How Life Finds A Way: Examining Evolution With Minimal Bacterial Cells

Category Biotechnology

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A new study in Nature has demonstrated that despite a decrease in its genetic information, synthetic bacterial cells evolved and regained their evolutionary fitness when pitted against the force of natural selection. These results highlight the power of evolution and natural selection, while also revealing that life is incredibly robust.

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Life finds a way. That’s the conclusion of a new study in Nature, which pitted synthetic bacterial cells against the force of evolution. Stripped down to a skeletal genetic blueprint, the artificial cells started with a losing hand for survival. Yet they thrived, evolving at a rate nearly 40 percent faster than their non-minimal counterparts. Over 2,000 generations, the streamlined cells regained their evolutionary fitness—the ability to survive, grow, and reproduce—that was initially lost after removing a large portion of their genes .

The synthetic bacterial cells evolved at a rate 40% faster than the non-minimal counterparts.

The results could herald a next generation of synthetic bacteria that pump out insulin and other life-saving medications, produce biofuels, or bio-degrade hazardous chemicals—by tapping into, rather than fighting against, the power of evolution. The crux was landing on a set of mutated genes that gave the minimal cell an advantage. The same technique might further refine artificial cells by guiding how next generations develop .

The synthetic bacterial cells started with 493 genes; the original bacteria had 901 genes.

Practical uses aside, we can now peek into natural selection itself. "It appears there’s something about life that’s really robust," said study author Dr. Jay Lennon at Indiana University Bloomington. "We can simplify it down to just the bare essentials, but that doesn’t stop evolution from going to work." Genetic Handcuffs Evolution is a double-edged sword. You know the basics. Genes randomly mutate .

When stripped down to a skeletal genetic blueprint, the synthetic bacterial cells lost their ability to survive, grow, and reproduce.

Most times they don’t have an obvious affect. In some terrible cases mutations kill offspring or cause diseases and haunt later genetic lines. But rarely, mutations provide the host with a superpower thanks to positive selection, which boosts evolutionary fitness and gives the animal a higher chance of passing down its genes. Examples include squids evolving color-changing skin that hides them from predators or, in humans, skin pigment adaptating to sunshine as we spread across the globe .

The study took place over 2,000 generations.

Not all genes are equal. Some, dubbed "essential genes," are critical for survival. These genes mutate but at a very slow rate. Changes are highly dangerous, potentially driving a species toward extinction. Think of these kinds of genes as a house’s foundation—fiddling with them during renovations could cause the whole structure to crumble. Other genes are far more flexible. Take Mycoplasma mycoides, a kind of bacteria that often lounges inside the guts of goats .

The results demonstrated that evolution can happen effectively even with minimal genetic material.

Over millennia, the bugs formed a symbiotic relationship with their hosts, shedding many genes naturally as they increasingly relied on their hosts for nutrition, while keeping genes essential for survival and reproduction. With just 901 genes, M. mycoides is a genetically petite bacteria. Back in 2016, scientists at the J. Craig Venter Institute further crunched its genome, creating a living creature with just 493 genes .

The scientists led by Dr. Jay Lennon at Indiana University Bloomington sought to understand evolution from its simplest basis.

The resulting cell, dubbed JCVI-syn3B, is the simplest autonomous organism to ever grace planet Earth. Upon learning about JCVI-syn3B at a conference, Lennon was hooked. "I was blown away by…the analogies of trying to understand something from its simplest basis," he said. But "if you create an organism that can reproduce, but then you allow it to experience the force of evolution…and mutation? I think this demonstrated that .

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