Phosphate Solubilizing Rhizobacteria Research Articles

Rizobactérias promotoras de crescimento de plantas isoladas de solos cultivados usando plantas Glycine max L. como isca

ABSTRACT: The current production of major crops, such as Glycine max L., has become increasingly adept on the use of bio-inputs, such as application of plant growth-promoting inocula. However, the evaluation of the potential of bacterial isolates from soils with different time histories of agricultural use are still scarce, and methods for isolation and testing of multifunctional microorganisms need to be continuously innovated and improved. Thus, we used G. max bait plants to attract rhizobacteria from soils obtained from three areas with different time histories of soybean cultivation. We evaluated the influence of the management and characteristics of soils on the phosphate-solubilizing bacterial population. We then tested the multifunctional potential of the isolated rhizobacteria for calcium phosphate (CaHPO4) and iron phosphate (FePO4) solubilization, considering their potential as microbial inoculants in the future. The use of bait plants enabled the isolation of 139 phosphate solubilizing rhizobacteria, including four strains with multifunctional potential. The largest number of solubilizing bacteria was obtained from the interaction of bait plants with soil from an area with a history of soybean cultivation for thirty consecutive years. The high concentration of P, Fe, and K found in the soil were associated with this occurrence. In the in vitro tests, the pH values of the culture media had a moderate negative relationship with the amounts of P made available by the isolates, indicating that other processes besides the availability of organic acids, may underlie the solubilizing action of the isolates. The rhizobacteria SAF9 (Brevibacillus sp.), SAF11 (Brevibacillus sp.), BRC11 (Pseudomonas fluorescens), and SAC36 (Bacillus velezensis) stood out as multifunctional and are indicated within a perspective of obtaining bioinoculants to promote plant growth directly, indirectly, or synergistically, contributing to increase the range of bio-inputs for soybean cultivation and more sustainable agricultural practices.

Competition and co-association, but not phosphorous availability, shape the benefits of phosphate-solubilizing root bacteria for maize (Zea mays).

Predicting the conditions under which rhizobacteria benefit plant growth remains challenging. Here we tested the hypothesis that benefits from inoculation with phosphate-solubilizing rhizobacteria will depend upon two environmental conditions: phosphate availability and competition between bacteria. We used maize-associated rhizobacteria with varying phosphate solubilization ability in experiments in soil, sterilized soil and gnotobiotic microcosms under conditions of varying orthophosphate availability, while we manipulated the intensity of competition by varying the number of isolates in plant inocula. Growth promotion by microbes did not depend on phosphate availability but was affected by interactions between inoculants: the beneficial effects of one Serratia isolate were only detectable when plants were inoculated with a single strain and the beneficial effects of a competition-sensitive Rhizobium was only detectable in sterilized soil or in microcosms inoculated with single strains. Moreover, microcosm experiments suggested that facilitation of a parasitic isolate, not competitive interactions between bacteria, prevented plants from gaining benefits from a potential mutualist. Competition and facilitation affected colonization of plants in microcosms but growth promotion by Serratia was more affected by inoculation treatment than culturable densities on roots. Experimental manipulation of seed inocula can reveal whether plant growth stimulation is robust with respect to competition, as well as the ecological strategies of different rhizobacteria. From an applied perspective, phosphate solubilization may not provide the mechanism for bacterial growth promotion but may indicate mutualistic potential due to phylogenetic associations. Importantly, benefits to plants are vulnerable to interactions between rhizobacteria and may not persist in mixed inoculations.

