Have you ever imagined a bacteria acting as your computer? Now it is possible with this
new groundbreaking field of engineering and biology combined called synthetic biology. It
involves constructing new genetic systems and turning cells into biological machines. This is
useful to scientists because they can manipulate genes to do what they need the genes to do. This
is seen in the form of Bacterial Computing.
Bacterial Computing is the use of bacteria to
solve mathematical problems. They can do
additions, subtraction, square roots, division
and logarithm functions. They can do this
because different genes allow the bacteria to
do different operations. This new invention
could possibly lead to bacteria solving computationally challenging mathematics problems.
Dr. Leonard Adleman, a well-known scientist, introduced the newly founded approach of
DNA Computing in 1994. He concluded that DNA had the same computational abilities as
computers and were very similar to them
because they could store information about a
gene in the same way as a hard drive. He
solved the Hamilton Path Problem, which the
goal is to find the shortest route between a
number of cities only going through each once.
He did this with seven cities by having each strand of DNA represent one city. He mixed these
molecules together in a test tube, which concluded in some strands sticking together. The chain
of these stands represents an answer and within seconds, all the possible combinations will be
created. He eliminates the wrong molecules through a process called magnetic beads separation,
which leaves behind the right paths. There were a few problems such as the DNA computer was
slow and needed human assistance at all steps. Now scientists have figured out how to use logic
gates in bacteria and make certain circuits give a certain math operation.
DNA computing is a form of Biocomputing that uses DNA, instead of the typical silicon
based computer technologies. The process of Biocomputing uses systems of biologically derived
molecules such as proteins and DNA, to perform computational operations. Another type of
Biocomputing is called Bacterial computing, which is manipulating the DNA of bacteria to do
computational functions. Scientists are now able to use bacteria instead of the silicon-based chips
in computers. This is the same process as DNA computing instead we use bacteria. This can
store data, transfer data and receive data along with mathematical operations. In the future, we
could possibly have computers made of bacteria.
With the knowledge, synthetic biologists now have of bacterial computing; they can do
mathematical operations such as logarithm functions and other simple math functions. Synthetic
Biologists have come up with new logic gates such as the AND gate, NOR gate and the NAND
gate. These gates gave the biologists the power to control the bacteria even more because now
they can control the function to start or stop if both, one or none of the chemicals are there. With
this new knowledge of logic gates, they were then able to create the circuits to perform the
different logarithms. They use a low-copynumber plasmid and a high-copy-number
plasmid. The low-copy-plasmid generates
positive feedback by comprising of promoters,
which generate transcriptions factors that bind
to
the promoters and alleviate saturation between
inducers and transcription factors. The highcopy-number plasmid comprises of promoters
that bind and shunt away the transcription factors from the LCP and reduce saturation between
the transcription factors and DNA. AraC, a transcriptional activator on the LCP circuit, induces
arabinose, which then activates the promoter on the HCP circuit. This produced mCherry, which
is used as a tracer or a marker when attached to the fluids and it also produces gfp. This circuit is
used to do the function In(1+x).
The scientists decided to use analog circuits, which can take in multiple inputs rather than
the digital circuits that can only take in two kinds of value. In addition to sensing a molecule,
analog circuits can also tell its concentration. The way they calculated the output of a function
was they recorded the concentration of the resulting mCherry in each circuit and the amount of
the input molecules, and created a graph. This graph represented the graph of the function, which
they could use to get
answer to any number
inputted to the function
within the range of the
graph. The researchers
modified the circuits to
expand the range of the
function, resulting in
more outputs.
For other functions such as In(x), scientists figured out that they needed to change the
circuit to do the function that they wanted. They had to change everything such as the promoters,
transcription factors and the proteins. By changing these promoters, transcription factors and
proteins, they were able to get different functions. For each function, it has its own circuit which
is different from the others. Changing the promoter or the transcription factor, changes the way
the molecules react and the rate in which the molecules are produced.
The researchers’ main goal was not to use bacteria for mathematical calculations, because
we already have very powerful computers and calculators to do that, but rather it is a proof-ofconcept. This shows just what one of many complicated analog circuits can do. This proves that
the researchers could control the bacteria to be able to get the bacteria to do mathematical
calculations. The researchers hope, having this new knowledge of bacterial computing, is to now
be able to make new remedies for cancer. They would also like to make a computer made out of
bacteria, which would be faster and more efficient compared to the computers we have now.
These are just some of the ideas they have for the future. The ideas are endless with the
information they have now.