Previous Article Next Article Abstract HTML Full-Text Article Metrics Similar Articles Request Permission Related Search Citation Alert By Google Scholar Comment On This Article Abstract In the 21st century, industrial applications of potential microbial enzymes have grown extensively and are still increasing to satisfy the requirements of the world's expanding population and to tackle the natural resources depletion. Due to the increasing demand of such enzymes, phytases have been thoroughly investigated to decrease the quantity of phytate in animal feed and human food. Phytases are a group of enzymes that are able to release phosphate from phytate, one of the superabundant forms of organic phosphate present in the natural environment. They comprise efficacious enzymatic groups that help in solubilizing phytate and therefore provide plants with a supportive environment. These enzymes can be obtained from different sources, for example, from animals, plants, and microbes. The microbial phytases have been recognized as more stable, efficient, and promising as compared to animal- and plant-based phytases. Phytate-solubilizing microbes use a sustainable and eco-friendly approach to reduce the consumption of chemically synthesized phosphate fertilizers that are widely used worldwide. These microbes have several biotechnological applications other than the agriculture sector, such as they can be used in fish feed, bioethanol production, the biomedical sector, and the paper and pulp industries. Notwithstanding the renowned importance of biotechnology, investigation on phytase-producing microbes and microbial phytases is noticeably restricted, and more efforts are required to develop the knowledge of phytases present in microbes and their application.

[This retracts the article DOI: 10.1016/j.heliyon.2022.e12579.].

Plant growth promoting bacterial strains were used as bioinoculants on cereal crops to improve plant growth and plant productivity. Crop responses to inoculation are complex because bacteria are not compatible with each other. Therefore, it is necessary to increase our understanding of the microbial ecology of crop rhizosphere under various agricultural techniques. In tropical agriculture, cattle manure is used as an organic fertilizer to increase soil fertility, however use of microbes as consortium have found as sustainable method for the enhancement of crops productivity. The purpose of this study was to evaluate the effects of three potential plant growth-promoting rhizospheric and endophytic bacterial strains EU-C3ST.R1, IARI-JR-44, and IARI-S-45 and organic fertilizers (cattle manure) individually and as consortia on maize (Zea mays L.) under both in-vitro and in-vivo conditions. A total of 123 bacterial strains were sorted out and screened for nitrogen fixation, phosphorus, and potassium solubilization. The potential N2-fixing; P and K solubilizing bacterial strains were identified using 16 S rRNA gene sequencing as Pseudomonas sp. EU-C3ST.R1, Micrococcus indicus IARI-JR-44, and Bacillus horikoshii IARI-S-45 respectively. The inoculation of these three strains on maize as microbial consortium and individual inoculum significantly increased the growth characteristic including height and biomass of the plants, as well as physiological characteristics i.e., chlorophyll, carotenoids, flavonoids, phenolics, and total soluble sugar content of the plant with respect to chemical fertilizers, cattle manure, and untreated control plant. The consortia were found to be more effective with respect to individual inoculants, cattle manure, and uninoculated control plants, so it can be utilized as biofertilizers for inoculation of cereal crops growing in hilly regions.

The earth’s surface consists of arid, semi-arid, and hyper-arid lands, where life is profoundly challenged by harsh conditions such as temperature fluctuations, water scarcity, high levels of solar radiations, and soil salinity. The harsh environmental conditions pose serious consequences on plant survival, growth, and productivity accessibility of nutrients reduces. To cope with the harsh environments and increase plant productivity, an extremophilic microbe has attracted agriculturists and environmentalists. The extremophilic microbes, adapted to extreme environmental conditions, offer an unexploited reservoir for biofertilizers, which could provide various forms of nutrients and alleviate the stress caused by the abiotic factors in an environment-friendly manner. Worldwide, minerals solubilizing extremophilic microbes are distributed in various hotspots and belong to three domains of life including, archaea, bacteria, and eukarya. The minerals solubilizing extremophilic microbes belong to diverse phyla, namely, Ascomycota, Actinobacteria, Basidiomycota, Bacteroidetes, Crenarchaeota, Deinococcus-Thermus, Euryarchaeota, Firmicutes, and Proteobacteria. Mineral solubilizing extremophilic microbes achieve the mineral solubilization of phosphorus, potassium, zinc, and selenium by secreting special compounds such as organic acid, exopolysaccharides, and different enzymes. Consequently, extremophilic microbes are becoming increasingly important in agriculture, industries and environmental biotechnology as well, paving the way for novel sequencing technologies and “metaomics” methods, including metagenomics, metatranscriptomics, and metaproteomics. The extremophilic microbial diversity and their biotechnological application in agriculture and industrial applications will be a milestone for future needs. The present review deals with biodiversity, mechanisms and potential biotechnological applications of minerals solubilizing extremophilic microbes.

