Solubilization Activity Research Articles

Halotolerant Enterobacter asburiae A103 isolated from the halophyte Salix linearistipularis: Genomic analysis and growth-promoting effects on Medicago sativa under alkali stress

Soil salinization negatively affects plant growth and threatens food security. Halotolerant plant growth-promoting bacteria (PGPB) can alleviate salt stress in plants via diverse mechanisms. In the present study, we isolated salt-tolerant bacteria with phosphate-solubilizing abilities from the rhizosphere of Salix linearistipularis, a halophyte distributed in saline-alkali soils. Strain A103 showed high phosphate solubilization activity and was identified as Enterobacter asburiae based on genome analysis. In addition, it can produce indole-3-acetic acid (IAA), siderophores, and 1-aminocyclopropane-1-carboxylate (ACC) deaminase. Genome mining has also revealed the presence of several functional genes involved in the promotion of plant growth. Inoculation with A103 markedly improved alfalfa growth in the presence of 100 mM NaHCO3. Under alkali stress, the shoot and root dry weights after bacterial inoculation improved by 42.9 % and 21.9 %, respectively. Meanwhile, there was a 35.9–37.1 % increase in the shoot and root lengths after treatment with A103 compared to the NaHCO3-treated group. Soluble sugar content, peroxidase and catalase activities increased in A103-inoculated alfalfa under alkaline stress. A significant decrease in the malondialdehyde content was observed after treatment with strain A103. Metabolomic analysis indicated that strain A103 positively regulated alkali tolerance in alfalfa through the accumulation of metabolites, such as homocarnosine, panthenol, and sorbitol, which could reduce oxidative damage and act as osmolytes. These results suggest that halophytes are valuable resources for bioprospecting halotolerant beneficial bacteria and that the application of halotolerant growth-promoting bacteria is a natural and efficient strategy for developing sustainable agriculture.

Bioinoculation Strategies for Enhanced Growth and Development of Economically Important Dalbergia latifolia Roxb

The present experiment was conducted to evaluate the plant growth properties of the native rhizospheric microflora of Dalbergia latifolia, an important medicinal, timber and biofuel plant. A systemic isolation, characterization and identification of rhizospheric soil, collected indigenously, initially produced 45 numbers of fungi and 3 numbers of bacteria. Both groups of organisms were characterized for their extracellular useful activity, especially phosphate solubilisation potential, and presented in terms of solubilisation index and solubilisation efficiency. Two fungi and two bacteria with good phosphate solubilization activity, along with NPK and organic manure, were selected and used in a pot culture experiment to promote the growth and development of Dalbergia latifolia under nursery conditions. Data recorded on 90 Days of plant growth exhibited the growth promotion of inoculated plants over control uninoculated experimental set. Results obtained on morphological and physiological growth parameters exhibited that the application of Aspergillus flavus followed by Burkholderia territorii + org. manure showed maximum shoot height and inoculation of Burkholderia anthina + Aspergillus sp. + NPK was significantly higher leaf area. Significantly longer root has been observed in Burkholderia territorii. However, a difference was observed in the number of leaves in Aspergillus flavus. + Org. manure and higher numbers of branches were observed in Aspergillus flavus only as compared to uninoculated control. Coinoculation of Aspergillus flavus + Penicillium simplicissimum showed better performance in fresh and dry shoot biomass as compared to other treatments. Burkholderia territorii + Org.manure produced higher fresh biomass of roots and coinoculation of bacteria Burkholderia territorii + Burkholderia anthina helped in enhancing root dry biomass. Dual inoculation of Aspergillus flavus + Penicillium simplicissimum gives better result in both fresh biomass of leaves and dry biomass of leaves. Application of Aspergillus flavus + Penicillium simplicissimum enhanced the total fresh biomass of the seedlings whereas supplementation of Burkholderia anthina + Penicillium simplicissimum enhanced the total dry biomass. Coinoculation of Aspergillus flavus + Penicillium simplicissimum showed higher RGR and coinoculation of Burkholderia anthina + Aspergillus flavus + NPK showed quite higher Leaf area ratio (LAR cm2gm-1). Co inoculation of Burkholderia territorii + Burkholderia anthina + Organic Manure showed highest root-shoot ratio and Coinoculation of Penicillium simplicissimum + Org. manure showed higher Net assimilation rate (NAR). However, Bacterial and fungal inoculants were also used as potent bioinoculants for the growth and establishment of crops of forest tree species.

