Siderophore Production Research Articles

Unleaded agriculture: Myth to reality by wetland microbial flora

AbstractWetlands, refer to the confluence with regards to land and water having a rich biological diversity with multiple purpose. As per the Ramsar Convention, framed in August 2002, East Kolkata Wetlands have been considered to be of global significance. Although inappropriate supervision of these wetlands, has led to the gradual deterioration of this wetland. In this present study, the soil sample was collected from these reclaimed agricultural wetlands of Chowbaga area, of East Kolkata areas with coordinates of 22.5296°N, 88.4207°E. The predominant or lingering bacterial flora was isolated from the soil surrounding the rhizospheric region of Cucurbita sp. and Zea mays and their plant growth promotion properties of the lingering bacterial flora were analyzed. These plant growth promoting rhizobacteria (PGPR) included some species of Bacillus sp. that could augment plant growth by different methodologies like nitrogen fixation, phosphate solubilization, phytohormone synthesis, and siderophore production. One of the bacterial isolates DPP(C) showed highest ability of siderophore production of 37.89% at 48 hours, whereas DCP(A) showed better capability in IAA production of 56.785 μg/mL than rest of the bacterial isolates. These reclaimed agricultural lands were found to have very high quantities of heavy metals, especially lead. All the bacterial isolates, were found to have great potential in lead mitigation, whereby they could adsorb up to 8.28% of lead. Some studies have shown the capability of microbial degradation for bioremediation of organic forms of lead and thereby can be removed from agricultural field for longer period of time. The prospective potential use of PGPR has gradually escalated, since it is one of the best substitutes against the constant usage of chemical fertilizers as well as pesticides. The use of these PGPR is one of the most reliable methods for ensuring sustainable agriculture. Furthermore, in future, the PGPR population will be correlated with the nutrient availability and productivity of the plants.

Plant–Entomopathogenic Fungi Interaction: Recent Progress and Future Prospects on Endophytism-Mediated Growth Promotion and Biocontrol

Entomopathogenic fungi, often acknowledged primarily for their insecticidal properties, fulfill diverse roles within ecosystems. These roles encompass endophytism, antagonism against plant diseases, promotion of the growth of plants, and inhabitation of the rhizosphere, occurring both naturally and upon artificial inoculation, as substantiated by a growing body of contemporary research. Numerous studies have highlighted the beneficial aspects of endophytic colonization. This review aims to systematically organize information concerning the direct (nutrient acquisition and production of phytohormones) and indirect (resistance induction, antibiotic and secondary metabolite production, siderophore production, and mitigation of abiotic and biotic stresses) implications of endophytic colonization. Furthermore, a thorough discussion of these mechanisms is provided. Several challenges, including isolation complexities, classification of novel strains, and the impact of terrestrial location, vegetation type, and anthropogenic reluctance to use fungal entomopathogens, have been recognized as hurdles. However, recent advancements in biotechnology within microbial research hold promising solutions to many of these challenges. Ultimately, the current constraints delineate potential future avenues for leveraging endophytic fungal entomopathogens as dual microbial control agents.

Characterization and Field Evaluation of Potential Fluorescent Pseudomonas Isolates on Growth and Yield Attributing Characters in Chickpea

The present investigation was conducted at the research and instructional farm, College of Agriculture, Indira Gandhi Krishi Vishwavidyalaya, Raipur, Chhattisgarh, India during rabi (October–December 2019) to evaluate the influence of fluorescent Pseudomonas isolates on chickpeas through characterization and field evaluation. Eighty-eight rhizosphere soil samples were derived from different locations in Bastar and Bilaspur districts of Chhattisgarh, India. Potential isolates were required for fundamental research and practical application of plant growth-promoting rhizobacterial strains on different crops. Among eighty-eight isolates, ten fluorescent Pseudomonas (visible under UV light at 360 nm) emitting strong fluorescence were selected for the course of the investigation and characterized for the production of siderophores, phosphate solubilization, indole acetic acid, 1-aminocyclopropane-1-carboxylic acid deaminase, and analysis of antagonistic potential. Of the 10 Pseudomonas isolates, 9704 was identified as the highest phosphate solubilizer, BSP-23 was identified as the highest indole acetic acid producer, and BSP-19 was the highest siderophore producer. Fluorescent Pseudomonas isolates BS-1, BS-4, 9809, BSP-14, and BSP-19 were identified to possess 1-aminocyclopropane-1-carboxylic acid deaminase-producing ability following qualitative analysis. Our present investigation indicates that beneficial effects of fluorescent Pseudomonas could be achieved through simple and cost-effective seed treatment. Three fluorescent Pseudomonas strains, 9704, BS-14, and 9829, consistently increased seed germination and improved plant growth and yield (BS-37.9% and 9704-35.7%) attributes in chickpeas. Besides, confrontation assays performed against R. bataticola expressed varying levels of inhibition. The phylogenetic affinities of 16S rRNA gene sequencing resolved the species identities of selected isolates.