Microbes are a worthwhile organism of the earth that could be formulated as consortium which can be utilized as biofertilizers. Consortium-based bioinoculants or biofertilizers are superior to single strain-based inoculants for sustainable agricultural productivity and increased micronutrient content in yield. The aim of present study was to evaluate the effect of different combinations of beneficial bacteria that are more effective than single-based bioinoculants. The current work focuses on the isolation of rhizospheric microorganisms from various cereals and pseudocereal crops and the development of a single inoculum as well as a bacterial consortium which were evaluated on wheat crop. A total 214 rhizospheric bacteria were sorted out and, screened for mineral solubilizing attributes i.e., phosphorus, potassium, zinc and selenium solubilization. Among all the bacterial isolates, four potential strains exhibiting P, K, Zn and Se-solubilizing attributes were identified with the help of 16S rRNA gene sequencing as Rahnella aquatilis EU-A3Rb1, Erwinia aphidicola EU-A2RNL1, Brevibacillus brevis EU-C3SK2, and Bacillus mycoides EU-WRSe4, respectively. The identified strains formulated as a consortium which were found to improve the plant growth and physiological parameters in comparison to single culture inoculants and control. To the best of our knowledge, the present investigation is the first report that has developed the consortium from bacterial strains Rahnella aquatilis EU-A3Rb1, Erwinia aphidicola EU-A2RNL1, Brevibacillus brevis EU-C3SK2, and Bacillus mycoides EU-WRSe4. A combination of bacterial strains could be used as liquid inoculants for cereal crops growing in mountainous regions.

The present investigation aims to isolate nitrogen fixing endophytic bacteria from cereals crops and their potential role in plant growth promotion of wheat (Triticum aestivum L.) for sustainable growth. In the present investigation, endophytic bacteria were isolated from different cereal crops growing in the Divine Valley of Baru Sahib, Himachal Pradesh, India and isolates were screened for nitrogen fixation. The nitrogenase activity exhibiting bacterial isolates were further screened for other plant growth promoting traits including solubilization of phosphorus, potassium, and zinc; production of indole-3-acetic acid, siderophores, ammonia, hydrogen cyanide and extracellular enzyme. The potential nitrogen fixing strains were molecularly identified and evaluated for the growth promotion of wheat. A total of 304 putative endophytic bacterial isolates were isolated from wheat, oats, barley, and maize using selective and complex growth media. Among 304 putative endophytic bacteria, 8 isolates exhibits nitrogenase activity. On the basis of nitrogenase activity and other plant promoting traits, two efficient strains i.e. EU-E1ST3.1 and EU-A2RNfb were molecularly identified using 16S rRNA gene sequencing and found that these strains belongs to genera Rahnella. The wheat inoculated with two selected nitrogen-fixing endophytic bacterial strains showed considerable enhancement in total chlorophyll, nitrogen, Fe and Zn content over the un-inoculated control. In comparison of two selected nitrogen-fixing endophytic bacterial strains, Rahnella aquatilis EU-E1ST3.1 was found to enhance better growth and physiological parameters and it might be developed as biofertilizers to establish a sustainable agriculture system. In the present investigation, the isolated potential nitrogen fixing endophytic bacteria could be used as biofertilizer or bioinoculant for growth of diverse cereal crops growing in hilly region for agricultural sustainability.

