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Currently, a diverse range of microbes and their products have been utilized in bioremediation for the management of rising environmental contaminants. These beneficial microbes include bacteria, actinomycetes, fungi, cyanobacteria, and it appears as cost-effective and sustainable approach of bioremediation. In the recent past, utilization of microbial enzymes appears as one of the alternative and effective approaches in biodegradation for various complex and toxic environmental contaminants. The enzymes synthesized by various microbial genera of bacteria actinomycetes, fungi, cyanobacteria have been applied on both organic and inorganic contaminants and effectively degrade or detoxify these contaminants. Some of the common enzymes such as hydrolases, oxidoreductases, oxygenase, peroxidases, and these enzymes have been broadly utilized for pollutants degradation. The use of microbial enzymes in bioremediation appears beneficial in terms of whole microbial cells utilization as well as their possible modification via the latest omics and technology for better effectivity and efficiency.

Nanoparticles (NPs) have received great notice due to their wide application in many areas of science, medicine, agriculture, and technology. They are at the forefront of the research community due to their unique structural, optical, and electronic properties, arising from their large surface-to-volume ratio and quantum confinement effect. Nanomaterials (NMs) have a wider specific surface area and a multitude of nanobased formulations like fertilizers, pesticides, insecticides, and fungicides are currently available in the market. The application of NMs as single carriers of agrochemicals may facilitate unregulated interaction of the NPs with soil components causing drastic modulations in the activity of soil microbiota and in some cases may also negatively impact soil fertility and therefore crop productivity. Specifically, the introduction of various types of NPs in soil leads to diverse responses in enzymatic activities of beneficial microbes. The systematic description of the production, applications, and mechanism of action of NPs on various components of soil resource could impart important clues for better management of NPs released into the natural environment. The present chapter provides the current information pertaining to the impact of NPs on plant performance, soil resource, and integral components, such as soil microbial community structure and function.

Nowadays environment faces rise in various contaminants of both organic and inorganic origin that adversely affect the texture productivity of soil, plants, and ultimately the health of human beings. The traditional physicochemical methods of environment management are still a major challenge due to their toxic residuals products and high cost effectiveness. Bioremediation or the remediation using microbes or their products is an emerging and sustainable method of contaminant management. The microbial strains including bacteria, cyanobacteria, and fungi secrete or synthesize various enzymes, metabolites, surfactant and also produce siderophore, EPS, HCN that help in transforming complex or toxic environmental contaminants such as hydrocarbons, petro products, heavy metals, pesticides, xenobiotics into simpler ones or even complete degradations. In this chapter, we summarize the different aspects of bioremediation and methodologies used by microbial strains used during the bioremediation of various environmental contaminants.

Salinity and accumulation of heavy metals in the soil are some prominent abiotic stress that limits yields and productivity of plant and soil. The physiochemical properties of the soil are highly specific and the ultimate requirement for optimum crop yields; however, the presence of any abiotic stress factors disturbs natural texture as well as physicochemical properties of the soil. Currently, to mitigate the challenges of salinity and heavy metals, various physical and chemical methods have been applied, but cost-effectiveness and the adverse impact of residues on the environment open a new door to find a sustainable and safe approach for the mitigation challenge of salinity and heavy metal stress. In this regard, plant growth-promoting bacteria (PGPB) can be a suitable alternative in mitigation of stress challenge by their natural, eco-friendly, and sustainable approach. Besides remediation, utilization of PGPB benefitted the soil as well as crops by maintaining the nutrients status, synthesizing phytohormones, and solubilizing phosphate.

