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reply 1:
I believe that evolution is the most convincing explanation for the emergence of
pathogenicity in bacteria from Pathogenicity Island’s standpoint. Pathogenicity islands
(PAIs), a subset of genomic islands, aid in the genesis of illness and contribute to its
spread. Genes for tRNA flank PAIs in bacteria. These portions of a chromosome are
linked to mobile genetic elements like plasmids and transposable elements. For a
genomic island to be considered a pathogenicity island, at least one pathogenicity gene
must be present. There is evidence that pathogenicity islands were formed through
horizontal gene transfer; since their G+C content differs from that of the rest of the
genome, they contain direct repetitions at the ends, they are related to transfer RNA
genes and are unstable2.
It appears that PAIs are acquired horizontally via one or more lateral transfer events,
according to the currently available data. Certain PAIs appear to be that of a single
enormous transfer event, but the arrival of other PAIs seems to be more “mosaic-like.” It
results from several discrete lateral transfer events that determine the “mosaic”
composition of certain PAIs. When compared to the rest of the genome, PAIs often
display dramatically different codon usage biases and much lower or more great GC
content, depending on the region of the genome 3. There is now more support for the
theory that known pathogen-associated genes (PAIs) are introduced into a genome by
lateral gene transfer from an unrelated or dissimilar species (donor) with a different GC
content and codon use than the recipient. The amount of GC present and the number of
codons used differ between donors and receivers. Depending on how closely related
the donor and recipient bacteria are, the PAI GC content may be comparable, if not
identical, to the core genome of the recipient. In part, because there has been little time
for genetic drift, changes in base composition imply that any visible lateral transmission
of PAIs has taken place very recently2.
As a starting point, two competing worldviews (Evolution and Creation) offer extensive
explanations for the origins of bacteria, their pathogenicity, and whether or not God
created them5. Pathogenic islands are most likely to have formed via natural selection
and creation processes. Many genomic islands’ characteristics point to their formation
due to horizontal gene transfer, and some may be absent from comparing closely
related varieties of the same or unrelated species. The GC content and codon usage of
these genes are unusual for genes in the bacterium’s core genome3. Several religious
individuals, including many scientists, believe that God created the universe and that
these processes led to the construction of galaxies, our solar system, and the
beginnings of life on Earth. Scientific explanations of evolution do not contradict one
other under this viewpoint, which is also known as “theistic evolution.” Darwinian
evolution’s primary mechanisms are described by the terms “genetic variability,”
“phenotypic creation,” and “natural selection.” It is only after these occurrences that
germs begin to appear. According to Genesis 1 and 2, the infectious disease doesn’t
arise until after the curse in Genesis4.
reply 2:
Pathogenicity islands are specific genetic characteristics on the chromosomes of
bacterial pathogens that are a subset of genomic islands. They are formed through
horizontal gene transfer via transduction, conjugation, and transformation (Libretexts,
2021). Strains of the non-pathogenic genes of the same or similar species do not have
these islands. Pathogenicity islands commonly code for virulence factors. They are also
responsible for quantum leaps in the evolution of microbial organisms. PAIs research
shows their presence in gram positive and gram negative bacteria from humans, plants
and animals. Understanding PAIs and their role in virulence provides us with more
information regarding the evolution of pathogens (Gal-Mor, 2006). These islands have
been shown to convert bacteria to symbiotic bacteria which allows for interactions and
alterations. Pathogenicity islands allow for the production of options within the genes to
create diversity in bacteria. Through gene transfer, islands of one bacteria can move to
another bacteria causing changes. Thus meaning that pathogenicity islands are
essential in the development of pathogenic and symbiotic bacteria (Purdom, 2009).
When thinking about the worldviews of Evolution or Creation in regards to the origin of
pathogenicity islands, I believe that the creation perspective best explains this concept.
