By Prof. B.K.P. Sinha, IFS (Retd.), Advisor, Dr. Somnath S. Pai, Asst. Professor & Ms. Kanika Bhargava, Ph.D Scholar, Amity University
TC Bureau: It is indeed one of the greatest irony of science that microbes, oldest self-replicating organism were the last to be discovered and has been largely ignored until the discovery of the microscope. This perhaps, is a human nature that they ignore everything, that we do not see. That probably explains the huge gap between discoveries of many things about astronomy, observing visible objects billions of kilometers away from us, long before we could appreciate the role of microbes in our lives. The difference between the telescope and microscope is not simply the arrangement of lenses. It speaks about our perception and the expectation of what we expect to see.. It is due to our interest in nature, in places that are not accessible to our limitation in sense. We are able to see the moon, the star, the sun with our naked eye. Because of this, when we see them through the telescope, these objects do not look mysterious. We see moon and stars but not the atoms or the molecules. When we cannot even understand that there is microbial world, why should we know about it?
The discovery of microbial world had to wait till 1655 when the Royal Society published a book Micrographia written by Robert Hook. Micrographia captured the interest and imagination of many people. Micrographia was the first best seller in science. Scientists took 4 years to understand about the structure and function of a cell, and unit of all the living organism. The quest and effort to understand the cell’s energy, growth and reproduction, that within every cell there is an assembly of protein, nucleic acid that carryout functions of living cells. It is not like taking electronic parts and building a T.V., radio amplifier. Nature has different types of cell, and we have a long way to go in understanding the activities in the cell. Though, over the years, scientists have made much progress in identifying microorganism or microbes which are microscopic that exist as unicellular, multicellular or in clusters. Taxonomically, therefore, they are divided into six major types, bacteria, archaea, fungi protozoa, algae and viruses. Today’s understanding of co-operation in nature is much deeper. Animals and plants have co-evolved and still continue to coexist with billions of diverse micro-organism that are required for a healthy living and proper development. There is no substitute for help from these little friends. But to our dismay we are taught to wage a war against micro-organism like anti-bacterial soap to antibiotics. And in our anxiety to get rid of them can turn into an unimaginable catastrophy for these can turn them into a deadly pandemic.
Microbes are important and useful in many ways, serving to ferment food, treat sewage, produce fuels, enzymes or other bioactive compounds. They are essential tools in biology as model organism and at times are put to use in biological warfare and bioterrorism, also. There are trillions of microbes living in or on our body, which help us to digest food, resist infection and protect our reproductive health. The ratio between human cells and microbes is by 10:1. Humans need bacteria and their genes more than most of us think. But the real champion of the system are those that devour whatever nutrients are in the air and turn them into healthy plant food. Whatever fertilizer is put into soils, microbes convert potentially toxic salts into a balanced diet for each specific type of plant, providing them with a continuous flow of nutrients.” Peter Tompkins and Christopher Bird observes in their book, “Secret to Soil”. Beer, wine, cheese would not have existed without help of microbes. So varied is the microbes’ alchemy that they can convert corn steep liquor , a waste, into penicillin. They produce thousand times of B2 vitamins than they can consume.
Now work of various scientists across the world has made it easier to understand what is life. There is a long sequential history and scientific commitment, interest and devotion to discover the various part of the cell, the nucleus, chloroplasts, mitochondria and Golgi bodies. These structures are smaller than 1000th of a millimeter. The diameter of most bacteria and other microbes is about 1-2 micrometers. Microbes have evolved as complex machines capable of splitting water with energy of sun, billions of years before the advent of terrestrial plants. We still do not know precisely when the first microbes evolved. It may be those organism which split hydrogen sulfide using light energy. These bacteria are very sensitive to oxygen. If exposed to the oxygen they lose their photosynthetic capability. In the above settings and present crisis of pandemic it is useful to understand the three important categories of microbes which seriously affect our lives. The categories are virus including bacteriophages and bacteria.
VIRUS: Viruses are like sales agents of foreign genes. They carry information in their DNA or RNA. They do not regenerate, without host cells, they have no mechanism to generate energy and cannot replicate themselves without the host. Modern genome sequencing technologies allow viruses to be characterized very quickly, but their biological functions take time. Further, rapid genome mutation rates generate quasi-species that complicate matters exemplified by the elusive HIV vaccine. When they enter into latency inside a human cell, it is well-nigh impossible to remove them from human genome.
The unique property of viruses, where it acquires the key attribute of a living system i.e. reproduction, when it infects its host cell. Host-virus interaction is highly specific and the biological range of viruses mirrors the diversity of potential hosts which means that its diversity is exhibited by its own wide array of mechanisms for survival and multiplication. Viral particles are generally small, like adenovirus which is a few nm in size. They consist of a molecule of either DNA or RNA enclosed in a protein coat or capsid, sometimes made up by an envelope of lipids, proteins and carbohydrates. The glycoproteins in the capsid ensures the specificity of virus and host cell interaction. The coat protects, viruses, genomes and facilitates viruses’ attachment and penetration into the host cell. Inside the host’s cell, it either takes over the hosts enzymatic machinery which later functions in association with the replication of virus or in some cases the genetic information of the virus gets incorporated in the host’s chromosomes and survives along with host replication. Viruses are known to infect wide variety of plants, animal hosts as well as, fungi and bacteria. However, most viruses are able to infect specific types of cells on only one host species.
An even larger marine virus that has been recently discovered, megavirus which has a genome of 1,259,197 bp which encodes 1120 putative proteins and is larger than the bacteria. There are multiple viruses that infects not only human but other viruses known as virophage and bacteria’s known as bacteriophage.
