Dr.K.Sivasubramani

Microbial symbionts offer various helps to the Host animal or Plant. In the gut and mouth-less flatworm,  Paracatenula endosymbiont plays a different role. What is Paracatenula? It is a flatworm that lives in subtidal sediments. Adult worm lacks mouth and gut. It grows to a maximum of 15mm in length and 0.4mm in width. It has a very smaller genome 1.34 Mb when compared to the related members without symbionts- 4Mb.     Paracatenula in sediment (Pic courtesy :   https://en.wikipedia.org/wiki/File:Paracatenula_sediment_OJ_2015.tif ) What are the symbionts? Candidatus Riegeria. It is a chemoautotrophic bacterium which lives inside the flat worm. Symbiosis The biomass of the bacterium is greater than that of the host. The bacterium lives in a special structure trophosome(tropho in greek is food). The role of the bacteria is to store the nutrients. Unlike some other symbiont the bacteria are not killed to release the nutrients, rather bacteria rel...

We know the role of microbes in agriculture both beneficial and harmful. It is quite interesting to know fungi are reared as farms. Ants belonging to different genera use plant chewate as a substrate to grow fungi as farms and graze them. Same thing is practiced by marsh snail  Littoraria irrorata.  Leaf cutting ants growing fungus. Image source:  http://www.harunyahya.com/image/miracle_in_the_ant/atta1.jpg  https://upload.wikimedia.org/wikipedia/commons/f/fc/Littoraria_irrorata.jpg Source and for further reading: http://schaechter.asmblog.org/schaechter/2015/11/a-snippet-who-invented-agriculture-the-ants-or-the-bees.html http://www.pnas.org/content/100/26/15643.full.pdf

We know the role of Noble laureate Sir Alexander Fleming in the discovery of Penicillin. But who is the first patient to receive Penicillin for treatment? It was Albert Alexander who was a constable in the county of Oxford, London. He was accidentally injured with a rose thorn. The wound was infected with Staphylococci and Streptococci and his condition became very serious. His head was covered with abscess and his eye was removed. Still he faced the risk of death. Howard Walter Florey He was treated by  Dr  Howard Walter Florey. The clinical application of Penicillin was tested only in mice and they haven't tried a human volunteer. Due to the terminal illness of Albert Alexander, they decided to try Penicillin on him.  Albert was given with 160mg of IV dose of Penicillin. He recovered well. But due to war time restrictions, they could not synthesis enough quantities of Penicillin. But the team successfully isolated Penicillin from the urine of Albert and gi...

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...