Phosphate Biofertilizer Research Articles

Production of phosphate biofertilizers as a booster for the techno-economic and environmental performance of a first-generation sugarcane ethanol and sugar biorefinery

The intensive use of fertilizers and pesticides in agriculture has a significant economic and environmental impact worldwide. Biofertilizers (aka microbial inoculants) could be a potential alternative to decrease costs and the environmental footprint linked to the use of fertilizers while boosting productivity through biological processes. This work aimed to perform a techno-economic-environmental assessment of an industrial biofertilizer production facility integrated with a sugarcane ethanol biorefinery. To this end, systems engineering tools were employed concurrently with techno-economic-environmental analyses to assess the integration of the different processes and their feasibility. Three processes for biofertilizer production are proposed varying in terms of downstream processing and the use of single or double microorganisms. Our findings indicate that the integration of biofertilizer production can enhance the biorefinery's NPV by as much as 137% in the most favorable scenario and by a minimum of 69% in the most unfavorable scenario. Regarding environmental consequences, in general, all scenarios demonstrate an improvement over the base scenario. Global sensitivity analysis showed that the solid-state fermentation and composite formulation steps of the biofertilizer process have the most substantial influence on both economic and environmental outcomes. The uncertainty analysis further unveils that the scenarios without fungus separation exhibited greater resilience in the face of market volatility. The retro-techno-economic study defined the economically viable region. Ultimately, this study demonstrates that the integration of biofertilizers into an ethanol and sugar biorefinery is a more sustainable alternative than the isolated biorefinery regarding the environmental and techno-economic aspects of sustainability.

Phosphate solubilization potential of rhizosphere fungi isolated from satoimo taro plant

Phosphorus is an essential nutrient required by plants for their growth and development. Phosphates bioavailability in nature is approximately 95-99% but insoluble, therefore the plant can not simply use them. The alternative to overcome phosphate deficiency is by utilizing phosphate solubilizing fungi. This research is aimed at selecting and characterizing phosphate solubilizing fungi in rhizosphere of saitomo taro (Colocasia esculenta var antiquorum). The test on isolate ability to solubilize phosphate was conducted through qualitative and quantitative. Qualitative was carried out by counting index of phosphate solubilization on solid Pikovskaya while quantitative was through counting concentration of phosphate solubilization through spectrophotometry at wave length 693 nm. The result of qualitative test showed that the highest index of phosphate solubilisation was 1.08 at isolate RTP25 while quantitative demonstrated that isolate RTP16 released highest concentration of phosphate solubilization with the amount 12.78 µgl−1. Isolate RTP 25 (by Trichoderma sp) and RTP16 (by Aspergillus sp) be potential to be developed as phosphate biofertilizer.

Quantitative and Qualitative Yield of Groundnut (Arachis Hypogaea L.) in Response to Intercropping Pattern and Integrated Application of Chemical and Biological Phosphorus Fertilizers

ABSTRACT Intercropping between cereals and legumes can increase resource use efficiency, agricultural productivity, and yield sustainability and reduce chemical inputs. For these reasons, this experiment was performed as factorial arrangement based on randomized complete block design with three replications in experimental station of Guilan Agricultural and Natural Resources Research and Education Center, Rasht, Iran in 2016 and 2017 cropping seasons. Experimental treatments included five levels of phosphorus fertilizer (PF) as triple super phosphate (TSP) including : 1- Zero (as control), 2–50 kg ha-1 TSP, 3–100 kg ha-1 TSP, 4–50 kg ha-1 TSP+200 g ha-1 Barvar2 phosphate bio-fertilizer (BPB) and 5–100 kg ha-1 TSP+200 g ha-1 BPB, and five IPs (IP) including: 1- maize (Zea mays L.) sole cropping, 2- groundnut sole cropping, 3- intercropped groundnut-maize with the ratio of 1:1, 2:1 and 1:2 rows, . Although, maximum grain yield of maize and groundnut was obtained in response to the application of 100 kg ha-1 TSP plus 200 g ha-1 BPB under sole cropping, the highest land equivalent ratio (LER) was observed under zero usage of TSP and intercropped maize-groundnut with the ratio of 1:1 rows. Crops in intercropping system have a complementary effect together. In this experiment, LER values greater than 1.00 indicated an intercrop advantage to sole crop. Results showed that IP increases the quantity and quality of products by increment in plant diversity, ecological balance, more utilization of resources, and reduction of damage by pests, diseases, and weeds in agricultural ecosystems.

