Biotransformation of Waste Biomass into High Value Biochemicals

Although industrial revolution is an important factor governing the development of a country’s economy, but at the same time, the industrial activities have been also accompanied by problem of waste biomass. This commensurate with the increase in industrialization, urbanization, and population growth is leading to production of enormous quantities of industrial waste biomass that may cause environmental and health hazards. However, the increased awareness and desire for a healthy environment among people leads to the need for better ways of waste minimization and pollution prevention and better use of resources in achieving the required industrial and environmental standards. The present book deals specifically with the valorization of waste biomass to small-volume high-value biochemicals only. The products which are produced in bulk quantities, such as biofuels, some organic acids, hydrolytic enzymes, biogas, and other traditional products from waste biomass, are not discussed. In this context, the current chapter discusses the different sources, types, and nature of waste biomass. The chapter also provides overview of the different management strategies applied for the value addition of different types of waste biomass. The chapter will provide insights into the role of waste biomass resources for developing bio-based economy/processes for industrial biotechnology and renewable energy in supporting sustainable development and economic competitiveness.

Due to economic, technical, and environmental reasons, the demand for liquid fuels all around the world is constantly increasing; bioethanol and other biofuels from lignocellulosic biomass might be one of the most important solutions for this proposal. Although biomass may be cheap, its processing costs may be high. Many technologies for converting biomass into biofuel have been developed, which include the physical pretreatment of biomass, acid or enzymatic saccharification of the pretreated biomass, and fermentation of the hexose and pentose released by hydrolysis and saccharification. In this chapter, the most frequently used and new physicochemical and biological pretreatment methods of lignocellulosic biomass are discussed.

The gradual rise in average global temperature over the last few decades is the evidence of adversities of climate change. Therefore, the research and development efforts to investigate and materialize innovative and economically viable methods to mitigate carbon emission have received unprecedented priority. One of the plausible methods to sequester carbon in a sustainable manner could be to fix carbonaceous materials on a very long-term basis by thermochemical transformation of agricultural biomass residues into biochar. It has been reported in the literature that the pyrolysis of organic materials can yield up to 50–70 % (w/w) biochar as a value-added product. Furthermore, biochar can have a carbon composition ≥60–80 %, which is equivalent to ≥2.20–2.94 ton CO₂ sequestered/ton biochar. Therefore, even after a conservative estimation (e.g., 20 % liberation of carbon from the biochar after land application) of kinetics of biochar-bound carbon loss, a substantial amount of CO₂ can be sequestered into soil for a very long term (≥100 s to 1,000 years or even more). On the other hand, amendment of agricultural soil with biochar has been found to enhance physicochemical as well as biological characteristics of the soil. Biochar can act as buffering agent for acidic soils; enhance water retention capacity, favorable matrix formation for beneficial microbial flora, and degradation of toxic compounds; and provide bioavailable nutrients to plants or to the beneficial microbial consortia. The present cost of commercially available biochar is ≅100–500 $/ton (without any carbon credit basis), which is considerably higher than other soil amendment chemicals, such as lime (≅50 $/ton), which is the main deterrent to its marketability. However, under one or more of the favorable conditions such as government subsidies/carbon credit gains, mass scale production (demand–supply dynamics), and data on long-term benefits correlated with techno-economics can make biochar commercially successful. This will have a substantial positive impact on mitigation of carbon emission.

Agro-industrial wastes are unavoidable waste materials continuously generated in bulk quantity. Most of these materials can be used as nutrient source for industrial fermentation. However, commercial fermentation of low-value high-volume products generally suffer financial crisis. Alternatively, sustainable biotransformation of agro-industrial waste into fine biochemical, such as aroma compounds and fragrances, has been widely investigated. Significant variation of substrate quality imparts great variations in the production methodology of these processes. Further, a range of microorganisms are known to be used and different genetic engineering strategies have been applied for improved bioconversion. Moreover, novel strategies for detection, identification, and purification of the final products have been developed, and in some particular cases, successful commercialization has also been achieved. To have, however, further benefit from this potential strategy, a systematic study of the type and nature of the feedstock and their abundance should be evaluated. Similarly, presently used processes and their scale-up potential should be determined and different options for their economic competitiveness should be identified. The goal of this chapter, therefore, is to improve the basic understanding of the interesting strategy and to summarize the recent advancements in production of aroma compounds and fragrances.

