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Sustainable crop production depends upon the rational use of chemical fertilizers and pesticides along with organic manures for better soil health. Owing to the constant production of crops from the soil, the latter is being depleted gradually of its nitrogenous and other nutrients. An ordinary crop takes about 25 lb of nitrogen (N) from an acre. It is, therefore, necessary to replenish the soil with the elements, which are removed by the crops year after year. Moreover, in recent years increasing fertilizer costs, and concern for sustainable soil productivity and ecological stability in relation to use of chemical fertilizers, have emerged as issues of vital concern. Furthermore, heavy reliance on chemical fertilizers tends to favour economically those farmers with large hectarage. These considerations have led to a renewed interest in the biofertilizers and organic manures such as FYM, compost and green manures. Biofertilizers which are formulations of bacteria, blue green algae or fungi helps in sustainable agriculture production either by providing plants with fixed nitrogen, available P or by other plant growth promoting substances. Organic matter (OM) is the life of the soil because it contains all the essential elements required for plant growth.

Introduction

Biofertilizers are microbial preparations containing living or latent cells of efficient strains of nitrogen fixing, phosphate solubilizing and cellulose decomposing microorganisms intended for seed or soil application and designed to improve soil fertility and plant growth by increasing the number and biological activity of beneficial microorganisms in the soil.

The objects behind the application of biofertilizers /microbial inoculants to seed, soil is to increase the number and biological / metabolic activity of useful microorganisms that accelerate certain microbial processes to augment the extent of availability of nutrients in the available forms which can be easily assimilated by plants. The need for the use of biofertilizers has arisen primarily due to two reasons i.e. though chemical fertilizers increase soil fertility, crop productivity and production, but increased / intensive use of chemical fertilizers has caused serious concern of soil texture, soil fertility and other environmental problems.Use of biofertilizers is both economical as well as environment friendly. Therefore, an integrated approach of applying both chemical fertilizers and biofertilizers is the best way of integrated nutrient supply in agriculture.

Biofertilizers, thus include i) Symbiotic nitrogen fixers- Rhizobium sp. ii) Non-symbiotic, free living nitrogen fixers- Azotobacter, Azospirillum etc. iii) Blue Green Algae (BGA) inoculants- Azolla-Anabaena, iv) Phosphate solubilizing microorganisms (PSM)- Bacillus, Pseudomonas, Penicillium, Aspergillus etc. v) Mycorrhiza vi) Cellulolytic microorganisms

Increasing food need, decreasing land availability and concurrently attenuating synthetic nutrients supply envisage the use of alternate supplementary inputs for the cultivation of crops. India is among the few nations where systematic farming started thousands of years ago. It was not only the source of income but was also a way of life. Agricultural activities and the techniques adapted to suit local needs and conditions. Different farming systems were followed by the farmers in different areas according to their needs and weather conditions. The produce was usually shared with other communities of the society involved in other professions. Almost all the nutrients removed by the crops were recycled to the soil directly or indirectly (Yadav and Mowade, 2005). In economic terms, the system followed by the then farming community was highly cost effective since all the inputs needed were locally available and practically no expenditure was incurred except labour. The traditional agriculture was though less productive but self-sufficient. With the advent of modern scientific discoveries, agriculture also changed its face, and with the introduction of high yielding varieties, synthetic fertilizers and effective plant protection measures through chemicals, Indian agriculture made rapid strides in the shape of Green Revolution. As an upshot of Green Revolution, the grain production increased two and a half folds in about three decades with a marginal increase in net-area under cultivation.

Abstract

Microbes are ubiquitously found in the environment. Their interaction with other living organisms could either be pathogenic or beneficial in nature. Soil as a rich source of microbes, researchers have extensively studied the plant-microbe interactions. The soil microbes supply the nutrients deficit plants with essential growth elements such as nitrogen, phosphorous, potassium, etc. and improve the texture and quality of the soil. Due to the destructive nature of chemical fertilizers to soil and environment, it was required to generate a more ecofriendly means of increasing the soil fertility. This led to the development of microbes based biofertilizers. The primary benefit of biofertilizers is to promote a healthy soil environment along with supplying essential nutrients to the plant. Again, biofertilizers can be tailor-made according to the specific plant or the climatic conditions. Fungal and bacteria based biofertilizers, either alone or in combinations are formulated for the plants. Lately, liquid fertilizers are increasingly finding their use in the biofertilizer industry due to their ease in manufacture and prolonged effect on plant growth. The scope of this chapter lays on the currently popular biofertilizers and recent trends in the biofertilizer industry.

