Characteristics. The genus Azospirillum belongs in the alpha-Proteobacteria class of bacteria. Azospirillum are gram-negative, do not form spores, and have a slightly-twisted oblong-rod shape. Azospirillum have at least one flagellum and sometimes multiple flagella, which they use to move rapidly.


What is the role of Azospirillum in nitrogen fixation?

Under certain environmental and soil conditions, Azospirillum can positively influence plant growth, crop yields and N-content of the plant. This plant stimulatory effect exerted by Azospirillum has been attributed to several mechanisms, including biological nitrogen fixation and auxin production.

How do you identify Azospirillum?

Under light microscope, they were gram negative, plump rods ranged from 3- 5 µm size and showed fast helically motility which confirmed their identification as Azospirillum sp. Azospirillum spp. are reported to stimulates plant growth by production of phytohormones.

Where are Azotobacter found?

Azotobacter representatives can commonly be found in soil, water, sediments, and plant roots (Aquilanti et al., 2004). Azotobacter species are generally found in slightly acidic to alkaline soils, which often governs the occurrence of certain species (Becking, 2006).

What is the role of Azotobacter?

Azotobacter is able to convert atmospheric nitrogen to ammonia, which in turn is taken up and utilized by the plants (Prajapati et al., 2008). Such bacteria are immensely resistant to oxygen during nitrogen fixation due to respiration protection of nitrogenase (Hakeem et al., 2016).

What is difference between Azotobacter and Azospirillum?

The key difference between Azotobacter and Azospirillum is that Azotobacter is a genus of bacteria that are mainly aerobic and endophytic diazotrophs. Meanwhile, Azospirillum is a genus of plant growth-promoting bacteria that are microaerophilic and surface-colonizing bacteria.

What is the habitat of Azospirillum and how it is useful for environment?

Bacteria of the genus Azospirillum are found primarily in terrestrial habitats, where they colonize roots of important cereals and other grasses and promote plant growth by several mechanisms including nitrogen fixation and phytohormone secretion [5,6].

How do you make Azospirillum?

In this method 400gm of Azospirillum biofertilizer is suspended in 500mL of water to make slurry and mixed with 10-12kg of seed until seeds are uniformly coated. The treated seeds are dried in shade and sown immediately. In transplanted rice, Azospirillum is generally used as root dip treatment.

Why is Azospirillum also known as N fixing Spirillum?

The genus Azospirillum owes its name to its N2-fixing capability (Azo-) and the spiral movements of the cell (-spirillum) [10]. These short, rod-shaped, slightly curved Gram-negative bacteria were first isolated from soil in the Netherlands in 1925 [11].

Is Azospirillum used as biofertilizer?

Azospirillum species were considered as nitrogen fixers that made them to be used as biofertilizers (Bashan and Levanony, 1990; Bashan and Holguin, 1997; Pereg Gerk et al., 2000; El-Komy, 2005; Bashan et al., 2004).

What is Azotobacter biofertilizer?

Azotobacter is a free-living nitrogen-fixing bacterium, which is used as a biofertilizer in the cultivation of most crops. … The shelf life of the biofertilizer is six months from date of manufacture. The Process requires locally available plant, machinery and raw materials for manufacture.

How do you isolate Azospirillum?

Azospirilla are isolated from enrichment cultures by streaking on solid media, Congo Red agar (CRA) (Rodrı́guez Cáceres, 1982) being a particularly useful differential medium due to the scarlet coloration of Azospirillum colonies.

How do you isolate azotobacter from soil?

2.2 Determination of Azotobacter The Azotobacter was isolated from the soil. Isolated the bacteria from the rhizosphere soil by making a series of dilution of soil from 10-1 to 10-7 on Azotobacter media and incubation for 48 h at 30ºC.

Which media used for isolation of Azospirillum?

For the isolation of Azospirillum spp., Nfb semisolid medium was used. After 24 h incubation, the Nfb semi-solid medium showed white colored pellicle (Fig 1 & 2).

How do you know if you have Azotobacter?

While growing, Azotobacter produces flat, slimy, paste-like colonies with a diameter of 5–10 mm, which may form films in liquid nutrient media. The colonies can be dark-brown, green, or other colors, or may be colorless, depending on the species. The growth is favored at a temperature of 20–30°C.

How do you grow Azotobacter?

Azotobacter grows well in Burk s liquid medium at pH range of 7 to 9 but fail to grow below the pH of 6. Moreover other parameters such as temperature, incubation time, aeration rate and inoculum size also have effects on growth of Azotobacter species.

What is Azotobacter cyst?

Azotobacter is a genus of Gram-negative, organotrophic, nitrogen-fixing soil bacteria. These bacteria undergo a differentiation process to form cysts, which are dormant cells resistant to deleterious conditions. A cyst consists of a contracted oval cell, called central body, covered with a two-layer capsule.

What is the difference between Azotobacter and Rhizobium?

The key difference between Azotobacter and Rhizobium is that Azotobacter is a free-living nitrogen-fixing bacterium present in the soil, while Rhizobium is a symbiotic nitrogen-fixing bacteria that form a mutually beneficial association with legume plants.

Can spirogyra fix nitrogen?

Spirogyra is one of the commonest green algae. It has no function in nitrogen fixation.

How do you use Azotobacter?

In sugarcane after two to three months of planting i.e. before earthing up 5-6 kg of biofertilizer per acre is applied by mixing with compost or soil. Although, Azotobacter fixes nitrogen non-symbiotically, it also fixes atmospheric nitrogen in the rhizospere region i.e. soil around the seedlings or trees.