Bacterial allelopathy: an approach for biological control of weeds.

Weed infestation is one of the most damaging biotic factors to limit crop production by competing with the crop for space, water, and nutrients. Different conventional approaches are being used to cope with weed infestation, including labor intensive manual removal and the use of soil-degrading, crop-damaging, and environment-deteriorating chemical herbicides. The use of chemicals for weed control has increased 2-fold after the green revolution and their non-judicious use is posing serious threats to mankind, animals, and biodiversity. The detrimental effects of these approaches have shifted the researchers' attention from the last two decades towards alternate, sustainable, and eco-friendly approaches to cope with weed infestation. The recent approaches of weed control, including plant and microbial allelopathy have gained popularity during last decade. Farmers still use conventional methods, but the majority of farmers are very passionate about organic agriculture and describe it as a slogan in the developed world. The effectiveness of these approaches lies in host specificity by selective bacteria and differential response towards weeds and crops. Moreover, the crop growth promoting effect of microorganisms (allelopathic bacteria) possessing various growth promoting traits, that is, mineral solubilization, phytohormone production, and beneficial enzymatic activity, provide additional benefits. The significance of this review lies in the provision of a comprehensive comparison of the conventional approaches along with their potential limitations with advanced/biological weed control approaches in sustainable production. In addition, the knowledge imparted about weed control will contribute to a better understanding of biological control methods.

Improved salinity tolerance in cucumber seedlings inoculated with halotolerant bacterial isolates with plant growth-promoting properties

To address salinity stress in plants in an eco-friendly manner, this study investigated the potential effects of salinity-resistant bacteria isolated from saline agricultural soils on the growth of cucumber (Cucumis sativus, cv. Royal) seedlings. A greenhouse factorial experiment was conducted based on a completely randomized design (CRD) with two factors, salinity at four levels and five bacterial treatments, with three replications (n = 3). Initially, fifty bacterial isolates were screened for their salinity and drought tolerance, phosphate solubilization activity, along with production of auxin, siderophore and hydrogen cyanide. Isolates K4, K14, K15, and C8 exhibited the highest resistance to salinity and drought stresses in vitro. Isolates C8 and K15 demonstrated the highest auxin production capacity, generating 2.95 and 2.87 µg mL− 1, respectively, and also exhibited significant siderophore production capacities (by 14% and 11%). Additionally, isolates C8 and K14 displayed greater phosphate solubilization activities, by 184.64 and 122.11 µg mL− 1, respectively. The statistical analysis revealed that the selected four potent isolates significantly enhanced all growth parameters of cucumber plants grown under salinity stress conditions for six weeks. Plant height increased by 41%, fresh and dry weights by 35% and 7%, respectively, and the leaf area index by 85%. The most effective isolate, C8, was identified as Bacillus subtilis based on the 16 S rDNA amplicon sequencing. This study demonstrated that inoculating cucumber seedlings with halotolerant bacterial isolates, such as C8 (Bacillus subtilis), possessing substantial plant growth-promoting properties significantly alleviated salinity stress by enhancing plant growth parameters. These findings suggest a promising eco-friendly strategy for improving crop productivity in saline agricultural environments.

Single-cell exploration of active phosphate-solubilizing bacteria across diverse soil matrices for sustainable phosphorus management.

