National Botanical Research Institute Research Articles

Pouzolzia friisii (Urticaceae, Boehmerieae), a new species from north‐east India

Based on a collection housed at LWG (Herbarium of CSIR–National Botanical Research Institute, Lucknow, India), collected by Singh et al. on 25 June 2017 from Nagaland state of India, Pouzolzia friisii A.Gupta & V.Wagh sp. nov. (Urticaceae) is described and illustrated. The species resembles Pouzolzia sanguinea var. fulgens, P. niveotomentossa and P. australis in its serrated leaf margins and the indumentum on the abaxial leaf surface however, P. friisii is quite distinct in its grayish or pale yellowish indumentum, 4‐merous sessile male flowers and densely pubescent fruiting perianths without wings and ribs. A detailed description, illustration, distribution map, and information on ecology, as well as phenology are presented.

The Herbarium of the National Botanical Research Institute, Lucknow

No Abstract.

Screening and biodiversity analysis of cultivable inorganic phosphate-solubilizing bacteria in the rhizosphere of Hydrilla verticillata.

The inorganic phosphate-solubilizing bacteria (IPB) in the rhizosphere of Hydrilla verticillata can convert insoluble inorganic phosphorus in the environment into soluble phosphorus that can be directly absorbed and utilized by Hydrilla verticillata. In this research, the roots and rhizosphere sediments of Hydrilla verticillata were collected from high-organic matter urban landscape water. The National Botanical Research Institute's Phosphate growth medium (NBRIP medium) was used to screen for efficient cultivable IPB. The 16S rRNA gene sequence analysis was used to determine the taxonomic affiliation of the strains, and ammonium molybdate spectrophotometry was used to detect the phosphate-solubilizing ability of the strains. The results show that a total of 28 IPB strains with good phosphate-solubilizing effect are obtained from the roots and rhizosphere sediments of Hydrilla verticillata. These IPB strains belong to two phyla, four orders, seven classes, nine families, and nine genera. Among these, Bacillus and Acinetobacter are the dominant genera, and the strains SWIH-7, SWIP-6, SWIP-7, SWIP-13, SWIP-15 and SWIP-16 are potential new species. The IPB strains isolated and screened in this research are rich in diversity, with potential new species and stable phosphate-solubilizing characteristic. These IPB strains are suitable for further development as microbial bacterial agents, which can be applied to promote the recovery of submerged plants in polluted water with high-organic matter, treatment of polluted water and ecological restoration of water.

Characterization and evaluation of potential halotolerant phosphate solubilizing bacteria from Salicornia fruticosa rhizosphere.

Soil salinization is a significant abiotic factor threatening agricultural production, while the low availability of phosphorus (P) in plants is another worldwide limitation. Approximately 95-99% of the P in soil is unavailable to plants. Phosphate-solubilizing bacteria (PSB) transform insoluble phosphates into soluble forms that plants can utilize. The application of PSB can replace or partially reduce the use of P fertilizers. Therefore, selecting bacteria with high solubilization capacity from extreme environments, such as saline soils, becomes crucial. This study aimed to identify twenty-nine bacterial strains from the rhizosphere of Salicornia fruticosa by sequencing the 16S rDNA gene, evaluate their development in increasing concentrations of NaCl, classify them according to their salinity response, and determine their P solubilization capability. The bacteria were cultivated in nutrient agar medium with NaCl concentrations ranging from 0.5% to 30%. The phosphate solubilization capacity of the bacteria was evaluated in angar and broth National Botanical Research Institute (NBRIP) media supplemented with calcium phosphate (CaHPO4) and aluminum phosphate (AlPO4), and increased with 3% NaCl. All bacterial strains were classified as halotolerant and identified to the genera Bacillus, Enterobacter, Halomonas, Kushneria, Oceanobacillus, Pantoea, Pseudomonas, and Staphylococcus, with only one isolate was not identified. The isolates with the highest ability to solubilize phosphorus from CaHPO4 in the liquid medium were Kushneria sp. (SS102) and Enterobacter sp. (SS186), with 989.53 and 956.37 mg·Kg-1 P content and final pH of 4.1 and 3.9, respectively. For the solubilization of AlPO4, the most effective isolates were Bacillus sp. (SS89) and Oceanobacillus sp. (SS94), which raised soluble P by 61.10 and 45.82 mg·Kg-1 and final pH of 2.9 and 3.6, respectively. These bacteria demonstrated promising results in in vitro P solubilization and can present potential for the development of bioinput. Further analyses, involving different phosphate sources and the composition of produced organic acids, will be conducted to contribute to a comprehensive understanding of their applications in sustainable agriculture.