Different types of abiotic stresses are the major environmental factors limiting crop productivity considerably. Abiotic stresses like drought, salinity, heavy metals/metalloids contamination, and extreme temperature variations are well recognized to alter the physiological and biochemical processes of a number of economically important crops, retarding growth and development of the affected crops. The management of crop productivity losses rendered through negative influences of abiotic stressors is therefore necessary to fulfill the food demand of the continuously rising human population and to ensure sufficient food availability. To date, different approaches based on the introduction of synthetic chemicals in agroecosystem have been deployed to alleviate the negative consequences of abiotic stress factors. However, such chemical approaches are expensive, not environmentally friendly, and may induce toxicity to different environmental components including agroecosystems. The application of biological agents and products thereof, referred to as “biostimulants,” on the other hand possesses promising potential in minimizing the harmful impacts of abiotic stress factors employing different mechanisms like the production of siderophores, induced synthesis of phytohormones like indole-3-acetic acid, auxin, and gibberellin, changes in soil characteristics, nutrient solubilization, enhancement in host uptake of beneficial nutrients, and modulation in root architecture leading to enhancement in plant growth. The present chapter encompasses the effects of different abiotic stresses on crop productivity, mechanisms underlying changes in crop processes at physiological and biochemical level, and sustainable management of negative influences of abiotic stresses on agricultural crops based on exploitation of biostimulants.

Coal is one of the most commonly utilized fossil fuel for energy production across the globe leading to higher amount of emission of sulfur dioxide (SO2) in the atmosphere. Combustion of coal containing higher contents of sulfur is a major factor responsible for acid rain and associated environmental degradation. The currently used physicochemical approaches for removal of sulfur from coal are expensive, toxic in nature, and inappropriate for different types of coal. The application of microbial resources for removal of sulfur from coal is an ecofriendly technique and could be successfully employed at industrial scale after laboratory scale process optimization. The process of sulfur removal by microbes is carried out by enzymes and is considerably influenced by different factors, including pH, temperature, nutrient composition, shaking or standing condition, coal types, and most importantly type of microorganisms used. Different bacteria and fungi isolated from coal contaminated site as well as noncontaminated site exhibiting sulfur removal potential can be used as next generation tool for the development of clean coal technology. Furthermore, through the application of modern genetic manipulation techniques, enhanced expression of genes responsible for desulfurization can be performed in order to accelerate the process of sulfur removal from coal. The present chapter is prepared with an aim to discuss the diverse microbial population participating in desulfurization, their efficiency, mechanism of sulfur elimination, role of important environmental factors along with possible applications, and challenges in industrial scale sulfur removal.

Rapid development of different metal-based industries and mining activities producing huge amount of metal-laden wastes has considerably deteriorated the quality of water and soil around the globe. The application of metal-based fertilizers has further aggravated the environmental contamination multifolds. Most of the metals released into water and soil ultimately find their ways into different plants and animals causing hazardous effects. The variety of microbes dwelling in metal-contaminated water and soil has evolved different oxidative mechanisms to escape the toxicity of metals. Some of the metal-oxidizing microbes derive energy during oxidation and produce metal oxides possessing the characteristic potential to adsorb toxic metal ions. The microbes can oxidize different metals such as iron, manganese, arsenic, and antimony present in their vicinity by cellular biochemical processes and thus offer an environment-friendly option for bioremediation of metal-contaminated water and soil. Very often, the oxidized forms of metals produced by microorganisms are more efficient adsorbent as compared to chemically synthesized metal oxides. Such metal-oxidizing microorganisms developed on filter could be employed for treatment of variety of metal-laden water and wastewater. The present chapter has tried to deal with different metal-oxidizing microbes and their possibility in bioremediation.

The improvement in cultivated ecosystems for enhancement in agricultural productivity is an essential step to support the rapidly rising human population. Pest infestation and changes in climatic conditions with possible negative consequences have further fueled the orientation of agricultural practices toward maximum crop productivity in a sustainable manner at the cost of available natural resources. The crop yield can be increased by enhancing the growth of crop plants and minimizing the losses caused by devastating plant diseases. The conventional practices of employing synthetic fertilizers and pesticides for improving crop yields pose great risks to environmental integrity and human health. In contrast, the deployment of growth stimulating organisms such as plant growth–promoting rhizobacteria and their products together with the living organisms and derived metabolic products such as microbial volatiles suppressing the growth of plant pathogens have promising potential in crop protection, thereby yield enhancement of cultivated ecosystem. Currently, the potential of numbers of bacteria, fungi, cyanobacteria, and mycorrhiza has been harnessed in agroecological management. However, the application under natural environmental conditions has certain challenges and requires extensive field investigation. Moreover, the application of living organisms and their products-based strategies for application in agroecosystem needs approval from regulatory bodies, restricting easy acceptance among farmers. This chapter deals with different biostimulants and biocontrol agents, mechanism of action, application in sustainable management of cultivated ecosystem, and challenges associated with exploitation under natural field condition.

