“Nothing in Biology Makes Sense Except in the Light of Evolution”.
– Theodosius Dobzhansky
12 Flasks with identical Escherichia coli populations + 25 mg Glucose +
other nutrients (1988)
Each new Day 1% of bacteria transferred to new flask containing fresh glucose.
After 75 Days Escherichia coli almost completes 500 generations
Some of them (ancestors) were preserved while remaining proceeded
for next generation.
Protocol followed for 25 years and still going on & on….
On generation number 6500, almost 3 years after experiment initiated there was a minute observation, it was regarding size of colonies formed by two types of Escherichia coli evolved in one of the flasks. One formed small colonies and other formed large colonies. Size of the colonies is directly proportional to the size of cells residing inside.
Lenski predicted that eventually one colony will out compete other colony. Other possibility is they may form ecosystem in which all the ecological interactions like competition, mutualism etc may take place. “He created his own Galápagos Islands,” Marx says.
The second major striking observation came when they saw Escherichia coli growing in flask containing glucose as well as citrate, recognizes “ohh there is another carbon source for utilization “ and one of the flask became turbid. After heavy analysis and experimental backup Lenski concluded that Escherichia coli switched on the gene coding for citrate transporter , 2933 base pair long which is otherwise silent.
Along with this Lenski also says,’ Each year pharmaceutical companies spends billions dollars trying to defeat evolution in microbes but rather than defeating they are causing selection in microbes and in effect causing antibiotic resistance.
Lenski who always describes himself as restless fellow to observe evolution so his lab created a program which will predict “Digital Evolution“. The software will gets evolved as it happens naturally. They created a virutal petri dish of digital organisms.
His Escherichia coli getting adapted and reaching fitness peak day by day. Today Escherichia coli reached to 62102.2 generations.Lenski’s experiment is going on till today, received funding from various sources.