Phosphate Solubilization Research Articles

Phylogenetic Analysis of Bacterial Isolates Recovered from Salt-affected Soils of Haryana & Punjab, India

Excessive saline/alkaline conditions present a significant challenge to the environment and ecology, impacting yield, plant growth, and soil health. This study focuses on isolating and characterizing halophilic bacteria from salt-affected areas in Haryana and Punjab, India. Morphological, biochemical, and molecular analyses were conducted to assess their potential as plant growth-promoting rhizobacteria (PGPR) for mitigating salt stress in salt-affected soils. Four bacterial strains, identified as HR3-PM, PB01-KB, PB-424, and PB-466, were isolated and characterized. Morphological and biochemical assays revealed diverse traits among the isolates, including phosphate solubilization, indole-3-acetic acid (IAA) production, and ammonia excretion. Molecular identification via 16S rRNA sequencing confirmed their taxonomic classification and revealed close homology to known bacterial species such as Klebsiella aerogenes, Pseudomonas mosselii, Lysinibacillus acetophenoni, and Pseudomonas stutzeri. Phylogenetic analysis provided insights into their evolutionary relationships. These salt-tolerant bacteria exhibit promising PGPR activities, suggesting their potential for sustainable agriculture and soil remediation practices in salt-affected soils. Harnessing their abilities could offer cost-effective and environmentally friendly solutions to mitigate soil salinity, enhance plant productivity, and contribute to global environmental stresses. Further research is warranted to fully understand and harness the biotechnological potential of these halophilic bacteria in salt-affected ecosystems, paving the way for a more sustainable environmental future.

Multiple omics revealed the growth-promoting mechanism of Bacillus velezensis strains on ramie.

Beneficial bacteria that promote plant growth can shield plants from negative effects. Yet, the specific biological processes that drive the relationships between soil microbes and plant metabolism are still not fully understood. To investigate this further, we utilized a combination of microbiology and non-targeted metabolomics techniques to analyze the impact of plant growth-promoting bacteria on both the soil microbial communities and the metabolic functions within ramie (Boehmeria nivea) tissues. The findings indicated that the yield and traits of ramie plants are enhanced after treatment with Bacillus velezensis (B. velezensis). These B. velezensis strains exhibit a range of plant growth-promoting properties, including phosphate solubilization and ammonia production. Furthermore, strain YS1 also demonstrates characteristics of IAA production. The presence of B. velezensis resulted in a decrease in soil bacteria diversity, resulting in significant changes in the overall structure and composition of soil bacteria communities. Metabolomics showed that B. velezensis significantly altered the ramie metabolite spectrum, and the differential metabolites were notably enriched (P < 0.05) in five main metabolic pathways: lipid metabolism, nucleotide metabolism, amino acid metabolism, plant secondary metabolites biosynthesis, and plant hormones biosynthesis. Seven common differential metabolites were identified. Correlation analysis showed that the microorganisms were closely related to metabolite accumulation and yield index. In the B. velezensis YS1 and B. velezensis Y4-6-1 treatment groups, the relative abundances of BIrii41 and Bauldia were significantly positively correlated with sphingosine, 9,10,13-TriHOME, fresh weight, and root weight, indicating that these microorganisms regulate the formation of various metabolites, promoting the growth and development of ramie. Conclusively, B. velezensis (particularly YS1) played an important role in regulating soil microbial structure and promoting plant metabolism, growth, and development. The application of the four types of bacteria in promoting ramie growth provides a good basis for future application of biological fertilizers and bio-accelerators.

Assessment of root colonization, identification, and phosphate solubilization activity of root endophytic fungi obtained from hybrid tomato Lycopersicon esculentum Mill. var. TNAU CO3

Assessment of root colonization, identification, and phosphate solubilization activity of root endophytic fungi obtained from hybrid tomato Lycopersicon esculentum Mill. var. TNAU CO3

Effect of Bio-Fertilizer Application on Agronomic Traits, Yield, and Nutrient Uptake of Barley (Hordeum vulgare) in Saline Soil.

