Chrome Azurol Research Articles

Fluorescent and colorimetric dual-mode recognition of Al3+ in tablets based on chrome azurol S and pH-switchable boron, nitrogen co-doped carbon dots.

The synthesis and characterization ofpH-sensitive boron and nitrogen co-doped CDs (B, N-CDs) is reported. The fluorescence of B, N-CDs exhibited pH-responsive behavior within the range pH3.0-6.0, attributed to their controlled aggregation and disaggregation. Interestingly, the fluorescence of B, N-CDs was quenched by the inner filter effect from chrome azurol S (CAS). With the subsequent addition of Al3+, the fluorescence of B, N-CDs was restored due to the formation of blue Al3+-CAS and B, N-CDs-Al3+ complexes. Consequently, a fluorescent and colorimetric dual-mode sensor for Al3+ detection was developed. The proposed sensor enabled Al3+ detection in the ranges and limits of detection of 3.75-22.5μM and 2.67μM for the fluorescent mode and 5-20μM and 4.8μM for the colorimetric mode, respectively. Furthermore, the efficacy of the sensor was validated through successful detection of Al3+ in tablet samples. The obtained B, N-CDs promised the application in acid condition and the proposed sensor isexpected tobe applied toin situ on-line detection of Al3+.

Functional and Proteomic Analyses of a Putative Carbamoyl Phosphate Synthase Large Subunit in Relation to Virulence, Arginine and Pyrimidine Biosynthesis, and Siderophore Production in Erwinia amylovora

The apple is a significant global fruit cultivated extensively worldwide. Fire blight, caused by Erwinia amylovora (Ea), poses a significant threat to global apple production. To control this disease, characterizing the virulence mechanisms/factors is imperative. Carbamoyl phosphate synthase is an essential enzyme in the biosynthesis of arginine and pyrimidine. However, the functions of this protein in Ea remains poorly understood. This study aimed to investigate the functions of the carbamoyl phosphate synthase large subunit in Ea (CarBEa). In a virulence assay using fruitlets, an Ea strain lacking CarBEa exhibited significantly reduced virulence on fruitlets. In the auxotrophy assay, this mutant failed to grow in minimal media lacking both arginine and pyrimidine, but growth was restored when both compounds were supplemented. The comparative proteomic analysis suggests that CarBEa is involved in diverse biological processes, including amino acid and nucleotide metabolism, and inorganic ion transport. Finally, we demonstrated that CarBEa is related to siderophore secretion/production by the chrome azurol S agar plate assay. This report provides valuable insights into the functions of carbamoyl phosphate synthase large subunit, which serves as a potential target for developing efficient anti-virulence substances to control fire blight.

Study of Plant Growth Promoting Abilities of Rhizobium Strains Isolated from Mungbean Root Nodules

Background: Plant Growth Promoting Rhizobacteria (PGPR) are a type of bacteria that use biofertilizers and other plant growth-promoting agents to increase plant output and growth. In the last several decades, there has been a global surge in the usage of beneficial soil microorganisms like PGPR for safe and sustainable agriculture due to the detrimental effects of artificial fertilizers on the environment and their rising prices. Plant-beneficial rhizobacteria have the potential to reduce the world's reliance on dangerous agricultural chemicals that upset agro-ecosystems. Today a large part of yield is lost due to the various stress mechanisms of plants. It could be classified into biotic and abiotic stress. These are generally a group of microorganisms that is found either in the rhizosphere or in the root nodules of plants. PGPR has beneficial impact, they colonize in the plant roots and improve crop yields and agricultural productivity and also produce some useful growth promoting growth hormones viz., IAA, Auxins, Cytokinin and Gibberellins. Methods: The bacterial isolates were screened for plant growth promoting traits such as phosphate solubilization, IAA production and siderophore production was tested qualitatively by using pikovskayas media, TSB (Tryptone Soy Broth) agar and Chrome Azurol Sulphate (CAS) blue agar respectively. Results: In present study out of the eight rhizobial isolates, five exhibited the phosphate solubilization zones, three shows negative result. However out of eight isolates five isolates produced IAA and three showed negative result. Among all isolates seven isolates were able to produce siderophore, while one showed negative result.

Characterization of Siderophore Produced by Bacillus velezensis YL2021 and Its Application in Controlling Rice Sheath Blight and Rice Blast.

