Azotobacter Spp Research Articles

Isolation and Characterization of Azotobacter and Phosphate Solubilizing Bacterial Isolates

Isolation from 20 soil samples collected from rhizosphere of watermelon was done on Ashby's medium and Pikovskaya's agar media.8 Azotobacter and 6 Phosphate solubilizing bacteria PSB isolates were obtained from all samples. All the obtained isolates of Azotobacter sp and PSB were gram negative. On morphological study it was observed that, all Azotobacter isolates were motile and positive for KOH test. In case of PSB, the colony shapes of 4 obtained isolates were circular and irregular in 2. All the isolates showed smooth appearance on the media with white colony colour. The biochemical results for both Azotobacter spp and PSB revealed that, most of them were positive for methyl red test, catalase test, starch hydrolysis, gelatine hydrolase test, oxidase test and indol test. Out of eight Azotobacter isolates, Isolate 4 (Azob-1) showed highest (14.25 mg/ml) N fixing ability whereas, from of six PSB isolates, Isolate1 (PSB-1) showed highest solubilising index (4.13) therefore these two isolates were found most efficient in their roles and therefore recommended for use for field experiments.

Effect of Commercial Biofertilizers on Growth and Yield of Antimalarial Compounds of Artemisia annua

Introduction: Artemisia annua is a medicinal plant grown by Ugandan farmers in Kabale and Kabarole. It is particularly used in preparation of antimalarial herbal teas used to control and prevent malaria. The content of these antimalarial compounds in A.annua (Anamed) grown in Uganda are low compared to cultivars in other countries but could be enhanced using economical, eco-friendly, and sustainable fertilizers (biofertilizers). Thus, the effect of commercially available biofertilizers in Uganda on A.annua antimalarial components was assessed.
 Methodology: Seven different commercially available biofertilizers containing nitrogen fixing strains and phosphate solubilizers obtained from the top biofertilizer distributors to Uganda (Shittah Agri and Biotech Pvt Ltd4 106 C22) and manufacturer (Kinyara Sugar Works Ltd.) were used. Their efficiency was assessed by measuring the vegetative growth characters and the content of flavonoids and artemisinin (using High Performance Liquid Chromatography, HPLC) and polysaccharides (using Ultra Violet visible, UV-vis spectrophotometer).
 Results: Though overall increase in growth was observed upon application of the biofertilizers, there was variation in the concentration of the antimalarial compounds. The highest kaempferol content and artemisinin content were observed in A. annua inoculated with Azotobacter spp. AZT (17.05 µg/ml and 1.43%) and Bacillus subtilis, BS (19.12 µg/ml, 1.42%) while the highest quercetin content was observed in A. annua inoculated with AZT (0.42 µg/ml) and Bacillus megaterium, BM (0.41 µg/ml). Additionally, fertilizers (biofertilizers and chemical fertilizers) decreased polysaccharide content.
 Conclusion: The findings demonstrate that application of commercially available biofertilizers in Uganda is beneficial in increasing concentration of artemisinin and flavonoids and thus can be utilized by Artemisia annua farmers in Uganda.

Assessment of the potentials of <i>Azotobacter</i> spp. as bioinoculants on the growth of potted maize plants

The use of chemical fertilizers in crop production has detrimental effects such as soil acidity and eutrophication. There is need for environmentally friendly approach in improving soil nutrients and agricultural productivity. This study aimed at the isolation of Azotobacter spp from the rhizosphere of crops and the use of these isolates as biofertilizer for the growth of potted maize plants under 5 treatments. These treatments were maize plant only (control), plant with once application of NPK fertilizer, plants with once, weekly and fortnights application of Azotobacter spp. as bio-inoculants. The counts of Azotobacter obtained from the rhizosphere of the crops ranged from 4.0 × 104 – 1.0 × 106 CFU/g. The three high ranking in-vitro biological nitrogen fixing and phosphate solubilization isolates were identified A. chroococcum, A. vinelandii and A. beijerinckii. At the 7th weeks of growth, 83.3 and 100% of the plants that received different levels of bio-inoculants had the perimeter of their girths greater than and significantly different from the controls when cultivated in 8.1 and 12.0 litre pots respectively. At least 91.7% of the plants that received bio-inoculants had higher heights than the controls. It is concluded that the application of Azotobacter bio-inoculants enhanced the growth of maize plants compared to the contro