Under salinity conditions, growth and productivity of grain crops decrease, leading to inhibition and limited absorption of water and elements necessary for plant growth, osmotic imbalance, ionic stress, and oxidative stress. Microorganisms in bio-fertilizers have several mechanisms to provide benefits to crop plants and reduce the harmful effect of salinity. They can be effective in dissolving phosphate, fixing nitrogen, promoting plant growth, and can have a combination of all these qualities. During two successful agricultural seasons, two field experiments were conducted to evaluate the effect of bio-fertilizer applications, including phosphate solubilizing bacteria (PSB), nitrogen fixation bacteria and a mix of phosphate-solubilizing bacteria and nitrogen fixation bacteria with three rates, 50, 75 and 100% NPK, of the recommended dose of minimal fertilizer on agronomic traits, yield and nutrient uptake of barley (Hordeum vulgare) under saline condition in Village 13, Farafra Oasis, New Valley Governorate, Egypt. The results showed that the application of Microbein + 75% NPK recorded the highest values of plant height, spike length, number of spikes/m2, grain yield (Mg ha-1), straw yield (Mg ha-1), biological yield (Mg ha-1), protein content %, nitrogen (N), phosphorus (P), potassium (K) uptakes in grain and straw (kg ha-1), available nitrogen (mg/kg soil), available phosphorus (mg/kg soil), total microbial count of soil, antioxidant activity of soil (AOA), dehydrogenase, nitrogen fixers, and PSB counts. The application of bio-fertilizers led to an increase in plant tolerance to salt stress, plant growth, grain yield, and straw yield, in addition to the application of the bio-fertilizers, which resulted in a 25% saving in the cost of mineral fertilizers used in barley production.

Dredging wastewater discharge from shrimp ponds affects mangrove soil physical-chemical properties and enzyme activities

Dredging wastewater discharge is a significant environmental concern for mariculture near mangrove ecosystems. However, little attention has been paid to its effects on the soil physical-chemical properties and enzyme activities in mangrove habitats. This study compared the soil physical-chemical properties and enzyme activities in the polluted area that received dredging wastewater from a shrimp pond with those in the control area without wastewater to explore the effects of wastewater discharge on the soil physical-chemical properties and enzyme activities. Variations in soil physical-chemical properties and enzyme activities across different tidal flat areas and depths were also examined. The polluted area exhibited lower soil salinity (10.47 ± 0.58 vs. 15.64 ± 0.54) and moisture content (41.85 ± 1.03 % vs. 45.81 ± 1.06 %) than the control area. Wastewater discharge increased soil enzyme activities, (acid phosphatase, protease, and catalase), resulting in higher inorganic nitrogen (13.20 ± 0.00 μg g−1 vs. 11.60 ± 0.03 μg g−1) but lower total nitrogen (0.93 ± 0.01 mg g−1 vs. 1.62 ± 0.11 mg g−1) in the contaminated zone. From the control to polluted area, there was an approximate increase of 0.43 and 0.83 mg g−1 in soil total phosphorus and soluble phosphate, driven by increased acid phosphatase. However, soil humus and organic matter decreased by 0.04 and 1.22 %, respectively, because of wastewater discharge. The impact of wastewater discharge on the soil physical-chemical properties and enzyme activities was most pronounced in the landward and surface soil layers (0–5 cm). The results showed that wastewater discharge altered soil physical-chemical properties and enzyme activities, accumulating soil bioavailable nutrients (inorganic nitrogen and soluble phosphate), but at the cost of reduced soil quality, especially organic matter, further adversely affecting the overall health of mangrove ecosystems. Prioritizing the management of wastewater discharged from mariculture adjacent to mangrove forests is crucial for mangrove conservation.

Multifarious plant growth-promoting traits of mangrove yeasts: growth enhancement in mangrove seedlings (Rhizophora mucronata) for conservation.

Plant Growth-Promoting Yeasts (PGPY) have garnered significant attention in recent years; however, research on PGPY from mangroves remains a largely unexplored frontier. This study, therefore, focused on exploring the multifaceted plant growth-promoting (PGP) capabilities of yeasts isolated from mangroves of Puthuvype and Kumbalam. The present work found that manglicolous yeasts exhibited diverse hydrolytic properties, with the predominance of lipolytic activity, in addition to other traits such as phosphate solubilization, and production of indole acetic acid, siderophore, ammonia, catalase, nitrate, and hydrogen cyanide. After screening for 15 PGP traits, three strains P 9, PV 23, and KV 35 were selected as the most potent ones. These strains also exhibited antagonistic activity against fungal phytopathogens and demonstrated resilience to abiotic stresses, making them not only promising biocontrol agents but also suited for field application. The potent strains P 9, PV 23, and KV 35 were molecularly identified as Candida tropicalis, Debaryomyces hansenii, and Aureobasidium melanogenum, respectively. The potential of these strains in enhancing the growth performance of mangrove seedlings of Rhizophora mucronata, was demonstrated using the pot-experiment. The results suggested that the consortium of three potent strains (P 9, PV 23, and KV 35) was more effective in increasing the number of shoot branches (89.2%), plant weight (87.5%), root length (83.3%), shoot height (57.9%) and total leaf area (35.1%) than the control seedlings. The findings of this study underscore the significant potential of manglicolous yeasts in contributing to mangrove conservation and restoration efforts, offering a comprehensive understanding of their diverse plant growth-promoting mechanisms and highlighting their valuable role in sustainable ecosystem management.

