetobacter baylyi ADP1 chromosomally based bioreporters, which were genetically engineered to express bioluminescence in response to salicylate, toluene/ xylene and alkanes, were functionalized with 18 3 nm iron oxide MNPs to acquire magnetic function. The efficiency of MNPs functionalization of Acinetobacter bioreporters was 99.96 0.01%. The MNPs-functionalized bioreporters (MFBs) can be remotely controlled and collected by an external magnetic field. The MFBs were all viable and functional as good as the native cells in terms of sensitivity, specificity and quantitative response. More importantly, we demonstrated that salicylate sensing MFBs can be applied to sediments and garden soils, and semiquantitatively detect salicylate in those samples by discriminably recovering MFBs with a permanent magnet. The magnetically functionalized cells are especially useful to complex environments in which the indigenous cells, particles and impurities may interfere with direct measurement of bioreporter cells and conventional filtration is not applicable to distinguish and harvest bioreporters. The approach described here provides a powerful tool to remotely control and selectively manipulate MNPs-unctionalized cells in water and soils. It would have a potential in the application of environmental microbiology, such as bioremediation enhancement and environment monitoring and assessment.

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Mentions: The concentration of MNPs in aqueous solution was determined to be 0.4 mg ml−1. The transmission electron microscopy (TEM) image (Fig. 1A) shows that the MNPs had almost spherical shape and the size distribution was around 18 ± 3 nm, which is consistent with the previous reports (Fakhrullin et al., 2010; García‐Alonso et al., 2010). Zeta‐potential of PAAH‐stabilized MNPs in water was positive (38 ± 6 mV) which makes these MNPs readily adhesive to bacterial cells which usually bear a negative surface charge. The magnetic behaviour of MFBs is demonstrated in Movie S1 (Supporting information) which shows spatial manipulation of MFBs (Acinetobacter ADPWH_lux) with a permanent magnet and the MFBs were ‘flipping’ following the magnetic field. Cells functionalized with MNPs had a strong magnetic property and can be readily collected. Figure 1B shows that almost all MFBs (Acinetobacter ADPWH_lux) were assembled to the magnetic side of a vial so that originally turbid cell suspension became transparent and clear within 10 min. It indicates that the MNPs functionalization endowed Acinetobacter cells a magnetotaxis‐like function. To examine the deposition and distribution of the PAAH‐stabilized MNPs on the cells, we used MNPs stabilized with FITC‐labelled PAAH to functionalize Acinetobacter ADPWH_lux which were visualized using epifluorescent microscopy. Figure 1C shows the uniform distribution of the fluorescently labelled MNPs on each cell, indicating the even functionalization of the MNPs on Acinetobacter cells. The TEM image of thin‐sectioned MNPs‐functionalized Acinetobacter strain ADPWH_lux indicates that the MNPs adhered to the cell surface (Fig. 1D). After examining the magnified TEM images we found that the MNPs exclusively attached to cell outer wall and no MNPs were found in cytoplasm (Fig. 1E). In addition, energy‐dispersive X‐ray (EDX) spectra of the MFBs (Fig. 1F) and scanning electron microscopy (SEM) images (Fig. S1) confirmed the presence of iron NPs on the cell wall.


Functionalization of whole-cell bacterial reporters with magnetic nanoparticle.

Zhang D, Fakhrullin RF, Özmen M, Wang H, Wang J, Paunov VN, Li G, Huang WE - Microb Biotechnol (2011)

© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3815799&req=5

Mentions: The concentration of MNPs in aqueous solution was determined to be 0.4 mg ml−1. The transmission electron microscopy (TEM) image (Fig. 1A) shows that the MNPs had almost spherical shape and the size distribution was around 18 ± 3 nm, which is consistent with the previous reports (Fakhrullin et al., 2010; García‐Alonso et al., 2010). Zeta‐potential of PAAH‐stabilized MNPs in water was positive (38 ± 6 mV) which makes these MNPs readily adhesive to bacterial cells which usually bear a negative surface charge. The magnetic behaviour of MFBs is demonstrated in Movie S1 (Supporting information) which shows spatial manipulation of MFBs (Acinetobacter ADPWH_lux) with a permanent magnet and the MFBs were ‘flipping’ following the magnetic field. Cells functionalized with MNPs had a strong magnetic property and can be readily collected. Figure 1B shows that almost all MFBs (Acinetobacter ADPWH_lux) were assembled to the magnetic side of a vial so that originally turbid cell suspension became transparent and clear within 10 min. It indicates that the MNPs functionalization endowed Acinetobacter cells a magnetotaxis‐like function. To examine the deposition and distribution of the PAAH‐stabilized MNPs on the cells, we used MNPs stabilized with FITC‐labelled PAAH to functionalize Acinetobacter ADPWH_lux which were visualized using epifluorescent microscopy. Figure 1C shows the uniform distribution of the fluorescently labelled MNPs on each cell, indicating the even functionalization of the MNPs on Acinetobacter cells. The TEM image of thin‐sectioned MNPs‐functionalized Acinetobacter strain ADPWH_lux indicates that the MNPs adhered to the cell surface (Fig. 1D). After examining the magnified TEM images we found that the MNPs exclusively attached to cell outer wall and no MNPs were found in cytoplasm (Fig. 1E). In addition, energy‐dispersive X‐ray (EDX) spectra of the MFBs (Fig. 1F) and scanning electron microscopy (SEM) images (Fig. S1) confirmed the presence of iron NPs on the cell wall.

Bottom Line: The MFBs were all viable and functional as good as the native cells in terms of sensitivity, specificity and quantitative response.More importantly, we demonstrated that salicylate sensing MFBs can be applied to sediments and garden soils, and semiquantitatively detect salicylate in those samples by discriminably recovering MFBs with a permanent magnet.The magnetically functionalized cells are especially useful to complex environments in which the indigenous cells, particles and impurities may interfere with direct measurement of bioreporter cells and conventional filtration is not applicable to distinguish and harvest bioreporters.

View Article: PubMed Central - PubMed

Affiliation: Kroto Research Institute, University of Sheffield, Broad Lane, Sheffield S3 7HQ, UK.

ABSTRACT
We developed a biocompatible and highly efficient approach for functionalization of bacterial cell wall with magnetic nanoparticles (MNPs). Three Acinetobacter baylyi ADP1 chromosomally based bioreporters, which were genetically engineered to express bioluminescence in response to salicylate, toluene/ xylene and alkanes, were functionalized with 18 3 nm iron oxide MNPs to acquire magnetic function. The efficiency of MNPs functionalization of Acinetobacter bioreporters was 99.96 0.01%. The MNPs-functionalized bioreporters (MFBs) can be remotely controlled and collected by an external magnetic field. The MFBs were all viable and functional as good as the native cells in terms of sensitivity, specificity and quantitative response. More importantly, we demonstrated that salicylate sensing MFBs can be applied to sediments and garden soils, and semiquantitatively detect salicylate in those samples by discriminably recovering MFBs with a permanent magnet. The magnetically functionalized cells are especially useful to complex environments in which the indigenous cells, particles and impurities may interfere with direct measurement of bioreporter cells and conventional filtration is not applicable to distinguish and harvest bioreporters. The approach described here provides a powerful tool to remotely control and selectively manipulate MNPs-unctionalized cells in water and soils. It would have a potential in the application of environmental microbiology, such as bioremediation enhancement and environment monitoring and assessment.

Show MeSH
Related in: MedlinePlus