Phosphate-solubilizing bacteria (PSB) are crucial for enhancing phosphorus bioavailability and regulating phosphorus transformation processes. However, the in situ phosphorus-solubilizing activity and the link between phenotypes and genotypes for PSB remain unidentified. Here we employed single-cell Raman spectroscopy combined with heavy water to discern and quantify soil active PSB. Our results reveal that PSB abundance and in situ activity differed significantly between soil types and fertilization treatments. Inorganic fertilizer input was the key driver for active PSB distribution. Targeted single-cell sorting and metagenomic sequencing of active PSB uncovered several low-abundance genera that are easily overlooked within bulk soil microbiota. We elucidate the underlying functional genes and metabolic pathway, and the interplay between phosphorus and carbon cycling involved in high phosphorus solubilization activity. Our study provides a single-cell approach to exploring PSB from native environments, enabling the development of a microbial solution for the efficient agronomic use of phosphorus and mitigating the phosphorus crisis.

Genome-based identification of phosphate-solubilizing capacities of soil bacterial isolates

Identifying genomic markers for phosphate-solubilizing bacteria (PSB) is vital for advancing agricultural sustainability. This study utilizes whole-genome sequencing and comprehensive bioinformatics analysis, examining the genomes of 76 PSB strains with the aid of specialized genomic databases and analytical tools. We have identified the pqq gene cluster, particularly the pqqC gene, as a key marker for (P) solubilization capabilities. The pqqC gene encodes an enzyme that catalyzes the conversion of precursors to 2-keto-d-gluconic acid, which significantly enhances P solubilization in soil. This gene’s importance lies not only in its biochemical function but also in its prevalence and effectiveness across various PSB strains, distinguishing it from other potential markers. Our study focuses on Burkholderia cepacia 51-Y1415, known for its potent solubilization activity, and demonstrates a direct correlation between the abundance of the pqqC gene, the quantitative release of P, and the production of 2-keto-d-gluconic acid over a standard 144-h cultivation period under standardized conditions. This research not only underscores the role of the pqqC gene as a universal marker for the rapid screening and functional annotation of PSB strains but also highlights its implications for enhancing soil fertility and crop yields, thereby contributing to more sustainable agricultural practices. Our findings provide a foundation for future research aimed at developing targeted strategies to optimize phosphate solubilization, suggesting areas for further investigation such as the integration of these genomic insights into practical agricultural applications to maximize the effectiveness of PSB strains in real-world soil environments.

A Protease from Moringa oleifera Lam. Exhibits In-vitro Blood Clot Solubilization and Fibrin Hydrolysis.

Thrombosis is the formation of abnormal blood clots in the blood vessels that obstruct blood flow and lead to thrombosis. Current treatments for thrombosis are associated with serious side effects. Therefore there is a need for alternative natural therapy. A fibrinolytic protease was isolated from fresh leaves of Moringa oleifera Lam. and characterized for its potential to solubilize blood clots and hydrolyse fibrin under in-vitro conditions. The isolated protease showed a single protein band on native-PAGE. It showed optimum fibrinolytic activity at pH 8.0, 37 oC with 50µg protein. The fibrinolytic activity of isolated protease was also confirmed by fibrin zymography. Km and Vmax of isolated protease were determined by the Lineweaver Burk plot. The isolated protease could solubilize 96.41% of blood clots by 96h under in-vitro conditions. In-vitro fibrin hydrolysis and blood clot solubilization activities shown by an isolated protease from leaves of Moringa oleifera Lam. suggest its fibrinolytic potential to dissolve blood clots. Being a natural molecule and from a dietary plant it can be explored as an alternative natural therapy against thrombosis.

Roles of Endophytic Fungi Isolated from Mangifera indica L. in Promoting Plant Growth.