Streptomyces rock phosphate ore biomining evaluation in vitro

The process of extracting metals from rock phosphate ore (RPO) by using microorganisms to convert them into soluble compounds is called biomining. Phosphorus is one of the elements proposed to be extracted from RPO. To understand the role of Streptomyces phospholyticus, 12 isolates of Streptomyces were isolated from RPO, their ability to grow on specific phosphate solubilization medium e.g., National Botanical Research Institute's phosphate growth agar (NBRIP) was studied, and the best strain with a 3 cm clear zone was selected. Its ability to grow at increasing RPO concentrations from 0.01 to 1 kgl−1 was investigated. This strain showed good growth, with extracellular red pigmentation for all concentrations, but no clear zone. In the modified liquid NBRIP, however, the Streptomyces growth patterns of the two concentrations of 0.25 kg and 1 kgl−1 RPO showed growth of single spherical red colonies with rhizoids on the surface, the colonies somehow grew and became embedded in the fine RPO granules. This ability to grow can resist gamma irradiation with a dose of 32 KGy. Within 3 days of growth, acidic and alkaline phosphatase were 76.2 and 67.1 μg p-nitrophenol g−1 ml−1, respectively. The RPO analysis showed that the %P in the ore was 16.5% at the beginning of the experiment, and after Streptomyces biotreatment, this percentage decreased to 8.4%, with a decomposition rate of 50.7%. This study, to our knowledge, is the first to investigate the efficiency of Streptomyces in mining phosphate rock ore in the laboratory, even at high concentrations, and to examine the role of irradiation as a preservative in increasing this efficiency.

Phosphate solubilizing bacteria from soils with varying environmental conditions: Occurrence and function

Phosphate solubilizing bacteria (PSB) is an advantageous way to supply phosphate (P) to plants. The Mediterranean climate of Morocco, especially the low-lying areas, is semi-arid with nutrient-depleted soils in which small-scale, low-income farmers dominate without access to expensive inorganic fertilizers. However, there is not a wide range of PSBs suitable for various agroecological situations. Furthermore, our understanding of the soil and climatic variables that influence their development is limited. This study aims to examine the impacts of specific environmental factors, such as climate and soil, on the abundance, potential, and diversity of PSBs in four agricultural regions of Morocco. To assess the possible impact of these factors on the P solubilization capacity of PSBs and plant growth-promoting (PGP) traits, we analyzed the soil and climate of each sample studied. Similarly, we tested the P solubilization efficiency of the isolates. The bacteria were isolated in a National Botanical Research Institute’s phosphate (NBRIP) agar medium. A total of 51 PSBs were studied in this work. The P-solubilization average of Rock P (RP) and Tricalcium P (TCP) of all strains that were isolated from each of the four regions ranged from 18.69 mg.L-1 to 40.43 mg.L-1 and from 71.71 mg.L-1 to 94.54 mg.L-1, respectively. The PGP traits of the isolated strains are positively correlated with the PSBs abundance and the sample characteristics (soil and climate). The morphological and biochemical characteristics of the strain allowed us to identify around nine different bacterial genera, including Bacillus, Pseudomonas, and Rhizobium. The findings showed that bacterial communities, density, and potency are closely correlated to various edapho-climatic conditions such as temperature, precipitation, soil nutrient status, and soil texture. These findings could be used to improve an effective plant-PSBs system and increase agricultural output by taking into account their specific ecological traits and plant growth mechanisms.