The Potential of Burkholderia sp. from Zea mays Roots as Plant Growth Promoting Rhizobacteria

Plant Growth-Promoting Rhizobacteria (PGPR) plays a crucial role in enhancing plant health, while Burkholderia sp. has been identified and has potential as a promising PGPR for maize plants. Recognizing the essential role of PGPR in plant health, this study explores how L-TRP addition might improve PGPR performance for better plant growth. Employing a completely randomized design, the study assesses the effects of Burkholderia sp. as PGPR on maize growth across three treatment groups: PGPR with L-TRP, PGPR without L-TRP, and a control group. The evaluation focuses on plant growth metrics, plant hormone production (auxin and gibberellin), and siderophore activity to gauge plant iron availability. Statistical analysis highlights that L-TRP supplementation notably increases auxin production in the PGPR + L-TRP group, surpassing the PGPR without L-TRP and control groups. Although both PGPR treatments elevate gibberellin levels compared to the control, auxin increase is the most significant outcome, indicating no substantial difference in gibberellin levels between the two PGPR groups. Enhanced siderophore production suggests improved iron assimilation for plants. The findings demonstrate that L-TRP supplementation with PGPR, particularly Burkholderia sp., effectively boosts maize growth, primarily through increased auxin and siderophore production. This combination presents a promising strategy for augmenting agricultural yields, especially for maize productivity, by leveraging the synergistic effects of soil microbes and nutrient supplementation.

Revealing the diversity of Jojoba-associated fungi using amplicon metagenome approach and assessing the in vitro biocontrol activity of its cultivable community.

Jojoba shrubs are wild plants cultivated in arid and semiarid lands and characterized by tolerance to drought, salinity, and high temperatures. Fungi associated with such plants may be attributed to the tolerance of host plants against biotic stress in addition to the promotion of plant growth. Previous studies showed the importance of jojoba as jojoba oil in the agricultural field; however, no prior study discussed the role of jojoba-associated fungi (JAF) in reflecting plant health and the possibility of using JAF in biocontrol. Here, the culture-independent and culture-dependent approaches were performed to study the diversity of the jojoba-associated fungi. Then, the cultivable fungi were evaluated for in-vitro antagonistic activity and in vitro plant growth promotion assays. The metagenome analysis revealed the existence of four fungal phyla: Ascomycota, Aphelidiomycota, Basidiomycota, and Mortierellomycota. The phylum Ascomycota was the most common and had the highest relative abundance in soil, root, branch, and fruit samples (59.7%, 50.7%, 49.8%, and 52.4%, respectively). Alternaria was the most abundant genus in aboveground tissues: branch (43.7%) and fruit (32.1%), while the genus Discosia had the highest abundance in the underground samples: soil (24%) and root (30.7%). For the culture-dependent method, a total of 14 fungi were isolated, identified, and screened for their chitinolytic and antagonist activity against three phytopathogenic fungi (Fusarium oxysporum, Alternaria alternata and Rhizoctonia solani) as well as their in vitro plant growth promotion (PGP) activity. Based on ITS sequence analysis, the selected potent isolates were identified as AspergillusstellatusEJ-JFF3, Aspergillusflavus EJ-JFF4, Stilbocreasp. EJ-JLF1, Fusariumsolani EJ-JRF3, and AmesiaatrobrunneaEJ-JSF4. The endophyte strain A. flavus EJ-JFF4 exhibited the highest chitinolytic activity (9 Enzyme Index) and antagonistic potential against Fusarium oxysporum, Alternaria alternata, and Rhizoctonia solani phytopathogens with inhibitory percentages of 72, 70, and 80 respectively. Also, A. flavus EJ-JFF4 had significant multiple PGP properties, including siderophore production (69.3%), phosphate solubilization (95.4 µg ml-1). The greatest production of Indol-3-Acetic Acid was belonged to A.atrobrunnea EJ-JSF4 (114.5 µg ml-1). The analysis of FUNGuild revealed the abundance of symbiotrophs over other trophic modes, and the guild of endophytes was commonly assigned in all samples. For the first time, this study uncovered fungal diversity associated with jojoba plants using a culture-independent approach and in-vitro assessed the roles of cultivable fungal strains in promoting plant growth and biocontrol. The present study indicated the significance of jojoba shrubs as a potential source of diverse fungi with high biocontrol and PGP activities.