Introduction 
In 1804, Nicolas Theodore de Saussure demonstrated that plants don’t uptake carbon from the humus, rather it comes from the carbon dioxide in the atmosphere. He further stated that soil is source of plant nutrients. Subsequently in 1840, Carl Sprengel proposed law of minimum which mean the growth is regulated by scarcest (minimum available) resource instead of total resources. During the same time, Justus von Liebig observed that the chemical elements nitrogen (N), phosphorus (P), and potassium (K) are essential for the plant growth. He strongly popularized the theory of mineral nutrients and law of minimum by developing the barrel with multiple holes at different height and filling water in it. It has opened the door of fertilizers industries; therefore, Justus von Liebig has been described as the “father of the fertilizer industry”. Consequently, many fertilizer companies started producing various chemical fertilizers all over the world. This had increased the productivity of the various crops. In India the first fertilizer factory which produced Single Super Phosphate (SSP) was started in Ranipet, Tamil Nadu in 1906 (Chaudhary, 2023). Before, green revolution we have established fertilizers industries of Ammonium Sulphate (1933), Ammonium Sulphate Nitrate (1959), Urea (1959), Ammonium Chloride (1959), Ammonium Phosphate (1960), Calcium Ammonium Nitrate (1961), Nitro phosphate (1965) and Di Ammonium Phosphate (1967). The green revolution ushered in 1967-68 was due to introduction of input responsive high yielding dwarf variety of wheat and use of chemical (mineral) fertilizers. These chemical fertilizers alone were responsible for increasing the yield of wheat by 233 per cent (Khunt et al. 2014&2015). If chemical fertilizers would not have been used for the crop production, we would not be in the position to feed the burgeoning human population. In the pursuit of increasing productivity, we injudiciously used chemical fertilizers and overlooked the deleterious effect of it on animal, human and environmental health. Production and use of chemical fertilizers, has increased the level of Green House Gases (GHGs) in the atmosphere. To reduce GHGs and their environmental impact, alternate source of plant nutrients viz., Farm Yard Manures (FYM), composts, organic waste-derived amendments, biofertilizers, etc. started gaining popularity. Organics are also considered unsafe as during its degradation it produces CH4. Further FYM is limitedly available. Contrary, biofertilizers

Biofertilizers act as complementary and supplementary sources of plant nutrients. Biofertilizers help in increasing the biologically fixed atmospheric nitrogen and enhancing phosphorus availability to the crops. Among the biofertilizers for increasing nitrogen supply, nitrogen fixing bacteria (Rhizobium, Azotobacter and Azospirillum), blue green algae (BGA) and Azolla are important. The availability of phosphorus is improved by phosphorus solublizing microorganisms (PSM) and mycorrhizae (VAM).

Rhizobium is of vital importance to various pulses and some of the oilseeds and fodder legumes as 80–90 per cent of their nitrogen requirement is met through biological nitrogen fixation (BNF). Rhizobium fixes atmospheric nitrogen ranging from 50–60 kg per ha in groundnut, 100–300 kg per ha in alfalfa. In pulses it is estimated at 50–110 kg/per ha. Field studies indicated a yield increase of 14–53 per cent due to Rhizobium inoculation. Nitrogen left over the demand of legumes in combination with the nitrogen present in roots of the legumes will enhance the soil fertility. Consequently the nutrient needs of the subsequent crop from applications will be reduced.

Preparations containing living cells or latent cells of efficient strains of microorganisms that help crop plants to uptake of nutrients by their interactions in the rhizosphere when applied through seed or soil.

Accelerates microbial processes in the soil.

