Potential Plant Growth-promoting Rhizobacteria Research Articles

Potential biocontrol agents involved in induction of defense related enzymes in brinjal (solanum melongena l.) Against phomopsis blight caused by phomopsis vexans

Phomopsis blight, caused by Phomopsis vexans (P. vexans) in brinjal plants is one of the main diseases in India. In order to manage this malady, we initially screened seed samples of 14 cultivars obtained from seed suppliers for the disease incidence. Based on the disease incidence and severity, the samples were categorized as resistant and susceptible cultivars of brinjal. It was established that MEBH-9' was a sensitive cultivar, while the Kolar local was resistant to the disease. Two ideal strains of Rhizosphere colonizing bacteria (RCB), Pseudomonas putida strain Has-1/c (HM229805), and Phylloplane Colonizing Bacteria (PCB), Bacillus subtilis strain Br/ph-33 (KJ867501), previously characterized as potential plant growth-promoting rhizobacteria, were tested for their potential biocontrol of this disease. Both susceptible and resistant cultivars' seedlings were treated with different combinations of PCB and RCB, PCB alone, RCB alone, and challenge inoculated with P. vexans. In order to ascertain whether there was signalling between defense enzyme activation and plant protection after PCB and RCB treatment, defense enzymes were quantified. Brinjal plants treated with PCB+RCB combination and challenge inoculated with P. vexans showed a significant increase in the activity of Phenylalanine ammonia-lyase (PAL), Peroxidase (POX), Lipoxygenase (LOX), Polyphenol oxidase (PPO), Catalase, Chitinase, β -1,3-glucanase, and Hydrogen peroxide (H2O2) content. The current study reveals that the defense enzymes and PR-proteins are gradually induced and accumulated, which enhance the resistance in brinjal plants against P. vexans-causing fruit rot disease.

Mitigation of Salt Stress in Rice by the Halotolerant Plant Growth-Promoting Bacterium Enterobacter asburiae D2.

Salinity is a major abiotic stress that seriously affects crop growth worldwide. In this work, we aimed to isolate potential halotolerant plant growth-promoting rhizobacteria (PGPR) to mitigate the adverse impacts of salt stress in rice. An isolate, D2, with multiple plant growth-promoting (PGP) characteristics was identified as Enterobacter asburiae D2. Strain D2 could produce indole-3-acetic acid and siderophore. It also exhibited phosphate solubilization and 1-aminocyclopropane-1-carboxylic deaminase activity. Genome analysis further provided insights into the molecular mechanism of its PGP abilities. Strain D2 inoculation efficiently stimulated rice growth under both normal and saline conditions. Compared with the non-inoculated plants, a significant increase in plant height (18.1-34.7%), root length (25.9-57.1%), root dry weight (57.1-150%), and shoot dry weight (17.3-50.4%) was recorded in inoculated rice seedlings. Meanwhile, rice seedlings inoculated with strain D2 showed improvement in chlorophyll and proline content, while the oxidant damage was reduced in these plants in comparison with the control group. Moreover, the K+/Na+ ratio of the inoculated rice seedlings exposed to NaCl and Na2CO3 was higher than that of the uninoculated groups. These results imply that Enterobacter asburiae D2 is a potential PGPR that can be used for alleviation of salt stress in rice.

Draft genome sequence of Bacillus velezensis strains AOA1 and AKS2, the potential plant growth-promoting rhizobacteria.

This report describes the draft genome sequence of Bacillus velezensis strains AOA1 and AKS2 isolated from maize rhizosphere soil in South Africa. Bacillus velezensis plays important biological roles as plant growth promoting rhizobacterium (PGPR). Bacillus velezensis strains also exhibit numerous biotechnological application potentials in agriculture and diverse industrial settings.

