Articles about Bacteria

MNT Knowledge CenterThe word bacteria is the plural of bacterium. Grammatically the headline should just say "What are bacteria?" The incorrect usage has been included in the headline to remind readers that it is wrong - and hopefully help correct an increasingly common mistake in the English language.

Bacteria are tiny living beings (microorganisms) - they are neither plants nor animals - they belong to a group all by themselves. Bacteria are tiny single-cell microorganisms, usually a few micrometers in length that normally exist together in millions.

A gram of soil typically contains about 40 million bacterial cells. A milliliter of fresh water usually holds about one million bacterial cells.

Planet Earth is estimated to hold at least 5 nonillion bacteria. Scientists say that much of Earth's biomass is made up of bacteria.

5 nonillion = 5, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000 (or 5x1030)
(Nonillion = 30 zeros in USA English. In British English it equals 54 zeros. This text uses the American meaning)

Bacteria come in three main shapes:

1) Spherical (like a ball)

These are usually the simplest ones. Bacteria shaped like this are called cocci (singular coccus).

2) Rod shaped

These are known as bacilli (singular bacillus).
Some of the rod-shaped bacteria are curved; these are known as vibrio.

3) Spiral

These known are as spirilla (singular spirillus).
If their coil is very tight they are known as spirochetes.

There are many variations within each shape group.


Bacteria morphology. Image by Vojtěch Dostál

Bacteria are found everywhere

Bacteria can be found in:

  • Soil
  • Radioactive waste
  • Water
  • Plants
  • Animals
  • Deep in the earth's crust
  • Organic material
  • Arctic ice
  • Glaciers
  • Hot springs
  • The stratosphere (between 6 to 30 miles up in the atmosphere)
  • Ocean depths - they have been found deep in ocean canyons and trenches over 32, 800 feet (10, 000 meters) deep. They live in total darkness by thermal vents at incredible pressure. They make their own food by oxidizing sulfur that oozes from deep inside the earth.

Scientists who specialize in bacteria - bacteriologists - say bacteria are found absolutely everywhere except for places that humans have sterilized. Even the most unlikely places where temperatures may be extreme, or where there may be a high concentration of toxic chemicals, have bacteria. These bacteria are known as extremophiles (an extremophile is any organism adapted to living in conditions of extreme temperature, pressure, or/and chemical concentrations) and can survive where no other organism can.

Bacteria cells

A bacterial cell differs somewhat from the cell of a plant or animal. Bacterial cells have no nucleus and other organelles (sub-units within a cell with a specific function) bound by a membrane, except for ribosomes. Bacteria have pili, flagella and a cell capsule (most of them), unlike animal or plant cells. An organism without a nucleus is called a prokaryote.


A diagram of a bacterial cell.

A bacterial cell includes:

  • Basal body - this anchors the base of the flagellum, allowing it to rotate.
  • Capsule - a layer on the outside of the cell wall. Some bacteria don't have a capsule.
  • Cell wall - a thin layer (membrane) outside the plasma membrane, and within the capsule.
  • DNA (Deoxyribonucleic acid) - contains all the genetic instructions used in the development and functioning of the bacterium. It is inside the cytoplasm.
  • Cytoplasm - a gelatinous substance inside the plasma membrane. Genetic material and ribosomes lie inside.
  • Flagellum - this is used for movement; to propel the cell. Some bacterial cells have more than one.
  • Pili (singular: pilus) - these spikes allow the cell to stick to surfaces and transfer genetic material to other cells. A study revealed that pili are involved in causing traveler's diarrhea.
  • Plasma membrane - it generates energy and transports chemicals. Substances can pass through the membrane (permeable). It is located within the cell wall.
  • Ribosomes - this is where protein is made (synthesized). Ribosomes are small organelles made up of RNA-rich granules.