Characterization of Fusarium Equiseti KUSF0105 with Respect to in-vitro Phosphate Solubilization under Varying Cultural Parameters

Presence of soluble phosphorous in the soil is an important determining factor for the overall growth and the development of the agricultural crops. Phosphate solubilizing microorganisms are the potential candidates for releasing the soluble phosphates from its bound complexes and thus make them available to the plants in utilizable forms. The present study was conducted to determine the effects of various culture parameters on the phosphate solubilization ability of the nonpathogenic Fusarium equiseti MF803160 isolated from soil sample of an agricultural field of Bamnabad village in Raninagar block II, Murshidabad, West Bengal, India. Nonpathogenic nature of the isolate was established by performing pathogenecity test on several seed plants. High phosphate solubilisation index (1.52) was found on Pikovskya agar medium. Phosphate solubilization was estimated by spectrophotometric method using molybdate vanadate reagent. Maltose (1800 ppm) and ammonium sulphate (1800 ppm) respectively were found to be most stimulatory in phosphate solubilization by the Fusarium isolate. Ammonium chloride also influenced phosphate solubilization nearly to the same extent (1780 ppm). Significantly, in acidic pH 4 (1830 ppm) and at 27°C temperature (1620 ppm), phosphate solubilization was found to be most satisfactory. Notably, with the increased in pH, phosphate solubilization declined gradually. Growth and phosphate solubilization of the isolate were completely checked at 37ºC. Thus, the Fusarium isolate could be exploited in agricultural fields as a potential phosphate biofertilizer.

Aplikasi Pupuk Hayati Fosfat dan Bahan Pembenah Tanah Organik untuk Meningkatkan Pertumbuhan dan Hasil Panen Jagung (Zea mays L) pada Tanah Masam

Acidity is still a serious obstacle for maize cultivation due to the very low availability of phosphorus. The use of phosphate biofertilizers, containing phosphate solubilizing bacteria as an active ingredient, together with organic ameliorants was expected to be able to provide phosphorus for plants and increase the organic C content in the soil. Experiment aimed to find the proper application of phosphate biofertilizers along with organic ameliorants to support the productivity of maize on acid soils. A factorial randomized block design was used with phosphate biofertilizers and organic ameliorants as the first factor and doses of inorganic P fertilizer as the second factor, all treatments was equipped with three replications. Results showed that the application of phosphate biofertilizers consisted of Enterobacter ludwigii, Bulkholderia vietnamiensis, and Citrobacter amalonaticus with the composition of chicken manure compost (25%): municipal waste compost (25%): coconut shell biochar (50%) at a dose of 5 tons/ha was able to increase plant dry weight and dry weight of shells per hectare by 248.87 g and 12.960 kg. The application of phosphate biofertilizers and organic ameliorants showed no significant effect to soil C-organic content. Phosphate biofertilizers and organic ameliorants can support the productivity of maize plants on acid soils

Effect of Harvesting Time and Phosphate Bio fertilizers on the Nutritive Value of Two Maize Varieties

Two Maize (Zea mays) varieties namely (Hudibia and Mugtama) and two harvesting times were used in this study to evaluate the effect of inorganic phosphorous(P2O5) and phosphate biofertilizers namely, Bacillus, mycorrhiza and the combination of them on maize forage quality. The evaluation was done by determining the percentage of CP, EE, OM, NDF, ADF, ADL, in vitro dry matter digestibility, and in situ degradability. A significant difference (P<0.05) was found between the two varieties for all parameters except for CP. Early time of harvest had the highest value of CP, EE, OM and DMD, and the lowest value of NDF, ADF and ADL. The highest percentage of organic matter (89.45%) was found for the treatment with bacteria alone, while the highest percentage of CP (12.9%) was found for the combination between bacteria and mycorrhiza, while the lowest percentage was found for the control. The highest value of DMD was recorded for the combination between bacteria and mycorrhiza while the lowest value was found for the control. The effect of inorganic phosphorous source (P2O5) and phosphorous biofertilizers on the fiber types was significant (P<0.05). For NDF the lowest value (52.52 %) was recorded in the combination between bacteria and mycorrhiza, while for ADF the combination between inorganic phosphorous and bacteria secured the lowest value (39.98). The highest readily degradable faction (a) was found in the Hudibia variety when fertilized by inorganic phosphorous + mycorrhiza, while the highest slowly degradable fraction (b) was found in the Mugtamaa Varity when fertilized by phosphorous+ bacteria. The highest potential degradability (PD) was found in Mugtamaa variety when fertilized by inorganic phosphorous+ mycorrhiza. From this study, it could be concluded that the combination between bacteria and mycorrhiza improved the nutritive value of the forage by increasing CP and DMD content and decreasing the NDF content.