Meiotic analysis of induced translocation heterozygotes in Lepidium sativum Linn.

Aim: To assess the cytological effects of Gamma rays on the pollen mother cells and post meiotic products of Lepidium sativum Linn. which resulted in isolation of translocation heterozygote and aneuploid gametes. Methodology: During the experiment, parameters such as Meiotic stages, chromosomal structure, and pollen fertility were studied. Fresh seeds of Garden cress were orderly arranged in plastic and divided into four groups. The fresh seeds of each group were individually irradiated with 60Gy, 150Gy, 300Gy, 450Gy and 600Gy @ 7.247KGyh-1 in the Floriculture Laboratory of National Botanical Research Institute (NBRI), Lucknow (India). The source for gamma ray irradiation was Cobalt-60. The irradiated seeds were sown in triplicates along with their respective controls. Results: Meiotic analysis of pollen mother cells (PMCs) at 300Gy showed translocation heterozygotes, however, in the control sets, the rate was negligible and phenotypically the plants were weak and short heighted. The cytological illustration of chromosomal configuration at diakinesis and metaphase I exhibited the superiority of tetravalents, bivalent and other forms of chromosomal associations such as multivalents. The induced translocation heterozygotes resulted in stickiness at metaphase and anaphase states along with the formation of bridges at anaphase stage. Due to chromosomal anomalies, the pollen fertility was reduced to 37.54±0.25% in contrast to control plants (98.20±0.16%). Interpretation: The current research work would be of paramount interest as translocation heterozygote serves as a source for raising aneuploid offspring having novel genetic combinations. Key words: Chromosomal anomalies, Heterozygotes, Lepidium sativum Linn, Meiosis, Pollen fertility

Isolation And Characterization Of Phosphate Solving Bacteria From Swamp Soil With High Levels Of Acidity

Phosphate solubilizing bacteria (PSB) are one of the microbes that play an important role in soil and plant cycles. Phosphate (P) is a very important macronutrient for plants. In soil, most of the P element is found to be unavailable to plants because it is fixed by Ca, Al or Fe. This research aims to identify BPF in acid soil which has the potential to dissolve phosphate elements. The method used in this research is the isolation of BPF from acid soil using the National Botanical Research Institute's Phosphate (NBRIP) medium, phosphate dissolution index test and UV Visual. Soils from overflow type C (TLC) swamps have higher diversity compared to TLB soils. The abundance of BPF in TLC soil was higher (5,4 107 CFU per gram) compared to soil from overflow zone B (TLB) (2,9 107 CFU per gram) because TLC soil had a lower acidity level than TLB. There were 55 BPF isolates obtained from these two types of soil. Two isolates (TLB1 and TLB2) had a better phosphate solubilization index and all potential isolates that were extracted and subjected to gDNA amplification showed a DNA band at 1330-1500 bp.

Development of Phyto-cosmetic Herbal Sindoor from Rosa indica L. and Its Characterization

Aim: The objective of this research study was to develop a liquid herbal sindoor containing flower petal extract of Rosa indica L., and to evaluate the stability, antioxidant and antibacterial activities of the developed formulation.
 Place and Duration of Study: The formulation was prepared in the Phytochemistry Division of CSIR- National Botanical Research Institute. The duration of the study period was 90 days.
 Methodology: The crude ethanolic extract of R. indica flowers was incorporated into a base for the preparation of liquid herbal sindoor. The antioxidant activity of this herbal product was evaluated according to the DPPH radical scavenging method, and the stability study of the formulation was evaluated for 90 days. The antibacterial activity was performed on those strains of bacteria, which are responsible for several skin infections using Disc Diffusion Assay.The HPLC- DAD analysis identified the anthocyanins cyanidin 3,5-diglucoside and pelargonidin 3,5-diglucoside in R. indica, flower extract.
 Results and Discussion: The formulation showed antioxidant activity and its stability was assessed in terms of pH values and color stability of the flower extract. It was observed that both these properties did not show any significant changes.
 Conclusion: The prepared herbal liquid sindoor was found safe to use having a potential to substitute the toxic lead tetraoxide (Pb3O4) containing sindoor available in the market.

