The Environmental Purposes of Phages
Bacteriophages are viruses that destroy bacteria, found in abundance within the biosphere; it can be found on our skin, in the ocean, and on the earth. there is an estimated population of 10³¹ of these phages, all of which target and destroy a bacteria that lives within their environment. Since the 1940’s, humans have used antibiotics as a convenience from serious cases to the average cold. The conventional availability of antibiotics has caused bacteria to evolve to survive the effects of antibiotics. The increasing presence of “superbugs” has created an incentive to utilize a formerly experimental method of phage therapy used in the 1930's, into a capable alternative.
Bacteriophages destroy bacteria in one of two cycles, the lytic and lysic. To summarize, the lysic cycle begins with the phage attaching to the bacteria, injecting its genetic material, and corrupting the nucleus to reproduce itself. As the population density increases, the bacteria will explode and release the phages. the Lytic cycle infiltrates the cell and destroys the bacteria completely.
These cycles play a significant role within our ecosystems, and offer several inquiries for scientists to answer.
Marine Phages
Within each environment that a phage lives, there are adaptations given to phages to survive in its environment and efficiently reproduce and destroy its target. A variety of species of phages that target certain bacteria are usually gathered to be used as a “cocktail” for certain infections. However, there are significant differentiations of each species of phage, especially within marine phages. Marine phages are often considered an essential asset to the microbial ecosystem, affecting horizontal gene transfer, bacteria mortality, and biogeochemical cycling. To elaborate, bacteria mortality decreases the rate at which carbon is transferred to higher trophic levels within an ecosystem. Despite the biodiversity within an ecosystem, only a small fraction of phage species generally stabilize and dominate an area. It is stated that in order for a population of bacteriophages to alter the population of bacteria within an ecosystem, the population density must be higher than 10(4) CFU/ ml
There are multiple genetic differences that provide resiliency. Marine bacteriophages from the western Mediteranean sea were tested in a study to observe how bacteriophages react to different elements, in order to test the diversity within the ecosystem. 26 phages were isolated, all but one of them were invulnerable to chloroform and all of them were not sensitive to ribonuclease. While the study isn’t necessarily representative of the entire population of phages, considering the lack of host bacteria diversity, it is still considerable that phages have unique trends. It was shown that the average phage lives within a prokaryotic host, while larger phages on average tend to target eukaryotic bacteria strains. The average phage has a head size of around 60–80 nm, and tail size greater than or equal to 100 nm. Other qualities measured include the composition of the nucleic acid and absorption rate (percentage of phages successfully absorbed into the host bacteria). Of these factors, there was no relation between the protein used and the absorption rate of the phage.
In general each of these phages contained two or three major proteins and a number of minor proteins that all had the same molecular weight. This may represent what a general ecosystem of phages is constituted of.
Environmental impacts
Cyanophages, Lysic and Lytic phages all contribute immensely to the bacterial ecosystem, so it should be a viable solution to be embraced to solve the issues of climate change. Everyday, lytic phages kill an estimated 20% of all marine bacteria, and also possess the ability to store carbon. Phages also have a variety of effects in the distribution of phosphorous and nitrogen into ecosystems. A study concluded that the higher presence of viruses predicted a carbon sink. Nitrogen-limited environments equates to a higher dispersion of nutrients, but heavily decreases the nutrient dispersion of zooplankton. This is also the same result for phosphorous-limited communities. Viruses actually increase their significance in multitrophic systems, as viral abundance means that more nutrients are dispersed by viruses rather than zooplankton.
Significantly, viruses actually are beneficial organisms for the environment by increasing the carbon sink of the ocean. 50% of the carbon on earth is sequestered by microbes. while Cyanobacteria does produce carbon and store oxygen, cyanophages also possess the capability to store carbon, while oxygen is dispersed.
Phages in Sewage
Wherever there are bacteria, there are also phages; many of these phages lie within the supernatant sewage, containing and expressing multiple bacterial enterotoxins. The gene expressed within the phage is known as stx1 and stx2, each of which are utilized to kill their host bacteria in the lysogenic process of transduction. This conduction of horizontal gene transfer of the stx gene produces several harmful effects of e. coli. To summarize, Phages can create pathogens by bacteria utilizing the genetic transfer.
The effects of the horizontal gene transfer by a lysogenic phage includes the stunted bacterial growth as well as metabolism alterations that effect the use of carbon sources for nutrients. However, it also includes an enhanced respiration rate with sugars. The sewers are a source of genetic exchanges, and a source to verify how often phages travel through humans.
Phages in Mammalian Tissue
Within mammalian tissue, the body immediately disposes the phages as waste product, and phages normally have no reaction unless the environment is unstable. unstable meaning, when the endothileal barriers begin to weaken due to bacterial infections, a convenience for phage therapy. The immune response to phages is relatively unknown, except that the body contains anti-phage antibodies that clear the circulatory systems. This proves an obstacle, as often times, phages are immediately cleared by the immune system. The purpose of this response is unknown considering the lack of tropism in the cells, as well as the fact that phages are only limited to prokaryotic hosts.
Phage therapy has been used to treat bacterial infections, cystic fibrosis, and more. It is an incredibly efficient treatment that is highly versatile in genetic modification.
Environmental propositions
Due to the qualities of marine phages that make them a carbon sink, many scientists have begun to innovate for new ideas to create farms of phages and to introduce them into the ecosystem as an effective carbon sink. This would be done by utilizing bioreactors to grow, and then to dump them into the ocean.
There has also been speculation that the use of antibiotics in agriculture will have to stop, and instead use bacteriophages as a disinfectant for livestock. Dairy products will have to be more available to meet the demands of the public while following health regulations. Lytic phage treatment will be available in the treatment of milk during processing, as bacteria in milk has devastating effects. Bacteriophages can also be used to increase crop yield, by using bacteriophages to treat bacteria that harm crops, such as Pseudomonas syringae, Ralstonia solanacearum, and Agrobacterium tumefaciens. The only issue is that bacteriophages can not kill fungi that inhibit grain production.
Bacterial infections as well as sanitation of the farm will also rely heavily on bacteriophages, and will also help expand the shelf-life of the products. While disinfectants may be the most useful cleaning material used, bacteriophages may increase the efficiency of disinfectants. Bacteriophages can be used to treat salmonella, as well as normal E. Coli bacterial infections within cows. However, some bacteria may evolve to be more resistant to phages, but most phages simply counteract by altering the genetic material that produces the resistant protein or by evolving.
Conclusion
Phages are a highly versatile and essential species to the biosphere, with highly specific tasks of regulating the biogeochemical cycles that control our ecosystems, while also providing beneficial genetic transfers for bacteria that allow them to survive. Phages offer versatile solutions for sanitation of the world’s agricultural industry, because more bacteria are becoming resistant to antibiotics; at the same time, the increase in demand for agricultural products has drastically increased. Phages are also shown to have an incredibly capable form of therapy that is being developed and constantly studying the environmental relations between tissue, bacteria, and phages. Phages may also be a potential solution as a carbon sink considering their flexibility within the marine ecosystem, sequestering carbon from the atmosphere ort letting carbon dissolve with the ocean, acidifying our ocean. bacteriophages serve multiple purposes that the scientific community has only began to research.