While evolution has many strong points, the creation worldview makes the most sense
to me and fits best with my beliefs. The evolution worldview truly doesn’t logically make
sense to me. This perspective feels that pathogenic bacteria could never have been
created by God so long ago; instead this complex concept has derived over time as a
result of the weakening of stronger bacteria ancestors. These two worldviews contradict
each other. The creation perspective argues that bacteria has many roles and was
originally created to be good but has adopted viral consequences due to the fall. Before
the fall, bacteria only existed in its beneficial ways not as pathogenic bacteria. It has
been found that microbes were created as a link between organisms and their
environment to make ecosystems and allow for symbiotic relationships to exist. This
concept deems microbes as organosubstrates. A researcher argues that these
organisms were created on the third, fifth, and sixth day of the creation story found in
Genesis. God created bacteria as a organosubstrate linkage (Purdom, 2009). As a
consequence of the fall, bacteria along with all of creation became cursed. Just like
labor pains, hard work, and other things listed in Genesis, bacteria was deemed to be a
curse of both beneficial roles and harmful pathogenicity. This theory has little to no
explanation for pathogenesis and microbes. We do think that pathogenic viruses are
caused as a result of mutations, the transfer of abnormal genes and alterations of
symbiotic relationships. All of this was created by God intentionally after the fall. T3SS
has been found to be essential in many symbiotic relationships. Many argue that T3SS
was created prior to the fall but changes were made after the fall that led it to act as a
pathogenic bacteria. This means that from a creation perspective, bacteria was
originally created for symbiotic relationships as a organosubstrate but after the fall
became pathogenic. This accounts for the higher number of similarities between
bacteria than differences. From an evolutionary worldview, one would credit these
similarities due to both being from the same species that can evolve and diversified over
time. Before the fall, during a time of only good, apoptosis still existed as the cells do
not fall under the living category but evolution believers would argue that these cells
were living. Furthermore, apoptosis is also viewed as a way to maintain the host’s body.
The creation worldview also argues that God created PAIs to supply a variety of genes
for bacteria since they would need them after the fall. This means that God knew what
would happen and created what was necessary to live out His plans. Pathogenic islands
seem to be created to allow the bacteria to have the ability to change and adapt to their
environment. This is how the good bacteria God created in the beginning with these
islands can alter itself to become pathogenic after the fall. This means that God created
these islands in the beginning knowing they would be needed for pathogenic bacteria in
the future. This complexity is not random as evolution argues, it was designed for a
purpose. At first, islands were used for symbiotic relationships and still do but they also
work as a way to convert bacteria to being pathogenic (Purdom, 2009). This is why all
bacteria are said to have been created for good by God as they are needed for
digestion and restoration maintenance in the environment. Bacteria still does this but
now also serves for pathogenic roles. Many say that bacteria is too specific and
complicated to have been created by God that it must have derived from years and
years of evoliving adaptation but a rebuttal from the creation perspective is that such
specificity cannot be caused merely by random mutations and changes. Bacteria
possess very specific and complex pathogenic mechanisms that cannot be explained
merely as the result of mutations.
Gal-Mor, O., & Finlay, B. B. (2006). Pathogenicity Islands: A molecular toolbox for
bacterial virulence. Cellular Microbiology,
8(11), 1707–1719.
https://doi.org/10.1111/j.1462-5822.2006.00794.x
Libretexts, B. (2021, January 3). 7.15d: Pathogenicity Islands. Biology LibreTexts.
Retrieved March 8, 2022,
from https://bio.libretexts.org/Bookshelves/Microbiology/Book%3A_Microbiology_(Boun
dless)/7%3A_Microbial_Genetics/7.15%3A_Genome_Evolution/7.15D%3A_Pathogenici
ty_Islands
Purdom, G. (2009). The role of Genomic Islands, mutation, – answers in Genesis. The
Role of Genomic Islands, Mutation, and Displacement in the Origin of Bacterial
Pathogenicity. Retrieved March 9, 2022, from
https://assets.answersingenesis.org/doc/articles/pdf-versions/arj/v2/origin-bacterialpathogenicity.pdf
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