Phosphate bio-solubilization and cadmium tolerance interplay in the root-microbe interface and consequences on root P absorption in wheat

Functional soil microbial communities, including phosphate solubilizing bacteria (PSB), are known for their ability to enhance P availability along with additional properties such as the immobilization of trace elements like cadmium (Cd). Bacterial P solubilization and tolerance to Cd are important biological processes that might occur simultaneously with positive influence on plant growth, thus physiological mechanisms controlling both processes need to be deciphered. This interplay was investigated in three PSB isolates (Bacillus siamensis "B. Siam", Rahnella aceris "R. Acer" and Bacillus cereus "B. Cer") and their consortium (PSBCs) with contrasting P solubilizing capacities (high-medium-low), through bacterial culture-based and plant inoculation experiments under increasing Cd concentrations and low P availability conditions (Tri-calcium P "TCP" and Rock P "RP"). Results show that PSB, particularly R. Acer and PSBCs, significantly increased P bioavailability (from TCP) under increasing Cd2+ concentrations (33 ppm “Cd33”, 67 ppm “Cd67”, 134 ppm “Cd134” and 201 ppm “Cd201”). The enhanced bioavailable P strongly correlated (B. Siam and PSBCs) with Cd bioaccumulation capacity, phosphatase enzyme activity, and organic acids (OA) production. Co-application of RP and PSB inoculation under Cd2+ stress (Cd8 and Cd16) improved wheat seedling root growth, P acquisition, and root hairs density in the piliferous zone and root cap. Moreover, inoculation with B. Cer significantly improved root inorganic P (Pi) (384 and 752%) and root acid phosphatases (176 and 131%) under Cd8 and Cd16 compared to uninoculated Cd-stressed seedlings. Such a beneficial root adaptation mechanism could be explained by the significant correlations (mainly under Cd16) between Pi content and morphological traits of wheat roots. Findings from this study demonstrate that P solubilization and Cd tolerance are likely interconnected rhizosphere processes triggered by inoculation that presumably induced the elongation of root hairs and likely the rigidity of the root cell wall to reduce Cd entrance while increasing P acquisition.

Endophytic Bacillus vallismortis and Bacillus tequilensis bacteria isolated from medicinal plants enhance phosphorus acquisition and fortify Brassica napus L. vegetative growth and metabolic content.

Phosphorus fertilization imposes critical limitations on crop productivity and soil health. The aim of the present work is to explore the potential of two phosphate solubilizing bacteria (PSB) species in phosphorus supplementation of canola (Brassica napus L.). Out of 38 bacterial isolates obtained from nine medicinal plants, two bacterial strains (20P and 28P) were proved as the most potent for the in-vitro tricalcium phosphate solubilization test. These isolates verified their activity toward different enzymes as nitrogenase and alkaline phosphatase. Also, 20P and 28P gave a high amount of indole-3-acetic acid, 34.16 μg/ml and 35.20 μg/ml, respectively, and were positive for siderophores production as they detected moderate affinity for iron chelation. Molecular identification confirmed that strain 20P was Bacillus vallismortis and strain 28P was Bacillus tequilensis. A pot experiment was conducted to study the effect of four different phosphorus concentrations (0%, 50%, 75%, and 100% P) each alone and/or in combination with B. vallismortis, B. tequilensis, or both bacterial isolates on the vegetative growth and some physiological parameters of canola. The combined treatment of 50% phosphorus + (B. vallismortis + B. tequilensis) was generally the most effective with respect to shoot height, shoot dry mass, leaf area, photosynthetic pigment fractions, total sugar content, and accumulated NPK content. In contrast, the rhizosphere pH reached the minimum value under the same treatment. These findings highlighted the potential use of PSB (B. vallismortis and B. tequilensis) along with phosphorus fertilization as a safe sustainable tactic.

