Dr.K.Sivasubramani

When we tried to assess the quality of air with settle plate technique we isolated some spider web like colonies. They might be  Bacillus mycoides . It is quite amazing that this bacteria has two types of curvature ie., clockwise and counter clockwise. A strain can produce either curvature not both. The direction of curvature can be changed by altering NaCl concentration. Source and Further reading http://crf.flib.u-fukui.ac.jp/dspace/bitstream/10461/14980/1/kiyou46.p9-14.pdf

In a discussion, we were talking about the history of Gram staining. Slowly talk shifted about the use of crystal violet MacConkey agar to inhibit  Gram positive bacteria. But how a simple dye inhibit a group of bacteria and become a selective agent? Here comes the answer, "The mode of action put forward by Steam & Stearn (1928) that the action of crystal violet is due to the formation of an unionized complex of bacteria with dye, is supported. Gram-negative organisms, such as  E. coli , have high isoelectric points and contain less acidic components than Gram-positive bacteria which usually have lower isoelectric points, so the former combine with crystal violet less readily and are more resistant to the dye. " Very happy to discuss science with youngsters... Source: http://onlinelibrary.wiley.com/doi/10.1111/j.2042-7158.1967.tb09550.x/abstract Image Courtesy: http://www.evidentcrimescene.com

As a microbiologist we know some aerobic microorganisms produce catalase and we test it by adding hydrogen peroxide to the culture. what do the catalase do in a microbial cell? Hydrogen peoxide is produced in microbial cell during the exposure to Oxygen. The enzyme catalase breaks down hydrogen peroxide to water and oxygen. 2 H 2 O 2  → 2 H 2 O + O 2 Even anaerobic organisms like  Methanosarcina barkeri  produce catalase under oxidative stress. In all animal cells and plant cells catalase is ubiquitously present. In humans the highest concentration of catalase is observed in Liver. Animals manage to survive even without catalase. Mouse with deleted catalase gene function normally. In humans deficiency of catalase may be linked with type II diabetes.The deficiency of catalase may lead to graying of hair due to the build up of hydrogen peroxide in body. Some insects like Bombardier beetle uses catalase in another way. It has sac of catalase and sac of hydrogen peroxide and...