The combined Application of Iron and Phosphate Solubilizing Bacteria to enhance Wheat (Triticum aestivum L.) growth and yield

This study had the objective of evaluating the efficiency of prepared iron and phosphate biofertilizers in improving wheat growth and yield. To isolate bacteria that dissolve iron and phosphate, different soil samples were collected from the Erbil governorate, a total of eighteen iron solubilizing bacteria were selected on a modified agar medium and all isolates belonged to Pseudomonas fluorescence. Twenty-two isolates of phosphate solubilizing bacteria were recognized and referred to P. putida, P.fluorescens, and Bacillus megaterium using microscopical, cultural, physiological and molecular tests. According to iron and phosphate solubilizing efficiency test, the most efficient isolate of iron solubilizing bacteria (Pfl3) and P-solubilizin bacteria (Ppu2, Bm14) were selected for biofertilizers preparation  Local and imported iron and phosphate biofertilizers were applied in pot experiment. Most biofertilizers were significantly increased yield components of wheat plants. Maximum shoot length, root length, tillers number,1000 seed weight, spike number and yield (99.60cm, 58.95cm, 22, 38.75g. 20, 5.52 ton/ha  respectively) were recorded by incoculation with P. Flourence + P. putida +B. megatrium significantly higher than uninoculated control and treatments with imported biofertilizer. It can be concluded that local iron and phosphate solubilizing bacterial isolates can be used for Fe and P biofertilizers.  &nbsp

Diversity, mechanisms and beneficial features of phosphate-solubilizing Streptomyces in sustainable agriculture: A review.

Currently, the use of phosphate (P) biofertilizers among many bioformulations has attracted a large amount of interest for sustainable agriculture. By acting as growth promoters, members of the Streptomyces genus can positively interact with plants. Several studies have shown the great potential of this bacterial group in supplementing P in a soluble, plant-available form by several mechanisms. Furthermore, some P-solubilizing Streptomyces (PSS) species are known as plant growth-promoting rhizobacteria that are able to promote plant growth through other means, such as increasing the availability of soil nutrients and producing a wide range of antibiotics, phytohormones, bioactive compounds, and secondary metabolites other than antimicrobial compounds. Therefore, the use of PSS with multiple plant growth-promoting activities as an alternative strategy appears to limit the negative impacts of chemical fertilizers in agricultural practices on environmental and human health, and the potential effects of these PSS on enhancing plant fitness and crop yields have been explored. However, compared with studies on the use of other gram-positive bacteria, studies on the use of Streptomyces as P solubilizers are still lacking, and their results are unclear. Although PSS have been reported as potential bioinoculants in both greenhouse and field experiments, no PSS-based biofertilizers have been commercialized to date. In this regard, this review provides an overview mainly of the P solubilization activity of Streptomyces species, including their use as P biofertilizers in competitive agronomic practices and the mechanisms through which they release P by solubilization/mineralization, for both increasing P use efficiency in the soil and plant growth. This review further highlights and discusses the beneficial association of PSS with plants in detail with the latest developments and research to expand the knowledge concerning the use of PSS as P biofertilizers for field applications by exploiting their numerous advantages in improving crop production to meet global food demands.