Studies on Isolation of Plant Growth Promoting Azotobacter spp from Soil Samples

Soil is the heterogeneous mixture of different kinds of microorganisms. Soil provides nutritive environment for the growth of microorganisms. One of the soil microbes is Azotobacter. The aim of present study was to isolate plant growth promoting Azotobacter spp. In the present study, 25 soil samples were collected from different locations of Akola and Akot region. In the study, 10 Azotobacter spp. were isolated. Azotobacter spp. was checked for phosphate solubilizing ability, stress tolerance (Temperature, pH, Salt), Nitrate Reduction, Cyst formation by using Burks medium and Indole Acetic Acid production using L- Tryptophan. Amongst the 10 isolates all were found to reduced nitrate, NH3 formation ability and IAA production, while two isolates H3 and C5 were only found to be have phosphate solubilizing ability. The seed germination test was also performed, Azotobacter showed promising results on the moth beans. The result reveals that Azotobacter could be a better source for crop improvement and soil fertility over the use of chemical fertilizers.

The effects of temperature, salt, and phosphate on biofilm and exopolysaccharide production by Azotobacter spp.

Inoculation of agriculturally important biofilms to plants under stress conditions has been of great interest in recent years. Therefore, in this study, biofilm- and exopolysaccharide (EPS)-forming ability of Azotobacter spp. was examined under different temperatures, NaCl concentrations, and phosphate levels. Azotobacter strains formed varying levels of biofilm and EPS depending on the tested factors. The pattern of biofilm formation was similar to that of EPS production under the conditions tested. Biofilm and EPS production at 28°C was consistently higher than at either 18 or 37°C. Biofilm production significantly increased in A. chroococcum strains (SBS2, SBS4, and SBS12) and A. vinelandii SBS6 with increasing salinity. Furthermore, a strong negative correlation was observed between biofilm or EPS production and increasing phosphate concentrations. Higher phosphate concentrations decreased biofilm and EPS production. In conclusion, contrary to temperature and phosphate effect, salinity differently affected biofilm and EPS production by Azotobacter strains.

Bioremediation of crude oil and its effect of residue in growth of wheat plants

Three strains of bacteria were studied to bioremediation crude oil in soil and in the laboratory. These bacteria were Azospirillum spp., Azotobacter spp. And Rhizobium spp. The results showed that Azospirillum spp. , Rhizobium spp. was more efficiency to bioremediation crude oil than Azotobacter spp., also the results showed that the higher number of bacteria was recorded in soil treatment with Rhizobium spp. in presence of crude oil in first week , and the number of this bacteria reached to 22.6 x 108 , but the lowest number of bacteria was recorded in soil without added crude oil (control), and the number reached to 2 x 107.The statistical methods obtained that no significant were recorded between different treatments . Also, the results showed that the numbers of bacteria in soil treatment with crude oil were decreased regularly from second week until ten weeks. The results showed that the height of the aerial parts of wheat plants reached to 73 cm in soil treatment with Azotobacter spp. And crude oil after 10 weeks, and the lower length reached to 47 cm. At the same time the results obtained that the higher wet weight of wheat plants was reached to 56 gm in soil treatment with Rhizobium spp., and in the presence of crude oil after 10 weeks, but the lower wet weight was reached to 25 gm in control. Also, the results showed that the higher of dry weight of wheat plants was reached to 23 gm in soil treatment with Rhizobium spp. and in the presence of crude oil after 10 weeks, but the lower dry weight was reached to 10 gm in control, however the statistical methods that no significant were recorded between the different treatments. Also, that all these bacteria have ability to removal crude oil in soil and in mineral salts medium.