Bacillus velezensis YL2021 has extensive antimicrobial activities against phytopathogens, and its genome harbors a catechol-type siderophore biosynthesis gene cluster. Here, we describe the characterization of siderophore produced by strain YL2021 and its antimicrobial activity in vitro and in vivo. A few types of siderophores were detected by chrome azurol S plates coupled with Arnow's test, purified and identified by Reversed-phase high-performance liquid chromatography (RP-HPLC). We found that strain YL2021 can produce different antimicrobial compounds under low-iron M9 medium or iron-sufficient LB medium although antimicrobial activities can be easily observed on the two media as described above in vitro. Strain YL2021 can produce at least three catechol-type siderophores in low-iron M9 medium while no siderophore was produced in LB medium. Among them, the main antimicrobial siderophore produced by strain YL2021 was bacillibactin, with m/z of 882, based on the liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis, which has broad-spectrum antimicrobial activities against Gram-positive, Gram-negative bacteria, the oomycete Phytophthora capsici and phytopathogenic fungi. Moreover, the antifungal activity of siderophore including bacillibactin observed in vitro was correlated with control efficacies against rice sheath blight disease caused by Rhizoctonia solani and rice blast disease caused by Magnaporthe oryzae in vivo. Collectively, the results demonstrate that siderophore including bacillibactin produced by Bacillus velezensis YL2021 is a promising biocontrol agent for application in rice disease control.

New Strain of Bacillus amyloliquefaciens G1 as a Potential Downy Mildew Biocontrol Agent for Grape

To obtain effective biocontrol strains for downy mildew of grape, 38 endophytic bacteria were isolated from fruits, seeds, and old stems of six grape varieties. Using spot inoculation mixtures of sporangial suspensions of Plasmopara viticola and biocontrol bacterial suspension, this screen yielded three strains (G1, G5, and G9) with good antagonistic effects against P. viticola. The growth inhibition rate was 100%, which was comparable to the effect of the positive control Bacillus subtilis strain CN181. The enzyme activity and the metabolites of strain G1 were examined on casein hydrolysate medium, sodium carboxymethyl cellulose agar plates, and chrome azurol sulfonate (CAS) agar plates. The antifungal protein component was identified by liquid chromatography–mass spectrometry (LC–MS). The results showed that strain G1 was more effective against Plasmopara viticola after two field trials, and the inhibition rates of strain G1 on the seventh day of the two field trials were 47.5% and 36.9%, respectively. Strain G1 was identified as Bacillus amyloliquefaciens based on morphological examination and 16S rDNA sequence analysis. It produced proteases, cellulases, and siderophores. Crude protein of the strain mainly included the putative segregation protein SpoVG, which inhibited P. viticola.

Evaluation of non-anatomical characteristics for wood identification of six Korean oak species

Summary This study aimed to investigate and compare the non-anatomical characteristics of six Korean oak wood species (Quercus variabilis, Q. serrata, Q. mongolica, Q. dentata, Q. aliena and Q. acutissima) to provide identification keys and quality indices for the effective utilization of these species. Non-anatomical characteristics, including heartwood fluorescence, fluorescence and color of water and ethanol extracts, froth test, chrome azurol S test and burning splinter test, were evaluated according to the International Association of Wood Anatomists (IAWA) lists. None of the six Korean oak species displayed heartwood fluorescence or fluorescence in the ethanol extract. Only Q. serrata exhibited bright blue fluorescence in the aqueous extract. Each species showed distinct colors in both water and ethanol extracts, and the water extract of all species was darker than that of the ethanol extract. A weak positive reaction in the froth test was observed only for Q. serrata. Furthermore, Q. variabilis and Q. acutissima showed positive reactions to both heartwood and sapwood in the chrome azurol S test. The burning splinter test revealed that only Q. acutissima was transformed into charcoal. Thus, water extract fluorescence and color, ethanol extract color, froth test, chrome azurol S test, and burning splinter test can be used to identify the six Korean oak species.

