46
2.5 Isolation of S-Triazine-Degrading Microorganisms
Several triazine-degrading bacteria were isolated from agricultural and other contaminated sites in various geographical regions. Minimal salt media containing
varying concentrations of s-triazine herbicides as the sole source of carbon and/or
nitrogen were used to enrich and isolate the efficient degraders. Enrichment can be
carried out by transferring the initial culture to fresh media containing herbicide
every week (up to 5–6 weeks). When the herbicide is first applied, a lag period is
observed before degradation proceeds. On subsequent exposures, immediate rapid
degradation of atrazine takes place. The addition of carbon source enhances the
microbial growth which in turn stimulate the biodegradation process. Nitrogen
amendment to the media inhibits the atrazine degradation in many bacterial strains
(Entry et al. 1993; Garces et al. 2007). Repeated exposure to atrazine increases the
degradation efficiency of the microorganism. After enrichment, potential atrazinedegrading isolates can be identified by clearance zone around the colony on minimal media agar plates containing triazine pesticide. Very limited reports are available
on anaerobic degradation of triazines compared to aerobic condition, perhaps due to
Table 2.3 Nanomaterials used for s-triazine pesticide degradation or removal
S-triazine
herbicide
Nanoparticle/nanocomposite
Process
References
Ametryn
Iron – functionalised with 1-butyl-3methylimidazolidium bromide
Adsorption
Ali et al. (2016)
Er
3+
:Y 3 Al 5 O 12 /Pt-(TiO 2 -Ta 2 O 5 )
Sonocatalysis
Li et al. (2017)
Atrazine
Penicillium sp. doped with nano
Fe 3 O 4 in polyvinyl alcohol-sodium
alginate gel beads
Biodegradation
Yu et al. (2018)
Alginate-stabilised silver
nanoparticle
Adsorption
Pal et al. (2015)
Zinc oxide
Ozonation
Yuan et al.
(2017)
Zero-valent copper
Hydroxyl radicalinduced degradation
Hong et al.
(2017)
Pd, PdO, and Ag-Pd on hierarchical
carbon structures
Degradation
Vijwani et al.
(2018)
Simazine
Au–TiO 2
Sonophotocatalysis
Sathishkumar
et al. (2014)
Diatomite-supported Zero-valent
iron
Degradation
Sun et al. (2013)
Al 2 O 3 and Fe 2 O 3
Sorption
Addorisio et al.
(2011)
Propazine
Titanium dioxide
Photocatalysis
Konstantinou
et al. (2001)
Cyanazine
Titanium dioxide
Photocatalysis
Konstantinou
et al. (2001)
Prometryne Titanium dioxide
Photocatalysis
Konstantinou
et al. (2001)
K. Rajendran et al.
2.5 Isolation of S-Triazine-Degrading Microorganisms
Several triazine-degrading bacteria were isolated from agricultural and other contaminated sites in various geographical regions. Minimal salt media containing
varying concentrations of s-triazine herbicides as the sole source of carbon and/or
nitrogen were used to enrich and isolate the efficient degraders. Enrichment can be
carried out by transferring the initial culture to fresh media containing herbicide
every week (up to 5–6 weeks). When the herbicide is first applied, a lag period is
observed before degradation proceeds. On subsequent exposures, immediate rapid
degradation of atrazine takes place. The addition of carbon source enhances the
microbial growth which in turn stimulate the biodegradation process. Nitrogen
amendment to the media inhibits the atrazine degradation in many bacterial strains
(Entry et al. 1993; Garces et al. 2007). Repeated exposure to atrazine increases the
degradation efficiency of the microorganism. After enrichment, potential atrazinedegrading isolates can be identified by clearance zone around the colony on minimal media agar plates containing triazine pesticide. Very limited reports are available
on anaerobic degradation of triazines compared to aerobic condition, perhaps due to
Table 2.3 Nanomaterials used for s-triazine pesticide degradation or removal
S-triazine
herbicide
Nanoparticle/nanocomposite
Process
References
Ametryn
Iron – functionalised with 1-butyl-3methylimidazolidium bromide
Adsorption
Ali et al. (2016)
Er
3+
:Y 3 Al 5 O 12 /Pt-(TiO 2 -Ta 2 O 5 )
Sonocatalysis
Li et al. (2017)
Atrazine
Penicillium sp. doped with nano
Fe 3 O 4 in polyvinyl alcohol-sodium
alginate gel beads
Biodegradation
Yu et al. (2018)
Alginate-stabilised silver
nanoparticle
Adsorption
Pal et al. (2015)
Zinc oxide
Ozonation
Yuan et al.
(2017)
Zero-valent copper
Hydroxyl radicalinduced degradation
Hong et al.
(2017)
Pd, PdO, and Ag-Pd on hierarchical
carbon structures
Degradation
Vijwani et al.
(2018)
Simazine
Au–TiO 2
Sonophotocatalysis
Sathishkumar
et al. (2014)
Diatomite-supported Zero-valent
iron
Degradation
Sun et al. (2013)
Al 2 O 3 and Fe 2 O 3
Sorption
Addorisio et al.
(2011)
Propazine
Titanium dioxide
Photocatalysis
Konstantinou
et al. (2001)
Cyanazine
Titanium dioxide
Photocatalysis
Konstantinou
et al. (2001)
Prometryne Titanium dioxide
Photocatalysis
Konstantinou
et al. (2001)
K. Rajendran et al.