A metal-eating bacteria might be important in the fight against multidrug-resistant bacteria. But how and why does the bacteria produce the antibiotics we need? That is what we try to discover using metabolomics techniques.
Multidrug-resistant organisms are causing a great crisis for the public health, representing a major cause of morbidity and mortality worldwide. This is because of their potential to produce invasive infections, the difficulty in controlling them in infected patients and their resistance to multiple antibiotics, which has significantly increased. It is therefore an urgent need for new class antibiotics that are effective against MDR.
Metals in medicine
The use of metals in medicine is not new. The development of molecule complexes with metals as potential medicinal agents has been on the rise in the last decades.
In my research, I study the metal-eating Pseudumonas strain.
The bacteria Pseudomonas is widespread in nature, and are widely studied in relation to the production of a large variety of bioactive compounds. In addition Pseudomonas are able to produce an organometallic antimicrobial compound (OAC) that can be an alternative treatment for infections caused by multidrug-resistant organisms. It does this by the help of metal, more specifically copper.
An agar plate was inoculated with Klebsiella pneumonia. The disc containing OAC was placed on the agar surface. Antimicrobial agent diffuses into the agar and inhibits growth of the microorganism and show the diameter of inhibition growth zone.
Ideal conditions for the eating of copper
One of our goals in the lab is to figure out the ideal conditions for the Pseudomonas to feed on copper and hence produce the basis for a potential antibiotic treatment targeting multi-resistant bacteria. However, can Pseudomonas produce organometallic antimicrobial compound in any medium?
In the new Bruheim lab at the Department of Biotechnology at NTNU we used different culture medium for Pseudomonas growth. We observed that only on a medium containing peptides with copper had organometallic antimicrobial compound production (pictures).
Extracts from culture medium.
TLC of extracellular metabolites of Pseudomonas in a specific culture medium. This technique separated the compounds of the extract and allowed to identify organometallic antimicrobial compound (OAC) under certain medium. The OAC band only was observed in medium with peptides and copper ( LB + Cu and NB + Cu)
The inportance of metabolomics studies
Why does the mineral medium (peptide free) not produce organometallic antimicrobial compound? How do the copper affect the metabolism of Pseudomonas?
I believe metabolomics studies can be very useful to answer these questions and to discover how Pseudomonas produce antibiotic compound. Metabolome analyses are a suite of analytical approaches that enable us to capture changes in the metabolites (small molecular weight components, typically less than 1500 Da) in biological systems. Bruheim group has a wide experience in using Mass spectrometry (MS) for this purpose.
The key challenge here is to be able to capture changes in a reproducible and reliant manner that is representative of the events that take place in vivo (in real life). Typically, the analysis is carried out in vitro in the laboratory, by isolating the system and extracting the metabolome. MS-based approaches enable us to capture metabolomic changes with high sensitivity and resolution. When developing the technique for different biological systems, there are similarities in challenges and differences that are specific to the system under investigation.
In my work, the goal is to answer some of the questions concerning the Pseudomonas production of organometallic antimicrobial compounds (OAC). One of the important things we have discovered is the necessity of peptides. So, I study how the copper and peptides affect the Pseudomonas metabolism to produce OAC needed for its potential targeting of multidrug-resistant organisms. By using the metabolomics tools. I am getting closer and closer to an answer.
From antibiotics to beer
I feel lucky to have this opportunity during my status as a visiting PhD student from Brazil. It is definitely a unique experience both professionally and socially. The subject is very interesting and taking part in all the stages of process design, sampling, experimental verification and bioinformatics analysis is very gratifying. Moreover, participating in other investigations at the Bruheim lab, such as beer project, allowed me to approach molecular techniques and try good beers.
This blog post is written by Miguel O. P. Navarro. He is a PhD guest researcher at Per Bruheim lab at the Department of Biotechnology at NTNU: