What Are Bacteria And How Do They Affect Our Food?

What are bacteria?

Before we can understand how bacteria affect your food, we need to define the term: what are bacteria?

How do we define bacteria?

Bacteria are single-celled microorganisms which can exist either as independent (free-living) organisms or as parasites (dependent upon another organism for life). They are about 0.5 to 2 micrometers in size. A grain of sand is 2 millimeters is size. This means you could fit 1000 bacterial cells into a single grain of sand. This means we can only see bacterial cells through the microscope.

Other than through the microscope, bacteria form what we call “colonies” which have millions of cells which allow us to easily see bacteria in a medium that is grown in the lab known as agar plates. This is the simplest method used, in order to identify and see bacteria. We use this method to count how many bacteria are present in for example a swab of a cutting board. Greater than 300 colonies is considered dirty and contaminated.

These were one of the very first organisms to exist on our planet, so they are very, very old and have co-existed with humans since the beginning. There are millions of different types of bacteria, some good for you and some very dangerous to your health.

Where can you find bacteria?

Bacteria live in water, soil, in plants and in animals. Bacteria are so prominent on earth that they also live in some of the most extreme environments, such as the deep ocean, hot springs and there is even evidence that bacteria lived on mars.

As an example, bacteria on a human associated level grows in your gut, on your skin and in your hair (eye-lashes included). So much so, that recent research has shown that the makeup of the different kinds of bacteria in your gut and skin is MORE unique than a fingerprint.

Bacteria also grows and survives in the food that we eat, raw meat and vegetables by design must be cooked so that we as humans can consume these foods without getting sick from the bacteria that thrive in these environments.

There are two main distinctions for bacteria which we define as gram-positive and gram-negative bacteria.

We use this distinction to group the various types of bacteria by how the look and behave. All commonly occurring bacteria fall under these two categories. Suffice to say we identify bacteria in the lab with a simple test that we use as a broad category to determine which bacteria we are looking at. This test is known as a Gram stain. This means that there are two main types of bacteria that look and behave differently from each other. With this method we are able to see bacteria under the microscope.

This test also helps us see the shape of the bacteria. There are three shapes, bacilli (rod-shaped), cocci (circular), and spirilla (corkscrew shaped).

What Do Bacteria Need to Survive?

There are 6 elements in the environment that allow bacteria to grow and survive:


Moisture Content


Nutrient Content




In general (with bacteria there are always exceptions) we see that bacteria can survive in a very large temperature ranges. Bacteria can live between 0 to 60 °Celsius (32 – 122 °Fahrenheit), however on a human associated level they grow at their best between 20 and 45 °Celsius (68 – 113 ° Fahrenheit).

This is because the bacteria that we are concerned with have adapted to our internal bodies, in order to infect and contaminate our bodies. Therefore the absolute best temperature is 37 ° C (98 ° F).

Moisture (Water activity)

Bacteria can grow mostly in moisture rich environments. In food, bacteria love moisture rich conditions. Water activity means how much water is available in a food product. Such an example would be cucumbers, there is a high availability of water in cucumbers, lettuce and celery (95%). When compared to dried spices (5 – 50%). Most bacteria need at least 80% water to survive.

Nutrient content

As we as humans need nutrients to survive, so does bacteria. With nutrient high content, food is a perfect source of nutrients for bacteria to grow. Which is why we need to have very good hygiene standards in the kitchen. Food is an ideal environment for bacteria. The skin of humans and animals are also an example of a high nutrient source for bacteria. Bacteria require sources of carbon, nitrogen, phosphorous, iron and a large number of other minerals.

pH (acidity)

The pH or acidity level also affects how bacteria grows and how effectively bacteria can survive within the environment. Bacteria in food ranges from 5 to 8 pH. This means items such as vinegar is unlikely to allow bacteria to survive.