Modulation of Growth and Antioxidative Defense Mechanism in Wheat (Triticum aestivum L.) Mediated by Plant-Beneficial Strain Pseudomonas veronii MR-15 under Drought Conditions

Drought stress severely influences plants in various ways and is considered an alarming threat to sustainable crop production worldwide. However, plant-growth-promoting rhizobacteria (PGPRs) have the natural ability to tolerate drought and enable plants to induce stress resistance by altering critical metabolic pathways. In this study, we isolated and characterized a drought-tolerant rhizobacterium from the ground nut (Arachis hypogaea). Sequencing of the 16S rRNA gene traced its lineage to Pseudomonas veronii, named MR-15. The strain exhibited natural capabilities to solubilize phosphate, produce indole acetic acid, and grow a drought medium containing PEG (polyethylene glycol). The seeds of two wheat varieties (Triticum aestivum) inoculated with MR-15 were grown under drought and fully hydrated conditions and showed a significant increase in plant biomass, enhanced cellular antioxidant enzyme activity, and reduced reactive oxygen species. The MR-15 strain also significantly increased pigmentation and protein contents compared to plants raised from seeds grown without inoculation. These beneficial effects were consistent under drought stress conditions, indicating that MR-15 effectively alleviated wheat plants from drought-induced cellular oxidative damage. The findings suggest that MR-15 has the potential to serve as a biofertilizer, and further experiments should be conducted to explore its role in promoting plant growth and yield under drought conditions, particularly in semi-arid and arid zones. This is the first study reporting Pseudomonas veronii as a potential PGPR strain.

Exploration of phyto-beneficial traits of halophilic rhizobacteria isolated from the mangrove halophyte Avicennia marina

The salinity of the soil exerts an adverse effect on plant development and yield. However, amid saline stress, certain halophilic bacteria enhance the growth of plants. In this investigation, the mangrove halophyte Avicennia marina’s (A. marina) rhizosphere soil was used as the source for the isolation of halophilic bacteria. The isolates’ growth capacity at different pH, salinity, temperature, and polyethylene glycol (PEG) was assessed, and it was found that 56% showed growth in media supplemented with 2–7.5% NaCl; 50% showed efficient growth at pH 6–8, 62% grow optimally at temperature 25–35 °C, and about 88% showed growth in media with 5% PEG. The isolates possess growth-promoting traits evidenced by nitrogen fixation (18%), ammonia production (31%), phosphate solubilization (88%), zinc solubilization (44%), and indole acetic acid (IAA) (88%) production. The isolates can produce extracellular enzymes, viz., protease (88%), amylase (62%), cellulase (56%), and lipase (31%). The bacterial isolate S1B1 that displayed maximum plant growth-promoting traits was selected as the potent and subjected to plant growth promotion studies. The potent isolate S1B1 enhances Solanum lycopersicum’s germination under different salinity compared to untreated seeds with germination of 64% at the maximum concentration of 2% NaCl. The potential halophilic plant growth-promoting rhizobacteria (PGPR) isolate was determined as Rossellomorea aquimaris (R. aquimaris) by 16s rRNA analysis. The results demonstrated that R. aquimaris recovered from the rhizosphere of halophyte A. marina found possible applications for enhancing plant development and productivity in salinity-affected soils.

Multifarious Plant Growth-Promoting Rhizobacterium Enterobacter sp. CM94-Mediated Systemic Tolerance and Growth Promotion of Chickpea (Cicer arietinum L.) under Salinity Stress.

