COLORS OF MICROBIAL LIFE- KILLER VIOLET

Chromobacterium violaceum

 A gram negative violet colored bacteria has captured attention of biologist worldwide because of its intriguing brilliant violet color. It is proving itself potentially useful in applied biology and in development of antibiotics and therapeutics. BUT this bacteria has a dark-side!It has not caused any dangerous epidemics like the plague or Ebola, but it is a killer😈. Also It has demonstrated its cancer cell killing properties in laboratory settings😇.  So Is it a killer? or a savior? or perhaps both?😕 Lets find out..

Chromobacterium grows along the inoculated area over the agar surface

Microorganism are ubiquitous. They are present almost everywhere and getting rid of them can be a task! This month we are collecting bacterial cultures from hospital and clinics for validating of our in-house PCR tests.

Chromobacterium violaceum cultures

Amongst those hundred tubes of  bacterial cultures there were couple of tubes displaying vibrant colors of violet, green, red, orange! Six years after graduating college I had forgotten how colorful the world of microbiology is! I once grew these bacteria in a pattern to read out my name in red and green to impress a girl 😎. In theses series of posts I'm going to discus few vividly colored bacteria🌈 and how important they are to us.
 

Bacteria in focus today is Chromobacterium, which has caught lot of attentions in scientific community. As you see in the picture this bacteria grows as smooth dark violet colonies. These four isolates are from different sources. The one in the extreme left was isolated from garden soil, the other three are from clinical specimens; second from left is a blood culture isolate, the one on its right was cultured from wound aspirate and the far right was isolated from skin abscess.

 The violet color of the bacteria is due to production of a secondary metabolite violacein.  This violet color compound is know to have antibiotic (it kills MRSA too), antiviral and anti cancer properties. Chromobacterium is not the only bacterium which can produces this chemical; Janthinobacter lividum a bacteria which comes from a completely different family makes violacein too! It grows on skin of the red-backed salamander protecting its host from fungal infections. In fact the genes which produces violacein was successfully cloned into Escherichia coli, along with other pigment producing genes from various bacteria (its a bacterial equivalent of lab rat!). 

The Cambridge 2009 iGEM team genetically introduced genes from various bacteria to produces "rainbow" E coli, first from right produces violacein

Group of scientists are already working to find a way to use it in killing colon cancer cells. It is one of the hottest topic to be working on! My intentions are not to study this bacteria but to design a specific and sensitive PCR based methods to save lives😇!

This violaecin compound may sound like its produced to benefit us. But its producer- Chromobacterium violaceum's intentions for us is anything but to benefit us😭! I'll give you a moment to settle this information. Yes you read that right this bacteria which holds key to the futuristic cancer treatment is dangerous😕😕! It causes rare, but server and often fatal infections in human (fatality >60%). Many case reports published in medical journals have shown evidence that this soil dwelling vibrantly colored beautiful tiny organism has killed people😟. 

Chromobacterium enters the unsuspecting host's body when cuts/wounds are exposed to soil/water or while swimming or during a traumatic injury. The bacteria can also enter the body through micro abrasions caused during sports or recreational activity in soil or water bodies. Chromobacterium violaecum is naturaly resistant to various antibiotics. This nasty little guy proliferates in the tissue and spreads through blood causing multiple abscess in organs like live, lungs, spleen and BRAIN😱😷! (AND NO! it doesn't turn you into a Zombie! There will be a posts on mind controlling pathogens next month😸)

We currently have four isolates of Chromobacterium (and looking for dozen more) to validate the PCR assay we designed. This assay would detect C violaceum from clinical samples in less than 6 hours. Routine microbial culture techniques may take 3 to 5 days to detect the bacteria causing the disease. In one of the case reports from south India, the microbial culture confirmed Chromobacterium violaceum on the fifth day, the but patient died on the third day after hospitalization due to multi organ failure.  The infections caused by bacteria such as Chromobacterium, Burkholderia, Stenotrophomonas are difficult to treat without identification and antibiotic susceptibility profiling; mortality is high even with treatment. A rapid sensitive and specific tests like real time PCR which can detect low levels of bacterial DNA in blood, wound or urine samples would aid in timely diagnostics, help in tailoring antibiotic therapeutic strategy and save lives.

We would upload results from the validations studies so soon as we done with it. So stay tuned :)

Pratik Vyas

Molecular Geneticist 
Orasen Bio World