Agriculture Reference
In-Depth Information
Fig. 5.1
Initial steps toward identification of candidate CT-PSB. (
a
) Primary isolation of bacteria
at cold temperatures; (
b
) initial screening of PSB in the chemically defined medium supplemented
with insoluble forms of P
i
;(
c
) confirmation of P-solubilizing activity at low temperature by
selected isolates
The most notable bacterial species isolated so far from natural soils of alpine and
sub-alpine regions and tested both for their tolerance to low temperatures and their
ability to efficiently dissolve inorganic phosphates (
CT-PSB) include
Pseudomo-
nas fluorescens
(Egamberdiyeva and H¨flich
2003
),
P. putida
(Pandey
et al.
2006b
),
P. lurida
(Selvakumar et al.
2011
),
P. corrugata
(Pandey and Palni
1998
),
P. fragi
(Selvakumar et al.
2009a
),
Pantoea agglomerans
(Egamberdiyeva
and H¨flich
2003
),
P. dispersa
(Selvakumar et al.
2008
),
Burkholderia
vietnamiensis
(Park et al.
2010
),
Rahnella
sp. (Vyas et al.
2010
),
Serratia
marcescens
(Selvakumar et al.
2007
),
Tetrathiobacter
sp. (Kumar et al.
2013
),
Mycoplana bullata
(Egamberdiyeva and H
¨
flich
2003
),
Achromobacter
sp. (Kumar et al.
2013
),
Acinetobacter rhizosphaerae
(Gulati et al.
2009
),
Bacillus
subtilis
(Rinu and Pandey
2009
; Malviya et al.
2012
),
B. megaterium
(Trivedi and
Pandey
2008a
),
Mycobacterium phlei
(Egamberdiyeva and H
¨
flich
2003
), and
Exiguobacterium acetylicum
(Selvakumar et al.
2009b
).
In general, the CT-PSB is a heterogeneous group, which includes species
belonging to distant related genera of both Gram-negative and Gram-positive
bacteria. Of these, Pseudomonads are by far the most relevant CT-PSB identified
and tested so far, followed by
Bacillus
species. In addition to their P
i
-solubilizing
abilities, CT strains of
Pseudomonas
and
Bacillus
also exhibit other “desirable
traits” such as N fixation and antagonism against phytopathogens (Pandey
et al.
2006b
; Mishra et al.
2008
). In accordance with this, growth promotion
abilities of CT
Pseudomonas
isolates have been demonstrated using a variety of
crops such as mung bean (Katiyar and Goel
2003
), wheat (Egamberdiyeva and
H¨flich
2003
; Trivedi and Pandey
2007
; Mishra et al.
2008
,
2009a
; Trivedi and Sa
2008
; Selvakumar et al.
2009a
,
2011
), maize (Pandey et al.
2006b
; Kumar
et al.
2007
), rice (Trivedi et al.
2007
), and lentil (Mishra et al.
2011
). Similar results
were obtained when using CT
Bacillus
strains to promote growth of lentil (Rinu and
Pandey
2009
; Mishra et al.
2009b
), rice, millet (Malviya et al.
2012
), and Indian
mustard (Kumar et al.
2013
). In addition to their P-solubilizing activities, some
CT-PSB strains have also shown some other interesting properties (Fig.
5.2
). For
¼
