The 20th century saw unprecedented advances in the manufacture of materials, with chemical and mechanical engineering approaches enabling plastics, composites, aerogels and more. Now in the 21st century, our newfound abilities in biological engineering open the door to a new paradigm - Grown Engineered Materials (GEMs). Rather than blending together and chemically-modifying existing bulk materials ex situ, GEMs will be produced in vivo in the precise, sustainable way that materials are made by nature - with cells working together at the micro scale to grow different polymers in parallel that interact to form self-patterned composites. Using a synthetic biology approach, this breakthrough project will develop and demonstrate the first generation of GEMs, producing these by co-cultivating a set of engineered microbes that we have demonstrated can be grown together as a stable consortium. These material-producing microbes will produce GEMs made from nanocellulose fibres and elastin-like polypeptides (ELPs). These are both repetitive biopolymers that on their own have industrially-attractive properties; bacterial-made nanocellulose is exceptionally pure, biocompatible and possess a high mechanical load capability, while yeast-made ELPs are environment-responsive and can be designed to collapse or extend due to changes in levels of salt, pH or temperature. Having these two biomaterials co-synthesised together from growing engineered cells offers a novel route to making exciting new materials that offer properties beyond those of their constituent parts. This approach is inspired by nature, where we witness plants building impressive biomaterials from weaving cellulose into a mechanically-robust composites by incorporation of different polymers such as lignin. For example, the natural co-production of cellulose in composites with other biopolymers enhances the compressive strength of plant cell walls and also enables new characteristics to emerge. To demonstrate the paradigm of GEMs, our UK and US groups will work together in this project to synthesise and test different ELP designs for how the proteins interact within a growing nanocellulose fibre network. Alongside this we will study, engineer and optimise yeast strains so that these ELP proteins can be efficiently secreted into the growing material by engineered yeast cells that stably co-culture with the cellulose-producing bacteria. By the end of the project we expect to be able to grow high yields of ELP-cellulose composites in just a few days from only our mix of yeasts and bacteria and low-cost growth media. We will assess the material properties of these prototype GEMs and then use synthetic biology tools, such as optogenetics and pattern formation to control how, where and when the composites are made at the micro-scale. This ambitious interdisciplinary research project will utilise many state-of-the-art approaches to biological engineering that our two groups have international expertise in. From synthetic protein polymer design, strain optimisation and synthetic biology genetic control, right through to systems biology, transcriptomics, machine learning and biomaterial characterisation. We plan to produce a range of ELP-cellulose composite materials that are genetically-tunable, so that changes in the way DNA is written in the microbial cells can predictably lead to changes in the materials and their properties. Our aim is to realise the paradigm of GEMs and provide the blueprint, engineered strains and synthetic biology toolkit for others to utilise this approach in the future.

Phenotypic variation is the raw material of evolution and the target of natural and sexual selection. However, evolution can only occur through changes in gene frequencies at the level of DNA. Our proposal capitalizes on a recently discovered adaptive morphological mutation to explicitly link how changes at the genomic level translate into changes at the phenotypic level, which are then subject to rapid and quantifiable evolutionary change in a wild population. We will study a mutation in the Pacific field cricket, Teleogryllus oceanicus, that erases sound-producing structures on male wings. Males ordinarily sing to attract females for mating, but in doing so, they also attract a deadly, acoustically-orienting parasitoid fly. The silencing mutation, flatwing, arose in a wild population in 2003 and rapidly spread to near-fixation over the course of approximately 20 generations because it protects males from attack by the fly. Silent flatwing males appear to act as satellites to the remaining callers in the population by intercepting and mating with responding females. The rapid spread of the flatwing mutation represents one of the fastest rates of evolution ever recorded in the wild. The mutation is a simple Mendelian trait inherited on the sex chromosome. The main goals of our proposal are to (1) identify in what region of the genome the mutation resides, and the underlying genetic changes, and (2) characterize broad-scale differences in gene expression between flatwing and normal-wing male crickets, and between crickets that have experienced different social environments resulting from the presence or absence of silent males. These goals will provide the evolutionary biology community with a better understanding of the type of genomic variation targeted by selection in the wild (e.g. coding genes vs. regulatory genes). Our results will also demonstrate how a major evolutionary event has knock-on effects on the regulation and expression of other genes, thereby exposing new phenotypic traits to selection. The T. oceanicus study system provides an excellent opportunity to demonstrate how evolution works in real time, in the wild, and how change in a single trait initiates a cascade of effects that alter gene expression, phenotypic traits, and selection pressure.