Serratia marcescens AB1: A rhizosphere bacterium mitigating the acetochlor stress on the soil environment

Microbial remediation, a significant research focus in bioremediation, shows promise in addressing pollution. In this study, the optimal medium for acetochlor-degrading bacteria AB1 was determined by the response surface method as 29.94 g L−1 sucrose, 10.06 g L−1 yeast extract, and 20.32 g L−1 NaCl. The single-factor method identified optimum degradation conditions, including a temperature of 30 °C, pH of 7.0, inoculation with 3% AB1, and an initial acetochlor concentration of 10 mg L−1. The strain reached a maximum degradation rate of 79.87% within 5 days. AB1 performed nitrogen fixation, phosphorus dissolution, potassium hydrolysis, siderophore production, and biofilm formation. In the presence of acetochlor, it also induced the upregulation of genes, wza and luxS. Utilizing a green fluorescent protein and rifampicin-resistant strain LAB1-gfp, it demonstrated stable colonization in maize rhizospheres and soils, enhancing growth and degradation. This reduced the acetochlor half-life to 12.77 days and increased soil enzyme activity, providing a theoretical foundation for acetochlor bioremediation.

A comprehensive comparative genomic analysis revealed that plant growth promoting traits are ubiquitous in strains of Stenotrophomonas.

Stenotrophomonas strains, which are often described as plant growth promoting (PGP) bacteria, are ubiquitous in many environments. A total of 213 genomes of strains of Stenotrophomonas were analyzed using comparative genomics to better understand the ecological roles of these bacteria in the environment. The pan-genome of the 213 strains of Stenotrophomonas consists of 27,186 gene families, including 710 core gene families, 11,039 unique genes and 15,437 accessory genes. Nearly all strains of Stenotrophomonas harbor the genes for GH3-family cellulose degradation and GH2- and GH31-family hemicellulose hydrolase, as well as intact glycolysis and tricarboxylic acid cycle pathways. These abilities suggest that the strains of this genus can easily obtain carbon and energy from the environment. The Stenotrophomonas strains can respond to oxidative stress by synthesizing catalase, superoxide dismutase, methionine sulfoxide reductase, and disulfide isomerase, as well as managing their osmotic balance by accumulating potassium and synthesizing compatible solutes, such as betaine, trehalose, glutamate, and proline. Each Stenotrophomonas strain also contains many genes for resistance to antibiotics and heavy metals. These genes that mediate stress tolerance increase the ability of Stenotrophomonas strains to survive in extreme environments. In addition, many functional genes related to attachment and plant colonization, growth promotion and biocontrol were identified. In detail, the genes associated with flagellar assembly, motility, chemotaxis and biofilm formation enable the strains of Stenotrophomonas to effectively colonize host plants. The presence of genes for phosphate-solubilization and siderophore production and the polyamine, indole-3-acetic acid, and cytokinin biosynthetic pathways confer the ability to promote plant growth. These strains can produce antimicrobial compounds, chitinases, lipases and proteases. Each Stenotrophomonas genome contained 1-9 prophages and 17-60 genomic islands, and the genes related to antibiotic and heavy metal resistance and the biosynthesis of polyamines, indole-3-acetic acid, and cytokinin may be acquired by horizontal gene transfer. This study demonstrates that strains of Stenotrophomonas are highly adaptable for different environments and have strong potential for use as plant growth-promoting bacteria.

