The Effects of Light on Bacillus Subtilis

Bacillus subtilis is a rod-shaped bacterium and is classified as Gram-positive, for its ability to be stained purple, and catalase-positive, for its ability to produce oxygen from hydrogen peroxide. This species of bacteria is especially difficult to remove from materials and water because of its ability to form a strong, protective endospore, which is a reproductive form of the bacteria that permits the microorganism to survive in extreme environmental conditions.

Effects of Light on DNA and RNA

• Ultraviolet light can interfere with the production DNA and RNA within cells. UV light alters the ability of nucleic acids, the building blocks of DNA and RNA, to properly form bonds with one another and thus prevents the stands of the molecules from forming properly. As opposed to continuous strands being produced, UV light will instead influence the production of broken pieces of the material, thus rendering them useless for reproduction and production of necessary proteins.

Effects of Pulsated Light

• A research article appearing in the February 2011 issue of the Journal of Microbiological Methods investigated the effects of pulsated light to prevent the contamination of food processing equipment by B. subtilis. The researchers used an airbrush to contaminate the surface of polystyrene with the bacteria and observed the effects of light to rid the surfaces the potentially harmful bacteria. The study found that populations of B. subtilis were reduced six-fold after treatment with pulsated light and the treatment was also effective in killing the spores of the bacteria.

Effect of UV Light to Disinfect Water

• Water is commonly disinfected by the use of ultraviolet light. A study appearing in the January 2011 issue of Water Research investigated the effects of UV light on B. subtilis spores and compared the results to those obtained from conventional mercury lamps. The study found that UV wavelengths of 269 and 282 nm effectively inactivated the bacterial spores in different samples of varying water qualities. The authors concluded that although both wavelengths were efficient in killing the spores, the 282 nm wavelength was slightly better.

Effects of UV LIght on B. Subtilis Spores

• Airborne bacterial spores can potentially have detrimental effects on human health. To cleanse the air of B. subtilis spores, a study was conducted to investigate the effects of UV light alone and in conjunction with thermal energy, or heat. As reported in the November 2010 issue of The Science of the Total Environment, up to 98.5 percent of B. subtilis spores were inactivated by increasing the temperature in addition to exposure to UV light. The study concluded that the combination of thermal energy and UV light was more effective than UV light alone.