Microbes releasing varieties of organic compounds considered as “signature markers” are known to play an important role in intra- and interkingdom interactions in below- and aboveground zones. The majority of volatile compounds released from the rhizosphere interface have shown possible roles in pathogen suppression. The production of microbial volatile organic compounds (mVOCs) in soil is influenced by various factors including the growth stage of the microbes, nutrient availability, temperature, oxygen availability, pH, and soil moisture content. Recent research has suggested that these signature molecules of microbial origin are insect repellant in nature, and have potential opportunities in managing crop losses occurring through insect pest infestation. Concerning the implementation of mVOCs, our knowledge on the potential use of such volatile compounds in large-scale agricultural and horticultural activities is still limited. In agricultural systems, mVOCs need to be applied under open-field conditions, which are very different from the in vitro conditions currently used in most studies. Despite the potential role of mVOCs in agriculture, field trials are still a big challenge due to several constraints. The present chapter explores the chemical diversity of mVOCs, interventions in plant–microbe and microbe–microbe interactions, as well as application potential in sustainable management of agricultural productivity.

Plant diseases have been recognized as one of the major challenges to food security worldwide. Every year, very large amounts of food produce are lost qualitatively and quantitatively due to plant diseases mainly caused by fungi, bacteria, nematodes, and parasitic plants, calling for the development of suitable control measures. The in-depth information on plant pathogen interaction and disease progression is one of the primary criterion for management. The early detection of plant diseases, in this regard is considered as one of the important strategy for effective minimization of plant diseases in order to enhance food security. The occurrence and spread of most of the plant disease are influenced greatly by different environmental factors like temperature, moisture content, soil characteristics, pathogen virulence, inoculum density, and host. Postharvest disease management by physical methods has not been proved successful under storage condition. The employment of chemical approaches is much expensive, not ecologically sound, induces resistance in plant pathogens, generates environmental hazards, and most strikingly results into accumulation of applied chemicals in crop produce. The practices of different biological methods including biocontrol methods, plant breeding, and genome editing for plant disease control, hence improved productivity, are environment friendly, economical, attractive, and bears possibility with application under field condition. However, the changing climatic conditions are thwarting the goals of food availability, thus posing severe threat to global food security. The present chapter is an effort to provide information relevant to plant diseases caused by different pathogens, impact on crop productivity, factors influencing the pathogen’s growth and disease development, and finally application of currently available chemical and biological approaches against the plant disease in order to achieve the goal of food security.

Worldwide, huge amount of food commodity losses are reported annually due to plant diseases caused by various kinds of pests or pathogens. The continuous and indiscriminate use of chemical pesticides to control plant diseases is known to adversely affect the natural environment, plant and soil ecology as well as the human health by toxic chemical residues. In this context, researchers and farmers have attempted to explore some new eco-friendly and sustainable method for disease management. Plant growth promoting bacteria (PGPB) as biological control agents are such an effective and better alternative to chemical pesticides. PGPB are heterogeneous group of bacteria directly and indirectly involved in growth promotion and disease management in plants. PGPB deploy different biocontrol mechanisms of action that include production of antibiotics, antimicrobial or volatile compounds, cell wall–degrading enzymes, induced systemic resistance, etc. Through these biocontrol mechanisms, they effectively control some devastating plant diseases. Present review describes the biocontrol mechanism of PGPB with special reference to cereal crops.

Agricultural intensification by the increased inputs of agrochemicals has resulted in several negative environmental consequences. Currently the precise use of agrochemicals is being recommended to improve crop yield and environmental health. Application of various precision agricultural practices is being promoted to attain the agricultural sustainability. Nanotechnology as a modern tool has been considered as a potential tool for the precise application of agrochemicals and efficient utilization by the crop plants in the agroecosystems. In this context, the application of spent nanocatalysts in the agroecosystems has been increased considerably for the management of these spent catalysts. Numbers of studies have shown significant impact of spent nanocatalysts on plant germination and growth behaviors. In this chapter a brief insight has been given on the development and application of novel nanomaterials (NMs) in agriculture and environment along with their fate and behavior. Further, recent developments in plant science regarding nanobiotechnology that focuses on agricultural practices, plant growth, and yield are also emphasized. Moreover an effort has been made to collate the studies dealing with the utilization of spent nanocatalysts and nanomaterials used in various value-added products in the agricultural systems.