IAA-producing plant growth promoting rhizobacteria from Ceanothus velutinus enhance cutting propagation efficiency and Arabidopsis biomass.

Climate-induced drought impacts plant growth and development. Recurring droughts increase the demand for water for food production and landscaping. Native plants in the Intermountain West region of the US are of keen interest in low water use landscaping as they are acclimatized to dry and cold environments. These native plants do very well at their native locations but are difficult to propagate in landscape. One of the possible reasons is the lack of associated microbiome in the landscaping. Microbiome in the soil contributes to soil health and impacts plant growth and development. Here, we used the bulk soil from the native plant Ceanothus velutinus (snowbrush ceanothus) as inoculant to enhance its propagation. Snowbrush ceanothus is an ornamental plant for low-water landscaping that is hard to propagate asexually. Using 50% native bulk soil as inoculant in the potting mix significantly improved the survival rate of the cuttings compared to no-treated cuttings. Twenty-four plant growth-promoting rhizobacteria (PGPR) producing indole acetic acid (IAA) were isolated from the rhizosphere and roots of the survived snowbrush. Seventeen isolates had more than 10µg/mL of IAA were shortlisted and tested for seven different plant growth-promoting (PGP) traits; 76% showed nitrogen-fixing ability on Norris Glucose Nitrogen free media,70% showed phosphate solubilization activity, 76% showed siderophore production, 36% showed protease activity, 94% showed ACC deaminase activity on DF-ACC media, 76% produced catalase and all of isolates produced ammonia. Eight of seventeen isolates, CK-6, CK-22, CK-41, CK-44, CK-47, CK-50, CK-53, and CK-55, showed an increase in shoot biomass in Arabidopsis thaliana. Seven out of eight isolates were identified as Pseudomonas, except CK-55, identified as Sphingobium based on 16S rRNA gene sequencing. The shortlisted isolates are being tested on different grain and vegetable crops to mitigate drought stress and promote plant growth.

Characterization and exploration of an As(III)-oxidizing bacterium TMKU1 for plant growth promotion under arsenic stress

Arsenic (As) pollution has been recognized as a serious global environmental problem. Though various remediation strategies are being explored to cope up with the As-toxicity, currently microbe-assisted detoxification of As is found to be the most promising technique for restoring As-contaminated rhizosphere soil for its eco-friendly nature. As(III)-oxidizing bacteria were reported to most suitable in this regard. In this study, an As(III)-oxidizing bacterium, TMKU1 was isolated from As-contaminated rhizospheric soil that could withstand up to 20 mM As(III) and 95 mM As(V). The strain was closely related to the genus Acinetobacter, according to 16 S rDNA analysis. The strain could transform ∼70% of As(III) to As(V) under aerobic culture condition. The transformation of As(III) was found to be catalyzed by arsenite oxidase, which is constitutive nature in this strain. The As(III)-oxidase was found to be encoded by the functional gene aioA harbored on the genomic DNA. The enzyme was localized mostly in the periplasm, and the partially purified enzyme showed the Km = 95.76667 μM and Vmax = 0.356341 M min−1g−1 protein. The novelty of this strain is that it could express plant growth promoting features like phosphate solubilization, siderophore production, IAA production and N2-fixation, both under stress-free and As-stress conditions. Seed bacterization with TMKU1 not only significantly increased the germination of chickpea seeds, but also shielded the seedlings from the As toxicity and accumulation. Overall, the results suggest that this bacterial candidate would be of potential use in agricultural practices for detoxification of As in crop field.

Evaluation of commercial importance of endophytes isolated from Argemone mexicana and Papaver rhoeas.