BACTERIOPHAGE: Bacteriophages are also a specifically useful virus. As the name suggests, the term itself was derived from “bacteria” and the Greek word phagein, meaning “to devour”. The diversity exhibited by bacteriophages nucleic acids is reflected in their modes of replication. Different strategies of propagation are exhibited by lytic and lysogenic phages where lytic phages produce multiple copies of themselves in a single burst of bacteria for its growth and lysogenic phages establish themselves as prophages by becoming part of bacterial machinery. Bacteriophages are composed of proteins that encapsulate DNA or RNA genome and may have either simple or elaborate structure that needs to be addressed thoroughly. Their genomes may encode as few as four genes and as many as hundreds of genes. Phages replicate within the bacterium following the injection of their genome into its cytoplasm. Bacteriophage are among the most diverse and common entities in the biosphere. They are omnipresent, they are found wherever the bacteria exist. On this planet there are an estimate of 1031 bacteriophages which is more than every other organism combined. One of the densest natural sources of these viruses are water and since the late 19th century they have been employed as an alternative to antibiotics in the former Soviet Union and Central Europe. They are seen as a possible therapeutic agent against multi-drug-resistant, extreme drug resistance and Pan drug resistant strains of many bacteria who are hereby mutating and developing resistance against the present antibiotics. According to CDC 2019, antibiotic resistant infections costs United States $55 billion annually, where estimated 2 million illnesses are due to infections and at least 23000 deaths per year alone let alone global data that would be beyond our imagination. A less belligerent and even an older approach of phage therapy where weaponizing of certain type of organisms, to combat the other type is an application of biological control, where these predators are delivered into the population that are targeting humans such as keeping of cats for the sake of rodent control i.e. using viruses of bacteria called phages to control bacterial population (Hokkanen. H.M.T et al., 1985; Harper.D. R et al., 2006).
BACTERIA OR SUPERBUGS:With the advent of MDR/XDR/PDR bacterial strains often called superbugs and with empirical, unrestrained and inappropriate use of antibiotics have added to the austerity of morbidity and mortality apart from additional hospital expenditures and increase in admittance days due to overstay in the hospitals. CDC’s Antibiotic Threat Report, presents antimicrobial resistance data from multiple surveillance sources in a comprehensive overview of resistant infections throughout the world. Some of these data are also embodied into the Antibiotic Resistance Patient Safety Atlas, which authorized for a detailed review of distinct resistance data (available at http://www.cdc.gov/hai/surveillance/ ar- patient-safetya atlas.html).
Horizontal Gene Transfer: Recent researchers in genetics have revealed an additional mechanism of co-operation among species .Now the scientists have realised that genes can be shared not only among the individual members of a species but also among members of different species without sexual reproduction.
Study of generous of several bacteria shows that many genes were not inherited from the previous generation. It is unlike usual gene transfer through mating of two organism, where gene transfer is known as vertical gene transfer. Horizontal Gene Transfer is common in bacteria where completely unrelated organism swaps genes without sexual reproduction. In other words it is quantum evaluation horizontal gene transfer is not gradual gene can be shuttled around the microbial world in the few decades. The process is quite rapid. Genes for resistance to antibiotics are now quite well spread among the microbes even being found in bacteria living deep in Antarctic ice. Many genes also appear to have been arrived in higher organisms by horizontal transfer.
All cells possess some mechanism for donating and withdrawing electrons and protons to and from hydrogen carrier. All cells create electrical field across membranes that either produce or consume ATP. Eukaryotic cells could not have existed or evolved into highly complex multicellular organisms had they not entered into a symbiosis with a primordial bacterium that now we know as choloroplasts and mitochondria. So the ATP energy with which our bodies function, is of bacterial origin. Finally, all cells on this planet are ultimately dependent on photosynthetic organisms which converts solar energy to create the electrical fields that generate the flux of electrons & protons making all life possible. Hence, the importance of plants cannot be over emphasized, but it might be of surprise that 50% of the earth’s atmospheric oxygen is from bacterial metabolism. In fact, bacteria form a vital cog in the elemental cycling on earth All higher organisms will eventually starve because of the unavailability of nutrients, especially nitrogen, which is made available by bacteria without much fuss compared to the highly energy intensive human-invented Haber process.
Conclusion: Succinctly, the recent trend of tinkering with transfer of bacterial genes to genomes of other species is fraught with danger for lack of understanding of unintended consequences for the evolutionary trajectory of life on earth. In our short history on the planet, we are becoming the most disruptive biological force .We are like modern Vashmasur. We are likely to inadvertently design and release microbes that can fundamentally disrupt the balance of electrons in the globe. That would be disastrous.
According to the Darwins theory of evolution, all species of organisms arise and develop through the natural selection where small, inherited variations increases the individuals ability to compete, survive and reproduce in this environment. And according to the theory of natural selection individuals produced each generation exhibit phenotypic variation that are heritable and those individuals with heritable traits which are better suited for the environment for survival survives in the end. There are millions of viruses, bacteria and other organisms in this environment all of which have a particular habitat and host for its survival. Whenever this natural balance is disturbed consequences of this imbalance leads to destruction. One can predict that the pandemic of COVID 19 is one such imbalance. Coronavirus was naturally hosted by the bats which was later transmitted to humans via animal still unknown. We need to ask ourselves certain questions which include: what led to the virus jumping from one species to another; how did we got here and How do we respond to this crisis? For COVID 19 one can suspect that wild animals sold at seafood market in Wuhan might represent an intermediate host that facilitated the emergence of virus in humans. Therefore, wild animals used for food consumption and other purposes by humans, urgently require microbiological investigations as human’s territorial encroachment of wildlife might be apocalyptic and disastrous.
In the ultimate analysis we must consider the fact that human beings are a transient species on this earth that might lead to its own downfall if not kept in check.