Water is one of the most important natural resources supporting the diverse array of life present on earth. Rapid diminution of fresh potable water reserves, contamination of existing ones, and generation of large amount of wastewater due to anthropogenic activities have compelled the scientists to develop methods to treat the contaminated water. Across the globe, millions of people are inaccessible to fresh drinking water. Multiple health issues are linked with the purification of drinking water supplied through different ways including bottled water, tap water, and borewells. The drinking water is most often contaminated with pathogenic microbes including bacteria, viruses, and protozoa beyond the recommended limits causing serious human health hazards. The pathogenic microbes commonly detected in water supplies include those related to dysentery, typhoid fever, vomiting, and cholera. Therefore, removal of human pathogens from drinking water is essential for health security. Numbers of physical and chemical techniques have been developed to make available the pathogen free drinking water. Techniques employing membranes for trapping hazardous biological contaminant are currently gaining momentum worldwide. This chapter deals with the sources of pathogens in drinking water, important waterborne diseases, and different aspects of nanofiltration techniques over other commercially used methods for removal of pathogens.

External input-based intensive agriculture practices have resulted in increasing food supply at the cost of considerable deterioration in soil quality and health. In addition, the release of various greenhouse gas emissions has also increased in recent years. For restoring soil health and productivity, and climate change mitigation, various organic amendments have been recommended for application in the soil. Depending upon the climatic variability, the soil responds differently to different amendments. Tropical agroecosystems are one of the extensively cultivated areas, and therefore, several studies dealing with agroecosystem responses have been performed under the present climate change scenario. In this chapter, we have explored the responses of the soil ameliorated with various organic amendments such as organic manure/compost, microbial fertilizers, vermicompost and biochar; and the impact of various amendments on soil physicochemical and biological properties. Moreover, soil respiration and microbial biomass under soils receiving these amendments have also been explored as the key indicators of soil viability. Overall, the chapter would provide a thorough understanding of the soil responses under different organic amendments in the present climate change scenario.

The changing climatic and weather conditions have affected the global food supply, especially cereal crops. Worldwide agricultural production is considerably affected by climate change and pressure induced by the ever-increasing human population and their food demand. The production in agriculture is also affected by the insufficient availability of quality seeds and affordable cost for farmers. Interestingly, genetically engineered stress-tolerant genotypes could play an important role in improving ever-increasing food demand under changing climatic conditions. Generally, plant genetic resources are used for the development of genetically engineered stress-tolerant diverse varieties. New and improved varieties of crops with a wider range of adaptation under changing climatic conditions may be a good move toward combating food scarcity for the increasing population and climate change. Seed industry and seed priming (treatment) have played a vital role in increasing agricultural productivity. The adverse effects of climate change on seed productivity and agriculture industry can be minimized by improved genotype, breeding, genetic diversity, seed priming (treatment), seed certification, seed marketing, etc. There is an urgent need to enhance seed productivity and search for suitable geographic regions for enhancing quality seed production. For the certification of seed, international procedures must be adopted for all the geographical areas of the world. This will also help in ease in the availability of quality seeds to farmers and public participation in plant breeding for the seed industry. Seed biopriming is one of the vital technologies in the management of biotic as well as abiotic stresses and guarantees uniform stand establishment under a stressed environment. Therefore research programs encompassing the identification of quality plant genetic resources, genetic manipulations of novel biocontrol agents (fungal and bacterial strains), and other beneficial applications need to be devised.