Hibiscus acid and hydroxycitric acid dimethyl esters from Hibiscus flowers induce production of dithiolopyrrolone antibiotics by Streptomyces Strain MBN2-2

Plants and microbes are closely associated with each other in their ecological niches. Much has been studied about plant–microbe interactions, but little is known about the effect of phytochemicals on microbes at the molecular level. To access the products of cryptic biosynthetic gene clusters in bacteria, we incorporated an organic extract of hibiscus flowers into the culture media of different Actinobacteria isolated from plant rhizospheres. This approach led to the production of broad-spectrum dithiolopyrrolone (DTP) antibiotics, thiolutin (1) and aureothricin (2), by Streptomyces sp. MBN2-2. The compounds from the hibiscus extract responsible for triggering the production of these two DTPs were found to be hibiscus acid dimethyl ester (3) and hydroxycitric acid 1,3-dimethyl ester (4). It was subsequently found that the addition of either Fe2+ or Fe3+ to culture media induced the production of 1 and 2. The Chrome Azurol S (CAS) assay revealed that 3 and 4 can chelate iron, and therefore, the mechanism leading to the production of thiolutin and aureothricin appears to be related to changes in iron concentration levels. This work supports the idea that phytochemicals can be used to activate the production of cryptic microbial biosynthetic gene clusters and further understand plant–microbe interactions.Graphical

An Expeditious and Sensitive Microprecipitation Approach Using Chrome Azurol S and Cetyltrimethylammonium Bromide for Visual Detection of Fe(II) and Fe(III) in Water

An Expeditious and Sensitive Microprecipitation Approach Using Chrome Azurol S and Cetyltrimethylammonium Bromide for Visual Detection of Fe(II) and Fe(III) in Water

In Vitro Screening of Endophytic Micromonospora Strains Associated with White Clover for Antimicrobial Activity against Phytopathogenic Fungi and Promotion of Plant Growth

Bacteria belonging to the genus Micromonospora are recognized as microorganisms with the potential to be used in biotechnology processes, given their beneficial influence on plant growth and the biocontrol of phytopathogens. In this study, nineteen Micromonospora isolates originating from the root nodules of white clover plants were taxonomically assigned based on the phylogenetic analysis of the 16S rRNA gene and four housekeeping genes. The antifungal properties of the bacteria against phytopathogenic Botrytis cinerea, Fusarium oxysporum, Fusarium equiseti, Sclerotinia sclerotiorum, and Verticillium albo-atrum were tested with the agar plug test and the dual culture test. The ability to produce various metallophores was determined with the agar plug diffusion test on modified chrome azurol S (CAS) agar medium. International Streptomyces Project-2 medium (ISP2) broth amended with 0.2% L-tryptophan was used to indicate the bacterial ability to produce auxins. The strains belonging to M. tulbaghiae, M. inaquosa, and M. violae showed in vitro potential as antimicrobial agents against the tested fungi. M. inaquosa strain 152, M. violae strain 126, M. violae strain 66, and M. violae strain 45 were recognized as the most efficient metallophore producers. M. alfalfae strain 55 and M. lupini strain 5052 were identified as the most promising auxin compound producers and, therefore, show potential as plant-growth-promoting bacteria.

Transcriptional regulation of the yersiniabactin receptor fyuA gene by the ferric uptake regulator in Klebsiella pneumoniae NTUH-K2044.

The ferric uptake regulator (Fur) is a global regulator that influences the expression of virulence genes in Klebsiella pneumoniae. Bioinformatics analysis suggests Fur may involve in iron acquisition via the identified regulatory box upstream of the yersiniabactin receptor gene fyuA. To observe the impact of the gene fyuA on the virulence of K. pneumoniae, the gene fyuA knockout strain and complementation strain were constructed and then conducted a series of phenotypic experiments including chrome azurol S(CAS) detection, crystal violet staining, and wax moth virulence experiment. To examine the regulatory relationship between Fur and the gene fyuA, green fluorescent protein (GFP) reporter gene fusion assay, real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR), gel migration assay (EMSA), and DNase I footprinting assay were used to clarify the regulatory mechanism of Fur on fyuA. CAS detection revealed that the gene fyuA could affect the generation of iron carriers in K. pneumoniae. Crystal violet staining experiment showed that fyuA could positively influence biofilm formation. Wax moth virulence experiment indicated that the deletion of the fyuA could weaken bacterial virulence. GFP reporter gene fusion experiment and RT-qPCRanalysis revealed that Fur negatively regulated the expression of fyuA in iron-sufficient environment. EMSA experiment demonstrated that Fur could directly bind to the promoter region of fyuA, and DNase I footprinting assay further identified the specific binding site sequences. The study showed that Fur negatively regulated the transcriptional expression of fyuA by binding to upstream of the gene promoter region, and then affected the virulence of K. pneumoniae.