Endophytic fungi have been shown to synthesize bioactive secondary metabolites, some of which promote plant growth through various mechanisms. In our previous study, endophytic fungi were isolated from mango trees (Mangifera indica L.). The present study examined fifty endophytic fungal isolates for mineral solubilization activity, ammonia production, and siderophore production. It was shown that these isolates could produce phytohormones indole-3-acetic acid and gibberellic acid, as well as inhibit plant pathogens, specifically Colletotrichum gloeosporioides and Lasiodiplodia theobromae. The results showed that all the isolated fungal endophytes exhibited various activities. Based on the findings, two fungal endophytes-Aureobasidium pullulans CY.OS 13 and Aspergillus tamarii CY.OS 144-were selected for dual inoculation in chili plants under pot-scale conditions to investigate their potential to improve growth-related traits such as seed germination, shoot and root length, biomass, and chlorophyll content. Seed treated with A. pullulans CY.OS 13 and/or A. tamarii CY.OS 144 showed a significant (p < 0.05) increase in seed germination and growth parameters of chili plants grown under pot-scale conditions. Particularly, chili plants whose seeds were injected with a combination of the two selected endophytic fungi showed the highest plant development traits. Therefore, the selected endophytic fungi have the potential to be used as biofertilizers, especially when combined. They could eventually replace chemical fertilizers because they are environmentally friendly, beneficial to humans, and can even promote sustainable agriculture.

Biofertilizer Production using Phosphate-solubilizing Pseudomonas spp. Isolated from Rhizosphere Soil: Towards Indigenous Biofertilizer for Enhanced Crop Productivity in Katsina, Nigeria

Study’s Novelty/Excerpt This study offers an approach to sustainable agriculture by isolating and identifying phosphate-solubilizing Pseudomonas species from the rhizosphere soil of Wagini ward, Katsina state, for the production of biofertilizers. The research highlights the significant phosphate-solubilizing activity of these native strains, which enhances phosphorus availability to plants through the secretion of organic acids and enzymes. By demonstrating the positive effects of these Pseudomonas-based biofertilizers on maize, beans, and millet, this study provides valuable insights into the development of eco-friendly, cost-effective biofertilizers tailored to local agroecosystems, thereby promoting sustainable agricultural practices in Nigeria. Full Abstract The utilization of biofertilizers holds promise as a sustainable approach to enhance soil fertility and crop productivity while reducing reliance on chemical fertilizers. Beyond nitrogen, phosphorus is integral to various aspects of plant metabolism, including cell division, growth, development, sugar breakdown, and nuclear transport. The present study focuses on isolating Pseudomonas as phosphate-solubilizing bacteria from the rhizosphere soil to produce biofertilizer. Ten samples of rhizosphere soil samples were collected from agricultural fields in Wagini ward, Batsari Local Government area, Katsina state. The isolation and identification of Pseudomonas species from the soil samples were conducted using standard microbiological techniques, followed by screening for plant growth-promoting traits (phosphate solubilization). Subsequently, selected Pseudomonas species exhibiting robust phosphate solubilization were assessed for their efficacy in biofertilizer production, after which the produced biofertilizer was tested on maize, beans, and millet. The formulated biofertilizers demonstrated remarkable positive effects on the tested crops’ growth compared to those that were not treated with the Pseudomonas-based biofertilizer after seven days of cultivation under controlled conditions. The results of this study revealed that the isolated Pseudomonas strains exhibited significant phosphate-solubilizing activity. This indicates their potential to release phosphorus from insoluble forms, making it more accessible to plants. The solubilization activity was attributed to the secretion of organic acids and enzymes by the Pseudomonas strains, which can dissolve complex phosphates. This study underscores the importance of tacking native microbial resources for the development of eco-friendly and cost-effective biofertilizers tailored to local agroecosystems, thereby contributing to sustainable agricultural intensification and food security in Nigeria.