Double Production in Groundnut with Phosphatic Biofertilizers

Abstract: Groundnut (Arachis hypogea L., 2n=20) is nitrogen fixing pulse crop, belong to Leguminocae family. The present study conducted on production of groundnut with phosphatic biofertilizers. The experiment was conducted at Madhav village and Sattasar village in May, 2015. The mycorrhiza solid powder dissolved with molasses + water to form organic product. The seed poured in the formulated organic product for 24 hrs. Later, the seed was placed in the prepared land. The seed emerged from the soil in 7-10 days and the flower appeared in the plant within 35 days after sowing. The healthy nodule was formed in the root organ with application mycorrhiza solid powder. The application of mycorrhiza solid powder progresses morphological growth, yield, soil property and soil biology. Keywords: groundnut, production, biofertilizer, nodule formation

Psychrophilic Bacterial Phosphate-Biofertilizers: A Novel Extremophile for Sustainable Crop Production under Cold Environment.

Abiotic stresses, including low-temperature environments, adversely affect the structure, composition, and physiological activities of soil microbiomes. Also, low temperatures disturb physiological and metabolic processes, leading to major crop losses worldwide. Extreme cold temperature habitats are, however, an interesting source of psychrophilic and psychrotolerant phosphate solubilizing bacteria (PSB) that can ameliorate the low-temperature conditions while maintaining their physiological activities. The production of antifreeze proteins and expression of stress-induced genes at low temperatures favors the survival of such organisms during cold stress. The ability to facilitate plant growth by supplying a major plant nutrient, phosphorus, in P-deficient soil is one of the novel functional properties of cold-tolerant PSB. By contrast, plants growing under stress conditions require cold-tolerant rhizosphere bacteria to enhance their performance. To this end, the use of psychrophilic PSB formulations has been found effective in yield optimization under temperature-stressed conditions. Most of the research has been done on microbial P biofertilizers impacting plant growth under normal cultivation practices but little attention has been paid to the plant growth-promoting activities of cold-tolerant PSB on crops growing in low-temperature environments. This scientific gap formed the basis of the present manuscript and explains the rationale for the introduction of cold-tolerant PSB in competitive agronomic practices, including the mechanism of solubilization/mineralization, release of biosensor active biomolecules, molecular engineering of PSB for increasing both P solubilizing/mineralizing efficiency, and host range. The impact of extreme cold on the physiological activities of plants and how plants overcome such stresses is discussed briefly. It is time to enlarge the prospects of psychrophilic/psychrotolerant phosphate biofertilizers and take advantage of their precious, fundamental, and economical but enormous plant growth augmenting potential to ameliorate stress and facilitate crop production to satisfy the food demands of frighteningly growing human populations. The production and application of cold-tolerant P-biofertilizers will recuperate sustainable agriculture in cold adaptive agrosystems.

The Effect of Mycorrhizal Fungi and Organic Fertilizers on Quantitative and Qualitative Traits of Two Important Satureja Species

The quantitative yield and essential oil percentage and composition of two important savory species in response to various fertilizers were explored in a field experiment as a factorial study based on a randomized complete block design with three replications in north Lorestan, Iran, in 2017–2019. The first factor was assigned to three mycorrhizal fungi (Funneliformis mosseae, Rhizophagus irregularis, and Glomus fasciculatum), phosphate biofertilizer (Baravar-2), fish manure (800 kg/ha), cattle manure (20 t/ha), vermicompost (5 t/ha), and a control (no fertilization); the second factor was assigned to two savory species, including Satureja khuzestanica and S. rechingeri. The results of the combined analysis of variance for the second and third years showed that the simple effects of fertilizers and species were significant on all recorded traits, except for some constituents of the essential oil. Among the mycorrhizal fungi, R. irregularis and S. khuzestanica outperformed S. rechingeri in all traits, except for essential oil content and yield. The interaction between year and species was significant for all traits. The essential oil content of S. rechingeri in the third year (5.1%) was 18% higher than that of S. rechingeri in the second year (4.3%) and 41% higher than that of S. khuzestanica in the third year (3.6%). According to the results, the foliar application of vermin compost at a rate of 5 t/ha can contribute to the sustainable production of both savory species, improving their growth and essential oil yield.

