In my previous module we were dealing mostly with antibiotics and of course the Penicillin. It was interesting to investigate the effect of Penicillin on different species of bacteria and try to produce some Penicillin during a period of few days. Well unlike Alexander Fleming that discovered Penicillin by chance, I was not that lucky enough to have my production successful. But that's what happens with Penicillin, in our lab you had be lucky to get a production :) So Penicillin is mould - Penicillium....and yes it grows on our food and on our bread especially when we leave it outside for several days. Some people can be allergic to it. Used as antibiotic, it is effective only towards certain types of bacteria, and like most of the antibiotics it is not universal. So that's why it is important to determine what infection we have and what type of bacteria has caused our infection in order to find the best treatment for it.
Some bacteria are gram-negative which have an outer membrane and that protects them better and makes them more resistant, other are gram-positive that have only one cell wall and more vulnerable. So the gram-positive bacteria are expected to be killed more easily by the antibiotic.
In my experiment I found out that Penicillin was most effective against the gram-positive Micrococcus Luteus and Bacillus Subtilis. It was less effective against Pseudomonas Aeruginosa and Enterococcus Faecalis. Staphylococcus Aureus and Serratia Marcescens were not bothered by it.
How do this bacteria become resistant to antibiotics then? That's quite interesting and quite complicated to explain for here, but they have certain filaments called 'sex pili' where they can transfer genetic information between eachother and that includes antibiotic resistance.
That's how Penicillin looked like ( the stripe in the middle). Not the most pleasant thing to look at, but quite important :)