Isolation and characterization of plant growth-promoting bacteria from medicinal plants Java cardamom (Amomum compactum) and bitter ginger (Zingiber zerumbet)

Abstract. Geraldi A, Clement C, Pertiwi MD, Lestari Y, Parinnata DH, Arsad RN, Sadikin RA, Luqman A, Santoso H, Kristanti AN, Manuhara YSW, Wibowo AT. 2024. Isolation and characterization of plant growth-promoting bacteria from medicinal plants Java cardamom (Amomum compactum) and bitter ginger (Zingiber zerumbet). Biodiversitas 25: 2556-2564. Java cardamom (Amomum compactum) and bitter ginger (Zingiber zerumbet) are valuable medicinal plants native to Indonesia with significant economic and pharmacological importance. While their pharmacological properties have been extensively studied, little is known about the role of their endophytic bacterial communities in influencing plant growth and development. Understanding the interactions between these plants and their associated bacteria could provide insights into novel strategies to enhance their cultivation. This study investigates the potential of endophytic bacteria associated with A. compactum and Z. zerumbet in promoting plant growth. Samples were collected from leaf, rhizome, and rhizosphere soil, followed by isolation and characterization of bacterial strains. Molecular identification revealed the presence of Methylobacterium aquaticum, Paenibacillus tyrfis, Priestia megaterium strain 1, Priestia aryabhattai, and Microbacterium arthrosphaerae among the isolated strains from A. compactum, while strains isolated from Z. zerumbet included Enterobacter mori, Pr. megaterium strain 2, and Pr. megaterium strain 3. Those results demonstrated that Pr. megaterium strains exhibited strong phosphate solubilization, nitrogen fixation, and cellulolytic activity, while Pr. aryabhattai and Pa. tyrfis showed significant nitrogen fixation and cellulolytic potential. Additionally, M. aquaticum, Pa. tyrfis, and Pr. aryabhattai exhibited anti-phytopathogenic activity against Xanthomonas campestris. These findings not only highlight the diverse beneficial attributes of the isolated bacterial strains but also suggest their potential application as biofertilizers and biocontrol agents in agriculture, offering a promising avenue for sustainable farming practices.

NaCl Modifies Biochemical Traits in Bacterial Endophytes Isolated from Halophytes: Towards Salinity Stress Mitigation Using Consortia.

Bacterial endophytes (120) were isolated from six halophytes (Distichlis spicata, Cynodon dactylon, Eragrostis obtusiflora, Suaeda torreyana, Kochia scoparia, and Baccharis salicifolia). These halophiles were molecularly identified and characterized with or without NaCl conditions. Characterization was based on tests such as indole acetic acid (IAA), exopolysaccharides (EPS), and siderophores (SID) production; solubilization of phosphate (P), potassium (K), zinc (Zn), and manganese (Mn); mineralization of phytate; enzymatic activity (acid and alkaline phosphatase, phytases, xylanases, and chitinases) and the mineralization/solubilization mechanisms involved (organic acids and sugars). Moreover, compatibility among bacteria was assessed. Eleven halophiles were characterized as highly tolerant to NaCl (2.5 M). The bacteria isolated were all different from each other. Two belonged to Bacillus velezensis and one to B. pumilus while the rest of bacteria were identified up to the genus level as belonging to Bacillus, Halobacillus, Halomonas, Pseudomonas, Nesterenkonia, and three strains of Oceanobacillus. The biochemical responses of nutrient solubilization and enzymatic activity were different between bacteria and were influenced by the presence of NaCl. Organic acids were involved in P mineralization and nutrient solubilization. Tartaric acid was common in the solubilization of P, Zn, and K. Maleic and vanillic acid were only detected in Zn and K solubilization, respectively. Furthermore, sugars appeared to be involved in the solubilization of nutrients; fructose was detected in the solubilization tests. Therefore, these biochemical bacterial characteristics should be corroborated in vivo and tested as a consortium to mitigate saline stress in glycophytes under a global climate change scheme that threatens to exacerbate soil salinity.