Explicating proficiency of waste biomass-derived biochar for reclaiming phosphate from source-separated urine and its application as a phosphate biofertilizer

In this study, a phosphate biofertilizer was prepared from waste corn biomass that adsorbed phosphorus (P) from source-separated urine (SSU). The biochar was modified with magnesium (MgB), and its performance was compared with biochar without magnesium modification (CCB). The functional characteristics, such as the morphology, structure, and texture of the prepared biochar, were studied. The surface area values of MgB were detected to be 614 m2/g. At the same time, the average pore diameters were 50 nm indicating the presence of well-developed mesopores in the material. SEM study that reveals the development of honeycomb-shaped porous structure in the biochars. The Mg-biochar was validated of its high phosphate removal competency, achieving 96 % of phosphate recovery from synthetic urine. Elemental analysis of the biochar, before and after treatment, by EDAX confirms adsorption of phosphate on the surface of MgB. MgB that recovered phosphate from urine significantly increased the Mehlich3 phosphate blend of the soil, which indicated that the phosphate recovered from SSU by the biochar could be utilized to increase the plant-available phosphate in the soil. Seed germination experiments that carried out with Biochar and Biochar with recovered P were the testimony that the recovered phosphate can indeed uplift the crop health by increasing the nutrient content of the soil. Effective application of the biochar for disinfection of the pathogen, Brevundimonas diminuta found in the collected SSU, was demonstrated with the high efficacy of over ∼80 %.

Plant Growth-Promoting Effect of the Chitosanolytic Phosphate-Solubilizing Bacterium Burkholderia gladioli MEL01 After Fermentation with Chitosan and Fertilization with Rock Phosphate

Phosphate-solubilizing bacteria (PSB) are important plant growth-promoting rhizobacteria that can increase soil fertility through the solubilization of insoluble inorganic phosphate and organophosphorus. In this study, a PSB, Burkholderia gladioli MEL01, was isolated and identified from rice–wheat rotation rhizosphere soil. MEL01 had an excellent phosphate-solubilizing capacity (reaching 107.69 mg/L) toward insoluble inorganic phosphate rock phosphate. HPLC analysis revealed that the mechanism of phosphate solubilization of MEL01 was probably due to secreted oxalic acid and gluconic acid transformation of phosphate from insoluble to soluble. MEL01 also exhibited 4030 U/L specific chitosanase activity when cultured with chitosan fermentation medium. Interestingly, the chitosan hydrolysis product chitooligosaccharide could significantly enhance the MEL01 phosphate-solubilizing capacity. Pot experiments showed that MEL01 chitosan medium fermentation liquor (MCMFL) could promote improvement of soil available phosphorus and pakchoi growth when supplemented with phosphate rock phosphate as the phosphate fertilizer. In addition, pot experiments demonstrated that MCMFL could also promote the growth of wheat, which could decrease the amount of compound fertilizer used. Microbial diversity analysis showed that the genera Pseudomonas, Burkholderia, Mycoplana, and Cellvibrio were enriched, which might participate in synergetic phosphate solubilization. Therefore, after fermentation with chitosan and fertilization with rock phosphates, MEL01 has potential as a phosphate biofertilizer in ecological agricultural production.

EFFECT OF ADDITION OF VERMICOMPOST, BIO AND MINERAL FERTILIZER ON THE AVAILABILITY OF SOME NUTRIENTS IN SOIL AND POTATO YIELD

A nitrogenous bio-fertilizer comibination was prepared contain Azospirillum lipoferum, and Azotobacter chroococcum bacteria. A phosphate bio-fertilizer consisting of Bacillus megaterium and Glomus mosseae fungus was also prepared. vermicompost was produced from earthworms imported from Iran and others isolated locally. A factorial experiment was carried to evaluate the effect of the interaction between these combinations and vermicompost types under levels of 0%, 25% and 50% of NPK. The results showed a significant superiority of the bio-fertilizer (nitrogen and phosphate) treatment in available nitrogen in the soil after harvest, number of tubers, yield per plant , and the total yield with 39.70 mg N kg -1, 11.03 tuber plant -1, 1367.40 g plant-1, and 43.76 Mg ha-1 respectively. While phosphate bio fertilizer treatment giving available phosphorus in the soil by 22.74 Mg P kg -1 , vermicompost produced from imported earthworms was superior in giving available phosphate in the soil with value 22.74 mg p kg -1 . While the tri interaction was superior for all studied characteristics.