Chickpea is one of the most important leguminous crops and its productivity is significantly affected by salinity stress. The use of ecofriendly, salt-tolerant, plant growth-promoting rhizobacteria (PGPR) as a bioinoculant can be very effective in mitigating salinity stress in crop plants. In the present study, we explored, characterized, and evaluated a potential PGPR isolate for improving chickpea growth under salt stress. A potential PGPR was isolated from rhizospheric soils of chickpea plants grown in the salt-affected area of eastern Uttar Pradesh, India. The isolate was screened for salt tolerance and characterized for its metabolic potential and different plant growth-promoting attributes. Further, the potential of the isolate to promote chickpea growth under different salt concentrations was determined by a greenhouse experiment. A rhizobacteria isolate, CM94, which could tolerate a NaCl concentration of up to 8% was selected for this study. Based on the BIOLOG carbon source utilization, isolate CM94 was metabolically versatile and able to produce multiple plant growth-promoting attributes, such as indole acetic acid, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, siderophore, hydrogen cyanide (HCN), and ammonia as well as solubilized phosphate. A polyphasic approach involving the analysis of fatty acid methyl ester (FAME) and 16S rRNA gene sequencing confirmed the identity of the isolate as Enterobacter sp. The results of greenhouse experiments revealed that isolate CM94 inoculation significantly enhanced the shoot length, root length, and fresh and dry weight of chickpea plants, under variable salinity stress. In addition, inoculation improved the chlorophyll, proline, sugar, and protein content in the tissues of the plant, while lowering lipid peroxidation. Furthermore, isolate CM94 reduced oxidative stress by enhancing the enzymatic activities of superoxide dismutase, catalase, and peroxidase compared to in the respective uninoculated plants. Overall, the results suggested that using Enterobacter sp. CM94 could significantly mitigate salinity stress and enhance chickpea growth under saline conditions. Such studies will be helpful in identifying efficient microorganisms to alleviate salinity stress, which in turn will help, to devise ecofriendly microbial technologies.

Genome sequence of an indole-3-acetic acid and siderophores producing Pseudomonas monsensis SARCC-3054 with the potential as a microbial inoculant for enhanced crop production.

The genome of Pseudomonas monsensis strain SARCC-3054 was sequenced after being confirmed as a potential plant growth-promoting rhizobacteria in both in vitro and in vivo assays. The 6.3 MB genome has a GC content of 60.2% and is divided into 59 contigs that contain several plant beneficial genes and proteins.

Potential Novel Plant Growth Promoting Rhizobacteria for Bio-Organic Fertilizer Production in the Oil Palm (Elaeis guineensis Jacq.) in Malaysia

The present study aimed to characterize the potential plant growth-promoting rhizobacteria (PGPR) based on biochemical tests based on eight bacterial isolates, and to identify potential PGPR based on the 16S rRNA sequencing molecular method. Eight potential PGPR strains (UPMC1166, UPMC1168, UPMC1254, UPMC1376, UPMC1389, UPMC1393, UPMC703 and UPMC704) isolated from the soils in the oil palm (Elaeis guineensis) estates across Malaysia were selected because of their most PGPR activities. They were screened for nitrogen fixation, phosphate and potassium solubilization, and production of indole-3-acetic acid (IAA). All isolates showed the ability to grow between pH 2 to 9 and survive from 2 to 15% (w/v) of the salt medium. Among the isolated PGPRs, four PGPRs (UPMC1166, UPMC1168, UPMC1254 and UPMC1389) showed the ability to fix nitrogen and had the potential to produce IAA. Furthermore, two PGPRs (UPMC1393 and UPMC1376) demonstrated the ability to solubilize phosphate, while three PGPRs (UPMC703, UPMC704, and UPMC1393) showed the ability to solubilize potassium. Therefore, all the above eight PGPR isolates can benefit the oil palm cultivation industry. The molecular identification based on 16S rRNA gene sequence revealed that UPMC1166 was identified as Bacillus methylotrophicus; UPMC1168 as B. siamensis; UPMC1254 as B. subtilis; UPMC1389 as B. albus; UPMC1376 as Lactobacillus plantarum; UPMC1393 as B. marisflavi; UPMC703 as Burkhoderiaanthina and UPMC704 as B. metallica. These novel strains can be further investigated for their viability and effectiveness for bio-organic fertilizer production and application in the immature stage of oil palm growth.

Schizotrophic Sclerotinia sclerotiorum-Mediated Root and Rhizosphere Microbiome Alterations Activate Growth and Disease Resistance in Wheat.

