Polyploid cyanobacterial genomes provide a reservoir of mutations, allowing rapid evolution of herbicide resistance.

Adaptive mechanisms in bacteria, which are widely assumed to be haploid or partially diploid, are thought to rely on the emergence of spontaneous mutations or lateral gene transfer from a reservoir of pre-existing variants within the surrounding environment. These variants then become fixed in the population upon exposure to selective pressures. Here, we show that multiple distinct wild-type (WT) substrains of the highly polyploid cyanobacterium Synechocystis sp.

Is it realistic to use microbial photosynthesis to produce electricity directly?

It is possible to generate small amounts of electrical power directly from photosynthetic microorganisms-arguably the greenest of green energy. But will it have useful applications, and what are the hurdles if so?

Development of a Biotechnology Platform for the Fast-Growing Cyanobacterium sp. PCC 11901.

sp. PCC 11901 reportedly demonstrates the highest, most sustained growth of any known cyanobacterium under optimized conditions. Due to its recent discovery, our knowledge of its biology, including the factors underlying sustained, fast growth, is limited.

Synthetic biology and bioelectrochemical tools for electrogenetic system engineering.

Synthetic biology research and its industrial applications rely on deterministic spatiotemporal control of gene expression. Recently, electrochemical control of gene expression has been demonstrated in electrogenetic systems (redox-responsive promoters used alongside redox inducers and electrodes), allowing for the direct integration of electronics with biological processes. However, the use of electrogenetic systems is limited by poor activity, tunability, and standardization.

A dual compartment cuvette system for correcting scattering in whole-cell absorbance spectroscopy of photosynthetic microorganisms.

Absorption spectroscopy is widely used to determine absorption and transmission spectra of chromophores in solution, in addition to suspensions of particles, including micro-organisms. Light scattering, caused by photons deflected from part or all of the cells or other particles in suspension, results in distortions to the absorption spectra, lost information and poor resolution. A spectrophotometer with an integrating sphere may be used to alleviate this problem.

The Development of Biophotovoltaic Systems for Power Generation and Biological Analysis.

Biophotovoltaic systems (BPVs) resemble microbial fuel cells, but utilise oxygenic photosynthetic microorganisms associated with an anode to generate an extracellular electrical current, which is stimulated by illumination. Study and exploitation of BPVs have come a long way over the last few decades, having benefited from several generations of electrode development and improvements in wiring schemes. Power densities of up to 0.

A Storable Mediatorless Electrochemical Biosensor for Herbicide Detection.

A novel mediatorless photo-bioelectrochemical sensor operated with a biofilm of the cyanobacterium PCC6803 . for herbicide detection with long term stability (>20 days) was successfully developed and tested. Photoanodic current generation was obtained in the absence of artificial mediators.

Biophotovoltaics: Design and Study of Bioelectrochemical Systems for Biotechnological Applications and Metabolic Investigation.

Biophotovoltaic methods rely on the fact that photosynthetic microorganisms, like many others, can export small amounts of electric current. For photosynthetic organisms, this current usually increases on illumination. This "exoelectrogenic" property may be of biotechnological interest, and may also provide useful experimental insights into the physiological status of the cell.

Electrochemical Characterisation of Bio-Bottle-Voltaic (BBV) Systems Operated with Algae and Built with Recycled Materials.

Photobioelectrochemical systems are an emerging possibility for renewable energy. By exploiting photosynthesis, they transform the energy of light into electricity. This study evaluates a simple, scalable bioelectrochemical system built from recycled plastic bottles, equipped with an anode made from recycled aluminum, and operated with the green alga .

Porous translucent electrodes enhance current generation from photosynthetic biofilms.

Some photosynthetically active bacteria transfer electrons across their membranes, generating electrical photocurrents in biofilms. Devices harvesting solar energy by this mechanism are currently limited by the charge transfer to the electrode. Here, we report the enhancement of bioelectrochemical photocurrent harvesting using electrodes with porosities on the nanometre and micrometre length scale.

Platinum-free, graphene based anodes and air cathodes for single chamber microbial fuel cells.

Microbial fuel cells (MFCs) exploit the ability of microorganisms to generate electrical power during metabolism of substrates. However, the low efficiency of extracellular electron transfer from cells to the anode and the use of expensive rare metals as catalysts, such as platinum, limit their application and scalability. In this study we investigate the use of pristine graphene based electrodes at both the anode and the cathode of a MFC for efficient electrical energy production from the metabolically versatile bacterium CGA009.

Electricity generation from digitally printed cyanobacteria.

Microbial biophotovoltaic cells exploit the ability of cyanobacteria and microalgae to convert light energy into electrical current using water as the source of electrons. Such bioelectrochemical systems have a clear advantage over more conventional microbial fuel cells which require the input of organic carbon for microbial growth. However, innovative approaches are needed to address scale-up issues associated with the fabrication of the inorganic (electrodes) and biological (microbe) parts of the biophotovoltaic device.

Photoelectrochemistry of Photosystem II in Vitro vs in Vivo.

Factors governing the photoelectrochemical output of photosynthetic microorganisms are poorly understood, and energy loss may occur due to inefficient electron transfer (ET) processes. Here, we systematically compare the photoelectrochemistry of photosystem II (PSII) protein-films to cyanobacteria biofilms to derive: (i) the losses in light-to-charge conversion efficiencies, (ii) gains in photocatalytic longevity, and (iii) insights into the ET mechanism at the biofilm interface. This study was enabled by the use of hierarchically structured electrodes, which could be tailored for high/stable loadings of PSII core complexes and Synechocystis sp.

Response to Weber et al.

