Agriculture Reference
In-Depth Information
phospholipases (Kannahi and Umaragini
2013
). Many PS fungi, for example,
Aspergillus fumigatus
(Yadav and Tarafdar
2003
) and
Trichoderma harzianum
(Aseri et al.
2009
), have also been reported to produce acid and alkaline phospha-
tase enzymes, respectively (Yadav and Tarafdar
2003
). In addition, PS fungi, for
example,
A. terreus
and
P. simplicissimum
, produced phytase, an enzyme which
releases soluble inorganic P from organic P compound (inositol hexaphosphate)
(Yadav and Tarafdar
2007
).
Inositol hexaphosphate
þ
water
!
Inositol
þ
phosphate
ð
catalyzed by phytase
Þ
4.5 Groups of Mineral Solubilizers
4.5.1 Fungi
Fungi are important component of soil microbiota constituting more of the soil
biomass than bacteria, depending on soil depth and nutrient conditions. Wide
ranges of soil fungi are reported to solubilize insoluble P.
Aspergillus
and
Penicil-
lium
among fungi are the most common P-solubilizing fungi (Seshadri et al.
2004
;
Wakelin et al.
2004
). Other fungal species like
Talaromyces
and
Eupenicillium
are
considered “key organisms” in the P cycle (Whitelaw
2000
). Most of the fungi, for
example,
A. terreus
,
A. flavus
,
A. awamori
,
A. niger
,
A. tubingensis
,
A. aculeatus
,
Penicillium digitatum
,
P. simplicissimum
,
Eupenicillium parvum
,
Sclerotium rolfsii
and species of
Fusarium
,
Rhizoctonia
, etc., have been found to solubilize inorganic
Ca-P, for example, tricalcium phosphates (Das et al.
2012
; Vyas et al.
2007
; Reddy
et al.
2002
), but had poor Al-P- or Fe-P-solubilizing ability (Illmer and
Schinner 1995).
4.5.2 Occurrence of Phosphate-Solubilizing Fungi
Phosphate-solubilizing fungi have been isolated from different habitats such as
agricultural soil, arctic region, husk waste, coffee plantation, forest soil, hill soil,
mangrove area, mine soil, rhizosphere of different crop plants, saline soil, terrestrial
soil, vermicompost, volcanic soils, etc., and are listed in Table
4.1
.
