Gut microbiota are complex microbial communities that colonise the human gut (which becomes colonised by the beneficial bacteria) soon after birth. These bacteria play important roles in both health and disease, and microbiota disturbance in newborn babies is linked to increased risk of chronic inflammatory diseases, allergies and infection. Antibiotic treatment, which is highly prescribed during the first few years of life, has been suggested as the most significant disturbance to the developing microbiota. It is also possible that exposing developing microbiota to high levels of antibiotics may contribute to the presence of antibiotic-resistant bacteria and transferable resistance genes. Studies such as these to improve the understanding of the impact of antibiotics on the developing microbiota are commonly performed in rodent models.
Why we funded it
This PhD Studentship aims to replace the use of rodent models in gut microbiota studies using wax moth (Galleria mellonella) larvae. There are a number of advantages to using G. mellonella larvae for gut microbiota research, for example, G. mellonella possess an innate immune system with many similarities to that of humans and the larvae can be fed artificial food supplemented with antibiotics and bacteria (which is non-toxic to the larvae).
There has been a significant increase in microbiota studies and a subsequent increase in the number of animals required for these studies. In 2006, over 48,000 studies were registered in PubMed using mice in microbiota studies, this rose to nearly 73,500 studies in 2016. Maxwell and Hall estimate that each experiment requires at least ten mice and each study consists of between one and ten experiments. There are approximately 30 groups in the Norwich Research Park performing related work suggesting that the use of G. mellonella could replace up to 500 mice annually in the Research Park alone.
Initially, the duration of antibiotic treatment necessary to produce larvae without an established gut microbiome will be determined by collecting longitudinal faecal and gut samples from treated and untreated larvae. Attempts will then be made to stably colonise G. mellonella with microbiota samples obtained from infants so the gut microbiota resembles that of a developing human. This colony of G. mellonella will have samples taken at regular intervals to determine when a stable population of bacteria has been established. Once stability has been reached, the G. mellonella will be treated with antibiotics as before. DNA samples will then be taken and deep sequencing analysis performed using shotgun metagenomics to analyse the effect of antibiotics on the microbiome. The data will be correlated to specific antibiotics so that the impact on the presence of commensal bacteria and antibiotic resistance genes/bacteria can be determined. Finally, the ability of introduced beneficial bacteria, such as found in probiotics, to restore the microbiota after being disturbed by antibiotics will be determined by analysing colonisation potential and the impact on the wider microbiota.
If Galleria can be established as a model for the infant gut microbiome then it can be used for a range of other experiments testing the effect of various treatments on the infant gut microbiome.