Table 22.4 (continued)
PGPR and Rhizobia
Heavy
metal
resistance
Proposed mechanism
References
Pseudomonas
aeruginosa OSG41
Cr(VI)
Bio-reduction of hexavalent chromium Oves et al.
(2013)
Rhizobium
leguminosarum RL 9
Ni(II)
Metal adsorption/desorption
Wani and Khan
(2013)
Pseudomonas
aeruginosa WI-1
Pb(II)
Metallothionein (encoded by bmtA
gene) mediated metal sequestration and
intracellular bioaccumulation
Naik et al.
(2011)
Sinorhizobium spp.
Zn(II), Cd
(II), Pb(II),
Cu(II)
Adsorption of heavy metal ions on cell
surface, intracellular accumulation of
heavy metal ions
Zribi et al.
(2011)
Ochrobactrum cytisi
Azn6.2
Cd(II), As
(II), Zn(II),
Cu(II)
Biosorption/
Desorption by lipopolysaccharides of
cell wall
RodríguezLlorente et al.
(2010)
Bacillus spp.,
Achromobacter spp.,
Brevundimonas spp.,
Microbacterium
spp.,
Ochrobactrum spp.
Ensifer spp.
Bosea spp.
Sinorhizobium spp.
Bordetella sp.
Ancylobacter
dichloromethanicum
As3-1b
Georgenia
ferrireducensAs5-12
Rhodococcus
erythropolisAs5-4a
As (III)
and As (V)
Reduction of As(V) into As(III) by
arsenate reductase encoded by ArsC
gene, efflux of As(III) by ArsB and
ArsA genes which code for As(III)
efflux pump and used proton motive
force and AS(III) activated ATPase
Another gene ACR3 homologous to
ArsB also codes for As(III) efflux protein in highly resistance strains
Either one or both types of genes in
combination confer resistance among
these bacteria
Cavalca et al.
(2010)
Mesorhizobium
sp. RC1,
Mesorhizobium
sp. RC4
Cr(VI)
Reduction of Cr(VI)
Wani et al.
(2009)
Cellulosimicrobium
cellulans KUCr3
Cr(VI)
Reduction of Cr(VI)
Chatterjee et al.
(2009)
Azotobacter
chroococcum
HKN-5
Bacillus megaterium
HKP-1
Pb(II), Cd
(II)
Adsorption of Pb
2+ and Cd
2+ on cell
wall
Wu et al. (2009)
Enterobacter
asburiae PSI3
Cd(II)
Complexation of metal by extracellularly secreted organic acids
Kavita et al.
(2008)
Rhizobium sp. RP5
Zn(II), Ni
(II)
Metal adsorption/desorption
Wani et al.
(2008a)
Rhizobium
leguminosarum RL 9
Zn(II)
Metal adsorption/desorption
Wani et al.
(2008b)
(continued)
480
K. Pramanik et al.
PGPR and Rhizobia
Heavy
metal
resistance
Proposed mechanism
References
Pseudomonas
aeruginosa OSG41
Cr(VI)
Bio-reduction of hexavalent chromium Oves et al.
(2013)
Rhizobium
leguminosarum RL 9
Ni(II)
Metal adsorption/desorption
Wani and Khan
(2013)
Pseudomonas
aeruginosa WI-1
Pb(II)
Metallothionein (encoded by bmtA
gene) mediated metal sequestration and
intracellular bioaccumulation
Naik et al.
(2011)
Sinorhizobium spp.
Zn(II), Cd
(II), Pb(II),
Cu(II)
Adsorption of heavy metal ions on cell
surface, intracellular accumulation of
heavy metal ions
Zribi et al.
(2011)
Ochrobactrum cytisi
Azn6.2
Cd(II), As
(II), Zn(II),
Cu(II)
Biosorption/
Desorption by lipopolysaccharides of
cell wall
RodríguezLlorente et al.
(2010)
Bacillus spp.,
Achromobacter spp.,
Brevundimonas spp.,
Microbacterium
spp.,
Ochrobactrum spp.
Ensifer spp.
Bosea spp.
Sinorhizobium spp.
Bordetella sp.
Ancylobacter
dichloromethanicum
As3-1b
Georgenia
ferrireducensAs5-12
Rhodococcus
erythropolisAs5-4a
As (III)
and As (V)
Reduction of As(V) into As(III) by
arsenate reductase encoded by ArsC
gene, efflux of As(III) by ArsB and
ArsA genes which code for As(III)
efflux pump and used proton motive
force and AS(III) activated ATPase
Another gene ACR3 homologous to
ArsB also codes for As(III) efflux protein in highly resistance strains
Either one or both types of genes in
combination confer resistance among
these bacteria
Cavalca et al.
(2010)
Mesorhizobium
sp. RC1,
Mesorhizobium
sp. RC4
Cr(VI)
Reduction of Cr(VI)
Wani et al.
(2009)
Cellulosimicrobium
cellulans KUCr3
Cr(VI)
Reduction of Cr(VI)
Chatterjee et al.
(2009)
Azotobacter
chroococcum
HKN-5
Bacillus megaterium
HKP-1
Pb(II), Cd
(II)
Adsorption of Pb
2+ and Cd
2+ on cell
wall
Wu et al. (2009)
Enterobacter
asburiae PSI3
Cd(II)
Complexation of metal by extracellularly secreted organic acids
Kavita et al.
(2008)
Rhizobium sp. RP5
Zn(II), Ni
(II)
Metal adsorption/desorption
Wani et al.
(2008a)
Rhizobium
leguminosarum RL 9
Zn(II)
Metal adsorption/desorption
Wani et al.
(2008b)
(continued)
480
K. Pramanik et al.