Is Azotobacter a fungi?

Arbuscular mycorrhizal fungi are ubiquitous and form a symbiotic association with many higher plants. … Azotobacter is a diazotrophic plant-growth promoting rhizobacteria that stimulates plant growth through nitrogen fixation and production of stimulating substances.

Why are cyanobacteria used as biofertilizers?

Cyanobacteria have an emerged potential as biofertilizer. They have the ability to utilize CO2, water, and nutrients to convert solar energy into biomass. Efficient applications of cyanobacteria have been reported in agricultural practices to reduce global warming by decreasing CO2 gas.

What do you mean by diazotrophs?

Diazotrophs are bacteria and archaea that fix atmospheric nitrogen gas into a more usable form such as ammonia. A diazotroph is a microorganism that is able to grow without external sources of fixed nitrogen. Examples of organisms that do this are rhizobia and Frankia (in symbiosis) and Azospirillum.

Which organism is most useful for soil fertility?

Nitrogen-fixing bacteria are required by the plants for absorbing nitrogen from the soil. Therefore bacteria is considered the most important microorganism for effective absorption of minerals and soil fertility.

Is frankia a nitrogen-fixing bacteria?

Frankia is a genus of nitrogen-fixing bacteria that live in symbiosis with actinorhizal plants, similar to the Rhizobium bacteria found in the root nodules of legumes in the family Fabaceae.

Is azotobacter photosynthetic?

Azotobacter is non-photosynthetic. It is aerobic bacteria and plays an important role in nitrogen fixation.

Is Trichoderma a fertilizer?

Trichoderma used in almost all type of crops, with or without any amendments, but if Trichoderma biofertilizer is used as an amendment with compost may gives better results than any other fertilizer. … The biofertilizer also used as soil conditioner, improves the population of plant beneficial microorganisms in soil.

Is cow dung a bio fertilizer?

Researchers from the Department of Agricultural Chemistry and Soil Science, Bidhan Chandra Krishi Viswavidyala and MSV Laboratories Private Ltd demonstrated the potential use of irradiated cow dung as a carrier of bio-fertilizers. …

What is bio fertilizer with example?

Group of biofertilizersNature of organismsNitrogen fixing biofertilizersAssociative symbioticPhosphorus solubilizing biofertilizersPhosphate-solubilizing bacteriaPhosphate-solubilizing fungiPhosphate mobilizing biofertilizersMycorrhiza

Where is Azospirillum brasilense found?

Azospirillum brasilenseScientific classificationGenus:AzospirillumSpecies:A. brasilense Tarrand, Krieg & Döbereiner, 1978

Which is the suitable medium for the cultivation of Azospirillum?

Azospirillum Medium with 0.17% Agar is used for cultivation of Azospirillum species. Malic acid is used as the carbon source. Azospirillum species grow well in presence of Malic acid and are not overgrown by other nitrogen fixers.

Is Azospirillum brasilense Gram positive or negative?

Azospirillum brasilense is a Gram-negative, nitrogen-fixing bacterium that colonizes the rhizosphere of various grasses and cereals. This strain has one of the largest genomes in the phylum Proteobacteria.

In which crop is Azotobacter used?

The population of Azotobacter is generally low in the rhizosphere of the crop plants and in uncultivated soils. The occurrence of this organism has been reported from the rhizosphere of a number of crop plants such as rice, maize, sugarcane, bajra, vegetables and plantation crops, (Arun, 2007).

How do you use Azospirillum biofertilizer?

Azospirillum is used for seedling root dip particularly for rice. 4 kg each of the recommended biofertilizers are mixed in 200 kg of compost and kept overnight. This mixture is incorporated in the soil at the time of sowing or planting. The inoculum should be applied 2-3 cm below the soil at the time of sowing.

Can we use biofertilizers with chemical fertilizers?

Results showed there was a 25% increase of lettuce yield for the treatment of ½ CF + biofertilizer compared to that of the CF treatment, indicating that at least 50% of chemical fertilizer can be saved as multifunctional biofertilizer was used along with chemical fertilizer (Table 2).

How does Azotobacter protect nitrogenase?

Cell Structure and Metabolism The cells’ uniquely high respiration rates allow the normally oxygen-sensitive nitrogenase to experience limited oxygen exposure. Azotobacter is also capable of producing a protein which protects the nitrogenase from sudden oxygen-provoked stress.

How many types of Azotobacter are there?

There are around six species in the genus Azotobacter 3 some of which are motile by means of peritrichous flagella, others are not.

What types of soils are preferred by Azotobacter?

Most Azotobacter species are sensitive to acidic soils such that their growth is favored by a neutral or alkaline medium (Becking 2006; Jiménez et al. 2011). Although Mn and Zn are required for the growth of soil microorganisms (Sylvia et al. 2005), their availability is related to soil pH (Rengel 2015).

What is Biofertilizer PPT?

Biofertilizers are natural fertilizers that are microbial inoculants of bacteria, algae and fungi (separately or in combination). which may help biological nitrogen fixation for the benefit of plants. They help build up the soil micro-flora and there by the soil health.

Which media is used for azotobacter isolation?

Azotobacter Agar (Mannitol) is used for isolation and cultivation of mannitol positive Azotobacter species from soil (4). It is also useful for maintenance of Azotobacter species by adding extra 1% Mannitol to the medium as specified by the American Type Culture Collection (1).