Antioxidants are a class of chemical substances naturally found in our food which can prevent or reduce the oxidative stress of the physiological system. The body is constantly producing free radicals due to regular use of oxygen. These free radicals are responsible for the cell damage in the body and contribute to various kinds of health problems, such as heart disease, diabetes, macular degeneration, and cancer. Antioxidants being fantastic free radical scavengers help in preventing and repairing the cell damage caused by these radicals.

Plants and animals are the abundant source of naturally producing antioxidants. Alternately, antioxidants can also be synthesized by chemical process as well as from the different kinds of agro-related wastes using biological process. Based on their solubility, antioxidants are broadly categorized into two groups: water soluble and lipid soluble. In general, water-soluble antioxidants, such as ascorbic acid, glutathione, and uric acid, have functions in the cell cytosol and the blood plasma. Ascorbic acid is a redox catalyst which reduces and neutralizes the reactive oxygen species (ROS), glutathione has antioxidant properties as reducing agent and can be reversibly oxidized and reduced, while α-tocopherol, carotenoid, and ubiquinol are the examples of lipid-soluble antioxidants and protect the cell membranes from lipid peroxidation. Another commonly used classification is on the basis of their mechanism of action, i.e., primary or chain-breaking antioxidants and secondary or preventive antioxidants.

Antioxidants can also act as prooxidants when these are not present at the right place at the right concentration at the right time. The relative importance of the antioxidant and prooxidant activities of an antioxidant is an area of current research.

This chapter discusses the types, sources, synthesis, uses, and protective efficacy of various antioxidants.

The increasing demand in pharmaceutical products for human welfare has encouraged remarkable attempts towards the development of biotechnological processes for the production of antibiotics using readily available agricultural residues. Immense availability and cost-effectiveness of agricultural residues compared to sugars offer greater advantages in commercial usage. However, these constituents are currently underutilised. Productions of antibiotics have been carried out by both solid-state fermentation (SSF) and submerged fermentation (SmF) using wide range of microorganisms. The advancement in the field of SSF and its advantage over SmF has opened its application for production of antibiotics utilising low carbon and energy sources. This chapter gives an insight on various approaches that are being carried out for antibiotic production using SSF. The biotechnological potential of lignocellulosic biomass, factors affecting the production and yield of antibiotics from specific microorganisms are accounted.

Plant hormones are signaling molecules that are present in small quantities. They act differently depending upon the concentration and environmental conditions. The main plant hormones are auxins such as indole-3-acetic acid (IAA), the gibberellins (GAs), abscisic acid (ABA), cytokinins, and ethylene. The effect of IAA varies with the concentration and the part of the plant where it is applied. Its exact mechanism of action is not completely known, but it is believed that it is involved in the activation of enzymes, which increases the plasticity of the cell walls, thereby increasing the cell volume and, consequently, the growth of the plant. The GAs are a large family of diterpenes, an important group of plant hormones, which exert several effects on the growth and development of plants, such as germination, growth of leaves, and flower development. Auxins stimulate the transfer activity of the vascular system, causing increased formation of xylem and phloem in woody plants. ABA is associated with the seed maturation and desiccation tolerance of viviparity. Cytokinins, such as zeatin, promote cell division and differentiation of organs, having widely used in the culture and handling plant tissue in vitro. It is also important to cite the ethylene, a gaseous hormone that stimulates fruit ripening, abscission, senescence, and, for some species, flowering. Considering the great importance of agriculture to the global economy, the demand for alternatives to the increase production of various agricultural products is justified. Plant hormones (phytohormones) appear then to increase the technical and economic efficiency of various agricultural production systems. Thus, this chapter focuses on plant hormones and phytochemicals, their structure, mode of action, and its great economic importance for agriculture as well as alternatives that enable their production and use on a large scale.