Ancient and remote quartzite caves as a novel source of culturable microbes with biotechnological potential

Quartzite caves located on table-top mountains (tepuis) in the Guyana Shield, are ancient, remote, and pristine subterranean environments where microbes have evolved peculiar metabolic strategies to thrive in silica-rich, slightly acidic and oligotrophic conditions. In this study, we explored the culturable fraction of the microbiota inhabiting the (ortho)quartzite cave systems in Venezuelan tepui (remote table-top mountains) and we investigated their metabolic and enzymatic activities in relation with silica solubilization and extracellular hydrolytic activities as well as the capacity to produce antimicrobial compounds. Eighty microbial strains were isolated with a range of different enzymatic capabilities. More than half of the isolated strains performed at least three enzymatic activities and four bacterial strains displayed antimicrobial activities. The antimicrobial producers Paraburkholderia bryophila CMB_CA002 and Sphingomonas sp. MEM_CA187, were further analyzed by conducting chemotaxonomy, phylogenomics, and phenomics. While the isolate MEM_CA187 represents a novel species of the genus Sphingomonas, for which the name Sphingomonas imawarii sp. nov. is proposed, P. bryophila CMB_CA002 is affiliated with a few strains of the same species that are antimicrobial producers. Chemical analyses demonstrated that CMB_CA002 produces ditropolonyl sulfide that has a broad range of activity and a possibly novel siderophore. Although the antimicrobial compounds produced by MEM_CA187 could not be identified through HPLC-MS analysis due to the absence of reference compounds, it represents the first soil-associated Sphingomonas strain with the capacity to produce antimicrobials. This work provides first insights into the metabolic potential present in quartzite cave systems pointing out that these environments are a novel and still understudied source of microbial strains with biotechnological potential.

Mild to moderate drought stress reinforces the role of functional microbiome in promoting growth of a dominant forage species (Neopallasia pectinata) in desert steppe.

Desert steppe ecosystems are prone to drought stress, which influences the ecological balance and sustainable development of grasslands. In addition to directly restrict plant growth, drought stress indirectly impacts plant fitness by altering the diversity and function of root-associated microbiomes. This begs the question of whether the functional microbiome of forage plants, represented by synthetic microbial communities (SynComs), can be leveraged to mitigate drought stress in desert steppes and promote the ecological restoration of these fragile ecosystems. A pot experiment was conducted to evaluate the role of SynComs in improving the plant growth and drought stress resistance of Neopallasia pectinata (Pall.) Poljak in desert steppe in Inner Mongolia, China. Six SynComs were derived from the rhizosphere and root endosphere of 12 dominant forage species in the desert steppe. Each SynCom comprised two to three bacterial genera (Bacillus, Protomicromonospora, and Streptomyces). We examined the capacities of different SynComs for nutrient solubilization, phytohormone secretion, and enzymatic activity. Under no water stress (75% soil water holding capacity, WHC), single strains performed better than SynComs in promoting plant growth in terms of stem diameter, root length, and plant dry weight, with the greatest effects observed for Streptomyces coeruleorubidus ATCC 13740 (p < 0.05). However, under mild to moderate drought stress (55% and 35% WHC), SynComs outperformed single strains in enhancing plant biomass accumulation and inducing the production of resistance-related substances (p < 0.05). No significant effect of single strains and SynComs emerged under extreme drought stress (20% WHC). This study underscores the potential of SynComs in facilitating forage plants to combat drought stress in desert steppe. Mild to moderate drought stress stimulates SynComs to benefit the growth of N. pectinata plants, despite a soil moisture threshold (21% WHC) exists for the microbial effect. The use of SynComs provides a promising strategy for the ecological restoration and sustainable utilization of desert steppes by manipulating the functional microbiome of forage plants.

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.

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.

In vitro P–solubilization activity of halophilic fungi in salt–affected soils and their potential as bio–inoculants

In vitro P–solubilization activity of halophilic fungi in salt–affected soils and their potential as bio–inoculants

Bioprospecting of Rhizobia as Plant Growth Promoting Rhizobacteria Potential from Root Nodules of Groundnut (Arachis hypogaea L.)

