One cannot agree less with this statement. If only we had a microscopic lens fitted in our eyes, we could see the vast number of microorganisms present on and around us. The concept of the existence of a microscopic world is quite ancient. The roots of Microbiology can be traced back to the Roman philosopher Lucretius (about 98–55 B.C.), and the physician Girolamo Fracastoro (1478–1553) suggested that disease was caused by invisible living creatures. After Leuwenhawk invented the microscope and theories such as spontaneous generation conflict rose to surface amidst the scientists, the golden age of microbiology took birth. Since then extensive research has been carried out in this field.
“For the first half of geological times our ancestors were bacteria. Most creatures are still bacteria and each one of our trillions of cells is a colony of bacteria” – Richard Dawkins
Microbiology is mainly classified into Prokaryotes, Eukaryotes and Archae. The topic of interest here is a small microscopic and almost invisible organism – Bacteria! Bacteria are a Prokaryote, meaning a primitive organism i.e. without a defined nucleus. Have you ever wondered how a bacterium – so small – is able to survive and become so efficient? One of the main features that bacteria incorporate is “communication”. They talk between themselves. Of course not verbally, but through chemical signals. In scientific terms it is called Quorum sensing.
Quorum sensing is basically the interaction between bacteria through chemical signals which help them to increase pathogenicity, antibiotic resistance, biofilm formation and to survive more efficiently. So, it is a cell signalling mechanism. Studies on these pathways of cell signalling started in the 1970s in Eukaryotic cells as a quest to find out the actual metabolism of a cell and was only restricted to eukaryotes and plant cells. Recently, scientists have geared up to understand the language and social networking between bacteria as it might solve a lot of mysteries of pathogenicity and diseases.
Quorum sensing can be divided into at least 4 steps: (1) Production of small biochemical signal molecules by the bacterial cell; (2) Release of the signal molecules, either actively or passively, into the surrounding environment; and (3) Recognition of the signal molecules by specific receptors once they exceed a threshold concentration, leading to (4) Changes in gene regulation.
This “social networking” between bacteria is a population dependent phenomenon. For example, if there is a single bacterium, the pheromones or biochemical signals produced by it is very less to create any effect, when the number of bacterium increases then the number of biochemical signals increases in the surrounding thus creating enough chemical reaction in order to cause an effect like luminescence or biofilm formation.
Here is an awesome video by Dr. Bonnie Bassler who explains this communication system. In one of her famous quotes she says “I think the easiest application to help people understand what quorum sensing is and why it is important to study is to tell them that if we could make bacteria, deaf and mute, we could create new antibiotics.”
Current research in this field:
- Disrupting bio film formation and thereby reduce biofilm formation by bacteria.
- Deriving medicines to stop the cell signaling and communication between disease causing bacteria.
An extensive research on quorum sensing will give a promising result for tackling the issue of antibiotic resistance.
- Prescott’s Microbiology, textbook by Christopher J. Woolverton, Joanne M. Willey and Linda Sherwood
- Brock Biology of Microorganisms