The paper industry is a composite one constituting different types of mills, processes, and products. The paper industries consume large amounts of resources, like wood and water. These industries also create huge amounts of waste that have to be treated. In our study, 23 endophytic bacteria were isolated from Argemone mexicana, and 16 endophytic bacteria were isolated from Papaver rhoeas. Seventeen and 15 bacterial endophytes from A. mexicana and P. rhoeas, respectively, showed cellulose-degrading activity. The biochemical and molecular characterization were done for endophytic bacteria with cellulolytic activity. The consortium of cellulose-degrading endophytic bacteria from A. mexicana showed endoglucanase activity (0.462IU/ml) and FPCase enzyme activity (0.269IU/ml) and from P. rhoeas gave endoglucanase activity (0.439IU/ml) and FPCase enzyme activity (0.253IU/ml). Degraded carboxy methylcellulose and filter paper were further treated by Saccharomyces cerevisiae and bioethanol was produced. Cellulose-degrading endophytic bacteria were also tested for auxin, siderophore production, and phosphate solubilization activities. Individual cellulose-degrading endophytic bacteria with plant growth-promoting activities were used as biofertilizers, tested for plant growth-promoting activities using Basmati Pusa 1121 rice, and plant growth parameters were recorded. The degraded paper enhances the growth of rice plants. Selected bacterial endophytes and their consortia from A. mexicana and P. rhoeas were powerful cellulose degraders, which can be further employed for ethanol production and as significant biofertilizers in agriculture.

Diversity and functional traits of seed endophytes of Dysphania ambrosioides from heavy metal contaminated and non-contaminated areas.

Seed endophytes played a crucial role on host plants stress tolerance and heavy metal (HM) accumulation. Dysphania ambrosioides is a hyperaccumulator and showed strong tolerance and extraordinary accumulation capacities of multiple HMs. However, little is known about its seed endophytes response to field HM-contamination, and its role on host plants HM tolerance and accumulation. In this study, the seed endophytic community of D. ambrosioides from HM-contaminated area (H) and non-contaminated area (N) were investigated by both culture-dependent and independent methods. Moreover, Cd tolerance and the plant growth promoting (PGP) traits of dominant endophytes from site H and N were evaluated. The results showed that in both studies, HM-contamination reduced the diversity and richness of endophytic community and changed the most dominant endophyte, but increased resistant species abundance. By functional trait assessments, a great number of dominant endophytes displayed multiple PGP traits and Cd tolerance. Interestingly, soil HM-contamination significantly increased the percentage of Cd tolerance isolates of Agrobacterium and Epicoccum, but significantly decreased the ration of Agrobacterium with the siderophore production ability. However, the other PGP traits of isolates from site H and N showed no significant difference. Therefore, it was suggested that D. ambrosioides might improve its HM tolerance and accumulation through harboring more HM-resistant endophytes rather than PGP endophytes, but to prove this, more work need to be conducted in the future.

Genomic insights into Streptomyces hygroscopicus subsp. hygroscopicus SRF1: a potential biocontrol agent against fusarium wilt with plant growth-promoting abilities in tomatoes

ABSTRACT Streptomyces sp. isolate SRF1 has previously demonstrated promising results in controlling various plant fungi under in vitro conditions. However, further exploration of its genome and its efficacy in disease control and plant growth promotion under in vivo conditions is warranted. This study aimed to utilise whole genome sequencing (WGS) to classify Streptomyces sp. isolate SRF1 at the species level and predict genes associated with antagonistic ability and plant growth promotion, thereby assessing its potential as a biocontrol agent against fusarium wilt and a promoter of plant growth. WGS was employed to elucidate the taxonomic classification of isolate SRF1 and predict genes involved in disease suppression and plant growth promotion. In vitro assays were conducted to evaluate its antagonistic activity against Fusarium oxysporum f. sp. lycopersici (Fol) and its production of cellulase, amylase, indole-3-acetic acid (IAA), and siderophores. Pot experiments were carried out using SRF1 cell suspension and culture filtrate to assess its efficacy against Fol and its impact on tomato growth. Real-time PCR analysis was performed to correlate gene expression levels with observed activities. The results showed that isolate SRF1 was classified as S. hygroscopicus subsp. hygroscopicus and demonstrated antagonism against Fol. Furthermore, WGS revealed genes or gene clusters associated with disease control, including those encoding antifungal agents such as butyrolactol A, nigericin, and hygromycin A. Additionally, genes responsible for auxin biosynthesis, siderophore production, and carbohydrate-digesting enzymes such as chitinase, cellulase, and amylase were identified, suggesting potential roles in disease suppression and plant growth promotion.

