Liquid handling robots are rarely used in the domain of artificial life. In this field, transitory behaviours of non-equilibrium man-made systems are studied and need an automatic monitoring and logging of results. In addition, artificial life experiments are dynamic with frequent changes, which makes it difficult to apply conventional liquid handling robots as they are designed to automate a pre-defined task. In order to address these issues, we have developed an open source liquid handling robot, EvoBot. It uses a modular approach, which gives us the possibility to reconfigure the robot for different experiments and make it possible for users to add functionality by just developing a function specific module. In addition, it provides sensors and extra functionality for monitoring an experiment, which allows researchers to perform interactive experiments with the aim of prolonging non-equilibrium conditions. In this paper, we describe the modular design of EvoBot, document its performance, and provide a novel example of an interactive experiment in artificial life, where the robot nurtures a microbial fuel cell based on its voltage output.

Microbial fuels cells (MFCs) are bio-electrochemical transducers that generate energy from the metabolism of electro-active microorganisms. The organism Physarum polycephalum is a species of slime mould, which has demonstrated many novel and interesting properties in the field of unconventional computation, such as route mapping between nutrient sources, maze solving and nutrient balancing. It is a motile, photosensitive and oxygen-consuming organism, and is known to be symbiotic with some, and antagonistic with other, microbial species. In the context of artificial life, the slime mould would provide a biological mechanism (along with the microbial community) for controlling the performance and behaviour of artificial systems. In the following experiments it was found that Physarum did not generate significant amounts of power when inoculated in the anode. However, when Physarum was introduced in the cathode of MFCs, a statistically significant difference in power output was observed.

OBJECTIVE:Biofilm microorganisms are known to have a much higher tolerance to antimicrobials compared to their planktonic equivalents. Therefore, traditional antimicrobial susceptibility testing may not extrapolate to clinical treatment of infections of biofilm origin, and as a result, there is a need to not only develop antimicrobials with antibiofilm activity, but also suitable in vitro testing methods for their evaluation. In this study, we report on a novel method of antibiofilm testing using a thermo-reversible matrix (poloxamer 407), coupled with live/dead staining of bacteria cultured from the matrix.METHOD:Pseudomonas aeruginosa (NCIMB 8626) was cultured in medium containing poloxamer 407 at 37°C for 24 hours to generate biofilms. The preparation was cooled to liquefy the poloxamer and allow recovery of the biofilm cells, which were then stained with SYTO9 to determine viability following exposure to four antimicrobials: polyhexanide, octenadine dihydrochloride, povidone-iodine and silver carbonate. Over an 8-minute time period, fluorescence levels were spectrophotometrically measured and compared with bacterial controls, cultured in the absence of poloxamer and without antimicrobial.RESULTS:Untreated cells showed no reduction in viability over this period. Importantly, planktonic cells were more susceptible to test agents compared with those of a 'biofilm' phenotype cultured in poloxamer. Antibiofilm activity was evident for all of the test agents, with highest relative activity seen with octenadine dihydrochloride.CONCLUSION:In summary, a novel and relatively rapid approach to screen compounds for antibiofilm activity has been described. The method uses standard laboratory equipment and can be readily adapted to test a wide range of microorganisms and other antibiofilm compounds.DECLARATION OF INTEREST:This research was, in part, supported by Advanced Medical Solutions in the form of a Knowledge Transfer Project. Mr J. Nosworthy was employed by Advanced Medical Solutions. There are no other conflicts of interests to declare.

The microbial fuel cell (MFC) is an energy transducer that can directly produce electricity from bacterial oxidation of organic matter. MFCs consist of two reaction chambers (anode and cathode) separated by a semipermeable membrane. This study describes the work carried out towards the optimization of critical MFC components, with 3D fabricated materials. The response of the optimized fuel cells, which were fed with soft materials such as gelatin, alginate and Nafion™, is also reported. The optimised components were the membrane and the cathode electrode. A conventional Nafion membrane was substituted with a custom made terracotta sheet and the electrode used was a single sheet of carbon veil coated with an activated carbon paste. The results showed that among the soft materials tested within the anodic chamber, gelatin performed the best; it also revealed that even after a 10-day starvation period gelatin demonstrated better longevity. These results show that MFCs have the potential to be 3D-printed monolithically using the EVOBOT platform.