EFFECT OF VARIOUS PHYSICOCHEMICAL PARAMETERS ON SIDEROPHORE PRODUCTION BY MARINE Pseudomonas aeruginosa MGPB31

Siderophores are low molecular weight compounds secreted by bacteria that 
 bind ferric iron with extremely high affinity. The siderophores help bacteria to 
 meet their iron needs under stress conditions as these compounds help in the 
 transport and storage of soluble form of iron in cells. In current study, we report 
 the effect of various physicochemical parameters that influence siderophore 
 production in marine Pseudomonas aeruginosa MGPB31. Siderophore 
 production was assayed using Chrome Azurol S (CAS) shuttle assay. The 
 maximum siderophore production (56% SU) was obtained in minimal M9 
 medium after 72 h incubation, followed by succinate medium (52% SU) and 
 King’s medium (51% SU). The M9 medium was then modified by replacing its 
 carbon, nitrogen and phosphate source. Enhanced siderophore production was 
 observed in modified medium comprising of glycerol (70% SU), tri ammonium 
 citrate (67% SU) and KH2PO4 (64% SU). The medium supplemented with iron 
 exhibited a significant reduction in siderophore production. The effect of 
 physical parameters like temperature, pH and agitation on siderophore 
 production revealed that the isolate exhibited maximum siderophore production 
 under static conditions in modified M9 medium devoid of iron at 25 ± 2°C and 
 neutral pH. The enhanced siderophore production obtained by marine P. 
 aeruginosa MGPB31 indicates its further applicability in fields of industry 
 agriculture and environment.

Qualitative and Quantitative Analysis of Siderophore Production from Pseudomonas aeruginosa.

Pseudomonas aeruginosa (P. aeruginosa) is known for its production of a diverse range of virulence factors to establish infections in the host. One such mechanism is the scavenging of iron through siderophore production. P. aeruginosa produces two different siderophores: pyochelin, which has lower iron-chelating affinity, and pyoverdine, which has higher iron-chelating affinity. This report demonstrates that pyoverdine can be directly quantified from bacterial supernatants, while pyochelin needs to be extracted from supernatants before quantification. The primary method for qualitatively analyzing siderophore production is the Chrome Azurol Sulfonate (CAS) agar plate assay. In this assay, the release of CAS dye from the Fe3+-Dye complex leads to a color change from blue to orange, indicating siderophore production. For the quantification of total siderophores, bacterial supernatants were mixed in equal proportions with CAS dye in a microtiter plate, followed by spectrophotometric analysis at 630 nm. Pyoverdine was directly quantified from the bacterial supernatant by mixing it in equal proportions with 50 mM Tris-HCl, followed by spectrophotometric analysis. A peak at 380 nm confirmed the presence of pyoverdine. As for Pyochelin, direct quantification from the bacterial supernatant was not possible, so it had to be extracted first. Subsequent spectrophotometric analysis revealed the presence of pyochelin, with a peak at 313 nm.

Peribacillus frigoritolerans T7-IITJ, a potential biofertilizer, induces plant growth-promoting genes of Arabidopsis thaliana.

