Bradley Classification of disease transmission routes for water-related hazards *
Jamie Bartram, Rachel Baum, Peter A. Coclanis, David M. Gute, David Kay, Stéphanie McFadyen, Katherine Pond, William Robertson, Michael J. Rouse in Routledge Handbook of Water and Health, 2015
Both general and water-related disease prevention may relate to reducing insect vector load or to reducing human exposure to insects. In some settings large-scale drainage has been very effective in disease prevention and this is true both in parts of Europe and in the south of the United States of America against malaria. Exhaustive elimination of small water containers (such as abandoned car tyres) has value in settings where they provide a suitable breeding site for the prevalent vector and where exhaustive intervention is feasible. Where biting occurs near water bodies (e.g. Simulium, tsetse flies), access to improved or household water may reduce exposure. Where vectors breed in household water storage containers, application of insecticides, both chemical and biological (Bacillus thuringiensis), to such containers is sometimes practiced (WHO, 2011). Since the development of the Bradley Classification, use of large-scale insecticide (including DDT) applications has grown and waned in popularity. General preventive measures also include case treatment, prophylaxis (including immunization) and the use of insecticide-treated bed nets.
Materialism and reductionism in science and medicine
R. Paul Thompson, Ross E.G. Upshur in Philosophy of Medicine, 2017
Consider larvae of the boll weevil and the corn borer. These are pests that can ruin a cotton crop or a corn crop. Since the 1950s, farmers have used a variety of pesticides. One that has the lowest environmental impact is a toxin produced by Bacillus thuringiensis (Bt). It is a bacterium that occurs naturally. Farmers – including organic farmers – have been spraying crops with either the bacterium or the toxin it produces for more than 60 years. For almost 20 years, a biotechnological solution has been developed. The segment of DNA that codes for the toxin produced by Bt has been inserted into the chromosomal DNA of cotton, corn and a number of other plants. Hence, each cell of the plant produces the toxin. As a result, the current exposure level of larvae pests to the toxin is exceptionally high. The concern, from the first regulatory approval of the genetically modified crops, has been the development of resistance to the toxin.
Ronald M. Atlas, James W. Snyder in Handbook Of Media for Clinical Microbiology, 2006
Use: For the rapid identification and isolation of Bacillus anthracis based on the detection of phosphatidylcholine-specific phospholipase C activity by 5-bromo-4-chloro-3-indoxyl-cholinphosphate hydrolysis. The medium incorporates chromogenic substrates for detecting specific enzyme activities in Bacillus anthracis, B. cereus, and B. thuringiensis. The enzymes targeted by the chromogenic medium are not present in other Bacillus species, allowing for specific isolation of these three Bacillus species. Inclusion of inhibitory compounds into the medium prevents the growth of environmental contaminants. The use of proprietary chromogenic substrates, X-IP and X-CP, allows for the differentiation of Bacillus anthracis from near-neighbors B. cereus and B. thuringiensis. Cream to pale teal-blue colored of Bacillus anthracis after 20-24h, teal-blue colonies of Bacillus anthracis after 36-48h at 35-37°C. Dark teal-blue colonies of Bacillus cereus/Bacillus thuringiensis after 20-24h at 35-37°C.
Nanoparticle-loaded microcapsules providing effective UV protection for Cry1Ac
Published in Journal of Microencapsulation, 2021
Yongjing Zhang, Aijing Zhang, Mengyuan Li, Kanglai He, Shuyuan Guo
The Gram-positive spore-forming bacterium Bacillus thuringiensis (Bt) is an insect pathogen (Bravo et al. 2011, Vachon et al. 2012). Its principal characteristic is the synthesis, during sporulation, of a crystal-like parasporal inclusion containing proteins called Cry or Cyt toxins (Aronson 2002, Vilas-Bôas et al. 2007, Sanchis and Bourguet 2008). Based on certain structural features, Cry toxins belong to α-Pore-forming toxins (PFT) which have α-helical conformation relating to membrane insertion and pore formation, and Cyt toxins are included in β-PFTs which tend to be rich in β-sheet inserting into membranes to form a β-barrel (Parker and Feil 2005). These toxins undergo the same toxic steps of solubilisation, proteolytic activation, receptor-binding, and membrane insertion to form pores of 10–20 Å diameter (Parker and Feil 2005). Finally, the target insect died because of the destruction of the osmotic pressure of midgut cells (Soberon et al. 2009). These inclusions are well-known for their insecticidal properties (De Maagd et al. 2001, Soberón et al. 2007) and are widely used for insect control, which makes Bt the most successful microbial pesticide (Becker 2000, Van Frankenhuyzen 2000, Sanchis and Bourguet 2008, Bravo et al. 2011, Sanahuja et al. 2011). However, environmental conditions, such as temperature and ultraviolet (UV) irradiation will reduce the insecticidal power and are constraints in the use of Bt products (Navon 2000, Rao et al. 2018).
Effect of bacterial toxin identified from the Bacillus subtilis against the Cnaphalocrocis medinalis Guenée (Lepidoptera: Crambidae)
Published in Toxin Reviews, 2023
Ramakrishnan Ramasubramanian, Sengodan Karthi, Sengottayan Senthil-Nathan, Haridoss Sivanesh, Narayanan Shyam Sundar, Vethamonickam Stanley-Raja, Govindaraju Ramkumar, Kanagaraj Muthu-Pandian Chanthini, Prabhakaran Vasantha-Srinivasan, Khaloud Mohammed Alarjani, Mohamed S Elshikh, Ahmed Abdel-Megeed, Patcharin Krutmuang
As a biocontrol agent, Bacillus thuringiensis (Sanahuja et al. 2011) is another Bacillus species that is widely used for controlling insects, such as chewing insects in the Coleoptera, Lepidoptera, and Diptera orders. It has remained hard to identify a biocontrol agent that kills sucking insects in plant-feeding hemipterans, such as aphids. In order to contribute to environment-friendly programs in agricultural pest management, it is essential to increase the number of microorganisms capable of acting as biocontrol agents, against rice leaffolders. Bacillus species have been highly sought after as biopesticides for controlling agricultural pests since they offer an attractive alternative to chemical pesticides in the last two decades (Radhakrishnan et al. 2017).
Microencapsulation of an indigenous isolate of Bacillus thuringiensis by spray drying
Published in Journal of Microencapsulation, 2019
Ardahan Eski, Zihni Demirbağ, İsmail Demir
Bacillus thuringiensis has been used as an alternative to chemical pesticides for pest management. The usage of spore-crystal mixture is limited in the field conditions, because they are adversely affected by environmental conditions. One of the best options to overcome this problem is microencapsulation. Microencapsulated formulation successfully improves the palatability and stability of B. thuringiensis and protect them from photodegradation (Teera-Arunsiri et al. 2003; Khorramvatan et al. 2014). The spray drying technique is the most common microencapsulation method and, it has been used to protect spores and crystals of B. thuringiensis from natural environmental stress.
Related Knowledge Centers
- Bacteria
- Endospore
- Insecticide
- Gram-Positive Bacteria
- Biopesticide
- Protein Crystallization
- Delta Endotoxin
- Genetically Modified Crops
- Strain
- Bacillus Thuringiensis Israelensis