2.1 Introduction

Microbes are the oldest form of the life on earth. These organisms date more than 3 billion years to a time when they were covered with oceans. They are so tiny in size that million microbes can fit into the eye of a needle. Without microbes, we can’t live. Thus, understanding microbes is vital to understanding past and future. Microbes play vary roles in the earth’s environment recycling dead plant and animal matter through the soil, removing CO₂ from the atmosphere by photosynthesis in the oceans and nitrogen from the atmosphere to form nitrogenous fertilizers plants. Microbes play an important role in nutrient recycling, management, organic matter, decomposition and increasing the crop productivity and quality against diseases. Over the past century, many of the basic scientific principles of plant nutrition and soil fertility have been explained. In developed countries, inorganic chemical fertilizers have been widely accepted as a major source of improving and maintaining soil fertility. Plants need sufficient nutrients in proper balance for normal growth and development. Seventeen plant nutrients are essential for proper crop development. Each is equally important to the plant, yet each is required in vastly different amounts. Our understanding of nutritional needs of crop plants begin from the famous five year willow tree experiment conducted by J.B. van Helmont (1579–1644).

Biofertilizers

Definition: Biofertilizers are defined as preparations containing living cells or latent cells of efficient strains of micro–organisms that help crop plant’s uptake of nutrient by their interaction in the rhizosphere when applied through seed or soil. They accelerate certain microbial process in the soil which augments the extent of availability of nutrient in a form easily assimilated by plants.

Types of biofertilizers

There are some types of biofertilizers:

1. Nitrogen fixing biofertilizers
2. Phosphorus solubilizing biofertilizers
3. Phosphorus mobilizing biuofertilizers
4. Biofertilizers for micro–nutrients
5. Plant growth promoting rhizobacteria

Biofertilizers focuses on microbial and biological resources that enhance nutrient availability and support crop nutrition. The chapter covers nitrogen-fixing organisms, phosphorus-solubilizing microorganisms, phosphate-mobilizing mycorrhizae, mineral-solubilizing biofertilizers, and plant-growth-promoting rhizobacteria. It explains applications, importance, liquid biofertilizer methodology, mass production, packaging, storage, and multiplication of bacterial, mycorrhizal, cyanobacterial, and Azolla-based inputs. By connecting microbial activity with nutrient cycling and plant growth, the chapter demonstrates the practical role of biofertilizers in reducing dependence on synthetic fertilizers and strengthening soil fertility. It provides an applied foundation for students, researchers, extension workers, and practitioners of sustainable agriculture. under diverse soil and climatic conditions and practice for field application in natural farming.

According to Li and Tian (2012) a pure-culture planktonic growth of bacteria is rarely found in natural environments.There is a physical interaction between the bacterial cells in biofilms (Kolenbrander, 2002; Watnick and Kolter,2000).The bacteria can organize into groups and can form well-organized communities. They also communicate for coordinated activities (Davey and O toole,2000; Watnick et al., 2000; Nadell et al., 2009). Quorum-sensing mechanisms are common in prokaryotic and single-celled eukaryotic organisms like fungi (van Bodman et al, 2008; Sordi and Muhlschlegal, 2009). For any biofilm structure to develop a high level of cell density is important (Kolenbrander et al., 2002; Kuramitsu et al., 2007 and Webb et al., 2003) and also for checking the effect of antibiotics against planktonic organisms in exponential growth phase using MIC and MBC.This can predict the antibiotic efficacy against rapidly dividing bacteria in acute infections. Papanna, Shobharani and Agrawal Renu (2010) studied the interception of quorum sensing signal molecule

Biofilms play an important part in biotechnology, immunology, biofouling and biodeterioration (Fleming and Wingender, 2001; Dunne, 2002). When the pathogenic cells adhere to the surface, it has been found that the transcription of the EPS genes get stimulated (Dunne, 2002). If EPS gene expression are monitored it can provide a good understanding of biofilm phenotypes (Allison and Sutherland, 1997; Helm and Naumann, 1995; Petersen et al., 2005). EPS serves many functions. It also enables the bacteria to capture nutrients (Pontefract,1991).The formation of biofilm goes through a mechanism which is different from species to species. Even the matrix thickness can be different from 0.2 to 1.0pm depending on the species and doubling time of the cells as thickness of 10 to 30 nm has been found in some bacteria species (Sleytr,1997). The cells secrete polysaccharides, proteins, nucleic acids and glycoproteins. Adherence on solid surfaces by microorganisms is a very complicated process that depends mostly on extracellular molecule production (Czaczyk and Myszka, 2007). The biosynthesis of EPS provides an optimal environment in which genetic material between the cells can be exchanged. This is needed for cell identification and the antigenic properties are helpful in serological characterization of the cells. Among the various compounds of extracellular carbohydrates are acetate esters, pyruvtes, formates, succinates, polysaccharides and proteins (Sutherland, 2001a).