Microbial fuel cells (MFCs) are energy transducers that convert organic matter directly into electricity, via the anaerobic respiration of electro-active microorganisms. An avenue of research in this field is to employ algae as the organic carbon fuel source for the MFCs. However, in all studies demonstrating the feasibility of this principle, the algal biomass has always been pre-treated prior to being fed to MFCs, e.g. centrifuged, dried, ground into powder, and/or treated by acid-thermal processes. The alternative presented here, is a flow-through system whereby the MFCs were continuously fed by fresh algal biomass. The system consisted of i) a culture of Synechococcus leopoliensis grown continuously in a photo-chemostat, ii) a pre-digester initiating the digestion of the phototrophs and producing a fuel devoid of oxygen, and iii) a cascade of 9 MFCs, hydraulically and electrically independent. This compartmental system could in theory produce 42W of electrical power per cubic metre of fresh culture (6·105cellsmL−1).

Microbial fuels cells (MFCs) are bio-electrochemical transducers that generate energy from the metabolism of electro-active microorganisms. The organism Physarum polycephalum is a slime mould, which has demonstrated many novel and interesting properties in the field of unconventional computation, such as route mapping between nutrient sources, maze solving and nutrient balancing. It is a motile, photosensitive and oxygen-consuming organism, and is known to be symbiotic with some, and antagonistic with other microbial species. In the context of artificial life, the slime mould would provide a biological mechanism (along with the microbial community) for controlling the performance and behaviour of artificial systems (MFCs, robots). In the experiments it was found that P. polycephalum did not generate significant amounts of power when inoculated in the anode. However, when P. polycephalum was introduced in the cathode of MFCs, a statistically significant difference in power output was observed.

The pH of the tongue biofilm is likely to influence microbial composition and ecology with consequent effects on the metabolic activities and generation of volatile sulfur compounds (VSC) and other malodour gasses. The aim of this study was to identify the effects of pH on the development of biofilms and hydrogen sulfide production using an in vitro tongue-derived biofilm model. Community level physiological profiling (CLPP) was employed to examine the influence of pH on the collective metabolic fingerprint of each tongue-derived biofilm. A sorbarod perfusion system (n = 6 sorbarods) was inoculated from a single suspension of tongue scrape sample and mixed community tongue-derived biofilms were grown at pH 5.5, 6.0, 6.5, 7.0 7.5 and 8.0. Biofilms were perfused with medium for 120 h and gas phase samples (n = 4 per biofilm) removed and analysed with a portable sulfide gas chromatograph before being sacrificed into 10 ml sterile PBS-diluent and cells suspended by vortex mixing. Further ten-fold dilutions were made (down to 10(-7)) and dilutions plated out onto selective (fastidious anaerobic agar (FAA) + 0.0025% vancomycin) and non-selective (FAA) media for enumeration of strict and facultative anaerobes respectively. Biofilm suspensions were also mixed with Biolog inoculation fluid and distributed into 96 wells of Biolog AN plates for CLPP. Tongue biofilms developed at pH 7.5 produced significant (p < 0.05) concentrations of H(2)S (≈52.2 ± SEM 5.6 µg H(2)S per ml biofilm gas phase) followed by tongue biofilm developed at pH 7.0 and 8.0 (≈43.2 ± SEM 3.5 and ≈ 39.6 ± SEM 7.3 µg H(2)S per ml biofilm gas phase respectively). Tongue biofilm developed at pH 6.0 and 6.5 produced approximately 21.5 ± SEM 2.3 and 37.1 ± SEM 1.7 µg H(2)S per ml biofilm gas phase respectively and tongue biofilm developed at pH 5.5 produced approximately 0.19 ± SEM 0.09 µg H(2)S per ml biofilm gas phase. Highest numbers of strict and facultative anaerobes were recovered from biofilms at pH 6.5 (1.10 × 10(12) and 2.07 × 10(12) cfu ml(-1) respectively), with a reduced number recovered from pH values above and below this range. CLPP and similarity index revealed biofilms at pH 6.5 and 7.0 most similar (S(j) = 78%) and most diverse in terms of metabolic activity. The biofilm at pH 5.5 was the least related to all others and least diverse. The sorbarod perfusion system, in conjunction with H(2)S analysis and CLPP, enables some of the physiological and ecological effects of pH at a local level within the biofilm on H(2)S production to be identified.