Phosphate solubilizing rhizobacteria inoculation to increase rock phosphates efficiency and improve maize growth

Rock phosphates are less soluble and agronomically not as efficient as the acidulated. However, some rhizobacteria can improve the solubilization of inorganic phosphates in the soil, raising the efficiency of the rock phosphates. The objective was to evaluate the development of maize plants in response to the application of soluble and rock P sources associated with rhizobacteria inoculation. A greenhouse experiment was carried out with six P sources: no P application; ​​Triple Superphosphate (TSPh); Gafsa rock phosphate (reactive); Itafós rock phosphate (non-reactive); TSPh + Gafsa; and TSPh + Itafós, and three inoculation forms: no inoculation, Burkholderia pickettii GN 2214 and Pseudomonas sp. fluorescens group P21. Plant height, stem diameter, leaf area, shoot dry weight (ShDW), root dry weight (RDW), total dry weight, cumulative P content in ShDW, RDW/ShDW ratio and relative agronomic efficiency were assessed. Agronomic efficiency and growth of the TSPh-treated plants were better than of those treated with rock phosphates. The association of TSPh with rock phosphates increases the agronomic efficiency and maize plant growth more than the isolated rock sources. Inoculation with P. fluorescens strain P21, improved the performance of maize fertilized with Gafsa phosphate, but had no effect when associated with Itafós phosphate. Together with TSPh, inoculation intensified shoot and root growth, indicating the potential to increase the efficiency of soluble sources as well.

Role of Phosphate Solubilizing Rhizobacteria in Growth and Productivity of Green Leafy Vegetables. A Review

Chemical based phosphate (PO4-3) fertilizers occupies significant place in agricultural domainand ought to be dangerous (e.g. cause chronic kidney disorders, eutrophication). Hence, world isyelling for an efficient substitute of PO4-3 fertilizer. This fertilizer is being used to escalate yieldof green leafy vegetables, which are loaded with health nutrients, consequently, world is fallingfor this Mediterranean mode of diet. Phosphate Solubilizing Rhizobacteria (PSB) could come tothe rescue and would be an economical and ecofriendly substitute of such fertilizer. This reviewdraws attention of researchers, to unveil the understudied aspects i.e. role and mechanisms ofPO4-3 solubilization, driven by PSB in association with green leafy veggies (viz, Cabbage,Spinach, Lettuce). As found that PSB application could give desirable results i.e. uplift theproductivity of green leafy vegetables and one if designed as biofertilizer, could ameliorateharmful effects of such fertilizer, caused upon human consumption

Plant growth promoting characterization of indigenous phosphate solubilizing rhizobacteria and effects on germination of some crops in Vietnam

Inorganic Phosphate Solubilizing Bacteria (PSB) are widely present in nature and have been successfully applied in fields in many countries. However, researches on indigenous PSB are still very limited in Vietnam. The objective of this study was to isolate and evaluate the growth promoting characteristics and effects on germination of seed of indigenous PSB for fertilizer production from PSB. Thirteen isolates of indigenous PSB were collected using selective isolation medium containing Ca3(PO4)2, of which eight added the ability to dissolve AlPO4 and five isolates added the ability to dissolve FePO4. Initial qualitative tests indicated that all thirteen PSB isolates were incapable of HCN and lipase production while other growth promoting activities including amylase, caseinase, cellulase, chitinase, pectinase, indole acetic acid, K solubility, Zn solubility, and N fixation varied according to PSB isolate. The collected PSB isolates had no effect on seed germination rate, root length, and hypocotyl length of plantules of soybean, rice, maize, cucumber, tomato, and chili by plate assay. This study had shown that PSB was also common in the rhizosphere of various crops in Vietnam. Therefore, isolation to enrich the indigenous PSB collection was essential for the screening of suitable PSB strains for subsequent fertilizer production.

Characterization of phosphate solubilizing plant growth promoting rhizobacteria isolated from pea rhizosphere (Pisum sativa)

The rhizosphere soil is a source for a diversity of microorganisms which play a vital role in the enhancement of plant health through the mechanism of symbiotic interaction thereby influencing the plant growth. The present study aimed at isolating potential phosphate solubilizing rhizobacteria from pea (pisum sativa) crop for which, rhizosphere soil samples were collected from two pea growing districts of Kashmir valley viz. Srinagar and Baramulla. Isolates were cultured on nutrient agar medium followed by serial dilutions and different colonies with morphological variations were isolated from each dilution. A total of 80 bacteria were isolated and maintained as pure cultures. Out of the 80 isolates, 25 strains showed phosphate solubilizing ability and amongst them, 9 were highly potential which were subjected to morphological and biochemical characterization. Furthermore, the potential bacteria were analysed for Indole Acetic Acid (IAA) production, which was found to be directly proportional to the plant growth promotion. After screening the best nine isolates PGP1, PGP10, PGP28, PGP40, PGP49, PGP52, PGP60, PGP72 and PGP75 were selected for their effect on growth and yield in field conditions using pea as test crop.

