8
and shoot growth of winter wheat, and increase N, P, and K contents of plant components. On the other hand, some bacteria have a role to fixation nitrogen
non-symbiosis such as Azotobacter, Azospirillum sp, that are able to fixes atmospheric nitrogen in loose association with plant roots and provides the host
plant by about 30-50 of nitrogen requirements Dalla et al. 2004. Bacillus bacteria if combined with Bradyrhizibum japonicum, can be used
to improve the root development and form nodules on roots, and increase the absorption of nutrients especially N in soybean plant Bai et al. 2003. Similarly,
the Phosphate Solubilizing Bacteria PSB Bacillus megaterium and Potassium Solubilizing Bacteria KSB Bacillus mucilaginosus, increased the availability of
P and K in soil, enhanced N, P and K uptake, and promoted growth of eggplant Han Lee 2005.
Wu et al. 2005 carried out a study to evaluate the effects of four biofertilizer containing an arbuscular mycorrhizal fungus Glomus mosseae or
Glomus intraradices with or without N-fixer Azotobacter chroococcum, P solubilizer Bacillus megaterium and K solubilizer Bacillus mucilaginous on
soil properties and the growth of Zea mays. They found, that the biofertilizer significantly increased the growth of Zea mays. Microbial inoculums not only
increased the nutritional assimilation of plant total N, P and K, but also improved soil properties, such as organic matter content and total N in the soil.
b. Produce Hormone
Many soil bacteria such as Azotobacter sp, Azospirillum sp and
Pseudomonas sp can be promote plant growth by production of phytohormon
such as auxin, Cytokinin, Gibberellins and abisic acacid Bottini et al. 2004; Safak Nilfer. 2006 which can be beneficial to stimulate plant growth and
increase plant production.
c. Biocontrol of Plant Diseases
Biological control is being considered as an alternative or a supplemental
way of reducing the use of chemicals in agriculture. There has been many studied to describing potential
uses of plant associated bacteria as agents stimulating plant growth and managing soil and plant health such as Pseudomonas sp and Bacillus
sp Glick 1995.
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PGPR group of bacteria as abiocontrol by directly or indirectly. Directly role by activity such as nutrition source, competition by colonization and
competition with bacteria pathogens at the root area Whipps 2001; Compant et
al. 2005 . While, mechanism indirectly with some PGPR to plant can also provide
systemic resistance against a broad spectrum of plant pathogens. Diseases of
fungal, bacterial, and viral origin, and in some instances even damage
caused by insects and nematodes, can be reduced after application
of PGPR and product compound allelochemicals Compant et al. 2005
.
Many of group PGPR such as biocontrol have ability to produce antibiotic like
phenazine-1-carboxyalic, 2,4-diacetyle
phloroglunicol, pyoluteorin,
pyrrolnitrin. Besides that system resistance plant also can be induced by bacteria
PGPR such as Bacillus, Pseudomonas, Azospirillum and Rhizobium Kloepper et al. 2004; Compant et al. 2005 and Fernando et al. 2005. Pseudomonas bacteria,
such as Pseudomonas fluorescens, have been applied directly to soils and seeds to prevent the growth of crop pathogens, and increasing the plant production.
Although biocontrol activity of microorgansims involving synthesis of
allelochemicals has been studied extensively with free-living rhizobacteria, similar
mechanisms apply to endophytic bacteria Lodewyckx et al. 2002, since they can
also synthesize metabolites with antagonistic activity toward plant pathogens
Chen et al. 2002. Moreover, Castillo et al. 2002 demonstrated that munumbicins, antibiotics produced
by the endophytic bacterium Streptomyces sp. can inhibit in vitro growth
of phytopathogenic fungi P. ultimum, and F. oxysporum. Subsequently,
it has been reported that certain endophytic bacteria isolated
from field-grown potato plants can reduce the in vitro growth of
Streptomyces scabies and Xanthomonas campestris through production of
siderophore and antibiotic compounds Sessitsch et al. 2004. Interestingly, the
ability to inhibit pathogen growth by endophytic bacteria, isolated from potato
tubers, decreases as the bacteria colonize the host plants interior, suggesting that
bacterial adaptation to this habitat occurs within their host and may be tissue type
and tissue site specific Sturz et al. 1999.