Phosphate Solubilizing Bacteria Isolation Medium: Rock Phosphate or Tricalcium Phosphate?

Phosphorus is one of the essential elements limiting vegetative production in the world. Although phosphorus is abundant in soils, a tiny part is available for plants. With phosphate solubilizing bacteria (PSB), phosphorus, insoluble in soils, is transformed into a suitable form for plants. This study aimed to determine tricalcium phosphate (TCP) activities and rock phosphate (RP) used to isolate PSMs. 118 bacterial isolates, which can phosphate solubilizing, were incubated for 72 h in National Botanical Research Institute phosphate (NBRIP) medium using TCP and RP as phosphate sources. At the end of the incubation, the amount of inorganic phosphorus (Pi) in the medium and the pH of the medium was determined. As a result of bacterial incubation, an average of 57.87 mg L−1 Pi was detected in rock phosphate medium, while this rate was found to be 421 mg L−1 in TCP medium. After 72 h of incubation, it was determined that the pH of the NBRIP media varied between 3.60 and 5.05, and TCP dissolved seven times more to rock phosphate. This study has shown that TCP alone in determining the isolation and effectiveness of PSMs is not indigenous.

Transcriptome profiling of genes regulated by phosphate-solubilizing bacteria Bacillus megaterium P68 in potato (Solanum tuberosum L.).

The insoluble phosphorus in the soil is extremely difficult to be absorbed and used directly through the potato root system. Although many studies have reported that phosphorus-solubilizing bacteria (PSB) can promote plant growth and uptake of phosphorus, the molecular mechanism of phosphorus uptake and growth by PSB has not been investigated yet. In the present study, PSB were isolated from rhizosphere soil in soybean. The data of potato yield and quality revealed that the strain P68 was the most effective In the present study, PSB identification, potato field experiment, pot experiment and transcriptome profiling to explored the role of PSB on potato growth and related molecular mechanisms. The results showed that the P68 strain (P68) was identified as Bacillus megaterium by sequencing, with a P-solubilizing ability of 461.86 mg·L-1 after 7-day incubation in National Botanical Research Institute's Phosphate (NBRIP) medium. Compared with the control group (CK), P68 significantly increased the yield of potato commercial tubers by 17.02% and P accumulation by 27.31% in the field. Similarly, pot trials showed that the application of P68 significantly increased the biomass, total phosphorus content of the potato plants, and available phosphorus of the soil up by 32.33, 37.50, and 29.15%, respectively. Furthermore, the transcriptome profiling results of the pot potato roots revealed that the total number of bases was about 6G, and Q30 (%) was 92.35-94.8%. Compared with the CK, there were a total of 784 differential genes (DEGs) regulated when treated with P68, which 439 genes were upregulated and 345 genes were downregulated. Interestingly, most of the DEGs were mainly related to cellular carbohydrate metabolic process, photosynthesis, and cellular carbohydrate biosynthesis process. According to the KEGG pathway analysis, a total of 46 categorical metabolic pathways in the Kyoto Encyclopedia of Genes and Genomes (KEGG) database were annotated to 101 DEGs found in potato roots. Compared with the CK, most of the DEGs were mainly enriched in glyoxylate and dicarboxylate metabolism (sot00630), nitrogen metabolism (sot00910), tryptophan metabolism (sot00380), and plant hormone signal transduction (sot04075), and these DEGs might be involved in the interactions between Bacillus megaterium P68 and potato growth. The qRT-PCR analysis of differentially expressed genes showed that inoculated treatments P68 significantly upregulated expression of the phosphate transport, nitrate transport, glutamine synthesis, and abscisic acid regulatory pathways, respectively, and the data from qRT-PCR were consistent with that obtained from RNA-seq. In summary, PSB may be involved in the regulation of nitrogen and phosphorus nutrition, glutaminase synthesis, and abscisic acid-related metabolic pathways. This research would provide a new perspective for studying the molecular mechanism of potato growth promotion by PSB in the level of gene expression and related metabolic pathways in potato roots under the application of Bacillus megaterium P68.