You might also like

Decoding The Human Brain - The Amazing Brain
Decoding The Human Brain - The Amazing Brain
10 Amazing Facts About The Brain
10 Amazing Facts About The Brain
10 Amazing Facts about the Human Body
10 Amazing Facts about the Human Body
The Human Brain Amazing Documentary HD 2015
The Human Brain Amazing Documentary HD 2015
SunGrow SunGrow Water Starter - Tap Water Conditioner: For Aquarium & Pond: Calms fish during Water Change: Protects fish with Aloe Vera extract
Pet Products (SunGrow)
  • DETOXIFIES TAP WATER Tap water contains many chemicals that harm fish. SunGrow Water Starter effectively neutralises heavy metals, rids of chlorine, chloramine...
  • CALMS & HEALS Introducing fishes to a new water tank can be stressful. SunGrow Water Starter is the trusted product aquarium owners use to neutralise water...
  • SAFE & NATURAL SunGrow Water Starter is made with aloe vera, making it safer than most chemical based water stabilizers. It s natural and helps the fish to...
  • EASY APPLICATION Simply add 1 cap (5 ml) of SunGrow Water Starter to every 2 gallons of water. If you notice damaged skin or fins on your fish, double the dosage...
  • FOR FRESH & SALTWATER No matter what water your tank has, SunGrow Water Starter is safe to use for both without affecting the pH level of your water. Use it...
Easy Peasy Science Fair Easy Peasy Science Fair Project Kit - Do Hand Sanitizers Really Work? - Grow Bacteria Simple and Easy
Toy (Easy Peasy Science Fair)
  • Grow bacteria from your fingers to see if hand sanitizer really works!
  • 2-3 day project! - Learn the valuable lessons a science fair project has to teach you without the mess, stress, or confusion.
  • Help with question, hypothesis, papers, graphs and data table!
  • 1 Gigabyte thumb drive contains 27 Journal prompts to help you learn about your project. Fillable Data Tables and Graphs. Prompts and examples for your papers and...
  • Convenient, pre-poured plates. Our plates are ready-to-use. There is no need to melt agar and pour the plates yourself!
Oral Essentials Mouthwash for Fresher Breath, Dentist Formulated, Alcohol Free, Sugar Free with NO Dyes, Preservatives or BPA. Non Toxic (Great Tasting and No Burning or Stinging) 16 Oz. Money Back Guarantee
Health and Beauty (Oral Essentials Inc.)
  • 100% 30 DAY MONEY BACK GUARANTEE: A High End Mouthwash, this artisanal formula combines French essential oils with organic aloe vera juice and salt from the Dead...
  • DENTIST FORMULATED MOUTHWASH: Beverly Hills, California is the epicenter for innovation in anti-aging, beauty, and medical fields. What better place to formulate...
  • ALCOHOL FREE AND PRESERVATIVE FREE MOUTH Rinse: Denatured Alcohol is used as a cheap preservative in most mouthwashes, and to create the stinging effect most people...
  • SUPPORTS HEALTHY GUMS AND TEETH The reason your breath is worse in the morning is because you re dehydrated! You could call our mouthwash a mouth moisturizer. It...
  • CONTAINS DEAD SEA SALT: Dead Sea salt is the world s most potent salt. People have been traveling to the Dead Sea for thousands of years to swim in its nutrient...
Booty Odor Neutralizing Spray - Wet Wipe Lover and Toilet Paper Hater Must Have - Intimate Wash for that Perfect Moment - Safely Eliminate Difficult Body Smells - Gentle pH Bleach Free Organic Formula
Beauty (Rubicoux)
  • THINK YOUR POO DON T STINK? - We scrub, scrub, and scrub with soap and wet wipes, but there is always that slight essence of foul left over, right? You didn t notice?...
  • WHEN S THE LAST TIME YOU CHECKED? - Do you know what you smell like down there? Probably most of us have no clue how we re doing down under, but our partner SURELY...
  • PEACE OF MIND IN THE BEDROOM - We spend so much time washing, making up, shaving, and we forget our most offensive area? It s 2016, everyone. Our spray will make...
  • THIS IS IMPORTANT - Booty Fresh isn t a miracle spray where you ll never have to take a shower again. But when soap, scrubbing, and wet wipes are NOT working, this...
  • ALL ORGANIC - PET USE OK - MADE IN THE USA - OVER 6 MONTH SUPPLY - THIS IS A CLEANSER AND NOT A PERFUME - HASSLE FREE GUARANTEE - Contact Amazon within 30 days for...
Pet Supplement Club Pet Supplements Club Probiotics For Dogs Powder Supports Nutritional and Digestive Health 5 oz
Pet Products (Pet Supplement Club)
  • SPECIFICALLY FORMULATED FOR DOGS - Unlike some brands that use human-strain probiotics or are generic formulations for animals, our Pet Supplement Club combination...
  • BETTER HEALTH CARE FOR YOUR DOGGIE - From puppies through to senior dogs, a good probiotic has many benefits: it can boost their immune system and help with improved...
  • EASY TO ADMINISTER - Because our product is a powder, it s simple to mix the required dosage in with either some food or liquid (e.g. water, dog-friendly fruit juice)...
  • SAFE, HEALTHY and NUTRITIONAL- Made at a USA Certified Natural Products Association (NPA) and an Approved Good Manufacturing Practice (GMP) facility, our canine...
  • RISK-FREE PEACE OF MIND - With the latest science at our disposal, we have created a probiotic that offers maximum effectiveness thanks to its blend of a dozen probiotics...

Q&A

Copyright © . All Rights Reserved