Description of the laboratory research work
Bacteria have evolved the ability to grow as surface associated populations and communities, where the cells are encased in a matrix of self-produced, extracellular polymeric substances (EPS). This adaptation increases the stress tolerance and antibiotic resistance as well as facilitating nutrient capture and inter-species interactions. My group studies how bacterial biofilms form, focussing on the specific genes involved in this process as well as the environmental and medical consequences of biofilm formation. In particular, we have studied the end-stage of biofilm development, dispersal. Discoveries from the group include the role of nitric oxide as endogenously produced dispersal signal and the role of filamentous phage in biofilm formation and control the the bacterial host. In addition, we are interested in how multi species biofilm communities form, including genetic, metabolic and EPS based responses. This program of research, the focus of this proposal, has made important discoveries such as shared defence mechanisms, enhanced biomass (through resource sharing), reduced genetic variation in biofilm communities and the role of quorum sensing in mediating species-specific interactions. This research platform has a strong mix of academic and applied science and is well supported by funding from national and international funding agencies as well as direct industry funding support.
1. Nitric oxide as a biofilm dispersing signal
As a biofilm matures, bacteria may experience resource limitations, e.g. carbon source or oxygen, and under such conditions, it would be advantageous to disperse from the biofilm to migrate to new habitats that are not resource limited. Nitric oxide (NO) is a small molecule that some bacteria produce under limiting conditions and perception of NO induces active dispersal from biofilms. In this program, we seek to define how bacteria produce, perceive and respond to NO to induce dispersal of the biofilm. This fundamental view of the NO signalling pathway can also be used to amplify the effect of NO as a dispersal signal. When coupled with Chemistry, novel, bespoke, NO donors can be designed for the control of biofilms. For example, we have developed NO donors that only release the NO in the presence of bacteria and this has significant implications for use as a medical therapeutic to control biofilm based infections.
2. Synthetic communities to model species interactions
My group developed and validated one of the first experimentally tractable and reproducible mixed species biofilm communities. We have demonstrated emergent properties of this community, including shared metabolism and shared stress defence mechanisms. This system is now the basis for detailed molecular studies of microbial communities.
3. Skin communities to understand the role of microbes in contributing to healthy skin
Leveraging the experience gained from the synthetic community in (a), we subsequently developed a biofilm community derived from microorganisms from the skin. This now enables us to characterise the mechanisms of interaction that dictate the relative abundances of individual species, which is linked to skin health.
4. Complex marine communities and their role in driving corrosion of metal surfaces
The role of microorganisms in the corrosion process are traditionally studied from a single species perspective and yet never reflects the natural corrosion process. This lack of correlation to the real world is a reflection of the fact that natural communities involved in this process involve many species. We have developed reproducible communities for the study of corrosion under more realistic conditions. This program also incorporates materials scientists and electrochemists such that we can address the problem in a holistic fashion.
5. The role of marine microbial communities in the settlement of macrofouling organisms
One of the open questions in biofouling is the role of the microbial biofilm in the recruitment of macrofouling organisms. Building on our expertise in establishing and characterising complex consortia, we have developed a program that will enable us to study the impact of the substratum on the formation of microbial consortia as well as the impact of different consortia on the settlement of higher organisms. Further, by working closely with surface scientists, we will develop coatings that encourage the growth of desired microbial communities to subsequently modulate macrofouling.
Full list of publications can be found here
- McDougald D, Rice SA, Barraud N, Steinberg PD, Kjelleberg S. 2012. Should we stay or should we go: Mechanisms and ecological consequences for bacterial dispersal from biofilms. Nature Reviews Microbiology 10:39-50.
- Flemming H-C, Wingender J, Szewzyk U, Steinberg P, Rice SA, Kjelleberg S. 2016. Biofilms: an emergent form of bacterial life. Nat Rev Micro 14:563-575.
- Lee KWK, Yam KHJ, Periasamy S, Mukherjee M, Kjelleberg S, Rice SA. 2016. Interspecific diversity reduces and functionally substitutes for intraspecific variation in biofilm communities. ISME J 10:846-857.
- Nair HAS, Periasamy S, Yang L, Kjelleberg S, Rice SA. 2017. Real time, in situ ratiometric imaging and quantification of c-di-GMP during biofilm development. J Biol Chem 292:477-487.
- Poh WH, Barraud N, Guglielmo S, Lazzarato L, Rolando B, Fruttero R, Rice SA. 2017. Furoxan Nitric Oxide Donors Disperse Pseudomonas aeruginosa Biofilms, Accelerate Growth, and Repress Pyoverdine Production. ACS Chemical Biology 12:2097-2106.
- Tan CHG, Lee KWK, Burmølle M, Kjelleberg S, Rice SA. 2017. All together now: Multispecies Biofilm Models. Environ Microbiol 19:42-53.
- Oh H-S, Constancias F, Ramasamy C, Yi TP, Yee MO, Fane AG, McDougald D, Rice SA. 2018. Biofouling control in reverse osmosis by nitric oxide treatment and its impact on the bacterial community. J Memb Sci 550:313-321.
- Zhu X, Oh H-S, Ng YCB, Tang PYP, Barraud N, Rice SA. 2018. Nitric oxide-mediated induction of dispersal in Pseudomonas aeruginosa biofilms is inhibited by flavohemoglobin production and is enhanced by imidazole. Antimicrob Agents Chemther 62:e01832-17
- Keshvardoust P, Huron VAA, Clemson M, Barraud N, Rice SA. 2020. Nitrite production by ammonia-oxidizing bacteria mediates chloramine decay and resistance in a mixed-species community. Microbial Biotechnology 13:1847-1859.
- Chilambi GS, Hinks J, Matysik A, Zhu X, Choo PY, Liu X, Chan-Park MB, Bazan GC, Kline KA, Rice SA. 2020. Enterococcus faecalis Adapts to Antimicrobial Conjugated Oligoelectrolytes by Lipid Rearrangement and Differential Expression of Membrane
Stress Response Genes. Frontiers in Microbiology