In the class that I'm teaching, we found that several PCR products, amplified from the 16S ribosomal RNA genes from bacterial isolates, contain a mixed base in one or more positions. We picked samples where the mixed bases were located in high quality regions of the sequence (Q >40), and determined that the mixed bases mostly likely come from different ribosomal RNA genes. Many species of bacteria have multiple copies of 16S ribosomal RNA genes and the copies can differ from each other within a single genome and between genomes. Now, in one of our last projects we are determining where ... Read more
Ribosomes are molecular machines that build new proteins. This process of synthesizing a protein is also known as translation. Many antibiotics prevent translation by binding to ribosomal RNA. In the class that I'm teaching, we're going to be looking at ribosome structures to see if the polymorphisms that we find in the sequences of 16S ribosomal RNA are related antibiotic resistance. This is related to our ... Read more


Do other organisms make antibiotics?
As far as I can tell, most of the commercially produced antibiotics are made by bacteria, fungi, and a bit chemistry (more on that in a moment).

It appears, however, that compounds with antimicrobial properties are made by just about everything. Just to make things complicated, these molecules are sometimes called "antibiotics" in the literature and sometimes they're not. Many of the molecules with antimicrobial activity are short peptides–chains of amino acids between 10 and 50 residues long (1 ... Read more

This is a multi-part series on antibiotic resistance in bacteria.

Eventually, we'll reach the ways in which bacteria develop antibiotic resistance, but before we get there, we'll spend a little more time on antibiotics themselves.

What have we learned so far?

1. Antibiotics are natural products, made by bacteria and some fungi. We have also learned about the difference between antibiotics and synthetic drugs. There isn't always a clear distinction since chemical groups can be added to antibiotics, making them partly synthetic ... Read more

What's the difference between a synthetic drug and an antibiotic?

Sometimes there's no difference at all. Let's take a look at chloramphenicol and couple of pencillins.

Chloramphenicol kills many different kinds of bacteria by interfering with their ability to make new proteins. Here's a point where language gets tricky. Originally, chloramphenicol was isolated and purified from Streptomyces (a kind of bacteria). But, chloramphenicol is small and chemists are able to synthesize it. So even though we consider antibiotics to be natural products, they don't ... Read more

Antibiotics are molecules of biological warfare. Produced by bacteria and some fungi, in response to extracellular signals, antibiotics represent a diverse group of compounds that inhibit bacterial growth at different points and different stages of the life cycle. We will get around to antibiotic resistance, but in these few words, I think I already wrote quite a bit. Admittedly, some of these ideas need a bit of chewing, if they are to be properly digested. Already, I can imagine hands raised and questions waiting to be asked.

What are antibiotics made of? ... Read more

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