150
O. M. Darwesh et al.
arsenic and cadmium were remediated from contaminated wastewater via producing
its nano-sized structures (i.e., quantum dots (QDs) by Antarctic Pseudomonas strains.
The importance of the produced Cd and As nanoparticles is due to its potential
semiconductor and spectroscopic properties (Glatstein et al. 2018).
In a different mechanism, it was reported that NP synthesizing microorganisms
itself can absorb and accumulate heavy metals including As, Co, Cu, Fe, Ni and Mg
from aquatic environment especially through these group of NP forming microbes
known as magnetotactic bacteria (Ambashta and Sillanpää 2010; Kabary et al. 2017).
The characteristic features of magnetosomes and magnetotactic bacteria such as large
surface areas and magnetic properties expedite their adsorption of pollutants and
removal from wastewater (Ali et al. 2018; Ranjan et al. 2019). While these microbes
can be simply affected by external magnetic field, it can be utilized for removing such
heavy metals from wastewater (Yan et al. 2017; Zhu et al. 2012). Magnetosome was
found to be efficient to remove up to 38 gkg
−1 fluoride water and was able to adsorb
Cu
2+ from wastewater through preparing a magnetic polymer with polyvinyl acetate.
The excellence of magnetosome as noble metal adsorbent is owing to high purity
of extracted metals compared with utilization of the artificial magnetic particles of
magnetosome (Das 2010; Yan et al. 2017). Thus, microbial magnetosome displays a
vital role in wastewater treatment, heavy metal removal and resource recycling (Liu
and Zhou 2008; Wang et al. 2020; Yan et al. 2017).
In addition to heavy metals, dye effluents discharged into the ecosystem are
another dangerous source of environmental contamination that affects sustainability
of natural resources (Darwesh et al. 2014). Degradation of dye could be achieved
by harmless way utilizing NPs. Biogenic nanoparticles that synthesized through
microorganisms can be utilized as a strong tool in this process (Sadhasivam et al.
2020). The application of biogenic iron NP for bioremediation of azo dye from the
environment was confirmed by Sharma and Shirkot (2019). Furthermore, the CuNPs
formed by a native Escherichia sp. were defined as photocatalysts for bioremediation of azo dye from textile effluents. The biogenic CuNPs decolorized 97.07, 90.55,
88.42 and 83.61% of congo red, malachite green, direct blue-1 and reactive black-5,
respectively, after 5 h of application under sunlight. These results were obtained at
a lower dyes concentration (25 mg L
−1 ), although the removal efficacy decreased
by increasing dyes concentration to 100 mg L
−1 (Noman et al. 2020). Similarly, the
biogenic synthesized AuNPs using some non-pathogenic Enterococcus species have
been reported to degrade 24.3–57.6%, and 88.85–97.36% of methylene blue and
malachite green dyes, respectively, within 24 h (Oladipo et al. 2017b). Other reports
have shown efficient degradation of dyes using microbe-mediated NPs (Ojo et al.
2016; Elegbede et al. 2018, 2019).
4.2 Application of Microbial-Synthesized NPs in Bio-Sensing
Knowing and assessing the problem is an important step to solve it; so the detection and monitoring of pollutants in an environment is an important step towards
O. M. Darwesh et al.
arsenic and cadmium were remediated from contaminated wastewater via producing
its nano-sized structures (i.e., quantum dots (QDs) by Antarctic Pseudomonas strains.
The importance of the produced Cd and As nanoparticles is due to its potential
semiconductor and spectroscopic properties (Glatstein et al. 2018).
In a different mechanism, it was reported that NP synthesizing microorganisms
itself can absorb and accumulate heavy metals including As, Co, Cu, Fe, Ni and Mg
from aquatic environment especially through these group of NP forming microbes
known as magnetotactic bacteria (Ambashta and Sillanpää 2010; Kabary et al. 2017).
The characteristic features of magnetosomes and magnetotactic bacteria such as large
surface areas and magnetic properties expedite their adsorption of pollutants and
removal from wastewater (Ali et al. 2018; Ranjan et al. 2019). While these microbes
can be simply affected by external magnetic field, it can be utilized for removing such
heavy metals from wastewater (Yan et al. 2017; Zhu et al. 2012). Magnetosome was
found to be efficient to remove up to 38 gkg
−1 fluoride water and was able to adsorb
Cu
2+ from wastewater through preparing a magnetic polymer with polyvinyl acetate.
The excellence of magnetosome as noble metal adsorbent is owing to high purity
of extracted metals compared with utilization of the artificial magnetic particles of
magnetosome (Das 2010; Yan et al. 2017). Thus, microbial magnetosome displays a
vital role in wastewater treatment, heavy metal removal and resource recycling (Liu
and Zhou 2008; Wang et al. 2020; Yan et al. 2017).
In addition to heavy metals, dye effluents discharged into the ecosystem are
another dangerous source of environmental contamination that affects sustainability
of natural resources (Darwesh et al. 2014). Degradation of dye could be achieved
by harmless way utilizing NPs. Biogenic nanoparticles that synthesized through
microorganisms can be utilized as a strong tool in this process (Sadhasivam et al.
2020). The application of biogenic iron NP for bioremediation of azo dye from the
environment was confirmed by Sharma and Shirkot (2019). Furthermore, the CuNPs
formed by a native Escherichia sp. were defined as photocatalysts for bioremediation of azo dye from textile effluents. The biogenic CuNPs decolorized 97.07, 90.55,
88.42 and 83.61% of congo red, malachite green, direct blue-1 and reactive black-5,
respectively, after 5 h of application under sunlight. These results were obtained at
a lower dyes concentration (25 mg L
−1 ), although the removal efficacy decreased
by increasing dyes concentration to 100 mg L
−1 (Noman et al. 2020). Similarly, the
biogenic synthesized AuNPs using some non-pathogenic Enterococcus species have
been reported to degrade 24.3–57.6%, and 88.85–97.36% of methylene blue and
malachite green dyes, respectively, within 24 h (Oladipo et al. 2017b). Other reports
have shown efficient degradation of dyes using microbe-mediated NPs (Ojo et al.
2016; Elegbede et al. 2018, 2019).
4.2 Application of Microbial-Synthesized NPs in Bio-Sensing
Knowing and assessing the problem is an important step to solve it; so the detection and monitoring of pollutants in an environment is an important step towards