Introduction

Biofilm formation is a series of complex process and accomplished mainly in five stages -Reversibleattachment, Irreversible attachment or colonization,Proliferation, Maturation &Dispersion. Usually biofilms comprise 10% of dry mass that represent microorganisms while the rest 90%derived from the matrix of biofilm. Microbial biofilms are aggregates of microorganisms embedded in self-produced matrices and adhere to an abiotic or biotic surface. Firstly, Marshall et al. (1971) threw light on the concept of biofilms &it’s complexity was discussed by many researchers. According to Donlan and Costerton (2002) “Biofilm as a structured community of microbial cells enclosed in a self-produced polymeric matrix and adherent to a surface to interface, and to each other” still remains the most appreciated definition of biofilms (Mishra et al., 2022). Basically, microbial biofilms are complex, dynamic and three dimensional heterogeneous structures in which cells are interconnected by EPS (Extracellular Polymeric Substances). Biofilms are found to be resistant against UV light, metal toxicity, antimicrobials and other chemical agents like soaps, detergents, disinfectant and other cleaning agents. Future insight the immense need to implicate effective methods for elimination of biofilms from the environment.

Microbial life abounds on a solid substrate. Water and some nutrients are sufficient to allow the microbial construction called biofilm. Biofilm-associated infections (BAI) can enhance chronic infections in which the bacterial pathogens can persist causing cross-contamination of the food products.

Giaouris et al. (2014) worked on the meat processing and biofilm formation by foodborne bacteria. Work on seafoods has been well worked by Mizan et al. (2015). Habimana et al. (2010) studied them in feed industry on Salmonella versus host resident flora strains. Lin et al. (2017) have studied the characteristics of some food borne pathogens. In a study by Rao et al. (2020) cold atmospheric plasma can be a solution to prevent biofilms.Ferriol-Gonzalez et al. (2020) worked out that bacteriophages can be helpful to remove biofims. According to Przekwas et al. (2020) in early stage of growth of the biofilm use of ascorbic acid can be helpful for the removal of biofilms. Apples can be protected from pathogenic bacteria by protecting them using harmless bacteria. It leads towards the development of alternative foodborne-pathogen-control strategies. Listeria monocytogenes is a big concern in the NE part of India.

Joana et al.(2016) have written a critical review on biofilms and have discussed newer methods to study biofilms. These have given a deep knowledge on the physiology, structure and composition of biofilms. More polar amino acids were present in ABPs but QSPs were made up of higher number of neutral amino acids.This helps in recognition. Web application WebLogo help in generating sequence logos (Crooks et al., 2004). The uncharged polar amino acid is present at the first, third and fifth positions.The basis of SVM model is on the amino acid composition of the peptides. The Weka model is based on selected eight inputs which is trained on the NT5 dataset and is accurate, sensitive and specific.Peptide drugs are FDA approved and a total of 242 sequences of biotech peptides/proteins are available at the Drug Bank database. To identify potential anti-biofilm activity for characterization the peptide sequences are submitted on the module of dPABBs. The prediction outcomes are displayed under the ‘Putative ABPs’ section(http://ab-openlab.