Nitrogen, phosphorus, and potassium are the three most essential micronutrients which play major roles in plant survivability by being a structural or non-structural component of the cell. Plants acquire these nutrients from soil in the fixed (NO3¯, NH4+) and solubilized forms (K+, H2PO4− and HPO42−). In soil, the fixed and solubilized forms of nutrients are unavailable or available in bare minimum amounts; therefore, agrochemicals were introduced. Agrochemicals, mined from the deposits or chemically prepared, have been widely used in the agricultural farms over the decades for the sake of higher production of the crops. The excessive use of agrochemicals has been found to be deleterious for humans, as well as the environment. In the environment, agrochemical usage resulted in soil acidification, disturbance of microbial ecology, and eutrophication of aquatic and terrestrial ecosystems. A solution to such devastating agro-input was found to be substituted by macronutrients-availing microbiomes. Macronutrients-availing microbiomes solubilize and fix the insoluble form of nutrients and convert them into soluble forms without causing any significant harm to the environment. Microbes convert the insoluble form to the soluble form of macronutrients (nitrogen, phosphorus, and potassium) through different mechanisms such as fixation, solubilization, and chelation. The microbiomes having capability of fixing and solubilizing nutrients contain some specific genes which have been reported in diverse microbial species surviving in different niches. In the present review, the biodiversity, mechanism of action, and genomics of different macronutrients-availing microbiomes are presented.

On earth, soil is one of the most essential parts of nature which plays critical roles in plant growth, water flow, waste products recycling and provides habitats to various organisms. Soil is the combination of organic matter, air, water minerals, and sixteen different essential nutrient elements which are categorized into primary macronutrients, secondary macronutrients, and micronutrients. The nutrients elements present in soil either in organic forms or organic forms interchanged by the various microbial mechanisms such including fixation, chelation and solubilization. The microbes from all three domain i.e., archaea, bacteria, and eukarya have been reported for exhibiting the various mechanisms and strain belonging to genera Arthrobacter, Burkholderia, Bacillus, Paenibacillus, Pseudomonas, Rhizobium, Natrinema, and Serratia are widely known for ruling the nutrients dynamics. The microbes playing role in nutrients dynamics, have great economic importance in agriculture sector as agriculturist is in pressure of producing high quality and quantity of food along with managing the sustainability. These microbes could solve agricultural problems such as soil degradation and environmental pollution by using them as bio-fertilizer over chemical-based products. A huge number of reports have supported such statements so, the purpose of the present review aims to complies microbial role in all category nutrients dynamics and their role in plant growth promotion.

In the past few decades, the pressure of higher food production to satisfy the demand of ever rising population has inevitably increased the use synthetic agrochemicals which have deterioration effects. Biostimulants containing beneficial microbes (single inoculants and microbial consortium) were found as an ideal substitute of synthetic chemical fertilizers. In recent years, microbial consortium is known as a better bioinoculant in comparison to single inoculant bioformulation because of multifarious plant growth–promoting advantages. Looking at the advantageous effect of consortium, in present investigation, different bacteria were isolated from rhizospheric soil and plant samples collected from the Himalayan mountains on the green slopes of the Shivaliks, Himachal Pradesh. The isolated bacteria were screened for nitrogen (N) fixation, phosphorus (P) solubilization and potassium (K) solubilization plant growth promoting attributes, and efficient strains were identified through 16S rRNA gene sequencing and BLASTn analysis. The bacteria showing a positive effect in NPK uptake were developed as bacterial consortium for the growth promotion of eggplant crop. A total of 188 rhizospheric and endophytic bacteria were sorted out, among which 13 were exhibiting nitrogenase activity, whereas 43 and 31 were exhibiting P and K solubilization traits, respectively. The selected three efficient and potential bacterial strains were identified using 16S rRNA gene sequencing as Enterobacter ludwigii EU-BEN-22 (N-fixer; 35.68 ± 00.9 nmol C2H4 per mg protein per h), Micrococcus indicus EU-BRP-6 (P-solubilizer; 201 ± 0.004 mg/L), and Pseudomonas gessardii EU-BRK-55 (K-solubilizer; 51.3 ± 1.7 mg/mL), and they were used to develop a bacterial consortium. The bacterial consortium evaluation on eggplant resulted in the improvement of growth (root/shoot length and biomass) and physiological parameters (chlorophyll, carotenoids, total soluble sugar, and phenolic content) of the plants with respect to single culture inoculation, chemical fertilizer, and untreated control. A bacterial consortium having potential to promote plant growth could be used as bioinoculant for horticulture crops growing in hilly regions.