Sclerotinia sclerotiorum, a widespread pathogen of dicotyledons, can grow endophytically in wheat, providing protection against Fusarium head blight and stripe rust and enhancing wheat yield. In this study, we found that wheat seed treatment with strain DT-8, infected with S. sclerotiorum hypovirulence-associated DNA virus 1 (SsHADV-1) and used as a "plant vaccine" for brassica protection, could significantly increase the diversity of the fungal and bacterial community in rhizosphere soil, while the diversity of the fungal community was obviously decreased in the wheat root. Interestingly, the relative abundance of potential plant growth-promoting rhizobacteria (PGPR) and biocontrol agents increased significantly in the DT-8-treated wheat rhizosphere soil. These data might be responsible for wheat growth promotion and disease resistance. These results may provide novel insights for understanding the interaction between the schizotrophic microorganism and the microbiota of plant roots and rhizosphere, screening and utilizing beneficial microorganisms, and further reducing chemical pesticide utilization and increasing crop productivity. IMPORTANCE Fungal pathogens are seriously threatening food security and natural ecosystems; efficient and environmentally friendly control methods are essential to increase world crop production. S. sclerotiorum, a widespread pathogen of dicotyledons, can grow endophytically in wheat, providing protection against Fusarium head blight and stripe rust and enhancing wheat yield. In this study, we discovered that S. sclerotiorum treatment increased the diversity of the soil fungal and bacterial community in rhizosphere soil, while the diversity of the fungal community was obviously decreased in the wheat root. More importantly, the relative abundance of potential PGPR and bio-control agents increased significantly in the S. sclerotiorum-treated wheat rhizosphere soil. The importance of this work is that schizotrophic S. sclerotiorum promotes wheat growth and enhances resistance against fungal diseases via changes in the structure of the root and rhizosphere microbiome.

Growth effects of Pseudomonas, a Plant Growth- Promoting Rhizobacteria on Spinach (Spinacia oleracea L.) - A Review

Plant growth- promoting rhizobacteria (PGPR), is a consortium of such bacteria which colonizes the roots of plants and show beneficial effects on growth and yield of plant. Pseudomonas is found to be most potent PGPR, occurring globally and having positive effect on productivity of plant. This review unravels several species of Pseudomonas which enhance growth and yield of spinach and can be used as biofertilizer. Certain species of Pseudomonas have been discovered which in absence of any chemical fertilizer can increase productivity of spinach alone. Investigation of such PGPR in case of spinach is quiet important as spinach cultivation make use of large amount of chemical fertilizers which are deleterious to health of crop, environment and human beings altogether. This review also introduces certain methods of inoculation of Pseudomonas sp. which encourages colonization around root or seeds of spinach, hence upgrading its association with spinach and yield in short. Thus, this review draws attention to explore more about Pseudomonas in case of green leafy spinach, inorder to gain large scale productivity and field application of it, which promotes organic farming and goodness of well-being.

Development of a Multicomponent Microbiological Soil Inoculant and Its Performance in Sweet Potato Cultivation.

The cultivation and consumption of sweet potato (Ipomoea batatas) are increasing globally. As the usage of chemical fertilizers and pest control agents during its cultivation may lead to soil, water and air pollution, there is an emerging need for environment-friendly, biological solutions enabling increased amounts of healthy crop and efficient disease management. Microbiological agents for agricultural purposes gained increasing importance in the past few decades. Our goal was to develop an agricultural soil inoculant from multiple microorganisms and test its application potential in sweet potato cultivation. Two Trichoderma strains were selected: Trichoderma ghanense strain SZMC 25217 based on its extracellular enzyme activities for the biodegradation of plant residues, and Trichoderma afroharzianum strain SZMC 25231 for biocontrol purposes against fungal plant pathogens. The Bacillus velezensis strain SZMC 24986 proved to be the best growth inhibitor of most of the nine tested strains of fungal species known as plant pathogens, therefore it was also selected for biocontrol purposes against fungal plant pathogens. Arthrobacter globiformis strain SZMC 25081, showing the fastest growth on nitrogen-free medium, was selected as a component with possible nitrogen-fixing potential. A Pseudomonas resinovorans strain, SZMC 25872, was selected for its ability to produce indole-3-acetic acid, which is among the important traits of potential plant growth-promoting rhizobacteria (PGPR). A series of experiments were performed to test the selected strains for their tolerance to abiotic stress factors such as pH, temperature, water activity and fungicides, influencing the survivability in agricultural environments. The selected strains were used to treat sweet potato in two separate field experiments. Yield increase was observed for the plants treated with the selected microbial consortium (synthetic community) in comparison with the control group in both cases. Our results suggest that the developed microbial inoculant has the potential to be used in sweet potato plantations. To the best of our knowledge, this is the first report about the successful application of a fungal-bacterial consortium in sweet potato cultivation.