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PGPR Plant Growth Promoting Rhizobacteria
Group of bacteria that actively colonize plant roots and increase plant growth and yield known as PGPR Wu et al. 2005. There are many species from
bacteria such as Azotobacter sp., Azospirillium sp, Azoaracus sp, Bacillus sp, Clostridium sp, Entrobacter sp, Gluconoacetobacter sp, Pseudomonas sp and
Serratia sp Somers et al. 2004. Plant growth promoting rhizobacteria PGPR can promote plant growth directly or indirectly. Directly by increasing plant
growth are through phytohormones, such as auxin, cytokinin and gibberellins Glick 1995. Indirect promotion of plant growth is through antibiotic type
compounds, enhanced resistance to pathogenic diseases andor abiotic stresses. The mechanisms by which PGPRs promote plant growth are not fully understood,
but some probability include: the ability to produce phytohormons Egamberdiyeva 2007, symbiotic N2 fixation Mrkovacki and Milic 2001, and
solubilization of mineral phosphates and other nutrients Cattelan et al. 1999. Effect PGPR to enhance plant growth depends on ability bacteria to form area
colonization in the root with high density, so that exists in the root region and becomes more steady to produce profitable product for the plant Rokazadi et al.
2008; Ashrafuzaman et al. 2009.
Description of Microbial Which Used As a Biofertilizer Bacillus sp.
Cells and straight rod-shaped, measuring approximately 0.5-2.5 x 1.2- 10µm, arranged in pairs or a chain with the tip rounded or square. Bacillus
including Gram-positive bacteria and movement with flagella. Endospora form oval, and sometimes rounded or cylindrical and highly resistant to many
unfavorable conditions. These bacteria are aerobic or facultative anaerobic, has a wide diversity, sensitive to heat and salinity. Bacillus including
chemoorganotrophy Organism, with spacious habitats, a small number of pathogen species are vertebrates or invertebrate Holt et al. 1994.
Bacillus is Gram positive bacteria, characterized by purple or bluish, thick- walled cells approximately 30-100 nm and are generally simple, uniform look
under the electron microscope observation Singleton 1999. Bacillus sp. TG1 is
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used in this study proved capable of producing IAA of 67.2 ppm in the medium containing tryptophan and able to dissolve phosphate.
Pseudomonas sp
Pseudomonas has the straight form or crooked stems slender, but not twisting where size 0.5-1.0 x 1,5-5,0 µm. Most of these species to accumulate
poly- -hydroxybutirat as carbon storage materials. These microbes are not covered by the capsules and do not have a break phase. Pseudomonas is a Gram-
negative bacteria, moved by using one or more flagella, rarely non motil, aerobic, have a perfect type of system respiratory metabolism with oxygen as an
alternative electron acceptor, in line with the growth of anaerobic conditions. Most of the species also does not require organic growth factors. Some
chemotrophic facultative species can use the H
2
or CO as energy source Holt et al. 1994. Bacterium Pseudomonas sp isolates PD13 used in this study proved
capable of producing IIA in medium containing tryptophan and also able to dissolve phosphate Ditjen PLA Deptan and LPPM IPB 2006.
Azospirllum sp
Azospirillum vibrioid shapes or straight rod 0.9-1.2 µm in length, is the group of Gram-negative bacteria, contain poly- -hydroxibutirat, characterisitic are
motil with vibrating motion in liquid media with an average of single polar flagella. Some pigment produce bright pink or dark pink pigment on agar medium
potato. Optimum growth temperature 34-37C, grow well at pH 7 or acid. This bacterial group is fixation nitrogen and growth depends on the condition of
oxygen or grow slightly better on a lot of air containing N
2
as ammonium salt. Under oxygen limitation, there many strains can not change NO
3
to NO
2
or N
2
O and N
2
. These bacteria grow well on organic acid salts, such as malate, suksinat, lactate, and pyruvate. Some species live freely in the ground and there are also
associated with the roots of cereal crops, grasses and tubers. This species does not induce root nodules Holt et al. 1994. Isolate bacteria Azospirillum sp IDM3
used in this study proved capable of producing IAA of 7.2 ppm in the medium containing tryptophan Ditjen PLA Deprtan and LPPM IPB 2006.
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Azotobacter sp
Azotobacter is a genus of usually motile, oval or spherical bacteria that form thick-walled cysts, and may produce large quantities of capsular slime,
elongated 1.4-2.0 µm diameter and rod-shaped cells. These bacteria being single and also couple, irregular colony, and sometimes a long chain with a variable.
Azotobacter does not produce endospora, but form cyst. This chemoorganotrophy bacteria, Gram negative, motility using flagella, or are not motil, aerobic, but can
also grow under low oxygen pressure. Azotobacter can be fixed N non symbiotic at least 10 mg N
2
per gram of carbohydrate usually in the form of glucose is consumed. In certain species, these bacteria use nitrate, ammonium salts and
certain amino acids as nitrogen sources, and able to grow in the pH range 4.8-8.5. While the pH optimum for nitrogen fixation and growth is 7.0-7.5. In the soil and
water, this species may be associated with the root of plant Holt et al. 1994.
Technology of Biofertilizer and Storage
a. Use Media Carrier Biofertilizer
