What are arsenic loving bacteria?


We all have learnt about how plants make food by the process called photosynthesis as part of our school curriculum. The general definition of photosynthesis at least till now is preparation of food by plants with the help of air, water and sunlight. But now, new developments suggest that there can be supplementary or totally different processes of photosynthesis which does not work on the earlier definition. Rather the new findings reveal that certain arsenic loving bacteria make use of arsenic to perform photosynthesis.  

A team of US geological survey headed by Ronald Oremland found  a new strain of bacteria the GFAJ-1 which seems to love Arsenic so much that arsenic is the  building block in these bacteria and have been termed as Arsenic loving bacteria. The water in this lake is very salty and alkaline with very high percentage of arsenites (AsO33-) and arsenates (AsO43-). 


What are arsenic loving bacteria?

The surprising discovery of an unknown bacterium in the salty hot water Mono lake of California has bowled over all the biological and life sciences expert. The lake is brimming with all sorts of minerals including arsenic and is located in  a volcanic region. It has been found that there are bacteria in this lake that substitute phosphorus for arsenic in its cell components.  While phosphorus is an important part of the ADP or energy molecule and helps in forming cell membranes in the form of phospholipids. While Arsenic on the other hand is chemically similar to phosphorous as these two elements belong to the same group in the periodic table  and have similar properties. Though these two are closely related they are on the opposite sides of the coin. One is life sustaining and one is life depriving. As Arsenic disrupts metabolic pathways. Arsenic has also been known to cause cancer when exposed to it on regular basis.  




How do bacteria use arsenic for oxidation?

In Northern Chile of South America, the natural water  has high concentrations of arsenic of 1100mcg/l. About nine strains of bacteria were isolated from this region that are found in this high concentrated arsenic water. They oxidize  Arsenite   by methylation to less mobile methyl Arsenate.  This knowledge can have useful applications as the bacteria can be used to treat arsenic contaminated effluents.


So can life exist without oxygen and water?

Until now, lack of water and oxygen have been considered as one of the main reasons for no life on moon and other planets. But in the wake of this recent discovery, our belief that oxygen and water are essential for life has to be changed and the way our scientists will search for life on other planets will change too. According to Ariel Anbar of Arizona State University we are aware of only one process of development of life which uses certain components and excludes others. But the recent discovery has put forth an interesting challenge to the astrobiologists as one of the most poisonous substances known to mankind has come up as a life growing component.


Carbon, hydrogen, nitrogen, oxygen, sulfur and phosphorus are the 6 building blocks of life on earth. But the discovery of arsenic loving bacteria has evolved a thought that other elements have a potential to develop life and might be present on other planets and satellites and this new discovery will change our perspective on what we look at the nurturing elements of life.

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