Lemons are always a popular food when anti-bacterial properties are mentioned. Indeed the pH does discourage the growth of bacteria, but is not a major factor when killing bacteria that occurs from cross-contamination. meats, spinach and milk are within the ideal pH range of bacteria. Yogurt has a pH just below the ideal range, and is general considered less risky than milk because of this.


Bacteria can grow in both oxygen rich and poor environments. This means sealed and unsealed products. Therefore, vacuum packed meals and foods are not free from concern. This also means exposing foods to the environment and leaving food uncovered allows bacteria to grow.


The longer bacteria are exposed to the above factors in their ideal conditions, the more established the bacterial cells become. These factors are all dependent on time, and bacteria can rapidly multiply within 15 to 45 minutes.


We now know that bacteria can survive in temperatures of between 0 – 65ºC (32 – 149ºF)

Grow best at 20 – 45 ºC (20 – 113ºF).

They rapidly multiply in 15 – 45 minutes in these ranges.

Moisture rich environments are favourable.

Can survive at pH of 3.0 – 7.5

Can survive in oxygen rich and poor conditions.

As you can see, bacteria are similar to humans in what they need to survive, hence there are human associated bacteria, and as a result, bacteria that occur in the foods that we consume.

The Rod In Your Hand

Moses was an elderly man, used to working alone with his animals. He spent much of his time in the desert with the hot sun beating down on his head. One day passed like the next. He thought that this was how his life would end. His life didn’t seem to have a compelling purpose. Was he content, or had he just given up?

Then God spoke to him. God was concerned with the same issue that concerned Moses. God wanted to deliver His people from their Egyptian oppressors, and He wanted Moses to be a part of that plan. God wanted to use a nobody like him, to be a somebody to others. Moses couldn’t even imagine doing any of the things that God mentioned. The only skill he had used for the past 40 years was leading a flock of animals here and there, making sure they were safe and had food and water, learning the terrain of the desert, and using his rod to guide them and keep them together. Surely God was mistaken. He wasn’t capable of doing such a great thing. He was just a common shepherd.

So he dared to argue with God. Who am I that you want me to do this? Who are you? They don’t even know you God? I don’t know how to speak eloquently? Can’t you find someone else more qualified? But God had another plan in mind. “What’s in your hand?” said the Lord. “A rod” he said. God said “Cast it on the ground.” When he did, it became a serpent. Then God told him to pick it up by it’s tail. When he did that, it became a rod again. God told him to use that rod that was in his hand to perform signs in front of the Egyptians. These signs would be proof that his message was from God and not man.

God’s Rod

A rod: a gnarly piece of wood. For years he had leaned on it, herded sheep with it, used it to protect and discipline them. It was one of the few things he carried with him, a required tool of the trade. And suddenly to God it was the key to his calling. It wasn’t anything that others would think of as powerful. But now it was the “rod of God”, and it was instrumental as God used him to deliver his people out of Egypt, and usher them to the gateway of their promised land. The previous 40 years that he spent in the desert had been his training ground as he learned to lean on God’s wisdom and not his own.

Recently, I had a conversation with a friend who was interested in changing careers. His current and future careers were as different as night and day. We talked for some time about various strategies that would help him to break into his new field of interest. Then he began talking about the needs of his colleagues in the field in which he currently worked. After asking him several questions it became evident that there was an opportunity to apply some of his interests and skillsets in his future career area, to meet needs in his current career area. Like Moses’ rod, the key to his future was right in his hand.

Your Rod

So what is your “rod”? What do you already have in your hand that is your key to your calling? Maybe you think you lack the skills, abilities or opportunity to accomplish the dreams that keep flowing through the back of your mind. Maybe you lack the education, information and connections to even figure out how to begin. But the God who has placed the calling within you knows. The lifetime of experiences that seem unrelated to your future calling may instead be your preparation for it. He’s just teaching you not to place your faith in your own abilities, because He has a different way of making things happen. He has a miraculous means of setting you in places you didn’t realize you could attain. He’ll use the tools that you have in your hand, the skills and experience that he has placed within you to accomplish His will, and to fulfill your calling.