Rhizobia are bacteria that symbiosis with host plant, as shown in the root nodules formation, and provide nitrogen that can be absorbed by plants in greater quantities than rhizobacteria. Available Nitrogen, which absorbed by plants, is the essential requirement for plant growth because its role in increasing yield and quality, hence it is needed in greater quantities than other nutrients. The study aimed to determine the macroscopic and microscopic diversity of rhizobia isolates from the groundnut nodules and their potential as PGPRs, and to identify 16S rRNA isolates with the best potential as PGPRs molecularly. The methods used were isolation from root nodules, screening of PGPR potential, molecular identification based on the 16S rRNA gene, and phylogenetic analysis to determine their kinship. Based on the isolation results, 17 Gram-negative isolates were obtained white to pink or orange color on AG media with various colony characteristics in terms of shape, margin, elevation, and texture. KT 20, which was selected as rhizobia isolate with the best potential as PGPR, has ammonium concentration of 23.12 ppm, synthesizes IAA with a concentration of 10.36 ppm, and phosphates solubilization activity, although its ability to synthesize proteases is low. The results of molecular identification of 16S rRNA showed that KT 20 belongs to the Rhizobium genus with a similarity of 99.48 % and bootstrap value of 96 %. HIGHLIGHTS Isolate KT 20 (identified rhizobia) has excellent ability in fixing nitrogen, which plants needs the most and legumes requires in large number Beside the ability of Isolate KT 20 to fix nitrogen, it also able to synthesize IAA, solubilize phosphate, and synthesize protease The ability of isolate KT 20 as PGPR was equal or better than other rhizobacteria that has been analyzed in other in vitro studies GRAPHICAL ABSTRACT

Antifungal Potential of Bacillus subtilis subsp. inaquosorum RLS76 for Management of Fusarium Wilt Disease of Bt- Cotton

Fusarium wilt is a destructive disease affecting Bt cotton that is caused by Fusarium oxysporum f. sp. vasinfectum. This seed and soilborne disease pose a significant risk to Bt cotton production worldwide, including India. Therefore, to cope with this problem in an eco-friendly manner, we explored the potentiality of the rhizobacterial isolate possessing antifungal activity as a natural arsenal against the fungal pathogen fusarium wilt of Bt cotton. The rhizobacterial isolate RLS76 inhibited 85.39% of the fungal phytopathogen in the dual culture method. The RLS76 isolate's 16S rRNA partial gene sequence was determined to be Bacillus subtilis subsp. inaquosorum RLS76, with a closest phylogenetic affiliation of 99.53%. The crude extract of Bacillus subtilis subsp. inaquosorum RLS76 demonstrated 34.38% inhibition of the growth of the pathogen after a week of incubation by using an agar well diffusion method. Bacillus subtilis subsp. inaquosorum RLS76 produced volatile organic compounds that inhibited the fungal growth of phytopathogens by 54.84% in a closed environment. Also, GCMS analysis of the crude extract of Bacillus subtilis subsp. inaquosorum RLS76 identified four compounds, namely Pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro-; Pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl); 2,5-cyclohexadiene-1,4-dione, 2,5-Dihydroxy-3-methoxy-6-methyl-; 9,12-Octadecadienoic acid (Z,Z)-,phenylmethyl ester. Out of four compounds, three exhibit antimicrobial activity except 2,5-Dihydroxy-3-methoxy-6-methyl. The RLS76 strain of Bacillus subtilis subsp. inaquosorum displayed a transition in hue, shifting from blue to orange, surrounding the colony on CAS medium by producing siderophore qualitatively. The quantitative siderophore produced in the crude extract was 86.06 SU after 60-72 h of incubation. The RLS76 strain of Bacillus subtilis subsp. inaquosorum also showed the ability to produce a proteolytic enzyme outside the cell. This enzyme caused a noticeable clear zone around the colony when the bacteria were grown on a skim-milk agar plate. The Bacillus subtilis subsp. inaquosorum RLS76 also exhibited phosphate solubilization activity with the clear halo around the colonies on NBRIP medium. All these results suggest that Bacillus subtilis subsp. inaquosorum RLS76 exhibits good biocontrol as well as a plant growth promoting candidate against the phytopathogen of Fusarium wilt of Bt cotton.