This study aimed to isolate plant growth and drought tolerance-promoting bacteria from the nutrient-poor rhizosphere soil of Thar desert plants and unravel their molecular mechanisms of plant growth promotion. Among our rhizobacterial isolates, Enterobacter cloacae C1P-IITJ, Kalamiella piersonii J4-IITJ, and Peribacillus frigoritolerans T7-IITJ, significantly enhanced root and shoot growth (4-5-fold) in Arabidopsis thaliana under PEG-induced drought stress. Whole genome sequencing and biochemical analyses of the non-pathogenic bacterium T7-IITJ revealed its plant growth-promoting traits, viz., solubilization of phosphate (40-73µg/ml), iron (24±0.58mm halo on chrome azurol S media), and nitrate (1.58±0.01µg/ml nitrite), along with production of exopolysaccharides (125±20µg/ml) and auxin-like compounds (42.6±0.05µg/ml). Transcriptome analysis of A. thaliana inoculated with T7-IITJ and exposure to drought revealed the induction of 445 plant genes (log2fold-change>1, FDR<0.05) for photosynthesis, auxin and jasmonate signalling, nutrient uptake, redox homeostasis, and secondary metabolite biosynthesis pathways related to beneficial bacteria-plant interaction, but repression of 503 genes (log2fold-change < -1) including many stress-responsive genes. T7-IITJ enhanced proline 2.5-fold, chlorophyll 2.5-2.8-fold, iron 2-fold, phosphate 1.6-fold, and nitrogen 4-fold, and reduced reactive oxygen species 2-4.7-fold in plant tissues under drought. T7-IITJ also improved the germination and seedling growth of Tephrosia purpurea, Triticum aestivum, and Setaria italica under drought and inhibited the growth of two plant pathogenic fungi, Fusarium oxysporum, and Rhizoctonia solani. P. frigoritolerans T7-IITJ is a potent biofertilizer that regulates plant genes to promote growth and drought tolerance.

Genomic insights and anti-phytopathogenic potential of siderophore metabolome of endolithic Nocardia mangyaensis NH1

Actinobacteria are one of the predominant groups that successfully colonize and survive in various aquatic, terrestrial and rhizhospheric ecosystems. Among actinobacteria, Nocardia is one of the most important agricultural and industrial bacteria. Screening and isolation of Nocardia related bacteria from extreme habitats such as endolithic environments are beneficial for practical applications in agricultural and environmental biotechnology. In this work, bioinformatics analysis revealed that a novel strain Nocardia mangyaensis NH1 has the capacity to produce structurally varied bioactive compounds, which encoded by non-ribosomal peptide synthases (NRPS), polyketide synthase (PKS), and post-translationally modified peptides (RiPPs). Among NRPS, five gene clusters have a sequence homology with clusters encoding for siderophore synthesis. We also show that N. mangyaensis NH1 accumulates both catechol- and hydroxamate-type siderophores simultaneously under iron-deficient conditions. Untargeted LC–MS/MS analysis revealed a variety of metabolites, including siderophores, lipopeptides, cyclic peptides, and indole-3-acetic acid (IAA) in the culture medium of N. mangyaensis NH1 grown under iron deficiency. We demonstrate that four CAS (chrome azurol S)-positive fractions display variable affinity to metals, with a high Fe3+ chelating capability. Additionally, three of these fractions exhibit antioxidant activity. A combination of iron scavenging metabolites produced by N. mangyaensis NH1 showed antifungal activity against several plant pathogenic fungi. We have shown that the pure culture of N. mangyaensis NH1 and its metabolites have no adverse impact on Arabidopsis seedlings. The ability of N. mangyaensis NH1 to produce siderophores with antifungal, metal-chelating, and antioxidant properties, when supplemented with phytohormones, has the potential to improve the release of macro- and micronutrients, increase soil fertility, promote plant growth and development, and enable the production of biofertilizers across diverse soil systems.

Properties of Potential Plant-Growth-Promoting Bacteria and Their Effect on Wheat Growth Promotion (Triticum aestivum) and Soil Characteristics

Plant-growth-promoting bacteria are an important economic and environmental resource as biofertilizers that can stimulate plant growth and improve agricultural yields. In this study, potential plant growth-promoting bacteria were isolated from soil samples collected in Russia. Strains that manifested active growth on a nitrogen-free medium, the Pikovskaya medium (with insoluble phosphates) and CAS (Chrome Azurol S) agar, were selected for the study. All bacterial isolates were identified by 16S rRNA gene sequencing analysis. Seventeen bacterial isolates of different species were purified and quantified for their ability to grow on nitrogen-free media; dissolve phosphate; and produce ammonium, indole-3-acetic acid, siderophores, and antifungal activity. Principal component analysis identified three groups of strains: one with the maximum signs of providing “plant nutrition”; one with signs of “antimicrobial activity”; and a group “without outstanding signs”. All 17 strains were involved in experiments involving growing inoculated wheat seeds (Triticum aestivum) in pots under natural environmental conditions, and were assessed by their effect on the wheat growth and yield as well as on the chemical composition of the soil. For the “plant nutrition” group, regression analysis revealed a connection between indicators of plant growth, ear length, and ammonium accumulation in the soil. However, in other groups, there were also strains showing a positive effect on plant growth, which suggests the necessity of involving additional factors to predict the ability of strains to affect plants when screened in the laboratory.