Streptomyces N2A, an endophytic actinobacteria that promotes soybean growth and increases yield and seed quality under field conditions

Sustainable agriculture based on the use of soil-beneficial microbes such as plant growth-promoting rhizobacteria (PGPR) and biocontrol agents (BCA) is gaining great consideration to reduce the use of agrochemicals for crop production. With this aim, in this study, a total of 78 actinobacteria were isolated from the rhizosphere and endosphere of soybean roots. Based on in vitro compatibility with Bradyrhizobium japonicum, the ability to produce phytohormones, siderophores, exo-enzymes, antifungal compounds and phosphate solubilization (PGPR traits), two endophytic strains, named N2A and N9, were selected to evaluate their effects on plant growth and development at greenhouse and field conditions. Greenhouse trials showed significantly promoted seedling emergence compared to control and the conventional fungicide treatment. Analysis of growth and development associated parameters at reproductive stages and maturity at greenhouse, but also and most importantly, in field experiments showed significant improvements. Plant biomass, node number, pod number, and consequently yield, were higher in plants previously treated with N2A and co-inoculated with B. japonicum compared to the conventional seed treatment. Furthermore, a significant increase in health status and vigor was observed for seeds harvested from the N2A-treated plants in relation to seeds obtained from the conventional treatment. Thus, we demonstrated that Streptomyces sp. N2A can replace traditional chemical fungicides to protect the seed during germination, allowing good implantation, but also, stimulating the growth and development of soybean crop increasing yield and seed quality at field conditions. Altogether, this supports the potential use of Streptomyces N2A as a PGPR for soybean crop production more efficiently and sustainably.

Isolation and characterization of dematiaceous endophytic fungi isolated from barley (Hordeum vulgare L.) roots and their potential use as phosphate solubilizers

Phosphorus is an element with limited availability in the soil. For this reason, to supply phosphorus to crops, farmers depend on chemical fertilization, which affects the production costs and the environmental quality of the soil and water. However, this situation can be mitigated by using phosphorus-solubilizing fungi. Therefore, the objectives of this work were to identify seven dematiaceous endophytic fungi (Dark Septate Endophytes (DSE) and non-DSE), isolated from roots of a commercial barley crop, and to evaluate their characteristics and behavior in vitro regarding parameters that allow their description and potential use to make fertilizer use more efficient and thus reduce the amount of fertilizer required. The growth rate of each strain at different temperatures and pH values, and their ability to solubilize iron (FePO4), aluminum (AlPO4) and calcium (Ca3(PO4)2) phosphates were evaluated. The fungal isolates belonged to four orders: Pleosporales, Xylariales, Hypocreales and Chaetothyriales. The strains had their highest growth rate between 16°C and 30°C, and a great diversity of responses to the different pH values evaluated. Furthermore, all strains showed ability to solubilize Ca3(PO4)2, two to solubilize AlPO4, and one to solubilize FePO4. The diversity observed among the fungal isolates in terms of their response to pH, temperature, and media containing different insoluble phosphates suggests their adaptability to a wide range of environments, and makes them suitable for further studies aimed to determine their potentiality as biofertilizers.

Comparative Analysis of Plant Growth-Promoting Rhizobacteria's Effects on Alfalfa Growth at the Seedling and Flowering Stages under Salt Stress.