Siderophores and competition for iron govern myxobacterial predation dynamics.

Bacterial predators are decisive organisms that shape microbial ecosystems. In this study, we investigated the role of iron and siderophores during the predatory interaction between two rhizosphere bacteria: Myxococcus xanthus, an epibiotic predator, and Sinorhizobium meliloti, a bacterium that establishes nitrogen-fixing symbiosis with legumes. The results show that iron enhances the motility of the predator and facilitates its predatory capability, and that intoxication by iron is not used by the predator to prey, although oxidative stress increases in both bacteria during predation. However, competition for iron plays an important role in the outcome of predatory interactions. Using combinations of predator and prey mutants (nonproducers and overproducers of siderophores), we have investigated the importance of competition for iron in predation. The results demonstrate that the competitor that, via the production of siderophores, obtains sufficient iron for growth and depletes metal availability for the opponent will prevail in the interaction. Consequently, iron fluctuations in soils may modify the composition of microbial communities by altering the activity of myxobacterial predators. In addition, siderophore overproduction during predation can alter soil properties, affecting the productivity and sustainability of agricultural operations.

Effect of Different Metals on Synthesis of Siderophores by Endophyte Bacteria Isolated from Various Annual Plants

Endophyte bacteria are microorganisms that pass all or part of their life cycle in the tissues of healthy plants without causing any obvious signs of disease. Most siderophore-producing endophytic bacteria could improve the plant growth. Here, the effect of metals, iron (Fe), nickel (Ni), and cobalt (Co), on the growth and siderophore production profiles of 30 endophyte bacterial isolates were investigated. The results of the Minimum Inhibition Concentration (MIC) tests showed that endophytes exhibit varying degrees of tolerance to heavy metals and the metal tolerance decreased in the order Fe3+>Ni2+>Co2+. It was revealed that while 10 isolates could not produce siderophores under any circumstances, 20 isolates produced siderophores at different degrees, and siderophore molecules synthesized and secreted by these 20 isolates had affinities for all three metals (Fe3+, Co2+, and Ni2+). In addition, siderophore production profiles of isolates under each heavy metal stress were investigated by adding these metals to the Chromium Azurol Sulfonate (CAS) medium at optimum concentration. The results suggested that siderophore synthesis could be one of the coping mechanisms of only two isolates with Co2+ and Ni2+ heavy metals. In the final stage of the study, molecular identification of a certain number of isolates selected according to their siderophore production values was carried out by 16S rRNA sequencing. As a result of the sequence analysis, 2 Pseudomonas sp., 4 Bacillus sp., 1 Chryseobacterium sp., 1 Staphylococcus sp., and 1 Peribacillus sp. were revealed.

The Transcription Factors AcuK and AcuM Influence Siderophore Biosynthesis of Aspergillus fumigatus.

The mold Aspergillus fumigatus employs two high-affinity uptake systems, reductive iron assimilation (RIA) and siderophore-mediated iron acquisition (SIA), for the acquisition of the essential trace element iron. SIA has previously been shown to be crucial for virulence in mammalian hosts. Here, we show that a lack of AcuK or AcuM, transcription factors required for the activation of gluconeogenesis, decreases the production of both extra- and intracellular siderophores in A. fumigatus. The lack of AcuM or AcuK did not affect the expression of genes involved in RIA and SIA, suggesting that these regulators do not directly regulate iron homeostasis genes, but indirectly affect siderophore production through their influence on metabolism. Consistent with this, acetate supplementation reversed the intracellular siderophore production defect of ΔacuM and ΔacuK. Moreover, ΔacuM and ΔacuK displayed a similar growth defect under iron limitation and iron sufficiency, which suggests they have a general role in carbon metabolism apart from gluconeogenesis. In agreement with a potential role of the glyoxylate cycle in adaptation to iron starvation, transcript levels of the malate synthase-encoding acuE were found to be upregulated by iron limitation that is partially dependent on AcuK and AcuM. Together, these data demonstrate the influence of iron availability on carbon metabolism.