Optimization of Siderophore Production in Three Marine Bacterial Isolates along with Their Heavy-Metal Chelation and Seed Germination Potential Determination.

Siderophores are low-molecular-weight and high-affinity molecules produced by bacteria under iron-limited conditions. Due to the low iron (III) (Fe+3) levels in surface waters in the marine environment, microbes produce a variety of siderophores. In the current study, halophilic bacteria Bacillus taeanensis SMI_1, Enterobacter sp., AABM_9, and Pseudomonas mendocina AMPPS_5 were isolated from marine surface water of Kalinga beach, Bay of Bengal (Visakhapatnam, Andhra Pradesh, India) and were investigated for siderophore production using the Chrome Azurol S (CAS) assay. The effect of various production parameters was also studied. The optimum production of siderophores for SMI_1 was 93.57% siderophore units (SU) (after 48 h of incubation at 30 °C, pH 8, sucrose as carbon source, sodium nitrate as nitrogen source, 0.4% succinic acid), and for AABM_9, it was 87.18 %SU (after 36 h of incubation period at 30 °C, pH 8, in the presence of sucrose, ammonium sulfate, 0.4% succinic acid). The maximum production of siderophores for AMPPS_5 was 91.17 %SU (after 36 h of incubation at 35 °C, pH 8.5, glucose, ammonium sulfate, 0.4% citric acid). The bacterial isolates SMI_1, AABM_9, and AMPPS_5 showed siderophore production at low Fe+3 concentrations of 0.10 µM, 0.01 µM, and 0.01 µM, respectively. The SMI_1 (73.09 %SU) and AMPPS_5 (68.26 %SU) isolates showed siderophore production in the presence of Zn+2 (10 µM), whereas AABM_9 (50.4 %SU) exhibited siderophore production in the presence of Cu+2 (10 µM). Additionally, these bacterial isolates showed better heavy-metal chelation ability and rapid development in seed germination experiments. Based on these results, the isolates of marine-derived bacteria effectively produced the maximum amount of siderophores, which could be employed in a variety of industrial and environmental applications.

Genomic and microbiological analyses of iron acquisition pathways among respiratory and environmental nontuberculous mycobacteria from Hawai'i.

As environmental opportunistic pathogens, nontuberculous mycobacteria (NTM) can cause severe and difficult to treat pulmonary disease. In the United States, Hawai'i has the highest prevalence of infection. Rapid growing mycobacteria (RGM) such as Mycobacterium abscessus and M. porcinum and the slow growing mycobacteria (SGM) including M. intracellulare subspecies chimaera are common environmental NTM species and subspecies in Hawai'i. Although iron acquisition is an essential process of many microorganisms, iron acquisition via siderophores among the NTM is not well-characterized. In this study, we apply genomic and microbiological methodologies to better understand iron acquisition via siderophores for environmental and respiratory isolates of M. abscessus, M. porcinum, and M. intracellulare subspecies chimaera from Hawai'i. Siderophore synthesis and transport genes, including mycobactin (mbt), mmpL/S, and esx-3 were compared among 47 reference isolates, 29 respiratory isolates, and 23 environmental Hawai'i isolates. Among all reference isolates examined, respiratory isolates showed significantly more siderophore pertinent genes compared to environmental isolates. Among the Hawai'i isolates, RGM M. abscessus and M. porcinum had significantly less esx-3 and mbt genes compared to SGM M. chimaera when stratified by growth classification. However, no significant differences were observed between the species when grown on low iron culture agar or siderophore production by the chrome azurol S (CAS) assay in vitro. These results indicate the complex mechanisms involved in iron sequestration and siderophore activity among diverse NTM species.

Siderophore-producing Pantoea ferrattrahens sp. nov. isolated from a clinical specimen and Pantoea ferramans sp. nov. isolated from soil at the bottom of a pond.