Alfalfa (Medicago sativa L.), a forage legume known for its moderate salt-alkali tolerance, offers notable economic and ecological benefits and aids in soil amelioration when cultivated in saline-alkaline soils. Nonetheless, the limited stress resistance of alfalfa could curtail its productivity. This study investigated the salt tolerance and growth-promoting characteristics (in vitro) of four strains of plant growth-promoting rhizobacteria (PGPR) that were pre-selected, as well as their effects on alfalfa at different growth stages (a pot experiment). The results showed that the selected strains belonged to the genera Priestia (HL3), Bacillus (HL6 and HG12), and Paenibacillus (HG24). All four strains exhibited the ability to solubilize phosphate and produce indole-3-acetic acid (IAA) and 1-aminocyclopropane-1-carboxylate (ACC) deaminase. Among them, except for strain HG24, the other strains could tolerate 9% NaCl stress. Treatment with 100 mM NaCl consistently decreased the IAA production levels of the selected strains, but inconsistent changes (either enhanced or reduced) in terms of phosphate solubilization, ACC deaminase, and exopolysaccharides (EPS) production were observed among the strains. During the various growth stages of alfalfa, PGPR exhibited different growth-promoting effects: at the seedling stage, they enhanced salt tolerance through the induction of physiological changes; at the flowering stage, they promoted growth through nutrient acquisition. The current findings suggest that strains HL3, HL6, and HG12 are effective microbial inoculants for alleviating salt stress in alfalfa plants in arid and semi-arid regions. This study not only reveals the potential of indigenous salt-tolerant PGPR in enhancing the salt tolerance of alfalfa but also provides new insights into the mechanisms of action of PGPR.

Cyanobacteria Based Nanoformulation of Biogenic CuO Nanoparticles for Plant Growth Promotion of Rice Under Hydroponics Conditions.

Synthesizing nanoparticles through a green synthesis approach is common nowadays. Cyanobacteria have attained great importance in the field of biosynthesis of nanoparticles as there is no use of toxic chemicals as reducing or capping agents for the synthesis of metal oxide nanoparticles. Micronutrient-based nano-formulations have become a topic of great interest in recent times due to their various advantageous properties and applications in agriculture. The current study aims to exploit the potential cyanobacterial strains isolated from different locations such as freshwater and soil ecosystems. The potential cyanobacterial isolates were screened based on their multiple plant growth promoting (PGP) attributes such as Indol acetic acid (IAA) production, siderophores, and phosphate solubilization. After the screening of cyanobacteria based on multiple PGP activities, the cyanobacterial strain was identified at the species level as Pseudanabaena foetida RJ1, based on microscopy and molecular characterization using 16S rRNA gene sequencing. The cyanobacterial biomass extract and cell-free extracts are utilized for the synthesis of CuO micronutrient Nanoparticles (NPs). The cyanobacterial strain Pseudanabaena foetida RJ1 possesses plant growth-promoting (PGP) attributes that provide reduction and capping for CuO NPs. The synthesized NPs were characterized and subjected to make a nano-formulation, utilizing the cyanobacteria-mediated CuO NPs along with low-cost zeolite as an adsorbent. The application of cyanobacterial biomass extract and cell-free extract provided an excellent comparative aspect in terms of micronutrient NP synthesis. The NPs in the form of formulations were applied to germinated paddy seeds (Pusa Basmati -1509) with varying concentrations (5, 10, 15mg/l). Effects of cyanobacteria based CuO NPs on hydroponically grown paddy crops were analyzed. The application of nano-formulations has shown a significant increase in plant growth promotion in rice plants under hydroponics conditions. There is no such type of comparative investigation reported earlier, and NPs of micronutrients can be utilized as a new economic nanofertilizer and can be applied to plants for their growth promotion.

Antagonistic activity and mechanism of Bacillus subtilis CG-6 suppression of root rot and growth promotion in Alfalfa

Root rot is a common disease, that severely affects the yield and quality of alfalfa. Biocontrol is widely used to control plant diseases caused by pathogenic fungi, however, biocontrol strains for alfalfa root rot are very limited. In this study, a Bacillus subtilis CG-6 strain with a significant biocontrol effect on alfalfa root rot was isolated. CG-6 secretes antibacterial enzymes and siderophore, phosphate solubilization and indoleacetic acid (IAA). The inhibition rate of strain CG-6 against Fusarium oxysporum was 87.33%, and it showed broad-spectrum antifungal activity. Inoculation with CG-6 significantly reduced the incidence of alfalfa root rot, the control effect of greenhouse cultivation reached 58.12%, and CG-6 treatment significantly increased alfalfa plant height, root length, fresh weight, and dry weight. The treatment with CG-6 significantly increased the levels of antioxidant enzymes (catalase, peroxidase, superoxide dismutase, and lipoxygenase) in alfalfa leaves by 15.52%–34.03%. Defensive enzymes (chitinase and β-1,3-glucanase) increased by 24.37% and 28.08%, respectively. The expression levels of regulatory enzyme genes (MsCAT, MsPOD, MsCu, Zn-SOD1, MsCu, Zn-SOD2, MsCu, Zn-SOD3, and MsLOX2) and systemic resistance genes (MsPR1, MsPDF1.2, and MsVSP2) increased by 0.50–2.85 fold, which were higher than those in the pathogen treatment group. Therefore, CG-6 could be used as a potential strain to develop biopesticides against alfalfa root rot.