Uncovering the secret weapons of an invasive plant: The endophytic microbes of Anthemis cotula

Understanding plant-microbe interaction can be useful in identifying the microbial drivers of plant invasions. It is in this context that we explored the diversity of endophytic microbes from leaves of Anthemis cotula, an annual plant that is highly invasive in Kashmir Himalaya. We also tried to establish the role of endophytes in the invasiveness of this alien species. We collected and processed leaf samples from three populations at three different sites. A total of 902 endophytic isolates belonging to 4 bacterial and 2 fungal phyla were recovered that belonged to 27 bacterial and 14 fungal genera. Firmicutes (29.1%), Proteobacteria (24.1%), Ascomycota (22.8%) and Actinobacteria (19%) were dominant across all samples. Plant growth promoting traits, such as Ammonia production, Indole Acetic Acid (IAA) production, Phosphate solubilization and biocontrol activity of these endophytes were also studied and most of the isolates (74.68%) were positive for ammonia production. IAA production, phosphate solubilization and biocontrol activity was present in 39.24%, 36.70% and 20.26% isolates, respectively. Furthermore, Botrytis cinerea, a pathogen of A. cotula in its native range, though present in Kashmir Himalaya does not affect A. cotula probably due to the presence of leaf endophytic microbial antagonists. Our results highlight that the beneficial plant growth promoting interactions and enemy suppression by leaf endophytes of A. cotula, may be contributing to its survival and invasion in the Kashmir Himalaya.

Plant-growth stimulating bacteria × environments/bio-formulations interactions on the growth-promoting activities of Serratia marcescens and Pseudomonas fluorescens on chili

Chile has been used as a spice because of its flavor and zest, which complement the minerals, vitamins, and other elements it contains when cooked. The objective of the current study was to determine how P. fluorescens and S. marcescens promote plant growth in Chili plants. The PGPR's phosphate solubilizing, IAA, NH3, HCN production, and antifungal activities were ascertained using in vitro experiments. During the study period 2020–2022, the experiment was conducted using a completely randomized block design, with three replications of the three treatments for each microorganism, as follows: 1) P. fluorescens: T0 (control, unsterile soil), T1 (P. fluorescens in rice husk), and T2 (P. fluorescens in sawdust); 2) S. marcescens: T0 (control, unsterile soil), T1 (S. marcescens in rice husk), and T2 (S. marcescens in sawdust) with no fertilizer. After seeding, the chili plant's parameters were measured at 15, 30, 45, 60, and 75 days and compared to the control using four traits: plant height, root length, shoot length, and the number of leaves per plant. The following bio-formulation, employing T0, enhanced plant height growth after seeding: In rice husk, Days 75 (B2 × D5 × T2) = 21.20 for S. marcescens > Days 75 (B1 × D5 × T2) = 20.83 for P. fluorescens > Days 60 (B1 × D4 × T2) = 19.17 for P. fluorescens Days 75 (B2 × D5 × T0) for S. marcescens in control, days 60 (B1 × D4 × T1 (16.43 cm) for P. fluorescens in sawdust, and days 75 (B1 × D5 × T0) for P. fluorescens in control. The root length (cm) for P. fluorescens in sawdust is 7.23 days (B1 × D5 × T2), which is more than P. marcescens in sawdust (days 60 B1 × D4 × T2), P. fluorescens in control (days 75 (B1 × D5 × T0) = 6.60 cm), and S. marcescens in control (days 75 (B2 × D5 × T0) = 6.60 cm), etc. Rice husk and sawdust were used to create the bio-formulations. The maximum plant growth was achieved at 75 days when S. marcescens was grown in a sawdust medium, including sawdust as a carbon source and carboxymethyl cellulose as a carrier source. When the different compositions of the bio-formulation were tested on chili plants, it was found that P. fluorescens and S. marcescens in sawdust bio-formulation were more effective.