In the current scenario of climate change, numerous strategies have been employed in the area of sustainable agriculture or plant science to generate plants, which can withstand various types of biotic and abiotic stresses. Currently, a range of biotic and abiotic stresses such as cold, draught, salinity, water deficit, or extreme pH is present that directly or indirectly influence the germination, growth, and productivity of crops. Seed priming has been developed as a crucial method to germinate the seed or increase plant resistance against various biotic and abiotic stresses. Seed priming is the induction of a particular physiological state in plants by the treatment of natural and synthetic compounds to seeds before germination. Seed priming with microbial inoculum, termed as “bio-priming,” involves the application of beneficial microbes, such as bacteria, fungi actinomycetes, to seed that enhance the uniformity, establishment, and growth of various crops. Seed bio-priming allows the bacteria to enter/adhere to the seeds and also acclimatization of microbes in the prevalent conditions. Seed priming with the use of endophytic microbial strains appears as more beneficial or stable than rhizospheric microbial strains due to better colonization adaptability and suitability under biotic and abiotic stress conditions.

Extensive application of herbicides, pesticides, weedicides along with nitrogen- and phosphate-based fertilizers has deteriorated the physicochemical and biological attributes of agricultural ecosystem, in addition to the resistance emergence in insect pests. Currently, many of the employed agrochemicals are of persistent nature and pose serious hazards to human and environment due to their biomagnifying nature at different trophic levels. The technological advances for the management of agrochemical contaminated soil system may involve different physical and chemical treatment methods. These methods are very much expensive, nonecofriendly, and may sometime lead to generation of even very toxic compounds of more persistent nature than pollutants intended for treatment. Contrary to this, bioremediation based on fungi may offer an easy, sustainable, and ecofriendly technology for restoration of contaminated soil system. In the present chapter, we have tried to discuss different anthropogenically introduced contaminants into soil, their impacts on natural soil characteristics, effect on native microbial community, beneficial soil annelids, arthropods, as well as different fungal genera involved in degradation, strategies based on fungal metabolism for degradation of different chemical contaminants, and limitations associated with application of fungi in agroecosystem to make the soil free from hazardous agrochemicals.

Nanomaterials have significantly affected the different disciplines of science especially agriculture, medicine, environment, and energy production. So far, numbers of nanomaterials with promising features have been synthesized relying on physical, chemical, and biological processes. Although physicochemical processes are efficient methods of nanomaterial synthesis, they could be expensive and environmentally hazardous. Since the biological activities of nanoparticles are considerably governed by their size, shape, and chemical attributes, characterization of synthesized nanomaterials using FTIR, SEM, TEM, XRD, and XPS is very much important while considering their application for human welfare. Further the development of ecologically sound techniques for precise determination of nanomaterials present in natural environment is therefore essential to know their fate and behavior after their release. One of the primary criteria for determining the toxicity of nanomaterials in plant system is seed germination assay. Different studies have shown differential impact of nanomaterials on seed germination, probably resulting from the differences in chemical nature and composition of seed coat in addition to sensitivity of particular plant species. Surprisingly, many of the currently synthesized nanomaterials have been recognized as emerging contaminants, calling for their effective management through eco-friendly technologies. Therefore wide-scale application of nanomaterials for field application in agriculture and medicine must be based on comprehensive toxicity assay on different plant physiological processes and thorough investigation of molecular mechanisms of nanomaterials interaction with plant’s system and their effect on vital processes.

Cyanobacteria are ancient photosynthetic prokaryotes and serve as a model organism for studies such as photosynthesis and earth elements cycling. Cyanobacteria also termed microbial cell factories, because of their ability to utilize carbon dioxide, as well as sunlight absorption in one way, act as primary producers of the aquatic ecosystem while on the other way the diazotrophic forms fix atmospheric nitrogen in paddy fields. Moreover, the successful invention of several fuels as well as fine chemicals from cyanobacteria is indicative of the advancement in synthetic cyanobacteriology in one hand while on the other knocking the door of the augmented application shortly. Unfortunately, the limited availability of genetic manipulation tools for either at single-gene level or pathway to the whole genome in cyanobacteria compared to other organisms handicaps the fundamental biology researches as well as further application and advancement in synthetic cyanobacteriology. However, the role of genetic tools in tuning gene expression, genome-wide manipulations, and carbon flux redirections is available in cyanobacteria. Furthermore, recently a noteworthy headway evolving to familiarizing novel and efficient genetic manipulations tools such as riboswitches, promoters, ribosome-binding site engineering, small RNA regulatory tools, genome-scale modeling strategies, and clustered regularly interspaced short palindromic repeats-associated nuclease has revolutionized the cyanobacteriology. The present chapter disapprovingly recapitulates the recent advancement on the applications and development as well as technical limitations also for the future projections of the toolboxes for genetic manipulation of cyanobacterial genes/genomes. Besides this, the chapter also briefly discusses the toolkits feasible for large-scale cultivation of cyanobacteria.