Over the last five years, research led by this team has made it apparent that the reaction of iodide with ozone at the sea surface plays an important role in controlling the chemical composition of the troposphere. This process directly controls the deposition of O3 to the oceans and is the dominant source of reactive iodine to the atmosphere, which leads to significant loss of tropospheric O3. Ozone concentrations are directly impacted but through changes to the atmospheric oxidants, indirect changes also occur to methane and aerosols leading to potential ramifications on climate, air quality and food security. This is likely a biogeochemical negative feedback for tropospheric O3 and oxidants, which, since it is dependent on both atmospheric O3 and ocean iodide concentrations, will have changed over time. Iodine is also an essential human nutrient. The transport of iodine from the oceans to the atmosphere and subsequent deposition over land is a pathway by which marine iodine may enter the terrestrial food chain, and iodine radioisotopes released to the sea may be dispersed. These iodine ocean-atmosphere processes are now being incorporated into chemical transport models but critical uncertainties remain. The marine iodide distribution is poorly understood, yet it is likely that it will be subject to change as a result of changes in ocean circulation, biological productivity and ocean deoxygenation. This proposal brings together marine and atmospheric scientists in order to address uncertainties in the marine iodine flux and associated ozone sink. Specifically, it aims to quantify the dominant controls on the sea surface iodide distribution and improve parameterisation of the sea-to-air iodine flux and of ozone deposition. This will be achieved through a combination of laboratory experiments, field measurements and ocean and atmospheric modelling.

Over the past two decades, improving seismic and geodetic data have revealed that many faults accumulate their slip via a suite of phenomena that are not predicted by conventional friction laws: via slow earthquakes, or fault slip events whose average slip rates are between 0.1 microns/s and 1 mm/s, a factor of 1 thousand to 10 million slower than the 1 m/s slip rates typical of earthquakes. Slow earthquakes are now found at most subduction zones, where they accommodate about half of the plate interface slip in the region down-dip of the seismogenic zone. But currently, we do not know which fault zone processes generate the aseismic slip we observe in slow earthquakes. It is important to improve our understanding of slow earthquakes because they occur next to the seismogenic zone. They are capable of triggering large and damaging earthquakes. In this project, we focus on the smallest but most abundant slow earthquakes: tremor. Tremor consists of hundreds to millions of small, closely spaced, slow earthquakes. The earthquakes can be rapidly observed and could be used to track larger-scale aseismic slip variations and to assess whether that slip could trigger hazardous seismic slip. But like other slow earthquakes, tremor remains poorly understood. The goal of this project is to determine which physical process creates tremor and limits its slip rates to around 1 mm/s. Several explanations of tremor's low slip rates have been proposed. It is possible that tremor is governed by the same frictional sliding process that governs normal earthquakes. Tremor may be slow only because the fault's frictional strength or normal stress is low, and thus is unable to drive rapid slip. Alternatively, a more novel physical process could limit tremor's slip speeds. Changes in pore fluid pressure might pull the fault shut, inhibiting rapid slip. Or tremor could be a collection of failed earthquake nucleations, which arise because of stress perturbations on a nominally stable fault. In the proposed work, we will use targeted seismological analysis to assess five proposed models of tremor generation. We will test specific model predictions using high-quality seismic data from some of the best-observed tremor in the world: that near Parkfield, CA. To test our model predictions, we will first examine how tremor is related to shorter and longer slow earthquakes. If tremor is governed by the same novel fault zone physics that governs larger slow earthquakes, there should be a continuum of slow earthquakes with a wide range of sizes and slip rates. The presence or absence of the continuum will be important for constraining the processes governing large and small slow earthquakes, as only a few of the proposed models of large slow earthquakes are consistent with the continuum's wide-ranging slip rates. We will search for 0.05 to 1-second-long events in this continuum using recently developed seismic analysis techniques. And we will examine the clustering of tremor, in order to (1) identify larger, hours-long slow earthquakes potentially within the continuum and (2) to constrain the relationship between tremor and larger-scale slip. Finally, to further test the models, we will move into the details of individual tremor events and probe the evolution of slip in individual tremor earthquakes. We will closely examine the seismic signals produced by tremor in order to determine how tremor's earthquakes' durations, sizes, and complexities vary from event to event. These data will let us determine how much of tremor's properties are controlled by particular rheologies and how much is due to local fault zone structure. By pursuing a suite of features that can test our models, we will be able to determine which physical processes generate the numerous small earthquakes that constitute tremor, so that we may better understand slow earthquake slip and more confidently use tremor to track large-scale slip at depth.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.