Viabilitas Azotobacter spp. pada Beberapa Kombinasi Media Pembawa

Azotobacter spp. Viabilities on Some Combinations of Carrier Media. The purpose of this research was to find suitable carrier media for the survival of Azotobacter spp. as a biological fertilizer, before being applied to the field. The method used in this research is explorative, by inoculating Azotobacter spp. Isolate on 4 types of carrier media, namely soil; cocopeat; wood dust and charcoal with a combination of the following: K1 (Land); K2 (soil + cocopeat); K3 (Soil + sawdust) and K4 (Soil + husk charcoal), which were repeated 3 times, so there were 12 experimental units. Analysis of N, P, K, C-organic and pH for soil media, while for cocopeat, wood powder and husk charcoal, an analysis of N and P, C-organic tissue and pH was carried out. The parameters observed were optical density at 2, 4, 6 and 8 weeks. The results showed that the survival of Azotobacter spp. in K4 carrier media (a combination of soil and husk charcoal) is more secure than other types of carrier media with optical density that has not decreased. Analysis of N and P for rice husk charcoal tissue gave the highest results, namely 1,680% and 1,351%, which were one of the supporters of this inoculant viability. Azotobacter spp. viability still guaranteed until 6 weeks incubation period, in several media, (soil + cocopeat), (soil + sawdust), and (soil + husk charcoal). The combination of media (soil + husk charcoal) gave the highest population increase at the 6 weeks incubation period.

Distribution of Heterotrophic and Nitrogen fixing Rhizobacteria in Irrigation Sites of Lake Alau Borno State Northeastern Nigeria

This study was conducted to know the population of rhizobacteria in both irrigation and non-irrigation sites of the dam. The dense population of these organism indirectly promote plant growth and development. Five sites (A, B, C, D and E) were used to collect soil samples randomly and transported to the laboratory for analysis. Total heterotrophic bacterial count was done using nutrient agar (NA) and nitrogen fixing bacteria was counted using Ashbey’s media (AM). The result shows that highest number of total heterotrophic bacteria in site C (46.0×106) cfu/g in irrigation site whereas higher count in non-irrigation site was (13.0×106) site D, the nitrogen fixing bacterial count in irrigation site was higher at site E with (12.0×106) and for the non-irrigation site was higher at site D with (14.0×106) The total heterotrophic bacteria isolated in the soil sample are the species of Bacillus alvei, Bacillus alvei, Bacillus cereus, Bacillus cereus, Pseudomonas putida, Klebsiella aeruginosa and Enterobacter aeruginosa. Likewise, the Nitrogen fixing bacteria isolated are the species of Rhizobium leguminosarum, Klebsiella pneumonia, Bacillus lentus, Azotobacter nigricans, Azotobacter tropicalis, Azotobacter spp, and Azotobacter tropicalis. The long history of agricultural activities in the lake area has directly influenced the diversity of microbial population in the area.

The Influence of Organic Fertilizers on the Abundance of Soil Microorganism Communities, Agrochemical Indicators, and Yield in East Lithuanian Light Soils.

Soil microorganisms are one of the main indicators used for assessing the stability of the soil ecosystem, the metabolism in the soil, and its fertility. The most important are the active soil microorganisms and the influence of the fertilizer applied to the soil on the abundance of these microorganisms. We aimed to investigate how the applied organic fertilizers affect the most active soil microorganisms, which determine the soil fertility and stability. Fungi, yeast-like fungi abundance, and abundance of three physiological groups of bacteria were analyzed: non-symbiotic diazotrophic, organotrophic, and mineral nitrogen assimilating. This study is valuable because relatively few similar studies have been performed on infertile Lithuanian soils. The first results of a long-term study were obtained. The results show the effect of fertilizers on trends in the changes of microorganism community diversity; however, more analysis is needed to assess the impact of organic fertilizers on the most active soil microorganisms. Therefore, the investigation was continued. The results of the 2020 quantitative analysis of culturable soil microorganisms show that the highest abundance of organotrophic and non-symbiotic diazotrophic bacteria were recorded during the summer season. Meanwhile, the abundance of bacteria assimilating mineral nitrogen and fungi was higher in autumn. Agrochemical parameters were determined at the beginning of the experiment. The highest concentration of Nmin in the soil was determined after fertilizing the plants with the combination of granulated poultry manure (N170) + biological substance Azotobacter spp. The yield of barley was calculated. It was found that the highest yield of spring barley in 2020 was obtained by fertilizing the experimental field with organic in combination with mineral fertilizers.

