Bacillus Thuringiensis
Background
Bacillus Thuringiensis (Bt) is a Gram-positive and soil-dwelling bacterium mostly used as a biological pesticide. Thuringiensis also occurs naturally in different types of butterflies and moths, in leaf surfaces, animal faeces, aquatic environments, insect-rich environments, and grain-storage and flour mills facilities (El-Menofy et al., 2014). Thuringiensis has been observed to a parasite in moths like Cadra calidella from laboratory experiments where many of the moths used in the experiment. Bt was discovered in 1902 by Bombyx mori in Japan. Bt is a ubiquitous bacterium with significant enzyme complement, which gives it the freedom and will to live in different sites. The bacterium remains latent within an environment of adverse conditions within its development (El-Menofy et al., 2014). The case of using practice in utilizing microorganisms in controlling pesticides and insects is not new. Being bacteria, the era of Bt had its beginning in 1901 when a Japans scientist isolated bacterium from dead silkworm larvae when researching the cause of a Scotto disease. During this time, the disease was the leading cause of wastes and the significant loss of silkworms in the nation. After the investigation, he named the bacteria Bacillus sotto. Few years after this research, another French scientist did the same isolation and correctly named the organism Bacillus thuringiensis (Palma et al., 2014).
Morphology
Bt is an aerobic Gram-positive and rod-shaped bacterium that has a vegetative cell of between 3.0-5.0 μm wide and 1.0-1.2 μm wide in length. The bacterium is usually mobile through peritrichous flagella though naturally not numerous. The flagella might bid towards the insect cells and is significant within its virulence (Rabinovitch et al., 2017). Some Bt stains cannot be tested in a modern laboratory through classical flagella as a result of autoagglutination, which occurs in NaCl (0.85%) within the absence of a particular antiserum. The spore of Bt bacteria contains an ellipsoidal shape though most can be found in cylindrical shapes located within the paracentral region when in a mother cell (Rabinovitch et al., 2017). Bt is not too strict at temperatures ranging between 10-50C and between 40-450C (El-Menofy et al., 2014). The main characteristic which differentiates the spices from other types sharing the same genes is the intracellular presence of crystals of proteins. Significantly, Bt is safe for human use and is highly used for environmental compatible biopesticides (El-Menofy et al., 2014). Additionally, the insecticidal Bt genes have been used in core crops which, when applied in the right way, renders the crops resistant to some insects hence providing a model for agricultural engineering.
Signs and Symptoms
Bacillus thuringiensis (Bt), is low toxic to mammals and particularly human beings. Some researchers and investigators have researched and have found no evidence of infection or sickness as a result of the exposure (Rabinovitch et al., 2017). Some products with Bt have shown skin and eye irritation. At one time, when testing the presence of Bt, some researchers used rats for the test (El-Menofy et al., 2014). As a result, when rats breathed in very high rates concentrated Bt, some showed crusty eyes, runny noses and goosebumps.
Additionally, some other rats showed a loss of weight and others being less active. In another study, people were used as the study materials. After being exposed to the concentrated rates of Bt, most of them were not affected.
Nevertheless, some people with hay fever repotted some symptoms (El-Menofy et al., 2014). The signs reported by these people included difficulties in sleep concentration and lack of speed, stomach upset and throat or nose irritation. Research has indicated that the presence of strains after testing was the main sign of the presence of aphid mortality.
Physical changes from the bioassays tested showed that Bt induced them. From an experiment conducted by Torres-Quintero et al. (2015), to tests the presence of Bacillus thuringiensis strains indicated that the different strains tested within the bioassay were responsible for the physical change and where induced by the infection of Bt (Rabinovitch et al., 2017). Bt works through making toxins that target larvae when eaten. Within the gut of the insect which eats the larvae, the toxins are activated. The activated toxins then breakdown the gut of the insect where the insect dies from starvation and infection (Rabinovitch et al., 2017). After infection and starvation, death to the insect can happen only within a few hours. There are different types of toxins produced by Bt, which can only be activated through the target insect larvae. It is a contrast to note that when people eat the same toxics created by the bacterial, they are not affected for they are not activated, therefore any harm which can happen (Rabinovitch et al., 2017). Each type of Bt toxin is correctly and highly specified to a particular target. Presently, insects are continuously exposed to the potentiality of pathogenic microorganisms and eukaryotic parasites. Some entomopathogens indicate a high degree of specificity and hence will only infect a specific type of insect’s species. In contrast, others are generalities and will, therefore, infect a large number of insects within different orders.
Treatment of Bacillus Thuringiensis (Bt)
The Bacillus Thuringiensis (Bt) is a naturally bacterial living in soil ideal for the controlling tent caterpillars, cabbage looper, gipsy moth, tomato hornworm, among other eating caterpillars trees and in other vegetables. The bacterial is most effective when applied to caterpillars during their 1st and 2nd instars or when they are still small. During treatment, it must be ingested by the insect, for it is a stomach toxin and harmless to animals, human beings and another insect beneficial (Rabinovitch et al., 2017). It biodegrades faster in sunlight and might require reapplication under heavy insect pressure. To maximize the effectiveness, it is essential to apply it in the evening or the late afternoon. When Bt enters the body of an insect, it is confined in the gut though it does not reproduce. The toxin is at this stage, broken down, just like other proteins in the diet (Rabinovitch et al., 2017). Toxins from Bt live in the body between 2 to 3 days. If breathed in, it can move to the blood, the lungs, kidneys and lymph. The Bt is then attacked by the immune system, where levels of the Bacterial decrease in the body quickly within one-day exposure.
