Bacillus thuringiensis: A story of a successful bioinsecticide

Abstract

Bacillus thuringiensis (Bt) bacteria are insect pathogens that rely on insecticidal pore forming proteins known as Cry and Cyt toxins to kill their insect larval hosts. At least four different non-structurally related families of proteins form the Cry toxin group of toxins. The expression of certain Cry toxins in transgenic crops has contributed to an efficient control of insect pests resulting in a significant reduction in chemical insecticide use. The mode of action of the three domain Cry toxin family involves sequential interaction of these toxins with several insect midgut proteins facilitating the formation of a pre-pore oligomer structure and subsequent membrane insertion that leads to the killing of midgut insect cells by osmotic shock. In this manuscript we review recent progress in understanding the mode of action of this family of proteins in lepidopteran, dipteran and coleopteran insects. Interestingly, similar Cry-binding proteins have been identified in the three insect orders, as cadherin, aminopeptidase-N and alkaline phosphatase suggesting a conserved mode of action. Also, recent data on insect responses to Cry toxin attack is discussed. Finally, we review the different Bt based products, including transgenic crops, that are currently used in agriculture.

Genetic and Biochemical Characterization of a Gene Operon for trans-Aconitic Acid, a Novel Nematicide from Bacillus thuringiensis

“…Recent, research has classified B. thuringiensis as a bacterial pathogen of alternative nematode hosts (2)(3)(4), which may help to explain the complex ecology of B. thuringiensis that was previously thought to have a sole insect host (2,5,6). This finding further contextualizes already established interactions between B. thuringiensis and nematodes (1)(2)(3)(4)7), including free-living and parasitic species.…”

The Metabolic Regulation of Sporulation and Parasporal Crystal Formation in Bacillus thuringiensis Revealed by Transcriptomics and Proteomics

“…Therefore, it is widely used as a biopesticide for agricultural and public health applications. More recently, some ICP genes have been successfully expressed in transgenic plants, leading to a higher yield and the lowered use of chemical pesticides (6).…”

Molecular and functional characterization ofcry1Actransgenic pea lines

“…The formation of lytic pores causes the uncontrolled release of ions, the collapse of the epithelia that stops the larvae from feeding and finally leads to the death of the larvae. Bravo et al, 2011 In line with this gap, we have reported the successful development of transgenic pea lines expressing cry1Ac gene from Bacillus thuringiensis. Negawo et al, 2013 The cry1Ac gene Cheng, Sardana, Kaplan, Altosaar 1998;Sardana 1996 is one of the commonly used Bt cry genes to develop transgenic lines in many plant species such as tobacco, cotton, maize, soybean, tomato and rice, Cheng, Sardana, Kaplan, Altosaar 1998;Perlak 1990;Bohorova 1999;Stewart Jr CN 1996;Mandaokar et al, 2000 to become resistant to Lepidopteran pests.…”