What are Bacteria

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I have a background in microbiology so love to share information about the microbial world and some of the many types of organisms that inhabit it. Often people are not fully aware of what a microorganism actually is, and more importantly how many of these organisms are essential for either life or some of the things we consider important in our lives.

Bacteria is one of those great examples, so in this post, I wanted to share some of my thoughts on bacteria and their relative importance, the good things that are involved in, and also some of the bad things that they can cause.

It should be noted (as always), that this post is a combination of my thoughts, some research and probably a bit of rambling. It is only designed to provide a fundamental amount of knowledge, and if you are interested in this you can consider looking wider for more technical information. This post is not designed to be overly technical and is designed as a very basic introduction.

What are Bacteria?

Bacteria are single-celled organisms with a fairly simple cell structure, their genetic information is contained within a single loop of DNA (although some have an extra circle of DNA called a plasmid) and they have cell walls but lack organelles and an organised nucleus. Most bacteria replicate through a process known as binary fission where the single cell divides into two identical daughter cells.

Depending on the species of bacteria, some can divide every 20 minutes (i.e., E.coli).

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How many different types of bacteria are there?

There are tens of thousands of species of bacteria, these are usually classified into five groups based on their shape which can include:

  • Spherical – cocci
  • Rod – bacilli
  • Spiral – spirilla
  • Comma – vibrios
  • Corkscrew – spirochatetes

Beyond these general types, bacteria can be grouped and identified using a process known as taxonomy which is essentially the science of naming and identifying things, within taxonomy bacteria can be identified at the following levels.

  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species

When we see bacterial names, we are often seeing something like genus and species for example Bacillus subtillus is the genus and species. Whilst this paper just represents the known species, it reports about 30,000 formally named species (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3160642/) in reality the number is likely much higher…

How do bacteria get their energy?

This is a very complicated area, and there are whole areas of study around how bacteria obtain their carbon source and also their energy sources, this can generally be summed up as:

  • Obtaining energy from photosynthesis
  • Obtaining energy from breaking down wastes and dead organisms into smaller molecules (decomposers)
  • Obtaining energy by breaking down chemical compounds in the environment (chemotrophs – i.e., nitrogen fixers)
  • Obtaining energy from other living things (mutualism & parasitism)

One of the more well-known types of energy production is cyanobacteria which produce energy through photosynthesis (similar to plants), one of the weirder types is Methylocella silvestris which converts methane and methanol for their energy.

What are some of the essential processes Bacteria are involved in?

Bacteria play a number of essential roles in life, these can vary from bacteria that live in our gut and help us break down food, to the bacteria that live in the soil and oceans and break down organic matter. In reality, without bacteria, our world would look far different to the world we currently know, both from an industrial perspective to a health perspective.

Within the gut bacteria fall into around five main phyla (Bacteroidetes, Firmicutes, Actinobacteria, Proteobacteria and Verrucomicrobia) with the most common being Bacteroidetes and Firmicutes. An example of a gut bacteria is Bacteroides fragilis which is reported to ferment a wide range of glycans (glucose, sucrose) as well as break down biopolymers, polysaccharides and glycoproteins into smaller molecules that can be used by other hosts (i.e., other bacteria). It should also be noted that bacteria in the gut are reported to play multiple roles, which can also include assisting in preventing pathogens from overtaking the system (under normal conditions).

In an industrial sense, many bacteria are essential for the production of materials we need for everyday life, a good example is Streptomyces griscus which is a type of bacteria that is used to produce Streptomycin (an antibiotic).

What are some of the issues Bacteria can cause?

Whilst bacteria play many important roles in everyday life, they can also cause several issues. Within the industrial space, there are many types of bacteria that break down inorganic compounds which can be detrimental as they result in the deterioration of materials, for example, a type of bacteria known as Iron Bacteria (e.g., Gallionella ferruginea) can result in microbial corrosion of iron pipes (especially in seawater applications).

Beyond the bacteria that cause issues in industrial settings, there are also a number of bacteria that are known to cause issues in humans, for example, Legionella pneumophilia is the bacteria responsible for Legionella (a pneumonia-like illness in susceptible people).

Bacteria – A Summary

As discussed there are tens of thousands of species of bacteria (possibly more) that shape the world as we currently see it, these bacteria get their energy from a number of sources including the sun, breaking down materials, and even though relationships with other organisms (either symbiotic or parasitic).

As you read this article, there are likely thousands of bacteria that are busily working in your gut to help you break down the food you consume forming a symbiotic relationship but also aiding in preventing infection (in normal cases), beyond ourselves bacteria are also busy breaking down organic matter (i.e., in forests) and also fixing inorganic material (like nitrogen) to help plants.

Not all bacteria are good though, with many leading to the deterioration of materials (e.g., iron pipes) and some causing infection in people (i.e., Legionella), nonetheless bacteria are essential for life as we know it, and without them, our evolution may not have gone the way it did (in my opinion).

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