Microbial products are being used from ages in known as well as unknown forms. Some common products harvested from microbes include proteins, amino acids, antibiotics, antibodies, secondary metabolites, organic acids, lipids, and so on. It also includes antivirals, polymers, surfactants, enzyme inhibitors, nutraceuticals, and many industrial and agricultural products. Moreover, sometimes the whole single celled microbes are harvested as a rich source of protein called single cell proteins. In a nutshell, all these products cover almost every economic sector like food, feed, agriculture, healthcare, fuel, textile, and pharmaceutical. Hence, these microbial products have serious socio-economic impressions and have unleashed enormous possibilities in terms of commercial production. However, only a small fraction of microbial products are exploited, and a larger chest remains to be achieved. In the chapter, the importance of microbes in the production of proteins, enzymes, and secondary metabolites are discussed in detail with special emphasis on sustainable agriculture.
TopIntroduction
Microorganisms have been utilized since ancient human civilization. In early 6000 BC at Babylonians and Sumerians there is first evidence of commercial utilization of yeast for the production of alcoholic beverages from barley (Prajapati and Nair, 2008). The microbial products have gained recognition globally for their widespread applications in several industries like chemicals, food, biofuel-bioenergy, textile, leather, agriculture, pharmaceuticals etc. Microbial production of chemicals, enzymes and secondary metabolites (Figure 1) are rapidly gaining interest because of less time consuming fermentation reactions, low energy input, ecofriendly, required low energy and utilize cheap raw materials for their growth (Singh et al., 2016). Moreover, with the help of modern molecular biology techniques such as, recombinant DNA technology and protein engineering, microorganisms can be manipulated to produce large quantities of products with desired properties (Parket al., 2019). The role of microbial community in agriculture sector is also significant. It is expected to reach nearly $306 billion by the end of this year, 2020 (McWilliams, 2015).
Figure 1. Important microbial products
Traditionally, the farming and agricultural practices were entirely dependent upon the natural fertility of soil where soil microbiota played crucial role in productivity and maintaining the soil quality. With the advent of industrialization, the agricultural sector witnessed an unprecedented surge in the crop productivity due to the availability of chemical fertilizers, pest control agents and development of agricultural technology. Further commercialization of agriculture provoked the use of such chemicals at an alarming rate contaminating the soil, water, environment and other natural resources. It even destroyed the niche of beneficial microbes in the soil, decreasing the natural fertility and quality of soil. These impacts could be reversed and sustainability could be attained if such chemical practices are limited and microbes and microbial products are given a chance.
In the present chapter, the center of attention are microbes including bacteria, fungi, algae, yeast archaea, products derived from them along with their applications in vivid industrial sectors. The applications of different microbes in the agricultural sector are emphasized along with their role in attaining sustainable agriculture.
TopImportant Microbial Products
Proteins
Microbial proteins (MP) are the dried cells of microorganisms, which includes bacteria, algae, fungi and yeast (Matassaet al., 2016). Generally, MPs are used as protein-rich food and feed additives for animal consumption (Rangharet al., 2019). Since ancient time’s different microorganism are used as a part of diet all over the world. Nowadays MPs are used as a replacement of animal or vegetable protein. Single-cell proteins (SCPs) are the substituted new word for microbial proteins since 60s (Nangul and Bhatia, 2020). Mostly they are the protein extract or microbial biomass, which are used as food sources or feed additives.
Conventional protein has several drawbacks over MPs, such as protein produced from conventional crop has shortage of land and some environmental disasters (drought, wind, flood etc.) (Ali et al., 2017). MPs are rich in essential amino acids, such as lysine, leucine, arginine, methionine, histidine etc. (Anderson and Jackson, 2000).Presently more than 25% of the world’s population suffers from malnutrition and hunger (Behrman et al., 2004; Prosekov and Ivanova, 2018), therefore, MPs can be used as a good replacement of traditional protein sources (Matassa et al., 2016). MPs are also rich in fats, carbohydrates, vitamins, minerals and nucleic acids (Sumanet al., 2015).