Bioformulation of Azotobacter spp. and Streptomyces badius on the productivity, economics and energetics of wheat (Triticum aestivum L.)

Wheat production is directly linked to energy inputs of high yielding varieties, chemical fertilizer and mechanization. In spite of their benefits, fertilizers are associated with high energy consumption. Thus there is need to develop energy-efficient agricultural systems with low input energy compared with the output of food. The only alternate to increase and/or sustain the productivity by developing a system in which nutrients are added through combined use of organic sources biofertilizers and PGPR's. Biofertilizers comprised of efficient strains of nitrogen fixing or phosphate solubilizing microorganism can play pivotal role in this regard. Thereupon the present investigation was planned with combination of chemical fertilizer and biofertilizer to find out the best combination and to get maximum profit with energy saving. The field experiment was carried out at two locations with nine different chemical and biofertilizer combination in randomized complete block design. Maximum grain yield was observed in 87.5% N and 87.5% P + Azotobacter spp and Streptomyces badius (seed treatment) at both the locations. Results indicated that Azotobacter spp and Streptomyces badius may be used synergistically as a potential source with reduction of chemical fertilizer to 12.5–25% without compromising yields.

ПРОРАСТАНИЕ СЕМЯН ЗЛАКОВ ПОД ВЛИЯНИЕМ КОМПОЗИЦИЙ АЗОТФИКСИРУЮЩИХ И ФОСФАТМОБИЛИЗУЮЩИХ БАКТЕРИЙ ИЗ ПОЧВ, ВОЗДЕЛЫВАЕМЫХ В УСЛОВИЯХ ДАЛЬНЕГО ВОСТОКА

Mineral fertilizers which can significantly increase crop productivity have an adverse effect on the soil and the environment as a whole when used for a long time. Microorganisms, as an alternative to mineral fertilizers, stimulate plant growth and development due to their ability to fix nitrogen, produce siderophores, phytohormones and enzymes, dissolve inaccessible elements of mineral nutrition, suppress plant pathogens, and increase consumption of water and nutrients. However, the effectiveness of such preparations highly depends on factors of a new environment. We believe that bacteria from soils that have long been exposed to various agricultural practices may be good plant stimulants. In the presented study, for the first time, we have isolated local active strains of nitrogen-fixing and phosphate-mobilizing bacteria from soils subjected to 74-year stationary intensive farming in the conditions of the Russian Far East and revealed isolates and their combinations which stimulate wheat and barley seed germination and seedling growth. The aim of the work was to study the plant-stimulating properties of nitrogen-fixing and phosphate-mobilizing bacteria from soils that have been actively exposed to mineral fertilizers for a long time. Bacteria were isolated from soils sampled in October 2015 (the experimental field 8, Federal Research Center for Agrobiotechnology FEB RAS, Ussuriysk, Primorsky Territory, Russia). The seeds of wheat Triticum aestivum L. cultivar Primorskaya 50, and barley Hordeum vurlage L. cultivar Tikhookeanskii (collection of the Federal Research Center for Agrobiotechnology FEB RAS) were treated. Of 68 bacterial isolates with different cultural and morphological properties, three isolates, the Acinetobacter spp. N1, Azotobacter spp. N2, and Clostridium spp. N3 were nitrogen fixers, and four isolates, the Serratia spp. P6, Bacillus spp. P7), Arthrobacter spp. P8, and Pantoea spp. P19 were phosphate-mobilizing bacteria. Tests with the monocultures of nitrogen-fixing and phosphate-mobilizing isolates and their different binary compositions showed a 13-51 % increase (p ≤ 0.05) in wheat seed germination energy and 15-54 % increase (p ≤ 0.05) in barley seed germination energy compared to the untreated control. Laboratory germination of wheat seeds increased by 2-32 %, barley seeds by 7-30 % compared to untreated control. The barley seedlings were 1.8 times longer, and the roots were 2.7 times longer. Th binary combination N2P19, P6P19, and P8P19 caused the highest height of seedlings (120-140 mm, p ≤ 0.05), and with P6P7, N2P19, and P6P19 the roots were the longest (120-130 mm, p ≤ 0.05). These results allow us to conclude that short-term soaking seeds in the suspensions of the tested nitrogen-fixing and phosphate-mobilizing isolates improves seed germination energy and laboratory germination, and increases shoot and root length. Binary bacterial compositions have a greater effect on seed germination than monocultures. The strains N1 (Acinetobacter spp.), N2 (Azotobacter spp.), and P19 (Pantoea spp.) are the best stimulants. Species-specific differences in plant response to the treatment is probably due to lack of genetic, biochemical and physiological complementarities between specific plant species and the bacteria.