Microalgae based biofertilizer: A life cycle approach

Waste, especially biomass in general, is a large reservoir of nutrients that can be recovered through different technologies and used to produce biofertilizers. In the present study, environmental impacts of the production of microalgae biomass-based phosphate biofertilizer compared to triple superphosphate through life-cycle assessment conducted in the Simapro® software were investigated. The functional unit of the analysis was 163 g of P for both fertilizers. Phosphorus was recovered from a meat processing industry effluent in a high-rate algal pond. Impacts related to the entire biofertilizer chain impacted mainly on climate changes (3.17 kg CO2eq). Microalgae biofertilizer had higher environmental impact than conventional fertilizer in all impact categories, highlighting climate change and terrestrial ecotoxicity. An ideal scenario was created considering that: all energy used comes from photovoltaic panels; in the separation step a physical method will be used, without energy expenditure (i.e. gravimetric sedimentation) and; biomass will be dried in a drying bed instead of the thermal drying. In this scenario, the impact of biofertilizer approached considerably those of triple superphosphate. When impacts of biomass cultivation and concentration stages were disregarded, drying step was of great relevance, contributing to increase biofertilizer impacts. More research is needed to optimize the algae production chain and determine the possibility of obtaining higher added value products more environmental attractive.

Analysis of heat treatment of chicken bones for the obtaining of phosphate biofertilizer

Analysis of heat treatment of chicken bones for the obtaining of phosphate biofertilizer

P Solubilizing Potential of Some Plant Growth Promoting Bacteria Used as Ingredient in Phosphatic Biofertilizers with Emphasis on Growth Promotion of Zea mays L.

Given the negative environmental impacts of chemical fertilizers, application of phosphate solubilizing bacteria (PSB) as an ecofriendly and safe approach are becoming increasingly popular as substitute to chemical P fertilizers. Nowadays phosphatic microbial fertilizers (PMF) which are formulated by integration of rock phosphate (RP), organic residues, and efficient microorganisms including PSB are being used as biofertilizers to meet plant phosphorus demand. Accordingly, in this study, first P solubilization efficiency of PSBs (including Pseudomonas fluorescens Tabriz, Pseudomonas putida Tabriz, Pseudomonas sp. C16-2O, Enterobacter sp. S16-3, Bacillus megaterium JK6, Bacillus firmus SN1, and Pantoeaagglomerans P5) was checked under in vitro conditions, then the effectiveness of formulated PMFs was evaluated in pot culture using an autoclaved soil. PMFs of seven PSBs were prepared by adding PSB to the substrate consisting of RP, sulfur powder, and bagasse. The results of in vitro investigation on phosphate solubility of PSBs in qualitative (HD/CD) and quantitative procedures in Sperber medium indicated that there were significant differences among the bacteria and different sources of phosphorus. Moreover, P solubility index (HD/CD) showed a good correlation (r = 0.75, p < 0.05) with P solubility in liquid medium. The highest phosphate solubilization was measured by P. agglomerans P5>Pseudomonas sp. C16-2O >Enterobacter sp. S16-3 > P. putida Tabriz > B. megaterium JK6 > P. fluorescens Tabriz > B. firmus SN1, respectively, and dissolution of phosphorus from tricalcium phosphate (TCP) was higher than from RP. The results obtained from the greenhouse experiments revealed that the application of PMFs on corn had significant effect on fresh and dry weights of shoot and root, and the concentration and content of phosphorus in the root and shoot of corn. The measured parameters in treatments P. agglomerans P5, Pseudomonas sp. C16-2O, Enterobacter sp. S16-3, P. fluorescens and P. putida were significantly higher than control. Although, P5 strain had highest mean in all measured parameters among bacterial strains used in this study, but we introduce new isolated bacteria (S16-3 and C16-2O) along with P5 for further researches. Overall, the two bacteria Enterobacter sp. S16-3 and Pseudomonas sp. C16-2O can be considered because of their positive effects on corn growth [44 and 42% increase in shoot dry weight (SDW) and 1.60- and 1.39-fold increase in root dry weight (RDW), respectively] and P nutrition uptake (both 68% increase in SDW and 1.87- and 1.62-fold increase in RDW, respectively).