A number of previous studies have reported microbial degradation of polyethylene [1,2]. Fourier transform infrared spectroscopy analyses of the products of degradation are, in many cases, contradictory, especially with regard to the relative intensities of different signals, suggesting that pathways are complex and may differ among organisms [1,2]. A detailed consideration of possible degradation products and pathways would have been beyond the scope of our initial brief report [3].

Polyethylene bio-degradation by caterpillars of the wax moth Galleria mellonella.

Plastics are synthetic polymers derived from fossil oil and largely resistant to biodegradation. Polyethylene (PE) and polypropylene (PP) represent ∼92% of total plastic production. PE is largely utilized in packaging, representing ∼40% of total demand for plastic products (www.

Electrical output of bryophyte microbial fuel cell systems is sufficient to power a radio or an environmental sensor.

Plant microbial fuel cells are a recently developed technology that exploits photosynthesis in vascular plants by harnessing solar energy and generating electrical power. In this study, the model moss species , and other environmental samples of mosses, have been used to develop a non-vascular bryophyte microbial fuel cell (bryoMFC). A novel three-dimensional anodic matrix was successfully created and characterized and was further tested in a bryoMFC to determine the capacity of mosses to generate electrical power.

Hydrocarbons Are Essential for Optimal Cell Size, Division, and Growth of Cyanobacteria.

Cyanobacteria are intricately organized, incorporating an array of internal thylakoid membranes, the site of photosynthesis, into cells no larger than other bacteria. They also synthesize C15-C19 alkanes and alkenes, which results in substantial production of hydrocarbons in the environment. All sequenced cyanobacteria encode hydrocarbon biosynthesis pathways, suggesting an important, undefined physiological role for these compounds.

Photosynthetic, respiratory and extracellular electron transport pathways in cyanobacteria.

Cyanobacteria have evolved elaborate electron transport pathways to carry out photosynthesis and respiration, and to dissipate excess energy in order to limit cellular damage. Our understanding of the complexity of these systems and their role in allowing cyanobacteria to cope with varying environmental conditions is rapidly improving, but many questions remain. We summarize current knowledge of cyanobacterial electron transport pathways, including the possible roles of alternative pathways in photoprotection.

A High Power-Density, Mediator-Free, Microfluidic Biophotovoltaic Device for Cyanobacterial Cells.

Biophotovoltaics has emerged as a promising technology for generating renewable energy because it relies on living organisms as inexpensive, self-repairing, and readily available catalysts to produce electricity from an abundant resource: sunlight. The efficiency of biophotovoltaic cells, however, has remained significantly lower than that achievable through synthetic materials. Here, a platform is devised to harness the large power densities afforded by miniaturized geometries.

Exploiting algal NADPH oxidase for biophotovoltaic energy.

Photosynthetic microbes exhibit light-dependent electron export across the cell membrane, which can generate electricity in biological photovoltaic (BPV) devices. How electrons are exported remains to be determined; the identification of mechanisms would help selection or generation of photosynthetic microbes capable of enhanced electrical output. We show that plasma membrane NADPH oxidase activity is a significant component of light-dependent generation of electricity by the unicellular green alga Chlamydomonas reinhardtii.

Phycobilisome-Deficient Strains of Synechocystis sp. PCC 6803 Have Reduced Size and Require Carbon-Limiting Conditions to Exhibit Enhanced Productivity.

Reducing excessive light harvesting in photosynthetic organisms may increase biomass yields by limiting photoinhibition and increasing light penetration in dense cultures. The cyanobacterium Synechocystis sp. PCC 6803 harvests light via the phycobilisome, which consists of an allophycocyanin core and six radiating rods, each with three phycocyanin (PC) discs.

Terminal oxidase mutants of the cyanobacterium Synechocystis sp. PCC 6803 show increased electrogenic activity in biological photo-voltaic systems.

Biological photo-voltaic systems are a type of microbial fuel cell employing photosynthetic microbes at the anode, enabling the direct transduction of light energy to electrical power. Unlike the anaerobic bacteria found in conventional microbial fuel cells that use metals in the environment as terminal electron acceptors, oxygenic photosynthetic organisms are poorly adapted for electron transfer out of the cell. Mutant strains of the cyanobacterium Synechocystis sp.

Biological photovoltaics: intra- and extra-cellular electron transport by cyanobacteria.

A large variety of new energy-generating technologies are being developed in an effort to reduce global dependence on fossil fuels, and to reduce the carbon footprint of energy generation. The term 'biological photovoltaic system' encompasses a broad range of technologies which all employ biological material that can harness light energy to split water, and then transfer the resulting electrons to an anode for power generation or electrosynthesis. The use of whole cyanobacterial cells is a good compromise between the requirements of the biological material to be simply organized and transfer electrons efficiently to the anode, and also to be robust and able to self-assemble and self-repair.

Comparison of power output by rice (Oryza sativa) and an associated weed (Echinochloa glabrescens) in vascular plant bio-photovoltaic (VP-BPV) systems.

Vascular plant bio-photovoltaics (VP-BPV) is a recently developed technology that uses higher plants to harvest solar energy and the metabolic activity of heterotrophic microorganisms in the plant rhizosphere to generate electrical power. In the present study, electrical output and maximum power output variations were investigated in a novel VP-BPV configuration using the crop plant rice (Oryza sativa L.) or an associated weed, Echinochloa glabrescens (Munro ex Hook.

Surface morphology and surface energy of anode materials influence power outputs in a multi-channel mediatorless bio-photovoltaic (BPV) system.

Bio-photovoltaic cells (BPVs) are a new photo-bio-electrochemical technology for harnessing solar energy using the photosynthetic activity of autotrophic organisms. Currently power outputs from BPVs are generally low and suffer from low efficiencies. However, a better understanding of the electrochemical interactions between the microbes and conductive materials will be likely to lead to increased power yields.