EFFECTS OF NITROGEN-FIXING AND PHOSPHATE-SOLUBILIZING MICROORGANISMS FROM THE FAR EAST AGRICULTURAL SOILS ON THE CEREAL SEED GERMINATION

Mineral fertilizers which can significantly increase crop productivity have an adverse effect on the soil and the environment as a whole when used for a long time. Microorganisms, as an alternative to mineral fertilizers, stimulate plant growth and development due to their ability to fix nitrogen, produce siderophores, phytohormones and enzymes, dissolve inaccessible elements of mineral nutrition, suppress plant pathogens, and increase consumption of water and nutrients. However, the effectiveness of such preparations highly depends on factors of a new environment. We believe that bacteria from soils that have long been exposed to various agricultural practices may be good plant stimulants. In the presented study, for the first time, we have isolated local active strains of nitrogen-fixing and phosphate-mobilizing bacteria from soils subjected to 74-year stationary intensive farming in the conditions of the Russian Far East and revealed isolates and their combinations which stimulate wheat and barley seed germination and seedling growth. The aim of the work was to study the plant-stimulating properties of nitrogen-fixing and phosphate-mobilizing bacteria from soils that have been actively exposed to mineral fertilizers for a long time. Bacteria were isolated from soils sampled in October 2015 (the experimental field 8, Federal Research Center for Agrobiotechnology FEB RAS, Ussuriysk, Primorsky Territory, Russia). The seeds of wheat Triticum aestivum L. cultivar Primorskaya 50, and barley Hordeum vurlage L. cultivar Tikhookeanskii (collection of the Federal Research Center for Agrobiotechnology FEB RAS) were treated. Of 68 bacterial isolates with different cultural and morphological properties, three isolates, the Acinetobacter spp. N1, Azotobacter spp. N2, and Clostridium spp. N3 were nitrogen fixers, and four isolates, the Serratia spp. P6, Bacillus spp. P7), Arthrobacter spp. P8, and Pantoea spp. P19 were phosphate-mobilizing bacteria. Tests with the monocultures of nitrogen-fixing and phosphate-mobilizing isolates and their different binary compositions showed a 13-51 % increase (p ≤ 0.05) in wheat seed germination energy and 15-54 % increase (p ≤ 0.05) in barley seed germination energy compared to the untreated control. Laboratory germination of wheat seeds increased by 2-32 %, barley seeds by 7-30 % compared to untreated control. The barley seedlings were 1.8 times longer, and the roots were 2.7 times longer. Th binary combination N2P19, P6P19, and P8P19 caused the highest height of seedlings (120-140 mm, p ≤ 0.05), and with P6P7, N2P19, and P6P19 the roots were the longest (120-130 mm, p ≤ 0.05). These results allow us to conclude that short-term soaking seeds in the suspensions of the tested nitrogen-fixing and phosphate-mobilizing isolates improves seed germination energy and laboratory germination, and increases shoot and root length. Binary bacterial compositions have a greater effect on seed germination than monocultures. The strains N1 (Acinetobacter spp.), N2 (Azotobacter spp.), and P19 (Pantoea spp.) are the best stimulants. Species-specific differences in plant response to the treatment is probably due to lack of genetic, biochemical and physiological complementarities between specific plant species and the bacteria.

