Agriculture Reference
In-Depth Information
Increased crop yields in both, field and greenhouse conditions.
Increased weight and quality of fruits.
Compatibility with organic production of agricultural crops.
Reduction of environmental pollution through reduced use of pesticides and chemical
fertilizers (Kennedy, 2001).
Bioremediation of soils contaminated with petroleum derivatives and heavy metals.
It is known that high concentrations of metals in the soil and plants affect crop
growth and the symbiotic relationships, and consequently, crop yields by disruption
of fundamental physiological processes, such as photosynthesis, respiration, protein
synthesis and carbohydrate metabolism (Khan et al.
,
2009). Different experiments
have demonstrated the great potential of plant growth promoting rhizobacteria
(PGPR) and mycorrhiza for detoxification of organic pollutants (Lucy et al.
,
2004,
Abdul, 2006). Sarabia-Ochoa et al.
(2010) refer different examples of bioremediation
by PGPR including lead and zinc (
Azotobacter chroococcum
HKN-5-1,
Bacillus
megaterium
HKP1,
Bacillus mucilaginosus
HKK-1), nickel (
Bacillus subtilis
SJ-
101), cadmium (
Brevundimonas
sp. KR013,
Pseudomonas fluorescens
CR3,
Pseudomonas
sp. KR017,
Rhizobium leguminosarum
bv. trifolii NZP561,
Mesorhizobium huakuii
subsp. rengei B3), nickel, lead and zinc (
Kluyvera ascorbata
SUD165,
Kluyvera ascorbata
SUD165/26). In particular, the ability of
Burkholderia
xenovorans
(formerly
Pseudomonas cepacia, Burkholderia cepacia
or
Burkholderia
fungorum
) to degrade, chloroorganic pesticides and polychlorinated biphenyls
(PCBs) is well documented. Kuiper et al. (2001) developed the concept of
rhizoremediation, in which contaminant-degrading rhizobacteria, living on or close
to the root, are selected for their ability to assimilate the root exudates rather than the
chemical pollutants.
Certain microorganisms possess a wide range of added values. For example, some strains
of
Pseudomonas
spp. have biocontrol activities against phytonematodes (Ali et al.
,
2002;
Haas & Kell, 2003) and mollusks that represent a problem in water reservoirs (Molloy &
Mayer, 2007). Some strains of
Pseudomonas cepacia
and
Pseudomonas solanacearum
are
capable of hydrolyzing fusaric acid, which is the causative agent of wilt by
Fusarium
sp.
(Sarabia-Ochoa et al., 2010).
Tsukamurella paurometabola
C-924 is a tricalcium phosphate-solubilizing bacterium
with nematicidal activity and capacity for producing indole acetic acid, proteases and
chitinases. This bacterial strain also possesses antagonistic activities against phytopathogenic
fungi such as
Sarocladium oryzae, Alternaria longipes, Pestalotia debaryanum
and
Pythium
palmarum,
and stimulates the growth of maize plants under greenhouse conditions (Marín et
al., 2013).
Several strains of
Paenibacillus polymyxa
have demonstrated plant growth promotion
through biological nitrogen fixation and phosphate solubilization, while being capable of
producing hydrolytic enzymes including proteases, 3-glucanases, cellulases, xylanases,
lipases, amylases and chitinases, and a wide variety of secondary metabolites including
auxins, cytokinins, lytic enzymes, and antibacterial and antifungal compounds. Likewise,
P.
polymyxa
causes structural changes in the root of plants and exerts control over different
phytopathogenic fungi such as
Botrytis
cinerea, Fusarium oxysporum, Pythium
spp
.,
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