Nitrogen-Fixing and Phosphate Solubilizing Potentials of Rhizobacteria from the Rhizosphere of Two Cassava Varieties in Iyamho Community

Microorganisms in close association with the roots of plants can enhance plant growth, through nitrogen fixation (NF) and phosphorus solubilization (PS). Although the type of microbes in close association with different plants varies, their population and genetic capabilities is affected by several factors. Therefore, in this study, the plant growth promoting properties of rhizobacteria present in the rhizosphere of two cassava varieties (Sweet cassava US, bitter cassava ST) indigenous to Iyamho community was explored. The samples were analyzed for total culturable heterotrophic bacteria community and the obtained isolates were screened for NF and PS abilities using a semi-solid N-free medium and Pikovaskya agar respectively. The bacterial population in both agar medium varied, however, the bacterial counts on Luria Bertani (3.67 x 105, 3.35 x 106) was higher than Nutrient agar (2.73 x 105, 2.68 x 105) after incubation for 24 hours at 37oC for sweet and bitter cassava rhizosp here respectively. Also, isolates from sweet cassava had the highest bacteria count in both Nutrient agar and Luria Bertani agar. A total of sixteen isolates were obtained, six phosphate solubilizers, five nitrogen fixers, and five without traits for either NF or PS. The Gram-negative bacterial group was more dominant across all isolates while the dominant genus was Bacillus. This study indicates that the nitrogen fixers and phosphate solubilizers are major constituents of the rhizomicrobe of cassava plants although the distribution varies across cassava varieties. However, sweet cassava rhizosphere harbored more nitrogen-fixing bacteria while both varieties had the same amount of phosphate solubilizing rhizobacteria.

CHARACTERIZATION AND POLYPHASIC IDENTIFICATION OF NOVEL RHIZOBACTERIA STRAIN ISOLATED FROM SAND DUNES ECOSYSTEM

The coastal sand dune ecosystem at the Parangtritis Coast of Yogyakarta, Indonesia has unique characteristics such as low moisture sandy soil, high salinity and low nutrient content. Fimbristylis cymosa is one of the plant species having the capability to survive in that unique ecosystem. In this study, rhizobacteria isolated from the rhizosphere of F. cymosa were isolated to be further analyzed on their phosphate solubilizing and antagonistic properties against Fusarium oxysporum which cause the Wilt disease. The isolates of Phosphate Solubilizing Rhizobacteria (PSR) having the most potential capabilities were then polyphasically identified based on phenotypic and genotypic characters followed by 16S rDNA sequencing. The results showed that four PSR isolates (I8, I11, I12 and I24) have high phosphate dissolution indices. The highest indices were observed in isolates I11 (3.08) and I12 (3.44), respectively. Analysis of the dual plate experiments for PSR I11 and PSR I12 isolates against the growth of F. oxysporum also showed quite high inhibitory activities, i.e., isolate PSR I11 was 42.40%, while isolate PSR I12 was 42.08%. The two isolates were polyphasically identified as Burkholderia dolosa. This study clearly showed that PSR I11 and PSR I12 isolates are very potential and prospective to be used as marginal land inoculants and as providers of phosphorus. This study also showed that the isolates are useful as biocontrol agents against F. oxysporum in plants. Keywords: inhibitory activity, phosphate dissolution index, phosphorus, polyphasic identification, sandy soil

EXPLORING POTENTIAL OF METAL RESISTANT AND PGP ATTRIBUTES OF PHOSPHATE SOLUBILIZING RHIZOBACTERIA ISOLATED FROM SOUTHERN PUNJAB, PAKISTAN