Effects of bacteria and nitrogen fertilizer on promoting maize (Zea mays L.) growth, yield and chemical constituents

A field experiment was carried out during two successive summer seasons (2016/ 2017- 2017/2018), at the College of Agricultural Studies, Sudan University of Sciences and Technology, to assess the effect of bacterial strains, nitrogen and their combinations on the performances of two maize genotypes Hudibi2 (C1) and ZML309 (C2). The form of two types of bacterial strains Bacillus megatherium var. phosphorous + Azotobacter spp + Azospirillium spp (B1) and Bacillus megatherium var. phosphorous + Azotobacter spp + Flavobacterium spp (B2), nitrogen applied at rates of 80kg/f (N) plus control. The treatments were arranged in a Randomized Complete Block Design (RCBD) in four replicates. The results showed that the combinations of B1 and B2 with N increased plant growth compared to B1, B2, and N each alone at both seasons. The general trend was the combinations (B2+N, B1+N) had significant effect on all growth parameters in both seasons. Yield components increased with combination (B2+N) followed by (B1+N), the maximum seed yield (5.0 and 2.8t/ha) was achieved by the interaction of (C2*B2+N) in the first season and (C2*B1+N) in the second season, respectively. Generally, in among all treatments, the combination of B2+N increased nitrogen content, crude protein and fiber irrespective to maize genotypes. Moreover, C2 showed the highest values as compared to C1. In conclusion, improvement in maize plant growth and yield are more prominent and significant when genotype ZML309 inoculated with Bacillus megatherium var. phosphorous + Azotobacter spp + Flavobacterium spp and supplemented with 80kg/f nitrogen.

Effectiveness of Organics with Nitrogen Levels and Bio-fertilizers on Soil Chemico-biological Properties of Wheat (Triticum aestivum L.) Crop [Cv.PBW-343] in Inseptisol

Aims: To enhance soil quality, production, productivity and profit maximization with higher economic returns through integrated farming practices. In addition, to fulfill the needs of farmers economical point of view, academic, society and social reforms.
 Study Design: Effectiveness of organics with nitrogen levels and bio-fertilizers on soil chemico-biological properties of wheat (Triticum aestivum L.) crop [Cv.PBW-343] in Inseptisol.
 Place and Duration of Study: The cumulative study period of 2018-19 and 2019-20, at research farm, department of soil science and agricultural chemistry, naini agricultural institute, sam higginbottom university of agriculture, technology and sciences, which is located at 25°58’ North latitude and 81°52' East longitude with an altitude of 98 meter above mean sea level and is situated 5km away on the right, bank of Yamuna river.
 Methodology: Randomized block design fallowed here with 12 treatment combinations replicated 3 times. Recommended dose of fertilizers i.e. nitrogen, phosphorus and potassium, was applied @ 120:60:40 kg ha-1 as urea (46% N), single super phosphate (16% P2O5), muriate of potash (60% K2O) and zinc sulphate (21% Zn). The Azotobactor spp. and Azospirilium spp. (seed inoculants), applied at 3 kg ha-1 with farm yard manure @ 5 tha-1, at 5 cm depth in furrows, before seed sowing was done on 13th and 14th of November (2018-2019) with spacing of 22.5 X 5 cm. Wheat cultivar used here is PBW-343 as a test crop.
 Results: The cumulative mean of low soil pH (6.82), electrical conductivity (0.37 dS m-1) and free lime content (13.55%), the higher cation exchange capacity (16.37 cmol (p+) kg-1), higher available nitrogen, available phosphorus, available potassium and available sulphur of 262.12: 21.75:220.51:32.57 kg ha-1, respectively, high available iron and zinc (i.e. 3.90 and 1.79 mg kg-1), low available manganese and copper (3.77 and 0.31 mg kg-1), further the cumulative mean of dehydrogenase enzyme activity (1.49 µg triphenyl-formazan g-1 day-1), alkaline phosphatase activity (186.35 µg para-nitrophenol g-1 hr-1) and microbial biomass carbon (37.59 g kg-1) was labelled in treatment (T9) consisting of 75% N + farm yard manure @ 5 t ha-1 + Azotobacter spp + Azospirillum spp (3 kg ha-1) + zinc in comparison to in-organic application over control.
 Conclusion: The combined application of farm yard manure, Azotobacter spp and Azospirilium spp along with in-organics, has led to improvement in soil health potential, nutrient availability and yield sustenance under wheat crop cultivation.