Currently the growing human population of the world is facing the challenge of low crop production. Changing climatic conditions and the adverse impact of biotic and abiotic stresses limit the growth and yield of crop production. Currently, a range of abiotic stresses including salinity, draught, heat, cold, accumulation of heavy metals, and xenobiotics not only affect the agricultural productivity but also the heath of human. Salinity is one of the severe stresses that limit the crop production, continuously increasing by an area throughout the world. Salinity largely influenced the root systems, physiology, and external morphology of the plant system. Salinity affects the productivity of the plants by generating reactive oxygen species that works as a signal of stress. For combating the salt stress conditions with the aim of sustainable development, recently, plant growth–promoting rhizobacteria (PGPR) are used as promising agents to promote the growth, biocontrol, and in the management of biotic and abiotic stresses in the plants. In this chapter, we focused on the salinity stress and the management strategies used by PGPR.

Recently from last few decades, indiscriminate use of chemical pesticides not only affects the texture and productivity of soil but also affects the environment, health-related issues, and the nontarget microorganism. In the paddy field ecosystem, cyanobacteria are the integral part, which actively involved in maintaining nutrient availability, soil fertility, yield enhancement via biological nitrogen fixation, mineralizing activity, etc. But the continuous and higher dose application of pesticides (either insecticides or herbicides) in the paddy fields leads to a toxic or inhibitory impact on the growth and physiology of native cyanobacterial species. In general, lower concentrations of insecticides or herbicides have a stimulatory effect on the various cyanobacterial species and enhance the growth, nitrogen fixation activity, photosynthetic pigments, whereas higher doses lead to even death of the microorganisms. Therefore in this chapter, we tried to summarize the ecotoxicological impact of pesticides on the growth and function of native cyanobacterial species in the paddy field ecosystem.

Phytoremediation is the technology based on plants for extraction, sequestration, and/or degradation of environmental contaminants. The process of phytoremediation is a green and nondestructive suitable alternative to widely practiced physicochemical approaches. Plant-based contaminant removal could be directly inside the plant or outside the plant body (explanta). The process of phytoremediation involves different biochemical and physiological mechanisms facilitated by absorption, accumulation, sequestration, transport, and degradation. Furthermore, plants are equipped with the property of metabolizing hazardous organic contaminants into nontoxic or comparatively less toxic forms. Numbers of organic contaminants including polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and halogenated hydrocarbons have been targeted for effective remediation by utilization of diverse plant groups. Currently, many experimental investigations have been conducted to develop genetically modified plants and endophytic bacterial strains harboring genes of interest displaying efficient contaminant degradation ability. Although the phytoremediation strategy for cleaning the organic contaminant seems promising with reference to the process cost, assessment, maintenance of soil biological activity, and carbon capture efficiency, the field-scale application has limited success because of changing environmental conditions, slow growth rate, and adaptability under given natural environment. Some of the limitations associated with phytoremediation could be managed through genetic engineering approaches; however, regulatory issues regarding their release under field conditions and very low public acceptance make the process unsuccessful at field scale. Essentially, extensive laboratory investigations are still needed to deploy the phytoremediation strategies for effective contaminant removal. The successful utilization of recombinant DNA technology together with the existing information on plant physiology, rhizosphere microbiology, and root exudates chemistry could be instrumental in gaining deep insights into the process of environmental contaminant removal.

Spoilage of food commodities by different microbes and associated toxins may cause potential health risks, particularly in tropical and subtropical countries. To control food spoilage, various synthetic chemicals with potential to induce ill effects on human and environmental integrity have been utilized indiscriminately. On the other hand, phytochemicals extracted from different medicinally important plants may be explored as green alternatives for prevention of microbial infestation of food commodities and toxin production. Phytochemicals such as terpenoids, phenols, glycosides, glucosinolates, alkaloids, lactones, and essential oils can regulate different key regulatory genes in food contaminating bacteria and fungi. So far, different classical as well as high throughput modern techniques have been employed to detect pathogenic microbes and their toxins in contaminated food system. The present article deals with the efficacy of phytochemicals as a potential green preservative together with the emphasis on their application as inhibitor of foodborne microbial toxins.