Phosphorus is highly required nutrient for proper plant functioning and growth but due to its highly reactive nature it changed its form after short period of time when we applied as fertilizer and become unavailable for plant uptake while Phosphate solubilizing rhizobacteria are powerful candidates that solubilize the P that is already present in soil. So, the present research based on the hypothesis to isolating, screening and optimizing the phosphate solubilizing rhizobacteria with potential of metalresistant and multiple PGPR attributes. Total 55 PSR strains were isolated out of which 20 strains (WUSB1,WUSB2, WUSB3, WUSB4, WUSB5, WUSB6, WUSB7, WUSB8, WUSB9, WUSB10, WUSB11, WUSB12, WUSB13, WUSB14, WUSB15, WUSB16, WUSB17, WUSB18, WUSB19, WUSB20) were selected with 4-8 (PSI) and 30-122?g/ml phosphate solubilization in NBRIP medium for one weekincubation at 370C. These strains were further analyzed for their physiochemical attributes, metal resistant, extracellular enzyme production and PGP attributes. Final results showed that one candidate designated the name as WUSB16 produce significant results i.e. having capacity to solubilize P 5.46 (PSI) on agar plate assay and 105?g/ml in broth assay, Acid and alkaline phosphatase production 20?mol PNPb ml-1 hr-1 or 15?mol PNP ml-1 hr-1 respectively. It showed metal resistant against ZnSO4, MnSO4 and CuSO4. Evaluation of PGP attributes indicated that the capacity of WUSB16 strain for auxin production was 100?g/ml, for siderophore and nitrogen fixation was stronger (+++), for Hydrogen Cyanide and ammonia production was medium (++) and for ACC deaminase was negative (-). From above results we can conclude that WUSB16 PSR strain with multifaceted PGP traits is the best candidate that have potential to utilized as Phosphate solubilizing bioinoculant.

Effect of Rhizobacteria Inoculation via Soil and Seeds on Glycine max L. Plants Grown on Soils with Different Cropping History

Field experiments testing the effect of phosphate-solubilizing rhizobacteria (PSRB) should consider the cropping history and the method used to inoculate the strains. We evaluated the hypothesis that PSRB previously isolated from soybean seedlings could be effective in promoting growth in this oilseed crop in soils with different cultivation periods. We also evaluated whether this growth promotion could be influenced by cultivation histories or the inoculation method (via seeds or soil). Thus, we conducted an experiment in five fields cultivating Glycine max during two seasons (2019/2020 and 2020/2021), to test the effectiveness of PSRB (SAF9-Brevibacillus sp., SAF11-Brevibacillus sp., and SAC36-Bacillus velezensis) compared with results observed for the inoculant BiomaPhos (mix of Bacillus subtilis and Bacillus megaterium). The present study was based on the evaluation of vegetative growth, nutritional and yield parameters, and microbial biomass carbon (MBC). PSRB were more effective than, or showed similar effectiveness to, BiomaPhos for most of the evaluated vegetative, nutritional, and yield characteristics. In the fields tested in the summer 2019/2020 crop, SAC36 and SAF9 strains stood out as growth promoters, whereas in the 2020/2021 crop, SAF11, SAC36, and BiomaPhos were notable. There did not seem to be a direct relationship between long histories of soybean cultivation as a monoculture and low yield in the field. However, yield seems to be associated with soil nutritional characters such as Ca, Mg, K, P, cation exchange capacity, and organic matter levels. PSRB inoculation positively affected nodulation (NN) and nodule dry mass (NDM) in the evaluated fields in the 2019/2020 crop, and the aerial part dry mass (APDM), NN, NDM, yield, and MBC of the evaluated fields in the 2020/2021 crop. In contrast, the inoculation method was observed to have a strong effect on APDM, NN, root dry mass, and MBC, as the plants inoculated via seed showed higher mean values than those in the plants inoculated via soil. This study demonstrated the growth-promoting potential of new phosphate-solubilizing strains, which may eventually be incorporated by the biostimulants market to freely compete with BiomaPhos.

Characterization of phosphate solubilizing plant growth promoting rhizobacterium Lysinibacillus pakistanensis strain PCPSMR15 isolated from Oryza sativa.