Indiscriminate use of chemical fertilizers increases agricultural productivity but on the other hand they harms the health of environment and humans. The multifunctional plant growth promoting bacterial strains could be an ideal alternative to synthetic chemical fertilizers. Looking into the benefits of plant growth promoting bacteria, the present study deals with the isolation of mineral solubilizing and Fe-chelating microbes from the rhizospheric regions of different crops growing in hilly regions of Baru Sahib. Isolated microbes were screened for the multifarious plant growth promoting attributes including solubilization of phosphorus, potassium, zinc, selenium; production of siderophores, ammonia, indole-3-acetic acid, hydrogen cyanide, and nitrogen fixation. The efficient mineral solubilizing and siderophores producing bacterial strains were identified as Serratia surfactantfaciens EU-C3SY2 (P-solubilizer; 144.5 ± 0.05 mg L− 1), Serratia marcescens EU-D1RNL1 (K- solubilizers; 46.9 ± 1.2 mg mL− 1), Serratia nematodiphila EU-D2SRY4 (Zn-solubilizer; 68.5 ± 0.03 mg L− 1), Erwinia persicina EU-B1RT3.1 (Se-solubilizer) and Serratia sp. EU-C1RK1 (siderophores producer; 69.16 ± 0.71 psu) using 16S rRNA gene sequencing. The selected efficient bacterial strains were used for the development of six different microbial consortia, which were evaluated for the growth promotion of oats crops under green house and open field conditions. Among the six different microbial combination, the consortium developed from EU-C3SY2, EU-D1RNL1, EU-D2SRY4, EU-B1RT3.1, and EU-C1RK1 were found as most effective. This microbial combination significantly increased the growth and physiological parameters of oats plants as compared to other developed microbial consortia, control, and agro-chemical fertilizers. The developed mineral solubilizing and Fe-chelating microbial consortium could be used as biofertilizers for crops growing in the hilly regions for agricultural sustainability.

The use of plant growth promoting microbes (PGP) microbes in agriculture has increased due to negative impact of the chemical fertilizers. PGP microbes enhance the plant growth and productivity by diverse mechanisms such as the biological nitrogen fixation; solubilization of phosphorus, potassium and zinc; production of siderophores, plant growth regulators, hydrolytic enzymes, and various phytohormones. PGP microbes as bio-inoculants have been used as sources to improve plant nutrients in sustainable agriculture. The present study was designed to investigate the impact of single as well as the co-inoculation of a nitrogen fixer (Acinetobacter guillouiae EU-B2RT.R1) and a potassium solubilizer (Acinetobacter calcoaceticus EU- LRNA-72) in combination with chemical fertilizers for growth promotion of onion. Each strain used as bio-inoculants positively impacted shoot length, root length, biomass, phenolic, flavanoids, total soluble sugars and chlorophyll content of onion. Thus, nitrogen fixing and potassium solubilizing bacteria could be a promising and potential alternative for utilizing as source of fertilizers to horticultural system and to maintain greater nutrients availability in soil for agricultural sustainability.

Globally, man-made agrochemicals plays crucial role in plant growth promotion and boost crop yield. The agrochemicals overuse leaves the detrimental damage on the environment and humans. Biostimulants developed from single or multiple microbes (archaea, bacteria, and fungi) could be the appropriate alternative of agrochemical which sustains the agriculture as well as environment. In the present investigation, 93 beneficial bacteria associated with rhizospheric and endophytic region were isolated using diverse growth media. The isolated bacteria were screened for macronutrients availing traits including dinitrogen fixation, phosphorus and potassium solubilization. The bacterial consortium was developed using selected bacteria with multifunctional attributes and evaluated for the growth promotion of finger millet crop. Three potent NPK strains were identified as Erwinia rhapontici EU-FMEN-9 (N-fixer), Paenibacillus tylopili EU-FMRP-14 (P-solubilizer) and Serratia marcescens EU-FMRK-41 (K-solubilizer) using 16S rRNA gene sequencing and BLAST analysis. The developed bacterial consortium inoculation on finger millet resulted in the improvement of growth and physiological parameters with respect to chemical fertilizer and control. The compatible mixture of bacteria was found to have more ability to increase the growth of finger millet and it might be utilized as biostimulants for nutri-cereal crops growing in hilly regions.

