Bacillus thuringiensis spores

Background

Bacillus thuringiensis (Bt) is a spore-forming, Gram-positive bacterium extensively studied for over a century and widely utilized as a biopesticide. Bt shares close genetic ties with Bacillus anthracis and Bacillus cereus, but it is uniquely characterized by its ability to produce crystal inclusions during sporulation. These crystals primarily comprise Cry and Cyt proteins, which exhibit toxicity towards specific insects. Despite the identification of numerous cry genes, only two transcriptional regulatory mechanisms have been described: the binding of sporulation-specific sigma factors SigE and SigK to cry gene promoters and the sporulation-independent control of the cry3 promoter by the main vegetative sigma factor SigA. Nevertheless, all identified Bt strains generate crystals within the same mother cell during spore formation.

AMPs and Their Synthetic Signaling Pathways in Combatting Bt

Detection of foreign elements by pattern recognition receptors triggers a signaling cascade that results in the production of antimicrobial peptides (AMPs). In response to Bt or its proteins, AMP expression is induced in several insects. These AMPs contribute to insect resistance by killing or inhibiting the growth of Bt, thereby clearing it from the midgut. The Toll, Imd, and JAK/STAT pathways mediate AMP synthesis. Typically, the Imd pathway responds to Gram-negative bacteria, whereas Gram-positive bacteria and fungi activate the Toll pathway. MyD88, downstream of Toll, facilitates NF-κB translocation to initiate AMP transcription and has been implicated in Bt resistance in O. furnacalis larvae.

Fig.1 Innate immune mechanisms activating synthetic AMP signaling pathways in response to Bt and its toxins.^1,3

Utilizations of Bt Spore-Related Products

Nanopore Platform for Aptamer Detection and Bt Spore Sensing

A versatile nanopore sensing platform has been engineered to detect any aptamer through the design of complementary DNA hairpins. This platform overcomes the major hurdle of detecting aptamer binding targets regardless of their size in nanopore systems. The signal-to-noise ratio is enhanced by removing most unwanted substances through simple sample preparation steps. To detect Bt HD-73 spores, DNA hairpins complementary to target-specific aptamers have been designed and characterized utilizing alpha-hemolysin nanopores. After the reaction of spores with aptamers and subsequent binding with complementary DNA hairpins, the platform exhibits a meager detection limit. It is compatible with a broad range of spore concentrations while remaining scalable to higher concentrations.

Developing Rapid Detection Tools for Bt Spore Monitoring

While approved Bt bioinsecticides are known to be safe for humans, rigorous monitoring of Bt dispersal is essential for cost-effectiveness and biodiversity preservation, highlighting the need for advanced, precise, and rapid tools to quantitatively detect Bt spores during and after spraying operations. To investigate the sensitivity and selectivity of commercially available detection reagents for Bt spores, antibodies and aptamers have been screened and tested for their efficiency in capturing Bt spores on functionalized GaAs biochips. Among seven cloned and expressed Bt spore proteins, Bacillus collagen-like protein A exhibits the strongest binding affinity. The thiolated aptamer and llama recombinant antibody demonstrate the highest Bt spore capture efficiency, highlighting their potential for GaAs-based biosensing device development.

Creative Biolabs offers a comprehensive array of Bt spore-related products, including assay kits and aptamers tailored for Bt spore detection. Additionally, we provide customized solutions, such as bespoke bispecific antibodies, designed to meet specific needs and requirements.

Bacillus thuringiensis spores Aptamer Analysis

Anti-Bacillus thuringiensis (Bt) spore aptamers are short, single-stranded DNA or RNA molecules that specifically bind to Bt spores. These aptamers are produced through SELEX technology and serve as powerful tools in disease research, detection assays, and functional studies due to their high specificity and affinity for Bt spores.

Fig.2 A diagram showing the polydiacetylene (PDA)-aptamer paper strip coating, the full detection workflow, and the key chemical structures.^2,3

The anti-Bt spore aptamers have shown great promise in advancing Bt spore functional research. These aptamers enable precise identification and quantification of Bt spores in various environments, enhancing the study of their role in diseases and infections. Moreover, these aptamers facilitate early detection of Bt spore contamination in agricultural and food products, offering significant value for monitoring and controlling Bt-related diseases. The aptamers also play an essential role in developing biosensors for real-time, on-site detection of Bt spores, contributing to the safety and quality control of food and environmental monitoring systems.

The anti-Bt spore aptamers provided by Creative Biolabs offer high specificity, stability, and versatility. We provide customized aptamers tailored to specific research needs, along with comprehensive services including production, optimization, and detection assay development. Our solutions support enhanced efficiency in Bt spore detection and functional studies.

References

1. Xiao, Zeyu, et al. "Involvement of an enhanced immunity mechanism in the resistance to Bacillus thuringiensis in lepidopteran pests." Insects 14.2 (2023): 151.
2. Zhou, Chaoge, et al. "Aptamer-conjugated polydiacetylene colorimetric paper chip for the detection of Bacillus thuringiensis spores." Sensors 20.11 (2020): 3124.
3. Distributed under Open Access license CC BY 4.0, without modification.