The rhizosphere soil is a source for a diversity of microorganisms which play a vital role in the enhancement of plant health through the mechanism of symbiotic interaction thereby influencing the plant growth. The present study aimed at isolating potential phosphate solubilizing rhizobacteria from rice (Oryza sativa) crop for which, four different rhizosphere soil samples were collected from different locations of Tiruvallur district, India. Isolates were cultured on nutrient agar medium followed by serial dilutions and different colonies with morphological variations were isolated from each dilution. A total of 52 bacteria were isolated and maintained as pure cultures. Out of the 52 isolates, 16 strains showed phosphate solubilizing ability and amongst them, 4 were highly potential which were subjected to morphological and biochemical characterization. Phosphate solubilizing bacterial strains when assessed for their possible effect of their inoculation on the growth and development of mung bean seeds significantly enhanced the growth of the plants. Furthermore, the potential bacteria were analysed for Indole Acetic Acid (IAA) production, which was found to be directly proportional to the plant growth promotion. Upon the comparative analysis of the four potential isolates, PCPSMR15 exhibited remarkable plant growth promoting traits. A detailed biochemical and molecular analysis identified the promising strain PCPSMR15 as Lysinibacillus pakistanensis. The present study, thus signifies the strain, PCPSMR15 for exploration as an inoculant for improving soil fertility, enhancing phosphorus availability to plants and improved crop production and sustainability.

Identification, characterization and optimization of phosphate solubilizing rhizobacteria (PSRB) from rice rhizosphere

Two billion people worldwide take rice (Oryza sativa L.) as a staple food. Phosphorus (P) and Nitrogen (N) are the major requirements of rice; although these are available in limited concentrations within rice growing regions. Among different types of Plant growth-promoting rhizobacteria (PGPR), Phosphate solubilizing rhizobacteria (PSRB) constitute an important class. These are known for plant growth promotion by enhancing P and N uptake. PSRB are nowadays used as biofertilizers to restore the soil health. Under the present investigation identification, characterization and optimization of phosphate solubilizing activity of these microbes at different pH, temperature and salt concentrations was carried out. Thirty-seven isolates were recovered from different regions of rice rhizosphere on Pikovskaya(PVK) agar among which 15 isolates were recovered from R.S. Pura, 12 isolates from Bishnah and 10 isolates were recovered from Akhnoor sector of Jammu, India. A prominent halo zone of clearance was developed around the colonies of 12 different isolates, indicating phosphate solubilization activity. Four distinct isolates were amplified, cloned and sequenced for taxonomic identification using 16S primers. The results indicated that PS 1, PS 2, PS 3, PS 4 were related to Pseudomonas aeruginosa, Bacillus subtilis strain 1, B. subtilis strain 2, B. subtilis strain 3, respectively. These strains when grown at a wide range of ecological factors showed maximum growth at pH between 6.8 and 8.8, temperature between 28 °C and 37 °C and salinity between 1% and 2%. Screening for phosphate solubilization activity revealed that the halo zone diameter formed by these isolates extended from 2.1 to 3.2 mm. The phosphate solubilizing efficiency (SE) ranged from 35.4 to 50.9 with highest value of 50.9 by PS4 and maximum P solubilization of 10.22 µg/ml was recorded by PS4 at 7th day. Phosphate solubilization activity of these identified PSRB strains can be utilized and explored in the rice growing belts of Jammu region which are deficient in phosphorus. MIC value for zinc sulphate heptahydrate in 12 isolates varied from 1 mg/ml to 6 mg/ml. Phosphate solubilization activity and MIC of these identified PSRB strains can be utilized and explored in the rice growing belts of Jammu region which are deficient in phosphorus.

Phosphate solubilizing rhizobacteria isolated from jujube ziziphus lotus plant stimulate wheat germination rate and seedlings growth.

