Bacillus thuringiensis (Bt) is a member of the genus Bacillus. Bt is not the only bacteria used as an insecticide; other bacteria such as B. popilliae and B. sphaericus are also employed; however, their spectrum of insecticidal action is far more limited than that of Bt. In addition to being safe for people, Bt is the most frequently used environmentally friendly biopesticide in the world. Aside from that, the insecticidal Bt genes have been introduced into numerous key crops, resulting in the crops being insect resistant and serving as a paradigm for genetic engineering applications in agriculture.
Bacillus thuringiensis, cadherin receptors, Prehistoric pest management tactics are described in the literature of ancient Egyptian and Chinese intellectuals, who claim to have used them. Gardeners for various Egyptian pharaohs were reputed to have kept bacterial collections for use against the insects that attacked and ruined the gardens around their palaces and tomb chapels, according to one legend. Later, in the third century, it was discovered that insects were suffering from diseases that were most likely caused by bacteria, viruses, and fungi. It is true that Aristotle wrote about insect diseases such as the foulbrood of the honey bee, which is still prevalent today (Apis mellifera). Louis Pasteur investigated silkworm diseases and distinguished between pebrine and flacherie disorders of the silkworm Bombyx mori, which he named after his mother. Kirby and Bassi also made substantial contributions to the field of insect pathology, and they, together with Pasteur, are often regarded as among the pioneers of infectious disease and pathogenic microbiology in the twentieth century.
Sporine
The first commercial insecticide based on Bt, was developed in France in 1938 and was primarily used to combat flour moths. It was the world’s first Bt-based pesticide. In the United States, Bt was first commercially synthesised in 1958, and by 1961, the Environmental Protection Agency had approved the registration of Bt-based bioinsecticides. Known as Bt crops, insect-resistant transgenic crops have grown in popularity since its introduction in 1996. These crops are proving to be highly efficient and are assisting in the reduction of the usage of chemical insecticides. According to the most recent estimates, more than 50% of the cotton and 40% of the maize planted in the United States is genetically altered to generate Bt insecticidal toxins. Pesticides (herbicides, insecticides, fungicides, nematicides, and fumigants) account for $25.3 billion of the global market for pesticides in the current year. Biopesticides currently account for about 2.5 percent of this industry, but their proportion is predicted to grow to approximately 4.2 percent, or more than $1 billion, by 2010. In the meantime,
Bacillus thuringiensis Life Cycle
The life cycle of Bt is divided into two parts, the first of which is vegetative cell division and the second of which is spore production, which is referred to as the sporulation cycle.
18 This rod-shaped cell (2–5 m long and roughly 1.0 m wide) splits into two uniform daughter cells through the creation of a division septum, which begins midway along the plasma membrane and extends along the whole length of the cell. Alternatively, the process of sporulation consists of seven stages19, which are as follows: (stage I) axial filament formation, (stage II) formation of the forespore septum, (stage III) engulfment, first appearance of parasporal crystals, and formation of a forespore, (stages IV to VI) formation of the exosporium, primordial cell wall, cortex, and spore coats, accompanied by transformation of the spore nucleo A Bt cell that has been fully sporulated, in which there are multiple parasporal crystals that are positioned along the side of the endospore. While sporulation is a unique genetically regulated biological phenomenon, the production of crystal proteins by Bt during this period is a unique genetically regulated biological phenomenon that, likely, relieves stress physically by offsetting water loss during spore formation and provides an additional survival advantage by exerting lethal action against host insects. Furthermore, the toxic action offers sufficient host resources to allow germination of the latent bacterial spore and the resumption of vegetative growth by the bacterial pathogen.
Conclusion
Interestingly, some Bt strains produce non-insecticidal proteins that crystallise into irregular-shaped parasporal inclusions, which are thought to be the result of a mutation.
Included in one isolate that had been treated with protease were inclusions that were hazardous to human cancer cells, including leukemic T (MOLT-4) and cervical cancer cells (HeLa). Cytotoxicity was determined to be dosage dependent. Parasporin, a non-insecticidal protein, was found to have significant cytotoxic action against the MOLT-4 and HeLa cell lines as well.