Phylogenetic analysis of halophyte-associated rhizobacteria and effect of halotolerant and halophilic phosphate-solubilizing biofertilizers on maize growth under salinity stress conditions.

The main objective of the present work was to evaluate plant growth-promoting abilities of bacterial strains from the rhizosphere of halophytes and their effect on maize growth under salinity stress. Halophilic bacteria were identified using 16S rRNA sequence analysis and their plant growth-promoting abilities were characterized. Phylogenetic analysis showed that bacterial strains belonging to Bacillus, Halobacillus and Pseudomonas were dominant in the rhizosphere of halophytes. More than 93% strains showed P-solubilization activity and IAA production. About 54% strains were able to produce ACC deaminase, 29% strains showed positive results for nitrogen fixation, 41 and 21% strains showed siderophores and HCN production ability respectively. More than 90% strains showed antifungal activity against more than two fungal pathogens and production of different hydrolytic enzymes. To study the plant growth-promoting effect on maize, five bacterial strains Bacillus safensis HL1HP11 and Bacillus pumilus HL3RS14, Kocuria rosea HL1RP8, Enterobacter aerogenes AT1HP4 and Aeromonas veronii AT1RP10 were used as inoculants; in the form of seed coat and enriched soil-based phosphate biofertilizers. All bacterial strains positively affected the maize growth as compared to non-inoculated control+NaCl plants. Plants inoculated with Bacillus HL3RS14-based soil biofertilizers showed maximum increase in dry weights of root (48-124%) and shoot (52-131%) as compared to control+NaCl (soil+rock phosphate, no inoculum). PGPR inoculations under salinity stress conditions showed high concentrations of proline, glycine betaine and malondialdehyde. These results indicated that under saline soil conditions, halophilic PGPR strains combined with carrier materials are promising candidates as biofertilizers.

Isolation and Characterization of the High Silicate and Phosphate Solubilizing Novel Strain Enterobacter ludwigii GAK2 that Promotes Growth in Rice Plants

Silicon (Si) and phosphorus (P) are beneficial nutrient elements for plant growth. These elements are widely used in chemical fertilizers despite their abundance in the earth’s crust. Excessive use of chemical fertilizers is a threat to sustainable agriculture. Here, we screened different Si and P solubilizing bacterial strains from the diverse rice fields of Daegu, Korea. The strain with high Si and P solubilizing ability was selected and identified as Enterobacter ludwigii GAK2 through 16S rRNA gene sequence analysis. The isolate GAK2 produced organic acids (citric acid, acetic acid, and lactic acid), indole-3-acetic acid, and gibberellic acid (GA1, GA3) in Luria-Bertani media. In addition, GAK2 inoculation promoted seed germination in a gibberellin deficient rice mutant Waito-C and rice cultivar ‘Hwayoungbyeo’. Overall, the isolate GAK2 increased root length, shoot length, fresh biomass, and chlorophyll content of rice plants. These findings reveal that E. ludwigii GAK2 is a potential silicon and phosphate bio-fertilizer.

Integrated Use of Maize Bran Residue for One-Step Phosphate Bio-Fertilizer Production.

The development of bio-fertilizer inoculants is important and desirable. Two phosphate-solubilizing Bacillus subtilis strains were inoculated onto maize bran residue (MBR), which was used as bio-fertilizer carrier and a primary source of nutrients in a medium used for semi-solid fermentation. Water holding capacity, swelling capacity, scanning electron microscopy, and shelf-life assays demonstrated that ground MBR had satisfactory properties for a bio-fertilizer carrier. The maximal soluble phosphorus (P) reached 642.7 ± 0.43mgl-1 in an orthogonal test under the following optimal conditions: a pH of 7.0, a cultivation temperature of 31°C, a medium water content of 160%, and a filling capacity of 500gl-1. The bio-fertilizer produced by MBR improved the growth of wheat (Triticum aestivum L.) and Chinese cabbage (Brassica rapa pekinensis) with respect to plant height (by up to 18.36%) and the lengths of roots (by up to 34.03%, 27.22%, separately) in a pot experiment. This study integrated the production and storage of a bio-fertilizer to realize the one-step production of a solid bio-fertilizer using MBR.