Jujube plant (Ziziphus lotus (L.) Desf.) can survive in arid climates and tolerates both biotic and abiotic stresses. Here, we isolated, for the first time in Morocco, nine phosphate solubilizing bacteria strains from jujube rhizosphere, designated J10 to J13, J15, & J153 to J156. Genotypic identification based on 16S rDNA sequencing, revealed six strains that belong to Pseudomonas (J10, J12, J13, J15, J153 and J154), two to Bacillus (J11 and J156), and one to Paenibacillus J155. Siderophores were produced by all strains. Proteases activity was missing in Pseudomonas sp. J153 & J154, whereas cellulase was restricted only to Pseudomonas sp. J10, Paenibacillus xylanexedens J155 and Bacillus cereus J156. Indole-3- acetic acid and ammonia were also produced by all strains, with a maxima of 204.28 µg mL−1 in Bacillus megaterium J11 and 0.33 µmol mL−1 in Pseudomonas sp. J153, respectively. Pseudomonas sp. J10 and B. cereus J156 grew on plates containing 1,500 µg mL−1 of nickel nitrate, while Pseudomonas sp. J153 withstood 1,500 µg mL−1 of either copper sulfate or cadmium sulfate. Phenotypic analysis of the potential of the isolates to promote early plant growth showed that wheat seeds inoculated with either P. moraviensis J12 or B. cereus J156 remarkably increased germination rate and seedlings growth. Lastly, antibiotic resistance profiling revealed that except for Pseudomonas sp. J11 and B. cereus J156, remaining strains displayed resistance at least to one of tested antibiotics. Collectively, Pseudomonas sp. J10, P. moraviensis J12, Pseudomonas sp. J153 and B. cereus J156, represent potential biofertilizers suitable for soils that are poor in P, and/or heavy metals contaminated.

Rhizosphere mediated growth enhancement using phosphate solubilizing rhizobacteria and their tri-calcium phosphate solubilization activity under pot culture assays in Rice (Oryza sativa.).

Phosphate solubilizing rhizobacteria are considered as an important alternative to increase the availability of accumulated phosphates through solubilization. These increase the growth of plant by enhancing the efficiency of fixing biological nitrogen. This was studied through a pot experiment involving two Phosphate Solubilizing Rhizobacteria (PSRB) isolates, Pseudomonas aeruginosa and Bacillus subtilis along with Tri-calcium phosphate (TCP) on availibity of nutrients, biological composition of soil and yield attributes of rice crop at its growth stages. Experiment was laid in factorial completely randomized design (CRD) comprising of eight treatments replicated thrice with two factors viz. factor 1 with or without TCP (1 g−1soil) and factor 2 with single or combined inoculation of PSRB isolates. Considerable enhancement in available content of potassium (K), phosphorous (P), nitrogen (N) in soil was found with TCP 1 g−1soil (P1) and consortium of Pseudomonas aeruginosa and Bacillus subtilis broth culture at crop growth stages. Highest increase in available N (17.13% and 19.1%), available P (232% and 265%), available K (19.6% and 29.2%) over control were recorded in B3 (consortium of Pseudomonas aeruginosa and Bacillus subtilis broth culture). Similarly, maximum nutrient uptake N (6.4%), P (15.8%) and K (8.9%) were recorded with same treatment. A considerable growth in soil microbial biomass carbon and dehydrogenase activity at crop growth stages was recorded on application of TCP 1 g−1soil (P1) and consortium of PSRB isolates' Pseudomonas aeruginosa and Bacillus subtilis (B3). Highest increase in microbial biomass carbon (16.4% and 16.5%) and dehydrogenase activity 34.7% and 43.8% over control were recorded in B3 (consortium of PSRB isolates Pseudomonas aeruginosa and Bacillus subtilis) and was found best among all treatments in terms of yield (63.2%) and yield attributes; number of panicles−1plant (54.8%), number of grains−1panicle (156%) and average panicle length (63.9%).

Complete Genome Sequences of Pseudomonas atacamensis Strain SM1 and Pseudomonas toyotomiensis Strain SM2, Isolated from the Date Palm Rhizosphere.

Here, we announce the complete genome sequences of two phosphate-solubilizing rhizobacteria, Pseudomonas atacamensis strain SM1 (genome size, ∼5.9 Mb) and Pseudomonas toyotomiensis strain SM2 (genome size, ∼5.2 Mb), isolated from the rhizosphere of date palms growing in the oasis agroecosystem of the United Arab Emirates (UAE).