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.

Molecular identification and characterization of endophytic bacteria from root of chamaecrista rotundifolia growing on the nigerian air force shooting range, kaduna.

Chamaecrista rotundifolia is one of the few plant species growing on heavy metal-contaminated Nigerian Air Force shooting range, Kaduna. This microbially unexplored plant species can have microbial association with endophytes. This study was aimed at isolating, identifying and characterizing endophytic bacteria associated with the roots of Chamaecrista rotundifolia growing on the Nigerian Air Force shooting range, Kaduna. The identification of the endophytic bacteria was done using standard biochemical methods and 16S rRNA sequencing analysis. The isolates were then screened for antibiotic resistance, plant growth promoting properties and heavy metal tolerance using standard techniques.  Varied concentrations of heavy metal salts (Pb2+, Cr3+, Ni2+ and Mn2+) were used to test the isolates for their heavy metal tolerance. Four endophytic bacteria isolated from the roots of C. rotundifolia were Aerococcus viridans, Peribacillus simplex, Staphylococcus simplex and Pseudomonas aeruginosa. Results on antibiotic sensitivity test revealed that the four isolates were resistant to most of the antibiotics. The isolates possessed plant growth promoting properties by showing positive results for Indole-3-acetic acid (IAA) production, 1-aminocyclopropane-1-carboxylic (ACC) deaminase activity and phosphate solubilizing. Results also revealed that the isolates showed some degree of tolerance to the heavy metals. The tolerance of both A. viridans and P. simplex to chromium and manganese showed significant difference (p&lt;0.05) across all the concentration levels of the metal salts. It is therefore concluded that Chamaecrista rotundifolia growing on Nigerian Air Force shooting range, Kaduna, is associated with endophytic bacteria which could be the reason the plant species thrive in heavy metal-contaminated site.&#x0D;  &#x0D;  

Identification of Rhizosphere Endophytes and Evaluation of Their Impact on Growth of Chia (Salvia hispanica L.)

Endophytic microorganisms promote root growth, improve nutrient uptake efficiency and produce more yields. By collaborating with endophytic microorganisms, plants experience enhanced growth. This study was focused on endophytes from Chia plants in Bhukkapatna, Tumakur with the objective of molecular characterization of efficient endophytic microorganisms and its impact on growth of Chia. Twelve bacterial isolates were identified, with eight displaying nitrogen fixation, phosphate solubilisation, potassium fixation, production of IAA, GA, siderophore and exopolysaccharide production. Molecular characterization using 16S rRNA revealed their identities as Pseudomonas fluorescens, Bacillus cereus, Stenotrophomonas maltophilia, and Enterobacter cloacae. Among these, Enterobacter cloacae (CEPB8) exhibited highest positive impact on Chia plant growth. In greenhouse conditions, treatments involving combinations of all four demonstrated the highest plant height (35.467cm) and biomass (158.37 grams) at harvest, surpassing the control group. Combined treatments outperformed individual strains, highlighting synergy. The study affirms that endophytic microorganisms significantly enhanced growth in Chia plant.

Evaluation of Phosphate Solubilization Microbe(PSM) Activity During Initial Operation of Constructed Wetland

Evaluation of Phosphate Solubilization Microbe(PSM) Activity During Initial Operation of Constructed Wetland

Short impact on soil microbiome of a Bacillus amyloliquefaciens QST713 based product that correlates with higher potato yield across USA.