Two Gram-negative facultative anaerobes were isolated from a sepsis patient with pancreatic cancer (strain PAGU 2156T ) and soil at the bottom of a pond (strain PAGU 2198T ), respectively. These two strains formed haloes around the colonies on chrome azurol S agar plates, indicating the production of siderophores. Two isolates assigned to the genus Pantoea based on the 16S rRNA gene were differentiated from established species by using polymorphic taxonomies. Phylogenetic analysis using four housekeeping genes (gyrB, rpoB, atpD, and infB) showed that strain PAGU 2156T is closely related to Pantoea cypripedii LMG 2657T (89.9%) or Pantoea septica LMG 5345T (95.7%). Meanwhile, strain PAGU 2198T formed a single clade with Pantoea rodasii DSM 26611T (93.6%) and Pantoea rwandensis DSM 105076T (93.3%). The average nucleotide identity values obtained from the draft genome assembly showed ≤90.2% between strain PAGU 2156T and closely related species and ≤81.5% between strain PAGU 2198T and closely related species. Based on various phenotypes, biochemical properties, and whole-cell fatty acid composition compared with related species, it was concluded that each strain should be classified as a new species of the genus Pantoea. In this manuscript, Pantoea ferrattrahens sp. nov. and Pantoea ferramans sp. nov. with strain PAGU 2156T (=NBRC 115930T = CCUG 76757T ) and strain PAGU 2198T (=NBRC 114265T = CCUG 75151T ) are proposed as each type strain.

Evaluation of Siderophore Production by Different Promising Microbial Isolates

Indian alkaline soils are deficient in iron due to high pH, high calcium carbonate, highly permeable coarse textured soils, and soils low in organic carbon content. This study is carried out to increase the iron use efficiency of soil by using promising microbial isolates. Production of siderophore by promising microbial isolates is a greatest invention which help in increasing uptake of iron. A short-term laboratory experiment was carried “To evaluate the siderophore productions by different promising microbial isolates using chrome azurol S assay technique”. Ten microbial isolates were inoculated on plate as well as in broth medium. Plates were observed for orange halo formation around the bacterial growth. The size of orange halo around the colony of each microbial isolates was measured. The broth cultures inoculated with inoculum, incubated at 28 ± 20C for 24-72 hr with constant shaking at 120 rpm. After the incubation, the culture broths were centrifuged at 10,000 rpm for 10 min. The cell free supernatants were subjected to quantitative estimation of siderophores by CAS-shuttle, absorbance was measured at 630 nm against a reference consisting of 0.5 ml of uninoculated broth and 0.5 ml of CAS reagent. Obtained results indicated that in both plate and broth assays medium inoculated with strain Pseudomonas fluorescens show significantly higher orange halo formation around the growth and maximum siderophore content in aliquot. Inoculation of this plant growth promoting microbial isolates will be the great achievement in replacing chemical fertilizers in agriculture.

Genetic diversity, plant growth promotion potential, and antimicrobial activity of culturable endophytic actinobacteria isolated from Aconitum carmichaelii Debeaux.

This study evaluated the phylogenetic diversity, plant growth promotion capacity, antifungal activity, and biocontrol potential of culturable actinobacterial endophytes isolated from the medicinal plant Aconitum carmichaelii Debeaux. Isolation of actinobacteria from healthy A. carmichaelii plants was carried out on six different media. Full-length 16S rRNA gene was amplified by PCR from the genomic DNA of each strain. Indole-3-acetic acid and siderophore production were quantitatively assessed by the Salkowski and Chrome Azurol S methods, respectively. Rice seeds germination and seedling growth were employed to evaluate plant growth promotion capacities of candidate strains. Dual-culture assay and pot experiments were performed to investigate the antifungal and biocontrol potential of isolates. We obtained 129 actinobacterial isolates from A. carmichaelii, and they belonged to 49 species in 7 genera. These strains exhibited diverse plant growth promotion ability, among which one strain significantly enhanced rice seeds germination, while 31 strains significantly facilitated rice seedling growth. SWUST-123 showed strong antifungal activity against four pathogens in vitro and was most compatible with Qingchuan cultivar. SWUST-123 reduced around 40% of southern blight disease occurrence compared to blank control treatment. . Aconitum carmichaelii harbored genetically diverse actinobacterial endophytes exhibiting diverse plant growth promotion and antifungal potential, some of which can be served as good candidates for biofertilizers and biocontrol agents.