Enhanced Crop Productivity and Sustainability by Using Native Phosphate Solubilizing Rhizobacteria in the Agriculture of Arid Zones

The importance of phosphate solubilizing rhizobacteria (PSB) has been well-document as an option for enhancing sustainable agriculture. As a particular group of plant growth promoting rhizobacteria (PGPR), PSB play an important role in the soil phosphorus cycle, increasing the bioavailability for growth and plant development. This study analyses the plant growth promoting effects of 5 strains (BN0009, BN0013, BN0015, BN0024, and BN0035) out of 180 isolated from Jarava frigida (Phil.) F.Rojas (Poaceae), a native grass from the Andean Atacama desert from North of Chile. The five bacterial isolated (BN strains) were identified as non-pathogenic Erwinia sp. and show a high phosphate solubilization capacity for Ca(PO4) ranging from 608.9 to 781.4 mg/L. Strains IAA production varies between 23.5 and 35.9 mg/L, siderophores, phosphatase (alkaline and acid) production was also observed, but none of the five isolated presented antagonism against plant pathogens Botrytis sp. and Sclerotinia sp. All isolates enhanced seed germination in Lactuca sativa and Solanum lycopersicum (excepting BN009). Additionally, all strains stimulated the early root elongation and seedling development in lettuce and tomato. Pot experiments displayed that BN0015, BN0024, and BN0035 significantly promote plant growth regarding root and leaf area, root and leaf weight, as well as leaf number compared with non-treated plants. In a field experiment with lettuce and two fertilization treatments (50 and 100% of the recommended crop fertilization), BN0024 application improved crop productivity compared to respective control. P content in plants with bacterial inoculations increased significantly compared to control in either fertilization treatment, suggesting an improved nutrient uptake. Also, lettuce with 50% fertilization and inoculation with BN0024 equate productivity with the control 100% fertilization. Finally, we discuss these results in the context of applicability to enhance the agroecosystem productivity in arid and semiarid zones.

Seed bio-priming with tri-species consortia of phosphate solubilizing rhizobacteria (PSR) and its effect on plant growth promotion

Three potential rhizobacteria namely Burkholderia gladioli (MTCC 10216), Pseudomonas sp. (MTCC 9002) and Bacillus subtilis (MTCC 8528) procured from IMTECH, Chandigarh (India) were evaluated individually and as consortia for its phosphate (P) solubilizing ability and effect of growth of fenugreek (Trigonella foenum-graecum L.) and tomato (Lycopersicon esculentum L.). Phosphate solubilizing ability of these strains individually and as consortia was tested on Pikovskayas agar medium, Phosphate solubilizing agar medium and National Botanical Research Institute phosphate agar medium containing six different sources of insoluble inorganic phosphate such as tri-calcium phosphate (TCP), di-calcium phosphate (DCP), zinc phosphate (ZP), ferric phosphate (FP), sodium di-hydrogen phosphate (SP), and aluminum phosphate (AP), and two organic P such as calcium and sodium phytate. The maximum P solubilizing ability was recorded in consortium-4 having all three potential bacterial strains. Phosphate solubilization after 7th day of incubation was 37.9 mg/100 ml of TCP, 40.01 mg/100 ml of DCP, 15.79 mg/100 ml of FP, 43.02 mg/100 ml of SP, no solubilization of ZP and AP, 39.75 mg/100 ml of calcium phytate and 24.01mg/100 ml of sodium phytate. Seed germination and the other plant parameters such as plant height and weight significantly increased in fenugreek and tomato seeds, bio-primed with consortium-4 followed by consortium-3. After bio-priming of seeds in pot assay, the level of phosphorus in soil got increased by 54% in consortium-4 treated soil followed by consortium-3 (47%) over untreated control soil. Based on these findings, consoritium-4 could be recommended as a good bio-inoculant for fenugreek, tomato and other crops in comparison to individual strains and other consortia.