Potato (Solanum tuberosum L.) is considered one of the most widely consumed crops worldwide, due to its high yield and nutritional profile, climate change-related environmental threats and increasing food demand. This scenario highlights the need of sustainable agricultural practices to enhance potato productivity, while preserving and maintaining soil health. Plant growth-promoting bacteria (PGPB) stimulate crop production through biofertilization mechanisms with low environmental impact. For instance, PGPB promote biological nitrogen fixation, phosphate solubilization, production of phytohormones, and biocontrol processes. Hence, these microbes provide a promising solution for more productive and sustainable agriculture. In this study, the effects of Bacillus amyloliquefaciens QST713 based-product (MINUET™, Bayer) were assessed in terms of yield, soil microbiome, potato peel and petiole nutrient profile as a promising PGPB in a wide range of potato cultivars across the United States of America. Depending on the location, potato yield and boron petiole content increased after biostimulant inoculation to maximum of 24% and 14%, respectively. Similarly, nutrient profile in potato peel was greatly improved depending on the location with a maximum of 73%, 62% and 36% for manganese, zinc and phosphorus. Notably, fungal composition was shifted in the treated group. Yield showed strong associations with specific microbial taxa, such as Pseudoarthrobacter, Ammoniphilus, Ideonella, Candidatus Berkiella, Dongia. Moreover, local networks strongly associated with yield, highlighting the important role of the native soil microbiome structure in indirectly maintaining soil health. Our results showed that treatment with B. amyloliquefaciens based product correlated with enhanced yield, with minor impacts on the soil microbiome diversity. Further studies are suggested to disentangle the underlying mechanisms of identified patterns and associations.

Isolation of endophytes from Dioscorea nipponica Makino for stimulating diosgenin production and plant growth.

Both bacterial and fungal endophytes exhibited one or more plant growth-promoting (PGP) traits. Among these strains, the Paenibacillus peoriae SYbr421 strain demonstrated the greatest activity in the direct biotransformation of tuber powderfrom D. nipponica into diosgenin. Endophytes play crucial roles in shaping active metabolites within plants, significantly influencing both the quality and yield of host plants. Dioscorea nipponica Makino accumulates abundant steroidal saponins, which can be hydrolyzed to produce diosgenin.However, our understanding of the associated endophytes and their contributions to plant growth and diosgenin production is limited. The present study aimed to assess the PGP ability and potential of diosgenin biotransformation by endophytesisolatesassociated withD. nipponica for the efficient improvement of plant growth and development of a clean and effective approach for producing the valuable drug diosgenin. Eighteen bacterial endophytes were classified into six genera through sequencing and phylogenetic analysis of the 16S rDNA gene. Similarly, 12 fungal endophytes were categorized into 5 genera based on sequencing and phylogenetic analysis of the ITS rDNA gene. Pure culture experiments revealed that 30 isolated endophytic strains exhibited one or more PGP traits, such as nitrogen fixation, phosphate solubilization, siderophore synthesis, and IAA production. One strain of endophytic bacteria, P. peoriae SYbr421, effectively directly biotransformed the saponin components in D. nipponica. Moreover, a high yield of diosgenin (3.50%) was obtained at an inoculum size of 4% after 6days of fermentation. Thus, SYbr421 could be used for a cleaner and more eco-friendly diosgenin production process. In addition, based on the assessment of growth-promoting isolates and seed germination results, the strains SYbr421, SYfr1321, and SYfl221 were selected for greenhouse experiments. The results revealed that the inoculation of these promising isolates significantly increased the plant height and fresh weight of the leaves and roots compared to the control plants. These findings underscore the importance of preparing PGP bioinoculants from selected isolates as an additional option for sustainable diosgenin production.

Diversity of endophytic bacterial community in rice roots and their roles in phosphate solubilization and plant growth

Root endophytic bacteria have significant beneficial effects on plant growth and health, while specific coexisting pathogenic bacteria can cause various diseases. In this study, we assessed the diversity and cultivability of the endophytic bacterial community in rice roots with a focus on their capacity for phosphate solubilization and impact on plant growth. Employing PacBio Single Molecule Real-Time (SMRT) and Sanger sequencing, we generated 16S rRNA gene libraries using metagenomic DNA extracted from the roots of three field-grown rice plants, along with genomic DNA from 156 associated bacterial isolates. QIIME 2-based microbiome analysis revealed dominant classified species at diverse taxonomic levels, including Arcobacter marinus, Paraburkholderia kururiensis, Lactobacillus plantarum, and Lactobacillus brevis. Furthermore, we effectively isolated 25.97% of rice root endophytic bacteria, with a notable 33.33% of pure culture endophytic bacteria exhibiting phosphate solubilization abilities. Finally, we revealed the inhibitory role of Burkholderia vietnamiensis and the growth promoting role of Paraburkholderia kururiensis subsp. Kururiensis in both the monocot model Brachypodium distachyon and the dicot Arabidopsis thaliana. Our study provided novel insight into the microbiome structure in rice roots and its potential to benefit rice cultivation and enhance overall crop health.