Endophytic microbes are plant-associated microorganisms that reside in the interior tissue of plants without causing damage to the host plant. Endophytic microbes can boost the availability of nutrient for plant by using a variety of mechanisms such as fixing nitrogen, solubilizing phosphorus, potassium, and zinc, and producing siderophores, ammonia, hydrogen cyanide, and phytohormones that help plant for growth and protection against various abiotic and biotic stresses. The microbial endophytes have attained the mechanism of producing various hydrolytic enzymes such as cellulase, pectinase, xylanase, amylase, gelatinase, and bioactive compounds for plant growth promotion and protection. The efficient plant growth promoting endophytic microbes could be used as an alternative of chemical fertilizers for agro-environmental sustainability. Endophytic microbes belong to different phyla including Euryarchaeota, Ascomycota, Basidiomycota, Mucoromycota, Firmicutes, Proteobacteria, and Actinobacteria. The most pre-dominant group of bacteria belongs to Proteobacteria including α-, β-, γ-, and δ-Proteobacteria. The least diversity of the endophytic microbes have been revealed from Bacteroidetes, Deinococcus-Thermus, and Acidobacteria. Among reported genera, Achromobacter , Burkholderia , Bacillus , Enterobacter , Herbaspirillum , Pseudomonas , Pantoea , Rhizobium , and Streptomyces were dominant in most host plants. The present review deals with plant endophytic diversity, mechanisms of plant growth promotion, protection, and their role for agro-environmental sustainability. In the future, application of endophytic microbes have potential role in enhancement of crop productivity and maintaining the soil health in sustainable manner.

Agrochemicals provide vital nutrients for plant growth to enhance crops yield, but they can pose major agro-environmental issues. Bioinoculants have attracted more and more attention due to their cost effective-eco-friendly and pollution-free characteristics. The aim of this study was to determine whether using a variety of bioinoculants that include both individual and group members could reduce the need for chemical fertilizer. In the modern era, individual and multiple strain formulation as bioinoculants and bacterial consortium is need of agricultural sustainability. A total 132 bacteria were sorted out from soil and internal tissues of the plant and screened for PGP characteristics including nitrogen fixer, phosphorus, and potassium solubilization. Among 132 bacteria, 13 were found to fix nitrogen, 17 and 14 bacteria were able to solubilize phosphorus, and potassium respectively. Efficient bacterial isolates were identified using 16S rRNA gene sequencing as Bacillus thuringiensis EU-CRP-15 (P-solubilizer), Bacillus horikoshii EU-CRK-18 (K-solubilizer), and Pseudomonas trivialis EU-CEN-2 (N-fixer). Inoculation of individual and consortium bioinoculants had a favorable effect on seed sprouting with the increase concentrations of inoculum. These three compatible and individual bacterial strains inoculated on sweet pepper enriched the growth and physiological characteristic of plant (plant length, root length, fresh weight, and biomass of the plant), and (chlorophyll, carotenoids, flavonoids, phenolics, and total soluble sugar content) over chemical fertilizers and untreated control plant. The plant growth promoting bacteria viz; N 2 -fixer as well as P and K solubilizers can be utilized as bioinoculants for the growth promotion of plants and increasing soil fertility.