Screening and Molecular Identification of Phosphate-Solubilizing Rhizobacteria from Mangrove Ecosystem of the Lombok Island

Phosphate solubilizing rhizobacteria can be used as a component in biofertilizer formulations to increase local and national food production without causing adverse risks to the environment compared to the use of chemical fertilizers. In this regard, screening and identification of phosphate solubilizing bacteria from the rhizosphere of several mangrove species that grow on the coast of Lombok Island has been carried out. The method of isolation used is the Pikovskaya method. Screening and identification activities have obtained 5 isolates of mangrove rhizosphere bacteria (BRM) which are indicated by their ability to form clear zones on Pikovskaya media, namely isolates BRM1 and BRM4 (isolated from the rhizosphere of Avicennia marina), BRM2 and BRM3 (isolated from the rhizosphere of Rhizophora apicullata), BRM5 (isolated from the rhizosphere of R. stylosa). All rhizobacteria isolates were identified as Gram-positive bacteria. Molecular analysis based on the comparison of 16S rRNA gene sequences of isolates with the genome database at GenBank (NCBI) using Mega 10 software, showed that all BRM isolates occupied the same cluster as bacterial species from the Genus Paenibacillus in the dendrogram of the phylogenetic tree, namely Paenibacillus sp. JWLB1 strain, Paenibacillus sp. Strain NO13, P. cineris strain cu1-7, P. favisporus strain CHP14, with genetic distance ranging from 1.3 to 1.4. Many species of the Genus Paenibacillus are currently known to play an important roles as plant growth-promoting bacteria. The BRM isolates obtained in this study can be further developed as a biofertilizer component (inoculant) in saline and dryland agriculture.

Sosialisasi Penggunaan Pupuk bioorganik-fosfat Pada Tanaman Cabai Merah (Capsicum annum L)

Bioorganic-phosphate fertilizer is an organic fertilizer enriched with phosphate solubilizing rhizobacteria (PSR). The addition of PSR to organic fertilizers is intended to improve the quality of organic fertilizer. The purpose of this community service activity is to socialize the use of bioorganic-phosphate fertilizers on red chili plants for reducing the use of inorganic fertilizers. This service activity used a participatory approach. As a target farmer partner is the "Bahtera" farmer group in Narmada Village, Narmada District, West Lombok Regency. This activity began with establishing a joint agreement between the community service team and the target farmers through a group discussion (FGD). The next activity was an extension activity about "bioorganic-phosphate fertilizer, its role, and benefits". Next, Activity of demonstration plot of integrated fertilizing was made at the farmer land to show the difference in yield with/ without used the combination fertilizer of bioorganic-phosphate and inorganic fertilizer. The chili yields show that fertilizing of the combination of bioorganic-phosphate and 75% of the recommended fertilizer dosage is higher than the 100% of the recommended dose. these community service activities achieve a positive response from farmers. This socialization activity needs to be carried out in other locations so that more farmers applying a fertilization pattern by combining bioorganic-phosphate and inorganic fertilizers

Molecular Characterization of Rhizobacteria (Isolate EO-4) as Potential Solvent of Phosphate in-vitro from the Mangrove Ecosystem of Teluk Awur, Jepara-Indonesia

Rejuvenation and conservation of mangrove ecosystems, especially the Teluk Awur mangrove ecosystem, Jepara Regency, can be done by using bacteria that are capable of supporting plant growth or called Plant Growth Promoting Rhizobacteria (PGPR). One of the mechanisms that support plant growth by the PGPR group is phosphate dissolving activity, because the phosphate in the soil is in the form of a compound that is difficult for plants to absorb. This study aims to determine the character of Rhizobacter isolates as a superior phosphate solvent in dissolving phosphates in-vitro from the Teluk Awur mangrove ecosystem, namely isolates coded EO-4. These isolates have similar microbiological and biochemical characters to the genus Enterobacter. Molecular characterization of isolates was carried out using the Polymerase Chain Reaction (PCR) method - 16S rRNA sequence analysis (comparing with 16S rRNA sequences in gene banks). The results showed that the phosphate-solubilizing rhizobacteria that were isolated had the same base pair percentage of 48% with Enterobacter pyrinus (access number NR_028875).