MU: By combining our expertise, we have begun to investigate the unknown microbiomes of several deep-sea sponges. Through this work, using cutting-edge DNA-sequencing technologies and novel strategies to maximise the diversity of bacteria we can grow from sponge samples, we have been able to isolate novel bacteria that produce antibiotic compounds that kill drug-resistant pathogens, including superbugs like MRSA and E coli.

JA: Antimicrobial resistance (AMR) is one of the biggest threats to global human health. How do your findings help?

MU: The risk posed by AMR requires that we find new antibiotics to fight drug-resistant infections caused by antibiotic-resistant bacteria. By looking in new natural environments, we may find new antibiotics that work in different ways to the ones we currently use.

In the case of our work on deep-sea sponges, it has been demonstrated in a number of studies that individual sponge species harbour relatively specific bacterial populations. The number of sponge species present in these unseen deep-sea environments has not been determined. It is likely that there are many new to science in these locations, each one with the potential of hosting new bacteria. These novel bacteria in turn are likely to produce antibiotics, and other medicines, that are new to science. We have only looked in detail at the microbiomes of two or three different sponge species and we’ve already potentially found some new antibiotics. Expand this to other sponge species we have not even seen and the possibilities are clear.

We’ve also only just begun to look at antibiotic compounds. There are many other lines of enquiry into medically relevant compounds that we’ve not started. Sponges and their microbial populations can produce anti-cancer compounds, analgesics, immune modulators and many other bioactive compounds.

KH: There is a real possibility that with the onset of deep-sea mining we could be destroying species that have important biomedical potential before we even know they exist. We may also be having an impact on the other ecosystem services that the deep sea provides, like climate regulation. At present our lack of understanding means it is difficult to predict potential outcomes beyond the obvious negative consequences. This, in turn, makes it difficult to make informed decisions about how this new industry operates and is managed.

JA: How significant is your discovery?

MU: By looking at the DNA of the bacteria that we have grown from the sponges, we can see that they are not the same as anything that has been grown previously. Some are closely related to previously seen bacteria, but others appear to be really quite novel, possibly new species. We have purified some antibiotic compounds from these bacteria and they are also new to science.

One way to ensure that new antibiotics work against the current drug-resistant superbugs is to use completely new antibiotics. There have been no new classes of antibiotic used in clinical therapy in the last 30 years. The antibiotic compounds we’re finding could be of new classes, giving them a head start against drug-resistant bacteria. This is very significant.

JA: The International Seabed Authority met in July to continue negotiations over a mining code that would govern eventual exploitation. Would mining threaten these sponge species?

KH: Deep-sea mining is a new industry in development. There are three types of deep-sea mining resource recognised, all pertaining to different deep-sea habitats. Polymetallic nodules are found on the abyssal plain, polymetallic sulphides are present as hydrothermal vents, and ferromanganese crusts on some seamounts and ridges.

All of these different resources offer a potential supply of important metals, rare earth elements and other minerals that are used in electronics and the renewable energy sector. We currently stand on the brink of exploitation of the deep sea for these resources. But as we may gain in one way, we potentially lose out in another.

