Bug of the week

By Vic Arcus 08/02/2010

I love microbiology. Microbes are simpler than plants or animals – just single cells dividing and expanding in number (exponentially!). Microbes invented photosynthesis, they invented antibiotics, they even invented sex. Simple, yet stunningly diverse, they live everywhere – in the soil, in the rocks, in the sea, on your skin, in your stomach. There’s a whole community of bugs living in your stomach and it is said that every individual human on the planet has a different population of microbes in the their digestive tract and could be uniquely identified by them. So I thought that I would start a series on cool bugs and where they live.

This weeks bug is called Chlorobium phaeobacteroides BS1 (microbes are given two latin-style names. The first, capitalised, signifies the genus and the second signifies the species. Often there is a “strain” number after the latin names). I’ll call this bug C. pha for short. This is bug of the week because of where it lives and what it can do. It lives deep in the Black Sea, down at about 100m. There’s not much going on down there and what’s more there is virtually no light. But C. pha uses photosynthesis to generate energy, so it absolutely needs light to survive. It’s survival depends on it being one of the most efficient photosynthesisers on the planet! Down at 100m in the Black sea there is about one million times less light than at the surface. This means that there are tiny, tiny flashes of light only intermittently. To describe it another way, if C. pha were a tree in a pitch black enclosure, it could survive off the light from a small candle 50 m away! To live down deep in the Black Sea, C. pha has doubled the size of it’s light harvesting machinery, made its conversion of light to energy extraordinarily efficient, and fine tuned all of its metabolism to survive on these tiny pings of light. It uses stealth and splits in two about once a year. That compares to E. coli living in your stomach, which divides every 20 minutes.

In an age when converting light into energy (for a genuinely renewable energy source) may be one of the most important processes that we can understand, it is good to meet one of the most efficient proponents of this process – Chlorobium phaeobacteroides BS1.