Bacillus sphaericus
Tracie Kost

Bacillus sphaericus is a rod-shaped, strictly aerobic, Gram positive bacterium which is used as an insecticide against certain strains of disease-carrying (or just annoying) mosquitoes.1 However, it is not these characteristics alone that have gotten B. sphaericus an excessive amount of attention in the past. The label of “Jurassic Park Bacterium”, which it received after being isolated and cultured from a several million year old extinct bee, in addition to its economically friendly insecticide ability are actually the properties most likely responsible for the attention B. sphaericus has received (at least in popular media).2

In 1995, Dr. Raúl Cano, a microbiologist at the California Polytechnic State University, and his student Monica Borucki were able to remove a fully intact extinct bee (Proplebia dominicana) from a piece of hardened amber which was estimated to be somewhere between 25 and 40 million years old. Under aseptic conditions, Dr. Cano and his team successfully removed some bacteria from the bee’s gut. The bacteria was cultured in trypticase soy broth (a nutrient-filled media), and after a short time colonies could be isolated. These colonies were determined by the team to be pure populations of B. sphaericus.3

The typical response to a story such as this is skepticism. This is understandable since it does seem far-fetched to imagine that any living species could possibly survive for millions of years. However, besides the fact that Dr. Cano and his team claim to have taken every precaution to keep their work environment completely sterile in order to avoid contamination by some other microbe, there are other reasons this story is plausible. One significant reason is that aerobic bacteria from the genus Bacillus (such as B. sphaericus) are known to be spore-forming bacteria, which means that they can become dormant for several years and would be able to withstand extreme temperatures and physical environments.4 Also, amber has been known to be a sort of preserving medium for other forms of life in the past.2 Regardless of all the arguments for validity of this discovery however, one should always be cautious in believing something like this without further investigation. As one author of an article related to the discovery of B. sphaericus in an extinct million-year-old bee pointed out in Time Magazine, there have been several similar discoveries in the past that have been proven wrong, such as “a team of British researchers [who] disclosed that the DNA they thought had come from an extinct mammoth belonged to a lab technician”.2

Today, B. sphaericus is used as a mosquito larvicide (an insecticide toxic to insects only in the larva stage of life).5 Only certain strains of the bacteria are toxic to mosquitoes (not the same strain as the one thought to be found by Cano inside the extinct bee). In the process of sporulation, these mosquito-toxic strains of the bacteria form crystals containing two different proteins which together are toxic to certain species of mosquito larvae when they are ingested.6 The benefit of using B. sphaericus as a mosquito larvicide versus other commercially available pesticides is that it is virtually non-toxic to pets, birds, fish, other worms and insects, humans, and the environment. The down-side of using B. sphaericus as a mosquito larvicide is that it can persist in the area for up to nine months because it is recycled through mosquito life cycles.7

References

[1] Thelabrat.com, http://www.thelabrat.com/restriction/sources/Bacillussphaericus.shtml

[2] Nash, M., Return of the Living Dead? Time Magazine May 1995.

[3] “Jurassic Park” Bacterium!, http://people.ku.edu/~jbrown/jurassic.html

[4] Perry, J.J.; Staley, J.T.; Lory, S.; Microbial Life, Sinauer Associates, Inc., 2002, p461-462.

[5] Wikipedia, http://en.wikipedia.org/wiki/Larvicide

[6] Baumann, P.; Clark, M.A.; Baumann, L.; Broadwell, A.H.; Bacillus sphaericus as a Mosquito Pathogen: Properties of the Organism and Its Toxins. Microbiological Reviews September 1991, 55, pp 425-436.

[7] Washington State Department of Health, http://www.doh.wa.gov/ehp/ts/Zoo/WNV/ larvicides/Bsphaericus.html

*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.

 

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