The release of various inorganic and organic chemicals from various industries such as petrochemicals, textiles, pharmaceuticals, agro-based industries, and tanneries is highly toxic to the environment and human health. Several processes and technologies such as physical, chemical, and advanced oxidation processes are available for treatment of these pollutants. However, these processes and technologies have their own limitations and the end products are also of toxic nature. Therefore, there is a need for identifying and exploring sustainable and eco-friendly methods which require a lesser amount of chemicals, are economically feasible, and produce nontoxic end products. The bioremediation approaches to clean up environmental pollutants are considered as emerging and sustainable methods recently. Bioremediation process is based on an integrated approach employing microbial communities such as actinomycetes, bacteria, fungi, and earthworms. It is considered as a sustainable process for management of organic pollutants-rich solid wastes and wastewater. Many microorganisms metabolize toxic chemicals to produce CO2 or CH4, water, and biomass. These pollutants may be enzymatically altered to metabolites that are less noxious or innocuous. Moreover, the solid residue generated in this process has been found to have a potential influence on soil macro- and micronutrients, indicating its application as organic manure. However, bioremediation technique required more research for its establishment at a larger scale with an emphasis on the environmental consequences of the end products. In this chapter, we have performed a literature survey based on biological methods for the management of organic pollutants. Microbes responsible for degradation processes have also been presented in the later part of the chapter. In this chapter, a thorough understanding of the bioremediation processes and methods applied for abatement and remediation of organic pollutants has been described in detail.

Inside plants, microbial communities live as endophytes without causing any disease symptoms or adverse impacts to the host plant. These microbial communities may comprise bacteria, fungi, and archaea. In the last few decades endophytic microbes have been broadly used in sustainable agriculture as biofertilizers, biocontrols, or inducers of abiotic stress tolerance. Successful colonization by endophytes in the host plant is a key factor for beneficial plant microbe interaction that results in various plant growth promoting mechanisms. Colonization includes a series of phenomenon such as attachment, entry, motility, transmission, and multiplication of endophytic populations within the host plant. In this chapter, we will discuss the mechanisms of colonization, the rhizophagy cycle, and genomic insights of endophytic behavior and functions that will aid in the advancement and application of endophytes in various aspects of sustainable agriculture.

Currently, pollution caused by organic contaminants is a global problem and there is an urgent need to explore new green and sustainable methods for the remediation of environmental pollutants. In this aspect, bioremediation technology has been considered as one of the most effective, low cost, and sustainable approach for the management of environmental pollutants of organic origin. From last few decades utilization or inoculation of endophytic microbial strains for the remediation of organic pollutants had been carried out in a regular manner for the management of various contaminants such as pesticides, herbicides, hydrocarbons, polyaromatic hydrocarbons, polychlorinated biphenyls, petroleum products, oil spill, etc. During the long course of host plant and endophyte relationship at the polluted site, microbial endophytes not only help in mobilization of contaminants but also help in plant growth promotion as well as tolerance development against various biotic and abiotic stresses. The in-depth understanding of plant and endophyte association would help remediate the contaminated sites in an effective manner.

Anthropogenic activities have aggravated the problem of environmental contamination globally. The currently used physicochemical methods have limitation requiring the search for environment-friendly options for contaminant removal from a system. Application of microbes, especially diverse bacterial species, is attractive because of their fast growth and easy adaptation even under harsh environmental conditions. Many of the xenobiotic compounds are either nonbiodegradable or slowly degradable by microbial communities. Because the indigenous bacteria are less efficient in degrading the pollutants, designing of engineered bacterial systems for enhanced degradation of hazardous contaminants could serve as a suitable approach for mitigating the impacts of pollutants on environment and human health. However, the release of transgenic bacteria for field application to clean the noxious contaminants is a matter of controversy. The release of engineered bacteria may affect the natural microbial diversity, and the genes for catabolism of a particular substance may be harbored by pathogenic microbes. Lots of research has been performed to detect the presence of transgenic bacteria under environmental conditions along with the development of suicidal genetically engineered microbes to restrict their transfer into native microorganisms. Hence, the use of genetically engineered bacteria could serve as a viable option for management of contaminated sites.

