Evolution of Bacteria

Bacteria have been around since the beginning of life on Earth. Bacteria fossils have been found in rocks dating back to the Devonian Period (419.2 million to 358.9 million years ago), and there are compelling claims that bacteria have existed since the early Precambrian Period, roughly 3.5 billion years ago. Bacteria have been present on Earth since the Paleoproterozoic, around 1.8 billion years ago, when cyanobacteria produced oxygen in the atmosphere. Bacteria have had plenty of time to adapt to their surroundings and produce numerous descendent forms as a result. This article will study the evolution of microbes and the evolution of bacterial and fungal growth media in detail.

Evolution from Bacteria to Humans

Process of Evolution of Microbes 

Bacteria evolve in the same way as other species do. This is accomplished by natural selection, in which advantageous adaptations are passed down to subsequent generations until the trait becomes widespread across the population. However, because bacteria reproduce via binary fission, which is an asexual method, the daughter and parent cells are genetically identical.

This makes bacteria vulnerable to environmental stresses, which can be mitigated by transferring genetic information through transduction, transformation, or conjugation. This permits bacteria to generate new genetic and physical adaptations, allowing them to adapt to their surroundings and evolve. Furthermore, bacteria can multiply in as little as 20 minutes, allowing for rapid adaptability and the evolution of new bacteria strains.

Human Evolution from Bacteria

• The nature of the initial ancestor involved in the birth of life is a hotly debated topic. It's been proposed that the first cell's genetic material was RNA because studies have revealed that RNA molecules may perform a variety of catalytic tasks. Early in this time period, the Bacteria and Archaea split from their common ancestor. Prokaryotes of the two categories tend to live in different kinds of settings and produce new species at varying rates. Many Archaea prefer habitats with high temperatures.

• Many of the methanogens in another large branch of the archaeal tree can thrive at high temperatures, and one major branch of the archaeal tree contains only thermophilic species. Thermophiles, on the other hand, make up only a small part of any large eubacterial branch.

• Bacteria and Archaea both have members that can grow at extremely high temperatures, as well as species that can thrive at extremely low temperatures. Another notable distinction is that bacteria have evolved to thrive in aerobic environments, whereas many archaea are obligate anaerobes. No archaea are required to be photosynthetic. The archaea could be a more primitive sort of organism with a genetic response to changing environmental conditions that are hindered. Due to its poor ability to adapt to new settings, the archaea may be constrained to severe conditions with little competition from other life forms.

• Mutations, which are changes in the sequence of nucleotides in an organism's DNA, occur frequently in all organisms, forcing them to develop or adapt to changing surroundings. The amino acid sequence of the protein encoded by that stretch of DNA may alter as a result of the changes in DNA sequence. As a result, the changed protein could be better or worse suited for function depending on the circumstances.

• Although many nucleotide changes in DNA have little influence on the fitness of the cell, if the nucleotide change improves the cell's growth even somewhat, the mutant form will be able to increase its relative numbers in the population. However, if the nucleotide mutation slows the cell's growth, the mutant form will be outgrown by the other cells and eventually die.

• The ability to transfer genetic information between species is a critical component of environmental adaptation. DNA exchange is an important aspect of the life cycle of higher eukaryotic organisms, and it can happen in any eukaryotic. Although the amount of DNA exchanged is modest, genetic exchange occurs in the bacterial world as well, and it can happen between distantly related organisms.

• Plasmid genes can be transferred to the bacterial chromosome and become a permanent component of the bacterium's heredity. Transposons are movable genetic components that can alter the order and presence of any genes on the chromosome in most organisms. Transposons may have a role in speeding up the evolution process.

[Image will be Uploaded Soon]

Mitochondria Evolved from Bacteria

Eukaryotes/Human Evolution from Bacteria:

• Protists are eukaryotes, which means their genetic material is arranged into a compartment, the nucleus, that is surrounded by a membrane and has membrane-delineated organelles. Prokaryotes would have been the first living creatures in the ancient earth's warm waters. The endosymbiotic hypothesis proposes that mitochondria (and chloroplasts) are descended from specialised bacteria (most likely purple nonsulfur bacteria) that somehow survived endocytosis by another prokaryote or cell type and became absorbed into the cytoplasm.

• Symbiont bacteria's capacity to conduct cellular respiration in host cells that relied on glycolysis and fermentation would have given them a significant evolutionary advantage. Similarly, host cells harbouring photosynthesis-capable symbiotic bacteria would have an advantage. The number of situations in which the cells could survive would have been considerably increased in both circumstances.

• Mitochondria do not have nearly enough DNA to code for all mitochondria-specific proteins, although a billion years or so of evolution could account for a gradual loss of independence. Although the endosymbiotic hypothesis is referred to as a theory, there is no experimental evidence to support it. The idea, which is the most likely explanation for mitochondrial origin, has only circumstantial evidence to back it up. The evidence required to convert the model from hypothesis to theory is almost certainly lost to time.

Antibiotic Resistance Directional Selection

Natural Selection of Bacteria

• There are numerous examples of bacteria rapidly evolving. Antibiotics were not employed in medical practice until the 1940s. Antibiotics were eventually shown to be effective against the majority of harmful microorganisms. Bacterial resistance to one or more antibiotics has increased since then, to the point where previously effective drugs are no longer effective against particular germs.

• Although this method can occur, most occurrences of antibiotic resistance in harmful bacteria are not the consequence of a mutation that affects the protein that the antibiotic assaults. Antibiotic resistance is frequently caused by bacteria producing enzymes that modify the antibiotic and render it inert. Transmissible plasmids, which transmit the genes for drug-inactivating enzymes from one bacterial species to another, are a crucial component in the spread of antibiotic resistance. Although the origin of the gene for these enzymes is unknown, mobile genetic elements (transposons) may have influenced their appearance and allowed them to be transferred to other bacteria.

Did You Know?

Thermotogae bacteria are thermophilic or hyperthermophilic, gram-negative staining, anaerobic bacteria that can thrive near hydrothermal vents with temperatures ranging from 55 to 95 degrees Celsius. They're regarded to be among life's earliest forms. These species were discovered near ancient hydrothermal vents in the Australian Apex Chert.  These fossils are likely to have belonged to early thermophilic bacteria and date back 3.46 billion years. This is due to the fact that these organisms do not require oxygen to exist, an element that was not abundant in Earth's early atmosphere. Furthermore, surviving species such as Thermotoga neapolitana, which resembles its ancestral form and still lives near these vents, have been used as evidence by some scientists to support this view.