Biotechnology is the technology that utilizes biological systems, living organisms or parts of these to develop or create different products. The application of microbes in sustainable agriculture and the environment is a rapidly growing segment in the novel world. Increasing food demand poses a great challenge to the traditional agriculture system. While the development of biotechnology applications began in 6000 BC., the development of genetic tools and cellular engineering was initiated in 1970. Genetically modified (GM) crops that are resistant to many pathogens and weeds have contributed to the increase of high yields in agriculture.
Biofertilizers are the preparation of live or latent cells of efficient strains of microorganisms used for application to accelerate the process of plant growth and development. They can add 20-200 Kg N/ha per year under optimum soil conditions and thereby increase the total crop yield by 15-25%. Rhizobium BGA, Azotobacter sp., Gluconacetobacter spp. stimulate the production of growth-promoting substances like Vitamin-B complex, Indole acetic acid (IAA) and Gibberellic acid. Phosphate solubilizing/mobilizing biofertilizers solubilize/mobilize about 30-50Kg P2O5/ha. Azotobacter inoculants applied to non-legume plants promote seed germination and the initial vigor of plants. Phosphate ions (PO43-) mobilize the Mycorrhiza (VAM fungi) and enhance the uptake of P, Zn, S & water leading to uniform crop growth & enhancing resistance to disease & hardiness of transplant stock. They act as antagonists and suppress the incidence of soil-borne pathogens thus helping in the control of diseases. Biofertilizers improve the physical properties, tilth, productivity and health of the soil. Nostoc, Anabaena and Scytonema have reclaimed the alkaline soils. Cellulolytic and ligninolytic microorganisms enhance the degradation/decomposition of organic matter in the soil.
Biopesticides are microbes possessing invasive genes that can attack the defense genes of weeds by killing them. Endospores of the Bacillus thuringiensis (Bt) are used as an organic pesticide because some strains produce crystals in the endospores that are toxic to insects when they consume endospores. Controversial crop plants are genetically modified with the Bt toxins genes to develop resistance to pests. Bioherbicides can persist for a long time in the environment which can exist for the upcoming growing season and affect target pathogens only. Seed coated with inoculants can be developed to protect the plants during their critical seedling stage.
Bioinsecticides are naturally-occurring substances from different sources that control insect pests. They are low toxicity to non-target microorganisms, easily degradable, highly effective in small quantities and effect on target pests only. The bioinsecticides contain microbes such as Beauveria bassiana, Metarhizium anisopliae or brunneum and Isaria fumosorosea contact with pests, affect the nervous and muscular system, paralyzing and eventually killing the insects and mites.
Bioremediation is the process that makes use of microorganisms to eliminate pollutants from soil. Microorganisms can sequestrate toxic metals by cell wall components, alternating biochemical pathways to block metal uptake, converting metals into innocuous forms by enzymes, enhancing the mobility by siderophores and reducing the availability of heavy metals. Desulfovibrio desulfuricans convert sulphate to hydrogen sulphate that reacts with heavy metals to convert an insoluble form of metal sulphides. The genetically modified strain of P. fluroscences HK 44 is able to sense pollution, signaling through bioluminescence.
Figure 1 - Role of biofertilizers and biopesticides in organic farming
References
Binte Mostafiz, S., Rahman, M., Binte, S., Rahman, M. and Rahman, M. (2012). Biotechnology: Role of Microbes in Sustainable Agriculture and Environmental Health Quantification and analysis of Somatic embryogenesis receptor like kinase gene expression on Malaysian Indica rice View project Low carbon pathways_GUP_UTM JB View project The Internet Journal of Microbiology Biotechnology: Role of Microbes in Sustainable Agriculture and Environmental Health. Agriculture And Environmental Health. The Internet Journal of Microbiology, [online] 10(1). doi:10.5580/2b91.
Dhir, B. (2017). Biofertilizers and Biopesticides: Eco-friendly Biological Agents. Advances in Environmental Biotechnology, pp.167–188. doi:10.1007/978-981-10-4041-2_10.
Berg, G. (2009). Plant–microbe interactions promoting plant growth and health: perspectives for controlled use of microorganisms in agriculture. Applied Microbiology and Biotechnology, 84(1), pp.11–18. doi:10.1007/s00253-009-2092-7.
Image courtesy
Featured image – https://www.peptechbio.com/blog-biofertilizers/
Figure 1 – https://www.sciencedirect.com/science/article/pii/B9780128223581000092