–Dr Dipon Sharmah
Every time I begin my microbiology class, I ask this question to my students: When you hear the word microbe – like bacteria, fungi or viruses – what kind of image, pleasant or unpleasant, comes to mind? More than 90 percent of the time, the answer is unpleasant. After the 2020 pandemic, the answer has been consistently unpleasant.
Recently my students celebrated International Microorganism Day, which falls on 17th September. The date honours Antonie van Leeuwenhoek, a Dutch merchant who first saw the microbial world, a world invisible to our naked eye.
Leeuwenhoek dealt in cloth. He was not a scientist. In his spare time, he ground pieces of glass into lenses so powerful that they could magnify an object several times over. He built them to count the threads in silk and linen, so that he could judge his cloth better and let his business grow. But curiosity pulled him elsewhere. He began looking at things around him: rainwater, pond water, the scum from his own teeth. In every one of them he found tiny creatures. He drew them carefully and wrote hundreds of letters to the Royal Society in London. In one letter, dated the 17th September 1683, he described the little animal forms in the scrapings of human teeth. That is why the world chose this date to celebrate International Microorganism Day.
What exactly are these microbes? The honest answer is that we still do not know much about them. The total number on Earth is still debated, with estimates running into the billions and possibly trillions of species. If you place a handful of rich soil on your palm, you are holding and directly facing more microbes than the entire human population of Earth. Their numbers and their diversity are enormous, and what we understand about them is still very little. Only recent research has begun to show their importance in our own bodies. A whole new branch of biology, the study of the human microbiome, is helping us to understand these microbes and their influence on us.
We carry an equal, and by some estimates more, number of microbes than our own body cells. These microbes are not idle. They help digest food, make certain vitamins and help train the body to fight disease from the day we are born. Picture two close friends walking into a sweet shop. One asks for a savoury samosa, the other for a sweet rasgulla. We put the choice down to taste, but now we are beginning to understand that the microbes in our gut can communicate with the body and may influence appetite and satiety. This is one reason we speak of our “gut feeling.”
Picture another scenario: two friends go trekking in the hills and both are caught in the same rain. One returns home and falls ill; the other stays well. A part of this difference may lie in the relationship between our immune system and our gut microbes.
The first colonisation of microbes in our body begins at birth. This is why researchers now study the difference between a natural birth and a birth by caesarean section. Several studies suggest that caesarean-born infants may have a higher risk of allergies, asthma, and metabolic disorders later in life.
Microbes are equally important outside us. If you walk into a forest, you will notice that there is no heap of dead leaves and fallen twigs. Nothing piles up forever. A wonderful army of microbes, mostly bacteria and fungi, begins its work, decomposing whatever has fallen. They return the nutrients back to the soil, so that plants can use them again. So, in nature, there is no such thing as a landfill.
We are taught that trees give us oxygen, and yes, they do. But the greatest share comes from the sea. Scientists estimate that about half of the oxygen produced on Earth comes from microbes in oceans.
We have also learned to put them to work. In 2015, while I was attending a conference in the United States, I saw waterless urinals. In place of flushing, helpful bacteria broke down the waste and removed the unpleasant odour. That was a decade ago, and these and many other ideas have surely grown since. We are now designing homes that help to proliferate beneficial microbes.
In our own crop fields, microbes enrich the soil by fixing nitrogen from the air. They serve as living biofertilizers that feed billions of us. Fungi, too, form intimate associations with plant roots. Some 500 million years ago, when the ancestors of plants began colonising the land, they did so in the company of fungi.
Our ancestors celebrated microbes long before they were discovered. In our kitchens, they are our old friends. Bread, curd, yoghurt, and cheese to name a few. Curd sets because of a bacterium called Lactobacillus. The batter for idli and dosa rises and turns pleasantly sour because of them. Many of our traditional foods are rich in probiotics, which contain good microbes whose value for gut health is now widely recognised.
Their gift to medicine is even greater. It was in 1928 that Alexander Fleming discovered the wonder drug penicillin. Since then, hundreds of antibiotics obtained from microbes have saved countless human lives.
But not every microbe is a friend. The pandemic has taught us an important lesson. Many others cause diseases like cholera, tuberculosis and typhoid. Humans have fought long and costly battles against them. For every microbe that harms us, countless others feed us, protect us and keep the Earth running.
We are only beginning to understand this wonderful world of microbes. They fill our air, fertilise our soil, and guard our health, and, in return, they ask for nothing. They were the earliest living creatures on primitive Earth and will likely outlast us.
That is enough reason to honour them. Let us celebrate microbes!
Short Bio: Dr Dipon Sharmah is Assistant Professor and Head of the PG Department of Botany at Jawaharlal Nehru Rajkeeya Mahavidyalaya, Andaman & Nicobar Islands, where he has taught since 2011.
