What is the Difference Between Bacillus Cereus and Bacillus Thuringiensis?

Bacillus cereus and Bacillus thuringiensis are two closely related bacterial species, which can be differentiated based on their genetic makeup and functional characteristics. The main differences between them are:

1. Presence of insecticidal toxins: The primary difference between B. cereus and B. thuringiensis is the presence of genes coding for insecticidal toxins, usually found on plasmids in B. thuringiensis strains. If these plasmids are lost, B. thuringiensis can no longer be distinguished from B. cereus.
2. Pathogenicity: B. cereus is a ubiquitous soil bacterium and an opportunistic human pathogen, causing contamination problems in the dairy industry and paper mills. It can cause gastrointestinal disorders. In contrast, B. thuringiensis is widely used as a biopesticide due to its ability to produce intracellular protein crystals toxic to a wide number of insect larvae.
3. Natural competence and plasmid exchange: B. cereus and B. thuringiensis strains are capable of natural competence, which allows them to take up and incorporate exogenous DNA. This means that plasmids carrying genes for insecticidal toxins could potentially be transferred between these species, blurring the distinction between them.

Various methods have been developed to differentiate between B. cereus and B. thuringiensis, such as using specific DNA probes based on variable regions of 16S rRNA, real-time PCR with a unique marker, and genome-guided MALDI-TOF MS based on variations in ribosomal proteins. These techniques help in identifying and discriminating between these closely related species, which have different functional characteristics and ecological implications.

Comparative Table: Bacillus Cereus vs Bacillus Thuringiensis

Bacillus cereus and Bacillus thuringiensis are both bacteria belonging to the Bacillus cereus group, but they have distinct characteristics and functional differences. Here is a table summarizing their differences:

The genetic difference between the two bacteria is mainly due to the presence of genes coding for insecticidal toxins, which are usually present on plasmids. This difference in toxin production is what distinguishes their functional roles, with B. cereus being an opportunistic pathogen causing food poisoning, while B. thuringiensis is commonly used as a biological pesticide against insects worldwide.