Screening of calcium- and iron-targeted phosphorus solubilizing fungi for agriculture production

The average efficiency of phosphorus fertilizer is relatively low around the world because the plant-available phosphorus can be readily immobilized by the soil minerals, such as iron, aluminum, and calcium, when phosphorus fertilizer is applied to the field. Phosphorus solubilizing microorganisms can release phosphorus from insoluble phosphorus and help plant grow. This study screened phosphorus solubilizing fungi (PSF) from 153 fungi species by Pikovskayas Agar media and National Botanical Research Institute's phosphate growth medium broth. There were 47 Ca-targeted PSF, and among them, 34 PSF could dissolve FePO4. Epicoccum dendrobii (B-27) was the best Ca-targeted PSF with the released free phosphorus of 35.49 ± 2.11s% in 4-day incubation, while Aspergillus sp. (A-5) was the best Fe-targeted PSF with 28.75 ± 6.43% of Fe–P dissolved. Besides, Penicillium sp. (Sarita-12) was superior in dissolving both Ca3(PO4)2 and FePO4 with 34.43 ± 2.22% and 24.27 ± 4.09% released in the supernatant, respectively. The growth kinetic experiments showed that except B-27, all the pH of the selected PSF inoculated media decreased during the incubation, indicating that inorganic/organic acids might be metabolized to dissolve the insoluble phosphorus. The results suggested that the phosphorus solubilizing capability of the selected PSF was different with Ca–P and Fe–P substrates. The screened Sarita-12 strain has great potential to be used as phosphorus-solubilizing bio-fertilizer in calcareous alkaline soils and acidic soils to enhance phosphorus assimilation by plants and improve the phosphorus fertilizer efficiency.

Isolation, Identification, and Characterization of Phosphate-Solubilizing Bacteria from Tunisian Soils

Soil microorganisms play an important role in maintaining natural ecological balance through active participation in carbon, nitrogen, sulfur, and phosphorous cycles. Phosphate-solubilizing bacteria (PSB) are of high importance in the rhizosphere, enhancing the solubilization of inorganic phosphorus complexes into soluble forms available for plant nutrition. The investigation of this species of bacteria is of major interest in agriculture, as they can be used as biofertilizers for crops. In the present study, 28 isolates of PSB were obtained after the phosphate enrichment of soil samples from five Tunisian regions. Five PSB species were identified by 16S rRNA gene sequencing including Pseudomonas fluorescens, P. putida, and P. taiwanensis, Stenotrophomonas maltophilia, and Pantoea agglomerans. Solid and liquid Pikovskaya's (PVK) and National Botanical Research Institute's (NBRIP) media containing insoluble tricalcium phosphate were used for the evaluation of the phosphate solubilization ability of the bacterial isolates by two methods: visual evaluation of the solubilization zone around colonies (halo) and determination of solubilized phosphates in liquid medium by the colorimetric method of the vanado-molybdate yellow. Based on the results of the halo method, the isolate of each species that showed the higher phosphate solubilization index was selected for evaluation of phosphate solubilization by the colorimetric method. In the liquid media, the bacterial isolates showed phosphate solubilization ranging from 535.70 to 618.57 µg mL-1 in the NBRIP medium, and 374.20 to 544.28 µg mL-1 in the PVK medium, with the highest values produced by P. fluorescens. The best phosphate solubilization ability and higher reduction in broth pH, which indicates higher organic acid production, were achieved in NBRIP broth for most of the PSB. Strong correlations were observed between the average capability of PSB to solubilize phosphates and both the pH and total phosphorous content in the soil. The production of the hormone indole acetic acid (IAA), which can promote plant growth, was observed for all five PSB species. Among them, P. fluorescens obtained from the forest soil of northern Tunisia showed the highest production of IAA (50.4 ± 0.9 µg mL-1).