Changing climatic conditions include the global rise in temperature and atmospheric pollution which adversely affect agricultural productivity. To mitigate the problems arising from the present climatic conditions and to ensure food security, sustainable agricultural practices are the ultimate need of the current scenario. In this context, the use of beneficial microbes, like fungi and bacteria, as plant or soil inoculants to act as biofertilizer, biocontrol, or to mitigate abiotic stress is one such sustainable approach to agriculture. In the present chapter, beneficial fungi microbes are discussed with regards to their use as biofertilizers, as biocontrol agents, and also in the process of mycoremediation of contaminated soil. Fungi are widespread in nature having rapid adaptability and diverse metabolic activities in natural systems. In soil, fungi can sustain under diverse environmental circumstances by producing different types of spores. These microbes make significant contributions to the maintenance of ecosystem functioning because of their decomposing behavior or as a biofertilizer or biocontrol agent.

The biosynthesis of nanoparticles from microorganisms is a safer, green, and ecofriendly technology that has received attention worldwide for various applications. Studies have shown that microbial processes involve both the intracellular and extracellular processes and lead to the synthesis and design of nanoparticles that are ecofriendly, cost effective, and easy to work with. This chapter summarizes the major uses of microorganisms in the biosynthesis of nanoparticles and their unique properties that make them useful for broad applications in agriculture, medicine, etc. We also discuss future perspectives of biogenic synthesis of nanoparticles by regulating important parameters, including the selection of biological source, incubation period, pH, temperature, etc.

The changing environmental conditions, especially global warming and climate variability, are major concerns and have an adverse impact over the future of agriculture. The changing climate has become a global issue which needs rapid policy development at national and international levels. The melting of massive Himalayan glaciers would considerably change the impact of temperature regimes which is necessary for blossoming of several crop plants. Thus, the current generation needs to find solutions to combat the negative impacts of environmental consequences on agricultural crops. Useful strategies include the conservation of the world’s huge biodiversity together with other natural resources. Modifications in currently used agricultural practices and the search for new plant species tolerant to different abiotic and biotic environmental stresses could help to mitigate the negative impact of climate change.

Anthropogenic climate change is of prime global concern and directly or indirectly affects the plant and microbial diversity of planet Earth. It is evident that anticipated increase in CO2, temperature, and altered precipitation are major consequences of climate change that has added the complexity and uncertainty to the plants and agroecosystem and threaten their sustainable management. Plant–microbe interactions are an important factor that influence the response of plants to alterations in climatic conditions. However, there are some beneficial plant-associated rhizobacteria and mycorrhiza that play an important role in reducing the ill-effects of climate change, such as drought, salinity, and plant diseases, etc. Apparently, it has been determined that climate change indirectly influences crop quality and plant–microbe relationships through the anthropogenic introduction of xenobiotics (pesticides, polycyclic aromatic hydrocarbons, etc.,) in terrestrial environments, posing risks to soil health by disturbing soil microbial enzyme activities and community structures. Considering the long-term effects of global climate change, it is essential to review the impacts of climate change on various life form sustaining components including soil–plant–microbe relationships with special reference to the belowground environment. This chapter could also help in predicting how plant–microbe interactions respond to climate change as well as the selection of suitable crops that would be able to produce more yields even under multistress conditions.

Actinomycetes are commonly known as filamentous, Gram-positive, spore-forming actinobacteria and are considered as both bacteria and fungi. In recent decades, actinomycetes have been used as a resource for the production of bioactive compounds and nanoparticles. Actinomycetes are also rich sources of various enzymes that have industrial importance and of many bioactive compounds with a diverse range of pharmaceutical properties like antibiotics, antimicrobials, antibiotics, etc. Today actinomycetes are also being used in nanotechnology for the synthesis of various nanoparticles used in sustainable agricultural processes as nanofertlizers or biocontrol agents. In this chapter, we summarize the role of actinomycetes in sustainable agriculture, in bioactive compound production, and in the field of nanotechnology.