There is a groundswell of interest in applying phototrophic microorganisms, specifically microalgae and cyanobacteria, for biotechnology and ecosystem service applications. However, there are inherent challenges associated with conventional routes to their deployment (using ponds, raceways and photobioreactors) which are synonymous with suspension cultivation techniques. Cultivation as biofilms partly ameliorates these issues; however, based on the principles of process intensification, by taking a step beyond biofilms and exploiting nature inspired artificial cell immobilisation, new opportunities become available, particularly for applications requiring extensive deployment periods (e.g., carbon capture and wastewater bioremediation). We explore the rationale for, and approaches to immobilised cultivation, in particular the application of latex-based polymer immobilisation as living biocomposites. We discuss how biocomposites can be optimised at the design stage based on mass transfer limitations. Finally, we predict that biocomposites will have a defining role in realising the deployment of metabolically engineered organisms for real world applications that may tip the balance of risk towards their environmental deployment.

Microalgae and cyanobacteria are effective platforms for environmental remediation (phycoremediation), particularly of air and water. There is limited scope to deploy suspension cultures due to space, cost and maintenance challenges—driving an imperative towards biofilm-based treatment systems; however, these systems are ill-equipped for rapid and mobile deployment. In this study we explored the main technical challenges to developing cheap, accessible and low-maintenance engineered biofilm systems (biocomposites) comprising cyanobacteria (Synechococcus elongatus) immobilised to a range of textiles (n = 4) by natural or synthetic latex binders (n = 16), chitosan or shellac. Biocomposite viability (measured as net CO2 uptake) was assessed over 20 days in semi-batch trials. No maintenance was required during this period as the humidity within the reactor was sufficient to support metabolism. Two commercial natural latex binders (AURO 320 and 321) supported strong growth within the biocomposite, outperforming suspension controls. There was variation in textiles performance, with an 80/20 polyester-cotton blend performing most consistently. Biocomposite formulation was varied in terms of binder solids content and cell loading rate, with 5% solids and 2.5% cell loading the most effective combination. We demonstrate the technical feasibility of fabricating functional textile-based cyanobacteria biocomposites and discuss this within the context of developing decentralised wastewater treatment services.

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A system of three open resonators which is controlled by a microprocessor is described. This facility allows simultaneous measurements of scattering phenomena to be made at chosen frequencies within the range of 10 GHz to 90 GHz. The microprocessor records the experimental data and provides output of results in graphical form either directly or in association with a mainframe computer. The system provides an advance in open resonator technology, allowing measurements to be made very quickly and at frequencies widely separated over the microwave and millimetre-wave bands.THE WORK TO BE DESCRIBED An achievement, which we have recently demonstrated, in the technology associated with open resonators is the ability both to control the operation of these resonators by a microprocessor and to use the facilities of the microprocessor to store, process and plot the data of a set of measurements over an extensive frequency range 10 -90 GHz. The greatly increased speed in measurement (relative to that possible with conventional result taking) thus obtained, significantly widens the scope of these resonators and extends their capabilities in measurements of, scattering cross-sections, cross-polar generation, propagation effects and dielectric properties. In this submission we illustrate the operation of the system by describing its use in the study of scattering by particles and in the measurement of resonator field profiles. Some emphasis will be placed on the situation where the object whose properties are to be measured is changing rapidly and the ability of the system to cope with thiu will be discussed. A further major advantage which has been realised by the automation of measurements, is that three separate resonators can be controlled simultaneously (here at frequencies centred on 10 GHz, 35 GHz and 70 GHz) so that measurements in the resonators are either made simultaneously or in quick succession. Measurements taken in open resonators are characterised by high accuracy resulting from the sensitivity associated with high valued Q-factors. The development of the three resonator system adds to this, the ability to make fast measurements over a very wide frequency range. The operation of the system and results obtained will be demonstrated by describing the following, (a) The system -resonators and the associated microprocessor operation.(b) Preliminary demonstration of simultaneous operation of the three resonators.