ISOLATION AND IDENTIFICATION OF AZOTOBACTER OF SOME TYPE OF LAND USE IN JEGU VILLAGES

Conventional farming systems have a negative impact on the life of Azotobacter. Through the results of this study, we want to provide information on the existence of Azotobacter in several rhizosphere of cultivated plants, and looking for isolates that have advantages as biofertilizers and decomposers. This research is an exploration of bacteria Azotobacter spp. from several plant rhizosphere namely: organic and inorganic rice paddy, cassava, coconut, and chocolate. Three samples was taken from each type of land use, so that the number of isolate sources were 15 samples. All analyzes were conducted at Soil Biology Laboratory, Faculty of Agriculture Udayana University. This study aims to find isolates of Azotobacter spp. which is superior to be utilized as biofertilizer and decomposer. Parameters used to support isolation and identification results are total population of bacteria Azotobacter spp., soil respiration, gram staining, halo zone and optical density. The results showed that organic rice rhizosphere was the best isolate source compared with inorganic rice rhizosphere, coconut, cassava and chocolate. Isolate from this organic rice rhizosphere has the highest total population (40.10 cfu x107g-1 soil), on positive catalase test yield bubbles and optical density (average 1.217ABS at 550 nm wavelength). While the superior isolates of Azotobacter spp. As biofertilizer and decomposer candidates are TSO2 isolates (samples from organic rice plant rhizosphere) with soil respiration rate (8.057mgC-CO2 kg-1 soil/day), high optical density (1.147 ABS on spectrophotometer with 550 nm wavelength) and highest halo zone diameter (10 mm).

Microorganisms in Biostimulants

In March 2016, the EU Commission presented a proposal for new regulations on fertilising material. The regulation includes product rules for a wide range of organic and inorganic products. Microbial biostimulants is one of the categories of products that are included. Biostimulants, in the draft EU regulation, are defined as fertilising materials that affect nutrient processes independently of the product's own nutrient content and with the purpose of improving nutrient utilisation, tolerance for abiotic stress or quality of the crop. Positive list in which species of these bacterial genera are listed: Azotobacter spp, Rhizobium spp., Azospirillum spp and Mycorrhizal fungi are a part of the regulation.
 Since the import and use of these organisms are the responsibility of both the Norwegian Food Safety Authority and the Norwegian Environment Agency, they asked VKM to submit a joint report on effects on health (humans, plants and animals), biodiversity and dispersal, quality of agricultural land and on soil environment.
 Conclusions:
 Health risks:
 Based upon our literature review, we have found no indication of any specific diseases in plants, animals or humans induced by the discussed microorganisms. A few reported cases of human disease are caused through wound infections or injections in immunocompromised patients. These represent a situation where any microorganism may induce infections and is not specific for the agents discussed in this report. In summary, the risk of any disease caused by the discussed microorganisms is considered negligible.
 Environmental risks:
 In soil the biodiversity, competition, adaptation and functional redundancy of microorganisms are extremely high. This means that introduced microorganisms have a very small chance for establishing, and even less so for affecting biodiversity and soil functioning. Introduction of nitrogen fixing species or fungi that can transport P to plants (mycorrhiza) will lead to an increase in the primary production. However, even a large increased activity for these processes will not outcompete naturally occurring symbiotic N-fixation or growth of inherently non-mycorrhizal plant species. Thus, the risks associated with introduced non-pathogenic microorganisms are very low.

Isolation, Characterization and Identification of Salt Tolerant Nitrogen Fixing Bacteria

The present investigation deals with the isolation and characterization of nitrogen-fixing bacteria (NFB) such as Azotobacter sp. and Azospirillum sp. from paddy field rhizosphere of Damietta governorate, Egypt. Twelve Azotobacter spp. and 12 Azospirillum spp.Were identified based on morphological and physiological characteristics. All isolates were tested for salt tolerance. The highest salt tolerant of Azotobacter spp. Were S2-8, S3-3, S1-3, S3-2, whil they S2-11, S1-1, S5-1, S3-6 in case of Azospirillum spp. were. Nitrogenase activity assay of the highest nitrogen fixing isolates was (S2-8) in case of Azotobacter sp. and (S2-11)in case of Azospirillum sp. Molecular identification showed that isolates were Azotobacter chroococcum and Azospirillm brasilense. Based on this study salt-tolerant isolates of Azotobacter chroococcum and Azospirillm brasilense could be highly used in cultivation of paddy soil in coastal environment.