Molecular Characterization and Mineralizing Potential of Phosphorus Solubilizing Bacteria Colonizing Common Bean (Phaseolus vulgaris L.) Rhizosphere in Western Kenya.

Phosphorus solubilizing bacteria (PSB) are a category of microbes that transform insoluble phosphates in soil into soluble forms that crops can utilize. Phosphorus in natural soils is abundant but poorly soluble. Hence, introducing PSB is a safer way of improving its solubility. The aim of this study was to genetically characterize and determine the mineralization capability of selected PSB colonizing rhizospheres of common beans in Western Kenya. Seven potential phosphorus solubilizing bacteria (PSB) were isolated from various subregions of Western Kenya. 16S ribosomal RNA gene sequencing and National Center for Biotechnology Information (NCBI), Basic Local Alignment Search Tool (BLAST) identified the isolates. The phosphate solubilization potential of the isolates was evaluated under agar and broth medium of National Botanical Research Institute's phosphate (NBRIP) supplemented with tricalcium calcium phosphate (TCP). Identified isolates were as follows: KK3 as Enterobacter mori, B5 (KB5) as Pseudomonas kribbensis, KV1 as Enterobacter asburiae, KB3 as Enterobacter mori, KK1 as Enterobacter cloacae, KBU as Enterobacter tabaci, and KB2 as Enterobacter bugandensis. The strains B5 and KV1 were the most effective phosphorus solubilizers with 4.16 and 3.64 indices, respectively. The microbes converted total soluble phosphate concentration in broth medium which was 1395 and 1471 P μg/mL, respectively. The least performing isolate was KBU with a 2.34 solubility index. Significant (p ≤ 0.05) differences in plant biomass for Rose coco and Mwitemania bean varieties were observed under inoculation with isolates B5 and KV1. PSB isolates found in common bean rhizospheres exhibited molecular variations and isolates B5 and KV1 are the potential in solving the insufficiency of phosphorus for sustainable crop production.

Exogenous Indole-3-Acetic Acid Production and Phosphate Solubilization by Chlorella vulgaris Beijerinck in Heterotrophic Conditions

The role of soil-borne microalgae in the edaphic ecosystem is barely known, especially concerning their plant-growth-promoting traits, although they are used as biofertilizers. In this study, a microalgal strain isolated from soil cultivated with maize was evaluated as an exogenous producer of indole-3-acetic acid (IAA) in potato dextrose broth—PD—and sugarcane molasses, with or without tryptophan, and phosphate solubilizer (in ‘National Botanical Research Institute’s phosphate’—NBRIP—medium with tricalcium phosphate)with plant-growth-promoting traits, under heterotrophic conditions. The species of microalga was identified, by sequencing the ITS region in the rDNA and the morphological characteristics, as Chlorella vulgaris. Its growth was significantly higher in the PD medium, with slower growth in molasses. The addition of tryptophan did not influence the growth of C. vulgaris in either medium, but it increased the production of IAA, mainly in the PD medium, to 265 µg mL−1. The microalga grew in the medium with insoluble phosphate, releasing phosphorus into the medium (30 mg L−1 after 72 h). This is the first study on the application of C. vulgaris as a phosphate solubilizer. More studies should be performed on C. vulgaris as a prospective plant-growth-promoting microorganism, besides its ability to produce exogenous IAA, and further investigations should be conducted on developing inexpensive culture media.