Probiotics are defined as “live microorganisms that, when administrated in adequate amounts, confer a health benefit on the host”. Bacterial strains selected as probiotics are predominantly from the genera, Bifidobacterium and Lactobacillus, which are indigenous to the human gastrointestinal tract. Probiotic bacteria are selected for potential application on the basis of particular physiological, biochemical and technological properties. The classification and identification of probiotic strains may give a strong indication of their safety and technical applicability; thus, probiotic bacteria have to be accurately identified and characterised at least at the species level. Safety and functionality screening also plays an important role in selection of probiotic straints for human use. Extensive investigations of biological active compounds from probiotic bacteria are directed primarily for the preparation of highly effective therapeutic products. Among these substances are bacterial polysaccharides and polar lipids. The general results of chemical, NMR and serological studies indicate the structural heterogeneity of the surface polysaccharides, which in turn might influence their biological activity, namely, the antigenicity. Current research on biological active compounds from probiotic bacteria is also directed at the elaboration of glycoconjugates products. By employing of new modification of supercritical fluid of carbon dioxide (scCO₂), polar lipids of lactic acid bacteria and bifidobacteria can be very effectively extracted. The role of biological active components from probiotic bacteria in treatment and prevention of autoimmune diseases, as well as their possible involvement in pathogenesis of autoimmune thyroid disease and celiac disease by the mechanism of molecular mimicry, was revealed. In prospect, the scCO₂ isolation technology of probiotic glycoconjugates may be combined with metabolic engineering and immunological studies in technologies aimed at manufacturing of highly effective therapeutic products.

Prebiotics are nondigestible dietary fibers that benefit the host health by stimulating the growth of probiotic microorganisms in the colon. Lactulose, galacto-oligosaccharides, fructo-oligosaccharides, xylo-oligosaccharide, malto-oligosaccharides, inulin, and its hydrolysates are some commonly used prebiotics comprising of two to ten sugar moieties. The end products of these prebiotics, i.e., acetate, butyrate, and propionate, act as energy sources for host organisms. Naturally, these can be obtained in small amounts through plant sources, such as chicory, onion, garlic, asparagus, artichoke, bananas, and tomatoes. These can also be produced at large scale by using microorganisms and their enzymes. Besides refined sugar molecules, these can also be synthesized by using agro-industrial waste/by-products, such as whey, wheat and rice straw, and sugarcane bagasse, making the production process more economical. Prebiotics have bifidus-stimulating ability, immunomodulatory effect, and antioxidant properties besides their role in reducing risks of cancer, acute gastroenteritis, osteoporosis, and hyperlipidemia. The prebiotic compounds can be employed for the fortification of different food products for the development of functional foods with high nutritional and therapeutic properties. This chapter provides a comprehensive overview on common prebiotics, enzyme involved, and their production by biotechnological strategies besides potential benefits.

Agricultural residues offer tremendous potential as sources of bioactive compounds. In most of the cases, the wasted by-products can present similar or even higher contents of bioactive compounds than the final product does. One of the most important sources of bioactive compounds present in the agricultural residues is the polyphenolic compounds. In addition, dietary ascorbates, tocopherol and carotenoids, which are present in agricultural residues, are well known for their antioxidant potential. The toxicity of synthetic antioxidants such as butylated hydroxyanisole, butylated hydroxytoluene and propyl gallates and also the growing interest of consumers in the security of nutritional additives has fostered research on natural sources and the screening of raw materials for identifying new and safe sources of antioxidants. Agro-processing industry generates large amounts of by-products such as peels, seeds, stones, trimmings, pods and pulp in different steps of processing. The processing of agricultural commodity leaves behind a substantial amount of residues which contains major classes of bioactive compounds, viz. flavonoids, hydroxycinnamic acid derivatives, phenolic acids, tannins ascorbates, carotenoids, tocopherols, phytosterols and arabinoxylans. Due to lack of facilities to harness the potential of these valuable by-products, such residues are disposed off in open spaces or municipal bins leading to environmental pollution problems. Effective utilization of these by-products for the production of antioxidants can help prevent pollution problems and offer new sources of bioactive compounds. This chapter presents the general aspects about natural antioxidants, extraction of bioactive compounds (mainly polyphenols) from agricultural residues, identification and characterization of major active compounds and potential use of these compounds in food and pharmaceutical industry.

