The living world contains a variety of life-forms, among them the microscopic world is vary complex. A whole new world hiding in front of our eyes, just because they are small. Bacteria are a group of microbes with no well developed nucleus but id greatly linked to our daily life. It is common knowledge that pathogenic bacteria cause a myriad of infections in humans and other animals ranging from skin infections to life threatening sepsis. Sometimes you may wonder how these tiny organisms are born, how they eat and how they multiply... Let's see one of these questions today..

How do bacteria eat?

            Bacteria are single celled organisms, with no proper nucleus. They do not have mouths. As different species of animals behave differently, various bacterial species behave differently too.

I make my own food

            Some of them make their own food, like plants, by photosynthesis. Have you heard of cyanobacteria? They are commonly known as blue green algae. Interestingly, they are the first life forms to produce oxygen. They are considered as the ancestors of chloroplast in plants. It is said that a eukaryotic cell (cell with a proper nucleus) which swallowed a cyanobacteria, had established a symbiotic relationship with it, and the bacteria evolved into chloroplast. There are some anoxygenic bacteria, which do photosynthesis but do not produce oxygen.

I get my food from other sources

            There are bacteria which feed on dead or decayed matter or some which damages living tissues. Anyway these bacteria require some special mechanisms to "eat" food. I think most of us know how our digestive system works. When we eat food, and the food reaches the intestine, a wide variety of enzymes are secreted, which will break down food into smaller particles and makes it easy to absorb, right? Similarly bacteria also produce certain enzymes, which are secreted outside- Extra cellular enzymes. These chemicals will break down the complex particles, and the smaller fragments are absorbed through cell wall and cell membrane of bacteria. Smaller particles are absorbed passively, while larger ones require special transporters or carriers. This can happen in human body when bacteria cause infection or in bacteria present in the environment.

I love chemicals

            Yet there is another bacterial group with a complicated name- chemolithotrophs. These are chemical loving bacteria. They "eat up" non-living minerals from the environment such as sulfur, iron etc., and create their own fuel for sustenance. Using energy from these minerals they utilize carbon dioxide  and nitrogen to build sugars, proteins and fats, for their cell structure. 

(This is a simplified version of how bacteria acquire nourishment. I have not mentioned about energy production in bacteria to keep it simple. Image credit: generated with AI using Google Gemini)

References:

1. https://en.wikipedia.org/wiki/Cyanobacteria 

2. https://pmc.ncbi.nlm.nih.gov/articles/PMC153454/

3. https://gzscienceclassonline.weebly.com/uploads/1/1/3/6/11360172/2017_bacteria_and_evolution__gz_.pdf

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