Determination of Antagonistic Activities of Endophytic Bacteria Isolated from Different Wheat Genotypes Against Fusarium culmorum

This study aimed to evaluate the physiological and biochemical properties and enzyme activities of endophytic bacteria obtained from different wheat genotypes, as well as their effectiveness against Fusarium culmorum, which causes root and crown rot in wheat. The results obtained from double culture tests of isolates against F. culmorum showed that the inhibition rate varied between 80.56% and 13.90%. The inhibition rate against F. culmorum was 80.59% for Bacillus subtilis (MM11), 69.41% for Stenotrophomonas maltophilia (EY5), and 61.10% for Enterobacter sp. (MY3) under in vitro conditions, the most effective isolates. Pseudomonas putida (EM9) and Pseudomonas orientalis (MM21) isolates gave positive results in all tests in the production of amylase, cellulase, phosphatase, ACC deaminase, and siderophore. To identify six promising isolates, 16S rRNA gene-based sequence analysis was utilized. The efficacy of bacterial strains against F. culmorum, pot experiments were conducted in a growth room (in vivo). The results demonstrated that the combination of S. maltophilia, Enterobacter sp., and B. subtilis (MY3+EY5+MM11) yielded the most favorable outcomes in terms of disease severity, plant height, wet weight, dry weight, root wet weight, and root dry weight. The combination of Stenotrophomonas rhizophila, P. putida, and P. orientalis (EY1+EM9+MM21) exhibited promising results. Utilizing effective bacterial strains is anticipated to reduce the dependence on and costs associated with chemical fertilizers and pesticides while minimizing their environmental impact. Furthermore, these strains show potential for commercial applications pending further validation procedures. The findings from this study significantly contribute to the field of biological control strategies against F. culmorum by leveraging the diverse capabilities of endophytic bacteria.

Effects of PGPB Inoculations on Plant Growth and Quality of Spray Carnation Cultivation in Greenhouse

This study was carried out to reveal the effects of beneficial bacteria on the development and quality of Dianthus caryophyllus under greenhouse conditions. The carnation seedlings were treated with Enterobacter ludwigii (KF29A) and Pseudomonas fluorescens (KF31B), which have nitrogen fixation, phosphate solibilizing and siderophore production properties, Paenarthrobacter nitroguaiacolicus (KF3B) with nitrogen fixation, ACC deaminase and siderophore production, Pseudomonas sp. strain VG242B (KF5A), which carries nitrogen fixing, phosphate solibilizing, and siderophore production properties together, Paenibacillus xylanilyticus (KF63C) with nitrogen fixation, phosphate solibilizing, ACC deaminase and siderophore production properties together and Pseudoalteromonas tetraodonis (TV126C) bacteria with nitrogen fixing, phosphate solibilizing and ACC deaminase properties were applied. In the study, in which phenological and morphological observations were made, the effects of bacterial inoculations were tried to be determined. The effects of beneficial bacteria treatments on the number of petals, the number of nodes, the length between the nodes and the weight of the branches in the carnation plant were statistically insignificant; effects on the parameters of bud first bloom time, full bloom time, time from planting to first harvest, number of flower buds and stem length (p

Exploring the impact of endophytic bacteria on mitigating salinity stress in Solanum lycopersicum L.