Abiotic and biotic stresses adversely impact the growth and productivity of the crops globally. Stressful environmental conditions affect the plants morphological and physiological characteristics. Increase in the ethylene production and its inhibitory effect on root development is one of the major challenges under stressed conditions. The association of the beneficial microbiomes with the plants plays a substantial role in improving the health and productivity under the stressful circumstances. Plant growth-promoting (PGP) microbiomes have inherent capabilities of supporting plant growth and development under different environmental conditions by different mechanisms. ACC (1-aminocyclopropane-1-carboxylate) deaminase production is an imperative trait of PGP microbiome for lowering the inhibitory concentrations of ethylene. ACC deaminase producing microbes thus allows the plants to better cope up with the stressed conditions. The ACC deaminase producing belong domains bacteria, and eukarya. The strains belonging to the genera Azospirillum, Bacillus, Brevundimonas, Hallobacillus, Paenibacillus, Providencia, Pseudomonas, Psychrobacter, Serratia, Stenotrophomonas, and Streptomyces laurentii have been reported as efficient and potential ACC deaminase producers. Looking forward the benefits of ACC deaminase producing PGP microbes with multiple PGP plant growth-promoting attributes as bioinoculants to protect plants from harsh environmental conditions make them a viable tool.

Potassium silicate rock is one of the main sources of soil potassium (K), which is the essential macronutrients for plant growth. Potassium is absorbed in the form of K+ ion by plants. The amount of K+ is a limited factor, thus excessive quantity of K fertilizer is being applied in agricultural field worldwide. The excessive K fertilizers application has a substantial negative impact on the environmental sustainability and economy. Silicate mineral weathering bacteria are one of the better substitutes of K fertilizer, which can weather the rock of potassium silicate and releases K+. In present study, silicate-mineral weathering bacteria (SMWB) from rhizospheric samples of cereal and pseudocereal crops were isolated and evaluated for the growth promotion of widely cultivable tomato. A total 154 rhizospheric bacteria were isolated and screened for potassium solubilizing attributes by using Aleksandrov agar media amended with K-alumino silicate and mica as insoluble source of potassium. Isolated bacterial strains were screened and found 56 bacterial strain exhibited silicate mineral weathering attribute. Among 56 bacterial strains, Bacillus albus EU-AN-25 was found to be the most efficient SMWB. The performances of these selected silicate mineral weathering isolates were found to promote plant growth higher than the recommended dose of chemical fertilizers and untreated control. The silicate-mineral weathering bacterium was found to have more efficient and could be employed as an agricultural tool for crops grown in high-altitude, low-temperature alpine, and sub-alpine regions.

Endophytic fungal communities have attracted a great attention to chemists, ecologists, and microbiologists as a treasure trove of biological resource. Endophytic fungi play incredible roles in the ecosystem including abiotic and biotic stress tolerance, eco-adaptation, enhancing growth and development, and maintaining the health of their host. In recent times, endophytic fungi have drawn a special focus owing to their indispensable diversity, unique distribution, and unparalleled metabolic pathways. The endophytic fungal communities belong to three phyla, namely Mucoromycota, Basidiomycota, and Ascomycota with seven predominant classes Agaricomycetes, Dothideomycetes, Eurotiomycetes, Mortierellomycotina, Mucoromycotina, Saccharomycetes, and Sordariomycetes. In a review of a huge number of research finding, it was found that endophytic fungal communities of genera Aspergillus , Chaetomium , Fusarium , Gaeumannomyces , Metarhizium , Microsphaeropsis , Paecilomyces , Penicillium , Piriformospora , Talaromyces , Trichoderma , Verticillium , and Xylaria have been sorted out and well characterized for diverse biotechnological applications for future development. Furthermore, these communities are remarkable source of novel bioactive compounds with amazing biological activity for use in agriculture, food, and pharmaceutical industry. Endophytes are endowed with a broad range of structurally unique bioactive natural products, including alkaloids, benzopyranones, chinones, flavonoids, phenolic acids, and quinines. Subsequently, there is still an excellent opportunity to explore novel compounds from endophytic fungi among numerous plants inhabiting different niches. Furthermore, high-throughput sequencing could be a tool to study interaction between plants and endophytic fungi which may provide further opportunities to reveal unknown functions of endophytic fungal communities. The present review deals with the biodiversity of endophytic fungal communities and their biotechnological implications for agro-environmental sustainability.