Physiological Quality of Bean Seeds Related To Azotobacter Spp.

Physiological Quality of Bean Seeds Related To Azotobacter Spp.

Determinación del potencial promotor del crecimiento vegetal de Azotobacter spp. aislados de la rizósfera de malezas en cultivos de maíz (Zea mays L.)

The chemical fertilizer represents for 20 and 30 % of cost the production a crop, used correctly increase productivity and profitability, however, each year increase the among of fertilizer to apply, due to deficiency of soil adsorption and absorption by the plant. Beging maize the third most important crop in Peru, with a significant impact on economic and social activity in 2014, only 40% of the offered maize corresponded of the production nacional. 37 weeds were identified associated with crops of maize from agricultural fields Monsefu districts and Reque, Lambayeque Region, with 68% being dicotyledonous against monocots with 32%. Bacteria were isolated from the rhizosphere of weeds, getting 305 pure cultures of bacteria, 133 of which (43.7%) were identified as Azotobacter spp. Investigated the biochemical reaction in nitrate reduction, utilization of sucrose, glucose, maltose, mannitol, rhamnose, glycerol and sorbitol. Identifying A. vinelandii (58%), A. paspali (13%), A. armeniacus (8%), A. nigricans (8%) and 13 cultives not the species was identified. With this cultives pure of Azotobacter spp. native was quantified to 36.03 ppm of fixed nitrogen as ammonia; 60.75 ppm of indole acetic acid and 6.06 ppm solubilized phosphorus was also determined the activity antagonistic to Fusarium verticillioides, proteolytic and chitinolytic. 20% of Azotobacter spp. native did not affect the emergence of simple hybrid hard yellow corn 144 agriculture, 33% positively affected and 47% negatively affected. In turn, none Azotobacter spp. affect negatively survival. The potential of the plant growth promoter of Azotobacter spp. isolated from weeds in maize crops in the region of Lambayeque been demonstrated.

Dry matter yield and forage quality traits of oat (Avena sativa L.) under integrative use of microbial and synthetic source of nitrogen

The natural microbes are potential contributor to build up soil nitrogen through transformation of molecular nitrogen to plant available forms. Therefore, in the present study, we investigated the contribution of biofertilizer to reduce the synthetic nitrogen application without deteriorating the yield and forage quality. The supplementary nitrogen rates included 0, 40, 80 and 120kgha−1 and the seed inoculation was carried out with the mixture of Azospirillum+Azotobacter spp. The experiment was laid out in randomized complete block design with factorial arrangement. The results indicated that organic matter contents and ether extractable fat were negatively associated with both nitrogen and inoculation factors. The inoculation produced 6.58%, 9.58%, 2.51%, 16.94%, 10.26%, 17.59%, 14.02%, 33.81% and 66.18% more No. tillers, plant height, leaf to stem ratio, dry matter yield, mineral matter contents, crude fibre, crude protein, crude protein yield and total digestible crude protein yield, respectively over uninoculation. The interactive effects indicated that inoculation alone without nitrogen application produced 19.16% and 6.87% more dry matter yield and crude protein (%), respectively. The beneficiary effects of biofertilizers on growth and dry matter of oat were more pronounced at intermediate level of inorganic nitrogen which was gradually decreased at higher nitrogen levels. The CP, CPY and DCPY achieved with inoculation alone were statistically equivalent to plots fertilized with 0 and 40kgNha−1. It is clear that plots sown with inoculated seeds must be fertilized with 80kgN to produce higher dry matter and economic returns. However, the highest protein contents in dry matter were recorded with highest fertilization level along with inoculation. By giving due attention to stimulatory effects of bacterial species in the present study, it is therefore, recommended to integrate the use of biofertilizers with supplemental dose of synthetic nitrogen source to sustain crop production.