In the era of climate change, plants are being compelled to adapt and endure progressively in unfavorable environments. Applying biostimulants to plants can improve their growth and resilience by mitigating the adverse effects of abiotic stresses. Endophytes are well-known for promoting plant growth and producing natural compounds. The current study focuses on the ability of endophytic bacteria to increase plant growth and reduce salt stress in tomato plants. Nine isolates from the stems of Fagonia indica and Ajuga bracteosa showed a variety of salt stress tolerances as well as solubilizing phosphate, indole acetic acid, ammonia production, siderophore production, and extracellular enzymes like protease, cellulase, and chitinase. Four Endophytic bacteria Enterobacter hormaechei (MOSEL-FLS1), Stenotrophomonas maltophilia (MOSEL-FLS2), Bacillus subtilis (MOSEL-S8), and Staphylococcus epidermidis (MOSEL-S9) were selected based on plant growth promoting traits and halotolerant assay. These endophytic bacteria were subjected to ex-situ activities to figure out their capacity to stimulate the growth of the tomato plant in the growth room under different concentrations of NaCl (50–200 mM). All bacterial strains stimulated tomato plant growth under salinity stress compared to uninoculated controls. Antioxidant enzymes (SOD and POD), chlorophyll, and proline level in the plants was increased after salt treatment. Moreover, the activity of antioxidant enzymes and their relative transcript levels were dependent on the concentration of salinity stress. These findings highlight the varied microbial community linked to medicinal plants and their capacity to promote plant growth, potentially mitigating salt stress through the regulation of osmolytes and antioxidant enzymes. This makes them promising contenders for biofertilizers.

Study on Plant Growth Promoting Traits of PGPR Isolates From Semi-Arid Kachchh, Gujarat Under Salt Stress Conditions

Salinity is a major problem in the agricultural sector, as it turns productive agronomical land to become unproductive. Therefore, Plant-growth-promoting rhizobacteria (PGPR), that live in the plant root zone named the rhizosphere, is one of the prominent solutions to overcome this problem in an eco-friendly manner as Rhizobacteria responds to osmotic stress and support plant development. Thus, the present study was aimed to characterize various traits of the PGPR strains isolated from saline soils of Kachchh. The characterization of the traits in the presence and absence of sodium chloride was assessed including IAA production (76.97±1.68 mg/l), Ammonia production (38.59±0.19 mg/l), Siderophore production (49.21±1.83%), Phosphate solubilization (4897.73±25.53 mg/l). When assessed for the salt tolerance of the strains in the presence of NaCl between 20-50 gm/L, the strain D6 exhibited a better growth even at 5% NaCl concentration (2.047OD). Further, the effect of PGPR on the growth of V. radiata was 100% in all the experimental setup, whereas in case of B. juncea, the highest germination of 96.67% was observed only in T2 and T1+T2+T3. Further, the molecular sequencing of the strains revealed the identification of the strains as Klebsiella quasipneumoniae, Bacillus paralicheniformis and Klebsiella pneumoniae.

Isolation and Molecular Profiling of Halotolerant Plant Growth Promoting Rhizosphere Fungi from Salt affected Agroforestry Plantation

Soil salinity is a major abiotic stress that adversely affects plant growth, and productivity. About 20% of irrigated lands are affected by salinity worldwide; In India, there are 6.74 million hectares of salt-affected lands. Salt-tolerant Plant Growth Promoting (PGP) microorganisms can enhance the growth of plants in such salt-stressed areas. Therefore, this study aimed to investigate the diversity of beneficial fungal communities, screen for their ability to support plant growth, and evaluate the production of various essential compounds in view of plant growth in salt-stressed lands. A total of 68 fungal colonies were isolated from 5 different agroforestry plantation sites in Karur, Tamil Nadu, South India at quarterly intervals. The isolates were screened for sodium chloride (NaCl) tolerance (0%, 5%, 10%, 15%, and 20% concentration). A total of 7 isolates showed considerable salt tolerance and were tested qualitatively in-vitro, for PGP traits such as phosphate, potassium, and zinc solubilization, nitrogen fixation, hydrogen cyanide production, siderophore production, and ACC deaminase production. Finally, 5 isolates with maximum values for PGP properties under 20% NaCl concentration were tested for the quantity of Indole-3-Acetic Acid (IAA) and Exo-polysaccharide (EPS) production. All 5 isolates were identified up to the species level using 18S rRNA gene sequencing. To the best of our knowledge, this is the first report on isolating saline-tolerant PGP Fungi (PGPF) from the rhizosphere region of Casuarina equisetifolia and Eucalyptus camaldulensis in Karur, Tamil Nadu, India. In the future, the bioformulation of PGPF and its application will boost the cultivation of tree saplings in this salt affected regions.