Every year a considerable amount of seafood is discarded as processing leftovers and current estimates revealed that the discard exceed over 20 million tons equivalent to 25 % of the total production. Common seafood processing by-products, including fish oil, fishmeal, fertilizer, pet food and fish silage, generate low income compared to that of effort employed to recycle the waste. Recent advanced biotechnology and biochemistry research has identified number of biologically active compounds form seafood processing by-products while giving a new insight to the classical by-product industry. Exploration of seafood processing leftover for bioactive compounds brings high value for the processing by-products. In this chapter focus was given for comprehensive understanding of seafood processing by-products, exploration of bioactive compounds and biological activities of by-product-derived compounds.

Statins are a class of antihypercholesterolemic (or cholesterol-lowering) drugs which act on the liver by reducing steroid biosynthesis by inhibiting the activity of HMG-CoA reductase, the enzyme responsible for the first step in the synthesis of cholesterol (and other biomolecules). This, in turn, causes the reduction of the concentration of LDL (low-density lipoproteins) associated with increased risk of coronary disease, stroke, and heart attack. The market for statins is around 25–30 billion dollars, with synthetic compounds such as atorvastatin having a large market share. However, microbial statins, such as lovastatin and pravastatin, have a market share around 10 %, while the semisynthetic simvastatin has a 50 % market. Extracts from Aspergillus terreus and Nocardia autotrophica, as well as raw biomass rich in statins from oyster mushroom or Monascus sp., are also sources of natural statins. This chapter describes briefly the action of statins, the market for these drugs, the potential for new microbial statins, and the production process for lovastatin and pravastatin.

Antimicrobial agents are substances of chemical or biological origin, which help in either inhibiting the growth or killing of the microorganisms, such as bacteria, viruses, fungi, algae, or other parasites. The demand for antimicrobial compounds (products) throughout the world has been continuously increasing as the population is more and more concerned about the health and hygiene. Global change in the lifestyle pattern and livelihood has resulted in generation of increasing quantities of solid wastes, which include agro-industrial residues. These residues are usually organic in nature which makes them potential candidates as feedstock for developing the bioprocesses through biotechnological interventions. The usage of these residues as substrates not only opens a new avenue in their utilization but also reduces the pollution concerns, which their disposal in the environment would have caused otherwise.

Numerous scientific investigations have reported the production of antimicrobial products from a variety of agro-industrial residues, such as vegetable peels, seeds, cereal, and fruits waste, and essential oils from the peel of various fruits, which have shown effective properties to be used as preservatives or food additives and in pharmaceuticals because of their antimicrobial, anti-inflammatory, and antioxidant characteristics. Antimicrobial products are also isolated from the plants as these are present in all parts of the plant, viz., bark, stalks, leaves, fruits, roots, flowers, pods, seeds, stems, latex, hull, and fruit rind, and are usually derivatives of phenolic acids and flavonoids. The hydroxyl groups of polyphenols are very reactive in neutralizing the free radicals by donating a hydrogen atom or an electron, chelating metal ions, inactivating lipid-free radical chains, and preventing hydroperoxide conversions into reactive oxyradicals. These are thus effective against various deadly diseases and for processed food preservation, pharmaceuticals, alternative medicine, and natural therapies.

A newer application on the usage of the antimicrobial has emerged in recent times with the aid of nanotechnology to fight against the disease-causing organisms, replacing heavy metals and toxins and may attain effective application in future.

Enzymes are important in all living cells because they act as biological catalysts that accelerate chemical reactions without being consumed in the process. Enzymes are crucial elements of every living entity and also address the dominant underlying causes of several health problems. Pharmaceutically important enzymes are an important component of the pharmaceutical market. They are broadly defined as prodrugs that target a specific biological reversible or irreversible reaction to treat a particular disease. Microorganisms are major source of pharmaceutically important enzymes, but several enzymes are also obtained from animal and renewable plant sources. Enzymes which are used for pharmaceutical applications include cysteine proteinases, asparaginase, streptokinase, urokinase, deoxyribonuclease I, hyaluronidase, pegademase, and glucocerebrosidase. Immobilized enzymes are also used in pharmaceutical industry. In pharmaceutical industry, the major applications of immobilized enzymes are the production of 6-aminopenecillinic acid using immobilized penicillin amidase which helps in the deacylation of the side chain of either penicillin G or penicillin V. There are several benefits of enzymes immobilization such as cost-effectiveness, protection from degradation and deactivation, retention of enzyme, enhanced stability, recycling, and repetitive use. The industrially important enzymes, such as α-amylase, protease, and alkaline lipase, are required in large volumes, but have an inherently low unit value so that they demand significantly lower manufacturing cost. On the other hand, pharmaceutical enzymes are produced in lower volumes and have inherently higher manufacturing cost.

