B. subtilis
- the bacterium that builds, breaks down, and collaborates
A Survivor in Dormancy
Bacillus subtilis is a soil-dwelling bacterium found almost everywhere – in soil, on plants, in water, and even in the human body. It is one of the most extensively studied bacteria in the world and serves as a model organism for understanding how bacteria live, interact with other living organisms, and survive under challenging conditions.
One of its most remarkable abilities is to form spores – a dormant state enclosed in a thick protective coat – which enables it to withstand extreme heat, drought, anti-bacterial agents, and other stresses. When conditions become unfavorable, it encases its DNA in this protective structure and waits until the environment improves. At that point, the spore germinates into an active cell and growth resumes. This strategy allows B. subtilis to spread over long distances, having the potential of remaining viable in the environment for several years, and rapidly colonize new habitats when the opportunity arises.
Ecosystem Decomposer and Plant Protector
In soil, B. subtilis acts as a decomposer, breaking down organic matter and releasing nutrients that plants can absorb. It also produces antibacterial and antifungal compounds that help plants defend themselves against harmful microorganisms and other damaging organisms such as nematodes. These compounds can spread through the soil, creating a microscopic shield around plant roots thus protecting them.
Some strains of B. subtilis can colonize root surfaces and form a biofilm that works as both a physical barrier and a chemical defense zone. This close interaction between plant and bacterium is an example of natural symbiosis that benefits both partners and reduces the need for chemical pesticides. In some agricultural systems, B. subtilis-based preparations are used as part of integrated pest management strategies, reducing the input of chemical fungicides and playing a crucial role in managing resistances of fungal diseases to commonly used fungicides.
Enzymes and Probiotics for Sustainable Solutions
B. subtilis is also an important industrial bacterium. It produces a range of enzymes – including proteases, amylases, and lipases – that break down proteins, starches, and fats. These are used in laundry detergents, food processing, wastewater treatment, and to remove unpleasant odors from surfaces and textiles.
Beyond industrial processes, B. subtilis is also used as a probiotic in for humans and in animal feed. By stabilizing the gut microbiota of livestock such as poultry and pigs, it supports better digestion, improved nutrient absorption, and reduced levels of harmful bacteria. This can help lower the need for antibiotics in animal production and promote more sustainable farming practices.
Building Materials of the Future
In recent years, B. subtilis has attracted attention in materials research, particularly for the development of self-healing concrete. In this approach, bacterial spores are mixed into the concrete, where they can remain dormant for years. When a crack forms and water seeps in, the spores are activated, grow, and produce calcium carbonate, which seals the crack.
This process can extend the lifespan of buildings and infrastructure, reduce maintenance costs, and lower the environmental footprint associated with producing new cement – one of the world’s most carbon-intensive industries.
A Model for Science
In research, B. subtilis has been a model organism for over a century. First described scientifically in the 1870s, it has since been used to unravel fundamental biological processes. It serves as a biological model for studying cell division, genetic regulation, biofilm formation, and chemical communication between bacteria.
It´s well-understood life cycle and genetics make it ideal for laboratory experiments, and discoveries from B. subtilis often apply to understanding other bacteria – including pathogenic species. Non-pathogenic to humans and easy to cultivate, it is also a popular teaching organism, from basic microbiology courses to advanced biotechnology.
Text written in collaboration with Dr Per Wessman, e-mail