Selection and validation of reference genes for quantitative real-time polymerase chain reaction analyses of Serratia ureilytica DW2

Background: Serratia ureilytica DW2 is a highly efficient phosphate-solubilizing bacteria isolated from Codonopsis pilosula rhizosphere soil that can promote the growth of C. pilosula; nonetheless, until now, no validated reference genes from the genus Serratia have been reported that can be used for the normalization of quantitative real-time polymerase chain reaction (RT–qPCR) data. Methods: To screen stable reference genes of S. ureilytica DW2, the expression of its eight candidate reference genes (16S rRNA, ftsZ, ftsA, mreB, recA, slyD, thiC, and zipA) under different treatment conditions (pH, temperature, culture time, and salt content) was assayed by RT–qPCR. The expression stability of these genes was analyzed using different algorithms (geNorm, NormFinder, and BestKeeper). To verify the reliability of the data, the expression of the glucose dehydrogenase (gdh) gene under different soluble phosphate levels was quantified using the most stably expressed reference gene. Results: The results showed that the zipA and 16S rRNA genes were the most stable reference genes, and the least stable genes were thiC and recA. The expression of gdh was consistent with the phosphate solubilization ability on plates containing the National Botanical Research Institute phosphate growth medium. Conclusion: Therefore, this study provides a stable and reliable reference gene of Serratia for the accurate quantification of functional gene expression in future studies.

An Enterobacter cloacae strain NG-33 that can solubilize phosphate and promote maize growth.

It is critical to identify and evaluate efficient phosphate-solubilizing bacteria (PSB) that enable P uptake from unavailable forms, and therefore improve the phosphorus (P) uptake efficiency of crops. The Enterobacter cloacae strain NG-33, belonging to PSB, was isolated and identified from calcareous rhizosphere soils in Nonggang National Reserve, Guangxi, China. The stain NG-33 could reduce the pH of the medium to below 5.6, and had the ability to release soluble phosphorus (P; 180.7 μg ml-1) during the culture in the National Botanical Research Institute's Phosphate medium (NBRIP), and produced such organic acids as gluconic acid (4,881 mg L-1), acetic acid (346 mg L-1), and indole-3-acetic acid (20.4 μg ml-1). It could also convert inorganic P in AlPO4 (Al-P) and FePO4 (Fe-P) into soluble P, with conversion efficiencies of 19.2 μg ml-1 and 16.3 μg ml-1, respectively. Under pot experiments and when compared controls without inoculating NG-33, the shoot and root biomass of maize seedlings showed increases by 140% for shoot biomass and by 97% for root biomass in loamy soil (P sufficient) inoculated with NG-33. In sandy soil (P deficit) supplemented with tricalcium phosphate and inoculated with NG-33, the soluble P content was significantly higher, 58.6% in soil and 33.6% in roots, meanwhile, the biomass of shoots and roots increased by 14.9 and 24.9%, respectively. The growth-promoting effects coupled to the significant increase in leaf net photosynthetic rate and stomatal conductance of plants grown in NG-33-inoculated soil. Inoculating NG-33 could significantly improve the diversity and richness of bacterial population and altered the dominant bacterial population in soil.

ISOLATION AND MOLECULAR CHARACTERIZATION OF PHOSPHATE SOLUBILIZING BACTERIA FROM RHIZOSPHERIC SOILS OF TROPICAL LOWLAND RICE