The use of cosmetics has taken a new course in recent years due to greater access to information and understanding by consumers, who are much more interested in the origin, safety, and sustainability of the products they purchase. A new class of personal care products referred to as biocosmetics have arisen through new technologies, such as nano- and biotechnology, and considering the concept of sustainable development. This class of products is safe for humans, obtained in harmony with the environment, using a variety of industrial wastes as raw materials, thus generating high-valued products and removing a large amount of pollutants. This chapter deals with the production of biocosmetics from textile and food industries, oils, organics, fruit and vegetable wastes, among others. Described description is given as to how these new technologies are revolutionizing the use of known materials which have been exploited for hundreds of years.

Living organisms, namely, prokaryotes and eukaryotes, are able to synthesize a variety of polymers, such as nucleic acids, proteins, and other polyamides, polysaccharides, polyesters, polythioesters, polyanhydrides, polyisoprenoids, and lignin. Microorganisms provide a source of biopolymers and biopolysaccharides from renewable sources. Bacteria are capable of yielding biopolymers with properties comparable to plastics derived from petrochemicals, though more expensive. They have the additional advantage of being biodegradable. A wide range of microbial polysaccharides have been studied, and structure/function relationships for a number of these macromolecules have been determined. These biopolymers accomplish different essential and beneficial functions for the organisms. Among the biopolymers produced, many are used for various industrial applications. Currently, the biotechnological production of polymers has been mostly achieved by fermentation of microorganisms in stirred bioreactors. The biopolymers can be obtained as extracellular or intracellular compounds. Alternatively, biopolymers can also be produced by in vitro enzymatic processes. However, the largest amounts of biopolymers are still extracted from plant and animal sources. Biopolymers exhibit fascinating properties and play a major role in the food processing industry, e.g., modifying texture and other properties. Among the various biopolymers, polysaccharides and bioplastics are the most important in the food industry. This chapter will discuss the sources of polymers, their biosynthesis by different organisms, and their application in different fields.

The carbon and energy sources used in fermentation process generally account for 50 % of the overall biosurfactant production cost. Thus, efforts are being made to explore potential of renewable agricultural wastes and nutritionally rich low-value industrial by-products as substrates to bring down the overall production cost of biosurfactants. The abundant agro-industrial wastes, such as distillery wastes, plant oils, oil wastes, starchy substances, and whey, are the potential candidates as they are available throughout the year. The integrated approach of developing efficient microbial strains capable of growing on these alternative substrates and designing of low-cost nutritionally balanced optimized medium could significantly reduce the production cost of biosurfactants. The efforts to design efficient bioreactors for obtaining maximum biosurfactant yield using low downstream processing inputs could make the process economically viable. The application of biosurfactants for therapeutic and biomedical purposes demands high purity levels which increase the cost of downstream processing. However, application of biosurfactant preparations for field scale bioremediation does not need high level purity and thus would be in contention with chemical surfactants in future.

Platform chemicals composed of 3–4 carbons are group of chemicals that can be used as important precursors for making a variety of chemicals and materials, including solvents, fuels, polymers, pharmaceuticals, perfumes, and foods. At present, most of the commercial platform chemicals composed of 3–4 carbons are produced from petroleum-based products. However, fossil-derived resources are nonrenewable and their amount is increasingly depleting. Additionally, application of these materials has number of environmental concerns. To overcome these problems, increasing interest has focused on the development of sustainable technologies for producing these platform chemicals from renewable resources. Researchers have made significant progress in biological production using metabolic of platform chemicals using engineering-modified microorganisms. However, the production efficiency still needs to be improved for it to become economically viable. Further work on engineering these strains and exploring their tolerances and the use of low-cost renewable substrate like biomass may increase the yields of green platform chemicals to an industrial scale. In this review we focused on the current status of the bio-based production of major C3–C4 platform chemicals, by direct microbial bioconversion of renewable materials.