Introduction Shrimp aquaculture is a rapidly growing sector worldwide due to transform the intensive cultural practices. The demand for shrimp in the global trade market has increased significantly. The commercially farmed shrimp species, Pacific white leg shrimp, P. vannamei, dominate the market compared to tiger shrimp, P. monodon. Achieving higher shrimp aquaculture production often involves employing high stocking densities and large volumes of feed. This intensification can lead to increased waste and the accumulation of toxic substances, resulting in water pollution, requiring costly management measures to address these issues (Liu et al., 2019; Abakari et al., 2021). Therefore, addressing waste management and water quality concerns is crucial for sustaining the productivity and profitability of shrimp aquaculture operations. In addition to these, several other associated problems – decline in available land resources, escalated environmental pollution, the spread of recurring diseases, the emergence of drug-resistant microorganisms, and the impacts of climate change – with the development of shrimp aquaculture were reported (Santos and Ramos, 2018). To avoid these issues, it is essential to regulate and implement sustainable shrimp aquaculture practices that can be achieved through species and system diversification and environmentally sustainable technologies. Adopting these BFT systems allows for a more sustainable and resilient aquaculture operation (Zhao et al., 2016; 2021).

1. Introduction
Internationally, agricultural systems have predominantly prioritized the production of a large volume of food rather than the nutritious value of the food produced (McGuire, 2015). According to the Food and Agriculture Organization (FAO), around 792.5 million individuals in developing countries experience malnutrition due to insufficient access to food that is rich in nutrients (FAO, 2020). In response to this difficulty, biofortification has garnered considerable interest. Biofortification is a process that involves the improvement of food crops via the application of traditional breeding methods, sophisticated biotechnology techniques, and agronomic practices (McGuire, 2015). This will aid in mitigating the problem of “hidden hunger” caused by the deficiency of vital micronutrients in impoverished and developing nations (Khush et al., 2012). India has a population of approximately 15.3 percent that is undernourished.
Regarding global rankings, India is ranked 101 out of 116 nations, with a score of 27.5 (Yadava et al., 2022). The increasing global population and the significant consequences of climate change have presented a demanding obstacle to achieving worldwide food security (FAO, 2020).

The diets of over two-thirds of the world’s population lack one or more essential mineral elements. This can be remedied through dietary diversification, mineral supplementation, food fortification, or increasing the concentrations and/or bioavailability of mineral elements in produce (biofortification) involving aspects of soil science, plant physiology and genetics underpinning crop biofortification strategies, as well as agronomic and genetic approaches currently taken to biofortify food crops with the mineral elements most commonly lacking in human diets: iron (Fe), zinc (Zn), copper (Cu), calcium (Ca), magnesium (Mg), iodine (I) and selenium (Se).

1. Introduction

Total population of India is estimated to cross 1.64 billion in 2050. Increasing population, decreasing economic status of Farmer, improper diet and nutrition, fixed farm land, degradation of cultivable land and malnutrition in Indian population is major key problem in 2 to 3 decades. More than 600000 children below 5 year age die due to improper nutrition each year in developing countries (White and Broadley, 1998). All the data provide a scary image about future. Almost 60% of the malnutrition children are iron deficient. Iron deficiency is very common among the girls; 30% each are deficient in zinc and iodine. The incomplete diet and malnutrition can lead to several disorder and degrade the human health (Shuman, 1998).

Introduction

Biofortification, also known as biological fortification, involves enhancing the nutritional content of food crops to improve bioavailability for the human population. This is achieved through the use of modern biotechnological techniques, conventional plant breeding, and agronomic practices. Unlike our current agricultural system, which primarily focuses on increasing grain yield and crop productivity, biofortification addresses the nutritional needs of the human population. The prevailing approach has led to a rapid increase in micronutrient deficiency in food grains, contributing to higher rates of micronutrient malnutrition among consumers. Biofortification presents a one-time investment that offers a cost-effective, long-term, and sustainable solution to combat hidden hunger (Sow and Ranjan, 2021a). Once biofortified crops are developed, there are no ongoing costs associated with purchasing fortificants and adding them to the food supply during processing. Agronomic biofortification methods involve the physical application of nutrients to temporarily enhance the nutritional and health status of crops. The consumption of such crops subsequently improves human nutritional status. Successful implementation of the biofortification initiative requires farmers to receive support for using micronutrient fertilisers on fortified cultivars and marketing assistance. Despite challenges, the biofortification of millets holds a promising future in addressing the issue of malnutrition.