Phosphate-solubilizing bacteria (PSB) can promote the dissolution of insoluble phosphorus in soil, enhancing the availability of soluble P and reducing the consumption of fertilizer and aid in sustainable agricultural development. The phosphate solubilising bacteria were isolated from the rhizospheric soils of the experimental site located in the ICAR-National Rice Research Institute's experimental farm in Cuttack, India. & the population of PSBs varied between 1-22.5 cfu/gm*104 and higher in DSR (Direct seeded rice) compared to TPR (Transplanted rice). Phosphate solubilization efficiency (PSE) of the isolates gave better result in Pikovskaya’s agar medium plates i.e. 188.9% in K6 (Kasalath, P80, DSR) rather than National Botanical Research Institute’s Phosphate growth medium (NBRIP) i.e. 73.3% for K6. The highest PSE% in C sources was found in lactose i.e. 166.7% for the isolate K9 (Kasalath, P0, DSR) and 180.0% for the isolate D17 (Dular, P80, TPR) for potassium nitrate as N source. The morphological study by staining characteristics showed that all the isolates were gram negative and cocci except D19 (Dular, P80, TPR) which was gram positive and rod shaped. Amplified fragments of oligonucleotide primers in RAPD characterization showed 51.81% polymorphism and 44.54% monomorphism. Based on dendrogram all the isolates were placed in group A except S11 (Dular, P80, TPR) which was placed in major group B showing great variation from all other isolates and group A consists of 6 minor groups in which minor group A6 was the largest containing 5 isolates i.e. Kasalath, P40, DSR (S13), Kasalath, P80, DSR (S14, S15, S16) & IR36, P40, DSR (S17).

Harnessing the phosphate-solubilizing ability of Trichoderma strains to improve plant growth, phosphorus uptake and photosynthetic pigment contents in common bean (Phaseolus vulgaris)

A promising strategy for dissolving, mobilizing and enhancing the utilization of the complexed form of phosphorus (P) in soil-plant systems is the use of effective phosphate solubilizing microorganisms. In the present study, six strains of Trichoderma spp. previously obtained from the common bean rhizosphere were investigated for their ability to solubilize tricalcium phosphate (TCP) in NBRIP (National Botanical Research Institute Phosphate) broth medium. All six strains were able to solubilize TCP to various extents, with solubilization ranging from 66.9 μg/ml to 328.4 μg/ml. A significant negative linear correlation (r = - 0.94; p < 0.01) was found between solubilized P and the pH of the culture medium. The highest solubilization activity (328.4 μg/ml), fungal growth (87.21 mg/100 ml) and pH fluctuation (7.0–4.06) were achieved by Trichoderma gamsii It-62. Under pot conditions, inoculation with Trichoderma gamsii It-62 remarkably improved plant height, shoot and root weight, P uptake, photosynthetic pigments and total protein content compared with untreated common bean seedlings. These increases were significantly higher upon combined inoculation of the bioagent with TCP addition. The obtained results indicate that Trichoderma gamsii It-62 might be a promising alternative for the release of fixed forms of phosphates present in the soil, thereby increasing soil fertility.

Isolation, Solubilization of Inorganic Phosphate, and Production of Organic Acids by Individual and Co-inoculated Microorganisms

Phosphate solubilizing microorganisms (PSMs) mineralize phosphate (PO4³−) to make phosphorous available for plant uptake. This study is designed to isolate the PSMs from the subtropical environmental samples. Total 35 bacterial and 18 fungal isolates were found to be effective P solubilizers depend on their ability of P solubilization that were determined qualitatively and quantitatively using National Botanical Research Institute Phosphorus media. Efficient PSMs that were solubilizing phosphate in maximum amount were identified as Pseudomonas aeruginosa, Serratia marcescens, Pseudomonas mosselii, Bacillus licheniformis, Bacillus subtilis, Bacillus species, Aspergillus flavus, Aspergillus foetidus, Aspergillus niger, Aspergillus tubingensis, and Penicillium chrysogenum. Among them, A. tubingensis was observed as the most efficient phosphate solubilizing strain. For the first time, combined phosphate solubilization activity of A. tubingensis with other efficient phosphate solubilizers was checked and found that A. tubingensis and P. aeruginosa acted synergistically and solubilized phosphate in increased amount. High-performance liquid chromatography results revealed that A. tubingensis produced variety of organic acids including succinic, gluconic, oxalic, and citric acids. Scanning electron microscopy results confirmed the presence of firmly attached large fungal hyphae on tri-calcium phosphate (Ca3(PO4)2). Thus, the results suggest that the use of these PSMs either single or combined as bioinoculants will help to increase the availability of soluble phosphorous.