Exploration of the rhizosphere microbiome of native plant Ceanothus velutinus - an excellent resource of plant growth-promoting bacteria.

Continuous demand for an increase in food production due to climate change and a steady rise in world population requires stress-resilient, sustainable agriculture. Overuse of chemical fertilizers and monoculture farming to achieve this goal deteriorated soil health and negatively affected its microbiome. The rhizosphere microbiome of a plant plays a significant role in its growth and development and promotes the plant's overall health through nutrient uptake/availability, stress tolerance, and biocontrol activity. The Intermountain West (IW) region of the US is rich in native plants recommended for low water use landscaping because of their drought tolerance. The rhizosphere microbiome of these native plants is an excellent resource for plant growth-promoting rhizobacteria (PGPR) to use these microbes as biofertilizers and biostimulants to enhance food production, mitigate environmental stresses and an alternative for chemical fertilizer, and improve soil health. Here, we isolated, purified, identified, and characterized 64 bacterial isolates from a native plant, Ceanothus velutinus, commonly known as snowbrush ceanothus, from the natural habitat and the greenhouse-grown native soil-treated snowbrush ceanothus plants. We also conducted a microbial diversity analysis of the rhizosphere of greenhouse-grown native soil-treated and untreated plants (control). Twenty-seven of the 64 isolates were from the rhizosphere of the native region, and 36 were from the greenhouse-grown native soil-treated plants. These isolates were also tested for plant growth-promoting (PGP) traits such as their ability to produce catalase, siderophore, and indole acetic acid, fix atmospheric nitrogen and solubilize phosphate. Thirteen bacterial isolates tested positive for all five plant growth-promoting abilities and belonged to the genera Pantoea, Pseudomonas, Bacillus, and Ancylobacter. Besides, there are isolates belonging to the genus Streptomyces, Bacillus, Peribacillus, Variovorax, Xenophilus, Brevundimonas, and Priestia, which exhibit at least one of the plant growth-promoting activities. This initial screen provided a list of potential PGPR to test for plant health improvement on model and crop plants. Most of the bacterial isolates in this study have a great potential to become biofertilizers and bio-stimulants.

Plant growth promoting and antimicrobial functionalities of rhizosphere Pseudomonas species in flooded rice soils of coastal Odisha

AbstractMicrobiome‐plant interactions have been carried out all over the world in the hunt for growth‐promoting bacteria to augment agriculture. Therefore, diversity and plant growth promotion (PGP) functions of the predominant Gram‐negative bacteria, Pseudomonas spp., of the flooded rice rhizosphere were analyzed. Out of three most potent plant growth promoting rhizobacteria (PGPR), phenotypic identity of two isolates (TB324, 325) was P. putida but another one (TB326) was P. chorii. Nevertheless, 16S rRNA phylogram claded all 3 (TB324, 325, and 326) potent isolates with P. putida. The isolates solubilized tricalcium phosphate (132.42–162.23 µg/ml), fixed nitrogen (75.46–325.41 nM ethylene/g bact./h), produced IAA (12.06–68.49 µg/ml), salicylic acid (6.54–6.75 µg/ml), hydrogen cyanide (0.03–0.05 ΔA625), siderophore (3.75–7.55 µM/ml), protease, cellulase and ammonia (TB326). Furthermore, the organisms differentially antagonized the phytopathogenic fungi viz. Xanthomonas oryzae, Magnoportha grisea, Aspergillus niger, Fusarium oxysporum, Helminthosporium sp., Curvularia sp. and Rhizoctonia solani, as well as, entomopathogens like Fusarium, Nomurae, Verticillium, and Paecilomyces spp., and Beauveria bassiana. TB324, 325, and 326 tolerated abiotic stresses like pH 3–12, NaCl 9%–12%, sea salt 14% and sodium acetate 0.9–1.0 M. Besides, the organisms possessed different phenazine genes and their cellular protein constituents were comparable. All Pseudomonas isolates enhanced growth of potted rice plants over control. TB 326 enhanced maximum root (18.9 ± 0.25 cm) and shoot (73.4 ± 0.81 cm) growth.

