Microbial Nanotechnology for Precision Nanobiosynthesis: Innovations, Current Opportunities and Future Perspectives for Industrial Sustainability.

A new area of biotechnology is nanotechnology. Nanotechnology is an emerging field that aims to develope various substances with nano-dimensions that have utilization in the various sectors of pharmaceuticals, bio prospecting, human activities and biomedical applications. An essential stage in the development of nanotechnology is the creation of nanoparticles. To increase their biological uses, eco-friendly material synthesis processes are becoming increasingly important. Recent years have shown a lot of interest in nanostructured materials due to their beneficial and unique characteristics compared to their polycrystalline counterparts. The fascinating performance of nanomaterials in electronics, optics, and photonics has generated a lot of interest. An eco-friendly approach of creating nanoparticles has emerged in order to get around the drawbacks of conventional techniques. Today, a wide range of nanoparticles have been created by employing various microbes, and their potential in numerous cutting-edge technological fields have been investigated. These particles have well-defined chemical compositions, sizes, and morphologies. The green production of nanoparticles mostly uses plants and microbes. Hence, the use of microbial nanotechnology in agriculture and plant science is the main emphasis of this review. The present review highlights the methods of biological synthesis of nanoparticles available with a major focus on microbially synthesized nanoparticles, parameters and biochemistry involved. Further, it takes into account the genetic engineering and synthetic biology involved in microbial nanobiosynthesis to the construction of microbial nanofactories.

Bioformulation of mineral solubilizing microbes as novel microbial consortium for the growth promotion of wheat (Triticum aestivum) under the controlled and natural conditions.

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.

Microbial Consortia: Promising Tool as Plant Bioinoculants for Agricultural Sustainability.

In the present scenario, growing population demands more food, resulting in the need for sustainable agriculture. Numerous approaches are explored in response to dangers and obstacles to sustainable agriculture. A viable approach is to be exploiting microbial consortium, which generate diverse biostimulants with growth-promoting characteristics for plants. These bioinoculants play an indispensable role in optimizing nutrient uptake efficiency mitigating environmental stress. Plant productivity is mostly determined by the microbial associations that exist at the rhizospheric region of plants. The engineered consortium with multifunctional attributes can be effectively employed to improve crop growth efficacy. A number of approaches have been employed to identify the efficient consortia for plant growth and enhanced crop productivity. Various plant growth-promoting (PGP) microbes with host growth-supporting characteristics were investigated to see if they might work cohesively and provide a cumulative effect for improved growth and crop yield. The effective microbial consortia should be assessed using compatibility tests, pot experimentation techniques, generation time, a novel and quick plant bioassay, and sensitivity to external stimuli (temperature, pH). The mixture of two or more microbial strains found in the root microbiome stimulates plant growth and development. The present review deals with mechanism, formulation, inoculation process, commercialization, and applications of microbial consortia as plant bioinoculants for agricultural sustainability.

Silicon derived benefits to combat biotic and abiotic stresses in fruit crops: Current research and future challenges.

Fruit crops are frequently subjected to biotic and abiotic stresses that can significantly reduce the absorption and translocation of essential elements, ultimately leading to a decrease in crop yield. It is imperative to grow fruits and vegetables in areas prone to drought, salinity, and extreme high, and low temperatures to meet the world's minimum nutrient demand. The use of integrated approaches, including supplementation of beneficial elements like silicon (Si), can enhance plant resilience under various stresses. Silicon is the second most abundant element on the earth crust, following oxygen, which plays a significant role in development and promote plant growth. Extensive efforts have been made to explore the advantages of Si supplementation in fruit crops. The application of Si to plants reinforces the cell wall, providing additional support through enhancing a mechanical and biochemical processes, thereby improving the stress tolerance capacity of crops. In this review, the molecular and physiological mechanisms that explain the beneficial effects of Si supplementation in horticultural crop species have been discussed. The review describes the role of Si and its transporters in mitigation of abiotic stress conditions in horticultural plants.

Microbial consortium with multifunctional attributes for the plant growth of eggplant (Solanum melongena L.).

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.

Plant endophytes: unveiling hidden applications toward agro-environment sustainability.

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-, ß-, 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.

Mutualistic Effect of Macronutrients Availing Microbes on the Plant Growth Promotion of Finger Millet (Eleusine coracana L.).

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.

Assessment of nitrogen-fixing endophytic and mineral solubilizing rhizospheric bacteria as multifunctional microbial consortium for growth promotion of wheat and wild wheat relative Aegilops kotschyi.

Microbes play crucial functions in maintaining the health and growth of the plants directly or indirectly by supplying nutrients. These microbes could be used as biofertilizers for the enhancement of soil health and growth of crops. In preset investigation, potential microbes from endophytic and rhizospheric region of Aegilops kotschyi growing in green slopes of Shivaliks, Himachal Pradesh were sorted out and screened for plant growth promoting attributes including phosphorus and potassium solubilization. The potential bacterial strains were identified through 16S rRNA gene sequencing and developed as microbial consortium for the plant growth of wheat and wild wheat relative Aegilops kotschyi. A total 125 isolates of bacteria were sorted out and among them 36 were found as P-solubilizers and 19 showed K-solubilization attribute and two highly potential bacterial strain were identified as Bacillus tropicus EU-ARP-44 (P-solubilizer; 270.5 ± 0.00 mg L-1) and B. megaterium EU-ARK-23 (K-Solubilizer; 51.3 ± 1.7 mg mL-1). The microbial consortium of Rahnella sp. strain EU-A3SNfb (N-fixer; MN294545), B. tropicus EU-ARP-44 (P-solubilizer) and B. megaterium EU-ARK-23 (K-solubilizer) evaluation in Aegilops kotschyi and wheat crop resulted in the enhancement of growth as well as physiological parameter including shoot/root length, fresh/dry weight and chlorophyll, carotenoid, total soluble sugar content, phenolic and flavonoid content as compared to un-inoculated control. Microbial consortium consisting of potential plant growth promoting (PGP) bacterial strains could be used as biofertilizer and bioinoculants in cereals crop growing in hilly region.