Prevention of Bacillus thuringiensis
The indiscriminate use of different chemical pesticides and insecticides towards the control of insects over recent years has contributed to the increased environmental risks and problems like persistence toxicity, which in turn have led to the severe acquisition of target resistance to pesticides (Schünemann et al., 2014). The greater spectrum insecticides, additionally, to the target pesticide, also can kill the non-target parasites and predators, which otherwise check the pesticide populations. Additionally, the pesticides keep on adding and accumulating throughout the terrestrial and aquatic food webs creating an ecological imbalance hence impairing human beings’ health. For prevention, there are increasing concerns concerning insect resistance, human health and environmental degradation, which paved room for problems for development (Schünemann et al., 2014). Owning to the mode of action, pesticide products are unlikely to pose any problem to vertebrates and human beings or the more significant majority of the non-target. Despite being used and useful in pest insect control in horticultural and agriculture crops, the products of Bt are safe. They can be used in aquatic environments toward the control of different activities, which have encouraged.
Complications of Bacillus thuringiensis
Bt super-infections is the core cause of mortality and complication after infections. Since Bt has been considered as a non-pathogenic towards human beings and is highly used in urban areas, it has been highlighted by many as the cause of complications (Torres-Quintero et al., 2014). Despite the different advantages associated with the complications associated with Bt needs proper control from different parties concerned. According to Caballero et al. (2020), Bacillus thuringiensis (Bt), is the most excellent used and needed ingridaitae for different biological pesticides. The different compositions of the δ-endotoxins (Cry and Cyt proteins) within the parasporal crystals effectively determine the poisonousness profile of every strain. Nevertheless, a more reliable method for the quantification and identification has not been found and hence available as a result of the high sequence genes identity, which encodes the toxins and δ-endotoxins (Palma et al., 2014).
Summary of Primary Article
Through the article, the researchers develop reducible and accurate mass spectrometry through a based method of liquid chromatography-tandem figure spectrometry monitoring different reactions [LC-MS/MS-MRM]. Isotopically labelled proteotypic peptides from every protein in a specific mixture were used to control the relative amount of every δ-endotoxins in the crystal. For the researchers to authenticate the method, some artificial mixtures with Cr2Aa, Cry 1Aa and Cry6Aa were put into the analysis (Caballero et al., 2020). As the investigators in the article claim, the purpose of the relative profusion of the different types of proteins through their method was in a better and good agreement together with the predicted values. After that, the method was then practical to the most shared and commercial Bt-based foodstuffs, Xen Tari GD, DiPel DF, VectoBac 12S and Novodor in where between the six and three δ-endotoxins were quantified and identified (Caballero et al., 2020). The novel method is of more excellent value for the classification of different Bt-based products, product and quality control registration for the Bt-based pesticides.
References
Caballero, J., Jiménez-Moreno, N., Orera, I., Williams, T., Fernández, A. B., Villanueva, M., … & Ancín-Azpilicueta, C. (2020). Unraveling the composition of insecticidal crystal proteins in Bacillus thuringiensis: a proteomics approach. Applied and Environmental Microbiology, 86(12).
El-Menofy, W., Osman, G., Assaeedi, A., & Salama, M. (2014). A novel recombinant baculovirus overexpressing a Bacillus thuringiensis Cry1Ab toxin enhances insecticidal activity. Biological procedures online, 16(1), 1-7.
Palma, L., Muñoz, D., Berry, C., Murillo, J., & Caballero, P. (2014). Bacillus thuringiensis toxins: an overview of their biocidal activity. Toxins, 6(12), 3296-3325. Retrieved from:
https://doi.org/10.3390/toxins6123296
Rabinovitch, L., Vivoni, A. M., Machado, V., Knaak, N., Berlitz, D. L., Polanczyk, R. A., & Fiuza, L. M. (2017). Bacillus thuringiensis characterization: morphology, physiology, biochemistry, pathotype, cellular, and molecular aspects. In Bacillus thuringiensis and Lysinibacillus sphaericus (pp. 1-18). Springer, Cham.
Schünemann, R., Knaak, N., & Fiuza, L. M. (2014). Mode of action and specificity of Bacillus thuringiensis toxins in the control of caterpillars and stink bugs in soybean culture. International Scholarly Research Notices, 2014.
Torres-Quintero, M. C., Peña-Chora, G., Hernández-Velázquez, V. M., & Arenas-Sosa, I. (2015). Signs of Bacillus thuringiensis (Bacillales: Bacillaceae) Infection in Myzus persicae (Hemiptera: Aphididae): Koch’s Postulates. Florida Entomologist, 98(2), 799- 802.