Molecular, biochemical, and comparative genome analysis of a rhizobacterial strain Klebsiella Sp. KBG6.2 imparting salt stress tolerance to Oryza sativa L.

One-third of global agricultural land is affected by salinity, thereby limiting the, productivity and sustainability of the cropping ecosystem. Rice is a globally important, economical crop but is largely affected by soil salinity , leading to loss of standing crop. Plant growth-promoting rhizobacteria (PGPR) can be a potential solution to this problem by improving soil fertility, tolerance to stress and ultimately enhancing crop yield. However, the usage of PGPR in alleviating stress is limited and requires further investigation. In the current work, a PGPR strain, namely, Klebsiella sp. KBG6.2 was isolated from the rice rhizosphere of salt-affected agricultural fields in Odisha, India., The strain was found to be imparting salt tolerance to rice seedlings grown up to 200 mM of sodium chloride. The rice seedlings when treated with sodium chloride and coinoculated with Klebsiella sp. KBG6.2 showed better germination percentage, biomass, shoot, root length, chlorophyll content, and reducing sugar accumulation. The PGPR treatment also led to a reduction in reactive oxygen species (ROS) production, as evidenced by reduced ROS scavenging enzyme (catalase, superoxide dismutase , and peroxidase) activities and lower accumulation of the corresponding mRNA as, verified by real time PCR analysis. This was further supported by the reduced, accumulation of malondialdehyde which is an indicator of stress-induced oxidative damage. The genome sequence analysis of the Klebsiella sp. KBG6.2 strain revealed, it to contain the required genes responsible for colonization and acclimation during stress conditions. The successful root colonization was further verified by scanning electron microscopy. Further, the obtained PGPR strain could provide saline stress tolerance to rice and serve as bioinoculant for sustainable agriculture in salt-affected areas. • Isolation and characterization of a potential PGPR strain named Klebsiella sp. KBG6.2. • The PGPR strain Klebsiella sp. KBG6.2 could be used to impart saline stress tolerance to rice. • A successful strain in maintaining cellular reactive oxygen species homeostasis.

Plant growth-promoting rhizobacterial inoculation to improve growth, yield, and grain nutrient uptake of teff varieties.

Inoculation of plant growth-promoting rhizobacteria (PGPR) improves the growth, yield, and plant nutrient uptake, as well as rhizosphere fertility, without harming the environment and human health. This study aimed to examine the effect of either individual or consortium of PGP bacterial inoculation on the growth, yield, and grain nutrient uptake of teff varieties. Three potential PGPR strains (i.e., Pseudomonas fluorescens biotype G, Enterobacter cloacae ss disolvens, and Serratia marcescens ss marcescens) were used for this study. Field evaluation was carried out in RCBD with 5 treatments. Highly significant (P < 0.001) differences were observed among treatments for plant height (PH), panicle length (PL), number of the total spike (NTS), shoot dry weight (SDW), grain yield (GY), and straw yield (SY). There was also teff variety that significantly (P < 0.01) affects PL, SDW, and SY. However, the interaction effect of the two factors (treatment*variety) did not significantly influence teff agronomic traits and grain nutrient uptake. The highest PH (133.5 cm), PL (53.2), NTS (30.9), SDW (18.1 t/ha), SY (10.7 t/ha), and GY (2.7 t/ha) were observed on Dukem variety (Dz-01-974) inoculated with PGPR consortium. Wherein 2.2 fold increase was observed in grain yield per hectare over the control. Inoculation of PGPR consortium showed better performance in promoting plant growth, yield, and grain nutrient uptake of teff varieties compared with the individual PGP bacterial application, and PGPR consortium could be used as inoculants to enhance teff production and productivity.

