Looking into nature for novel biofilm-modulating agents

Posted on November 27, 2019   by Georgios Efthimiou

Antimicrobial resistance (AMR) is one of the most difficult problems we face. Scientists are increasingly turning to nature to find novel antimicrobials and agents to help in the fight against AMR. Dr Georgios Efthimiou from the University of Hull is looking for novel agents that can prevent biofilm formation, a phenomenon that can make infections incredibly difficult to treat. He presented his work at the ‘Antimicrobial drug discovery from traditional and historical medicine’ Focused Meeting which took place in October.

Microbial biofilms are considered to be a major health hazard, leading to serious infections that are difficult to treat. Usually biofilms are produced when microbes attach themselves to a surface and excrete a polysaccharide matrix that protects them from antibiotics, disinfectants and the attacks from our immune system. Biofilms have also been associated with medical device-related infections, chronic wound infections and foodborne disease outbreaks in food processing areas. However, not all biofilms are bad. For instance, the ability of probiotic bacteria to form biofilms helps them to colonise the intestine.

My lab at the University of Hull is aiming to identify novel biofilm-modulating compounds by screening a variety of extracts of natural sources, such as honey, propolis, medicinal plants and common herbs.

This screening is done by using plastic 24-well plates and the classic biofilm assay. The microbes are allowed to grow in liquid broth for 24 hours (or more, depending on the strain) and gradually form biofilms at the bottom of the well. The biofilms are then washed with water and stained with crystal violet. Extracts of the various natural sources can be added either at the beginning of the screening, to investigate the ability of each to prevent biofilm formation (or growth), or after the biofilm has been produced, aiming to test the ability of the extract to eradicate the already-formed biofilms. Different extract concentrations, pathogens and time points can be examined.

After the identification of effective extracts, we move on to finding out which compound is modulating the biofilm by a process known as bioassay-guided fractionation. This involves analysis of the compounds in the extract by mass spectrometry and testing different fractions on microbes, as described above, until the biofilm-modulating compound is identified. This step is important, as good knowledge of the inhibitory or activating mechanisms will lead to more effective treatments and interventions.

The applications of such compounds are of great importance for the healthcare industry. If a natural agent inhibits biofilm formation then it can be used for designing new wound-dressing products, disinfectants and detergents or developing new antibacterial treatments, perhaps in combination with a strong antibiotic. On the other hand, if it promotes biofilm formation, then it can be used for improving probiotic colonisation in the gut or on the skin – the skin microbiome has attracted a lot of scientific attention lately, as it has been shown to be very important for both wound recovery and skincare e.g. anti-ageing. 

Furthermore, such compounds can be used in a variety of engineering cases, such as biofouling removal and purification of water pipe systems. Therefore, our growing team at Hull aims to liaise with industrial partners and further explore the applicability of our extracts and chemical compounds. We welcome PhD and MRes applicants, as well as summer interns and visiting researchers from around the world.

You can visit Dr Efthimiou’s lab website at:  https://efthimioulab.weebly.com/