Synergistic effect of co-culture rhizosphere Streptomyces: A promising strategy to enhance antimicrobial activity and plant growth-promoting function

Rhizosphere Streptomyces is one of the important types of rhizosphere microorganisms that plays an important role in promoting plant growth and controlling plant diseases to maintain agricultural ecosystem balance and green ecological agriculture development as beneficial bacteria. Microbial co-culture simulates the complex biocommunity in nature, which has more advantages than the monoculture with a synergistic effect. As the key signal mediums of microorganisms, plants, and their interactions, microbial metabolites are of great significance in revealing their functional mechanism. In this study, two potential plant growth-promoting rhizobacteria, Streptomyces albireticuli MDJK11, and Streptomyces alboflavus MDJK44, were selected to explore the effects of co-culture and monoculture on plant growth promotion and disease prevention, and the metabolic material basis was analyzed by metabonomics. Results showed that Streptomyces MDJK11, MDJK44 monoculture, and co-culture condition all showed good growth promoting and antimicrobial effects. Moreover, as compared to the monoculture, the co-culture showed the advantage of a synergistic enhancement effect. LC-MS-based metabonomics analysis showed the metabolic material bases of Streptomyces for plant growth promotion and disease prevention were mainly plant hormone and antibiotics and the co-culture condition could significantly stimulate the production of plant hormone promoters and macrolide, cyclic peptide, and aminoglycoside antibiotics. The study proved that the co-cultures of S. albireticuli MDJK11 and S. alboflavus MDJK44 have great potential in crop growth promotion and disease prevention.

Influence of Kosakonia sp. on the Growth of Arachis hypogaea L. on Arid Soil

The current study focused on enumerating the potential plant growth-promoting rhizobacteria (PGPR) from the rhizosphere of Arachis hypogaea L. Among the several colonies grown on an Ashby plate, only seven isolates (Ah1 to Ah7) had nitrogen-fixing potential. The Ah4 isolate showed higher potential for plant growth-promoting (PGP) activities than the other isolates. This isolate was recognized as Kosakonia sp. MGR1 through 16S rRNA sequencing with 99.7% similarity to nitrogen-fixing Kosakonia genus and 61% match with K. cowanii in phylogenetic tree analysis. Kosakonia sp. MGR1 had the potential to produce an excellent quantity (26.17 µg·mL−1) of indole-3-acetic acid (IAA) in 6% tryptophan-enriched media than the other concentrations (2%, 4%, 8%, and 10%). Additionally, it contained remarkable phosphate-solubilizing efficiency of tricalcium phosphate (29.3 µg·mL−1) in 5 days of incubation. The growth conditions of Kosakonia sp. were optimized as 35 °C, pH 7.5, and 48 h of incubation with glucose. The isolate MGR1 produced 96.35 ± 3.45, 89.6 ± 5.61, and 99.21 ± 5.24 µg·mL−1 of IAA, nitrogen, and soluble phosphate, respectively. Furthermore, Kosakonia sp. MGR1 had the potential to enhance the growth and biomolecule contents of A. hypogaea L. The results concluded that Kosakonia had admirable PGP activities; hence, it showed a significant impact on the active growth and biomolecules of A. hypogaea L.

A Review of Endophytes\' Ability to Promote Plant Development on Medicinal Herbs

Abstract: Countless microbes live in the bodies of animals and plants. Plant growth is aided by the interaction between microbes and plants. They can be used as bio-fertilizers because of their nutrient intake and nitrogen-fixing capacity. These bacteria produce important metabolites and secondary metabolites that can be used to treat cancer and other chronic human diseases. They play a key role in the decomposition of heavy metals in the soil. In other words, they have a positive impact on agriculture, medicine, biotechnology, and food science. Plant growth-promoting rhizobacteria (PGPR) are commonly used to improve the growth of a wide range of crops, such as seed germination, plant weight, and harvest yields. Plant development is triggered by PGPR colonization because bacteria produce plant hormones such as indole-3-acetic acid, cytokinin, and gibberellins, as well as enhanced mineral and nitrogen availability in the soil. They are also known to defend their host plants from harmful bacteria in some cases. The role of PGPR in connection to medicinal plants and their impact on the development of botanicals is an area where there is still a lot of research to be done. This review highlights the potential PGPR–medicinal plant interactions that could boost the medicinal plant's effectiveness, particularly in farmed plants. The significance of medicinal plant endophytic microbes for bioactive potentials.

Soil Microbes Drive the Flourishing Growth of Plants From Leucocalocybe mongolica Fairy Ring

Fairy ring is a natural phenomenon in which fungal fruiting bodies occur as a ring on a spot. This ring is produced due to spore ejection by Basidiomycetous fungi and forms a lush growing plant belt. However, the drivers for such formations and the potential plant growth-promoting rhizobacteria in fairy ring soils remain unknown. Fairy rings formed by Leucocalocybe mongolica were selected in this study. Soil characteristics and microbial (bacteria and fungi) community structures between beneath and outside the fairy rings were compared through high-throughput sequencing. Beneficial bacterial resources were excavated using dependent culturable methods. Soil electrical conductivity and available potassium were higher in the soil beneath the ring than outside it. These parameters were positively correlated with the dominant microbial community, but microbial diversity was lower. In the soil beneath the fairy ring, Bacteroidetes and Basidiomycota were more abundant, whereas Verrucomicrobia was less prevalent. Bacillus pumilus (strain BG-5) was isolated from the soil beneath the ring. Strain BG-5 can solubilize phosphorus and produce indole-3-acetic acid, NH4+, and siderophores. Furthermore, strain BG-5 enhanced salt tolerance and promoted the growth of Arabidopsis thaliana, wheat (Triticum aestivum), and cotton (Gossypium hirsutum) seedlings. This study indicated the presence of abundant beneficial microbes driving the flourishing growth of plants in the fairy ring soil and provided bio-resources for agricultural growth-promoting agents.

Endophytic PGPR from Tomato Roots: Isolation, In Vitro Characterization and In Vivo Evaluation of Treated Tomatoes (Solanum lycopersicum L.).

Plant-growth-promoting rhizobacteria (PGPR) are soil bacteria colonizing the rhizosphere and the rhizoplane which have an effect on plant growth through multiple chemical compounds. Rhizobacteria with beneficial effects for plants could therefore be used to reduce the dependence on synthetic chemical fertilizers in conventional agriculture. Within this study, 67 endophytic fungi and 49 bacteria were isolated from root samples from 3 different commercial productions: an off-ground tomato production in a greenhouse, an organic production and a conventional production, both in a soil tunnel. Following morphological selection, 12 fungal and 33 bacterial isolates were genetically identified. Thirteen bacterial isolates belonging to nine potential PGPR species were then applied to tomato seedlings established in sterile substrate. The ability of these bacteria to produce indole acetic acid (IAA) and solubilize phosphate was also evaluated. They all were IAA producers and solubilized phosphate. The most interesting strains for growth promotion were found to be the isolates Pseudomonas palleroniana B10, Bacillus subtilis B25, Bacillus aryabhattai B29 and Pseudomonas fluorescens B17. The isolates P. fluorescens B17, B. aryabhattai B29, B. subtilis B18 and Pseudomonas moraviensis B6 also increased root growth. This study proposed a quick protocol for isolating and testing potential endophytic PGPR that should be characterized further for the direct and indirect mechanisms of growth promotion.