Michael A. Packer

Influence of anode potentials on selection of Geobacter strains in microbial electrolysis cells

Through their ability to directly transfer electrons to electrodes, Geobacter sp. are key organisms for microbial fuel cell technology. This study presents a simple method to reproducibly select Geobacter-dominated anode biofilms from a mixed inoculum of bacteria using graphite electrodes initially poised at -0.25, -0.36 and -0.42 V vs. Ag/AgCl. The biofilms all produced maximum power density of approximately 270 m Wm(-2) (projected anode surface area). Analysis of 16S rRNA genes and intergenic spacer (ITS) sequences found that the biofilm communities were all dominated by bacteria closely related to Geobacter psychrophilus. Anodes initially poised at -0.25 V reproducibly selected biofilms that were dominated by a strain of G. psychrophilus that was genetically distinct from the strain that dominated the -0.36 and -0.42 V biofilms. This work demonstrates for the first time that closely related strains of Geobacter can have very different competitive advantages at different anode potentials.

A cost-effective microbial fuel cell to detect and select for photosynthetic electrogenic activity in algae and cyanobacteria

This work describes the development of an easily constructed, cost-effective photosynthetic microbial fuel cell design with highly reproducible electrochemical characteristics that can be used to screen algae and cyanobacteria for photosynthetic electrogenic activity. It is especially suitable for benthic varieties, those that attach to surfaces. The anode chamber of the cell uses disposable polystyrene sample bottles (pottles) with a simple-to-apply carbon coating. These chambers can be used to grow photosynthetic microorganisms without a cathode for electrochemical characterization or with a cathode and load applied to provide electrogenic selective pressure. The utility of the design for screening, isolating and analysing photosynthetic electrogenic microorganisms under a wide variety of conditions is demonstrated. Several genera of benthic cyanobacteria from both New Zealand and Antarctica were shown to be electrogenic including Pseudanabaena, Leptolyngbya, Chroocococales, Phormidesmis, Microcoleus, Nostoc and Phormidium. A benthic strain of the eukaryote Paulschulzia pseudovolvox (Chlorophyceae) was isolated and identified, which had very good electrogenic qualities.

Characterisation of Antarctic cyanobacteria and comparison with New Zealand strains

Cyanobacterial mats are common in Antarctic lakes, ponds and on moist soils. The species comprising these mats have adapted to tolerate extreme conditions (e.g. high salinities and UV radiation, freezing and extended periods of darkness). In this study, cyanobacterial mats were collected from shallow melt-water ponds in Pyramid Trough in Southern Victoria Land, Antarctica. Eight strains were isolated and characterised by morphological and molecular (16S rRNA gene sequences) techniques and their fatty acid methyl ester (FAME) and lipid class profiles determined. These data were compared to parallel information obtained from cyanobacterial cultures isolated from New Zealand. In general, the morphological and molecular characterisation complemented each other, and the Antarctic strains identified belonged to the orders: Oscillatoriales (six), Nostocales (one) and Chroococcales (one). Two of the Antarctic strains (CYN67 and CYN68) showed low similarity (<96% 16S rRNA gene sequence) when compared to other cultured cyanobacteria. The fatty acid (FA) profiles from the Antarctic and New Zealand strains shared many similarities with palmitic (C16:0), stearic (C18:0) and oleic acid (C18:1n-9) most abundant. In contrast, the lipid class analysis differed among geographic locations with Antarctic strains containing higher amounts of hydrocarbons and eicosapentaenoic and hexadecatrienoic acids.

Isolation and characterisation of halo-tolerant Dunaliella strains from Lake Grassmere/Kapara Te Hau, New Zealand

Strains of the chlorophyte genus Dunaliella were isolated from Dominion Salt NZ Ltd evaporation ponds at Lake Grassmere/Kapara Te Hau, New Zealand. Five halo-tolerant groups were characterised using morphology, molecular phylogenetic analysis and physiological response to varying culture conditions. Species identification based on morphological characteristics of cell size, shape and flagella to cell length ratio was supported by molecular internal transcribed spacer one and two regions (ITS-1, ITS-2) and 5.8S ribosomal RNA gene sequences. Investigations into salinity and photostress response were performed using pulse amplitude modulation (PAM) fluorometry, and high-performance liquid chromatography (HPLC) quantification of pigment profiles with an emphasis on carotenoid production are presented. Cryo-preservation storage was successfully applied to all strains.

Food and Feed Applications of Algae

Microalgae and seaweeds have a long history and increasingly important applications as both food ingredients and animal feed. The vast majority of algal species have yet to be evaluated for these applications. However, due to their extensive diversity, it is likely that they will lead to the discovery of many new algal products and processes in the future. This chapter covers algae as food, feed, nutraceuticals, functional food and food ingredients as well as production systems for food from algae.

The Cawthron Institute Culture Collection of Micro-algae: a significant national collection

ABSTRACT The Cawthron Institute Culture Collection of Micro-algae (CICCM) is a unique, nationally and internationally significant collection of 450 strains of approximately 100 micro-algae and 50 cyanobacteria species, both living and cryopreserved. The collection comprises 13 taxonomic classes and underpins research into the ecology and taxonomy of the isolates and the biotoxins they produce and their toxicity. The CICCM expanded significantly in the 1990s after a major harmful algae bloom event in the Hauraki Gulf, New Zealand. Since 2000, it has underpinned development of molecular detection tools and enabled development of new chemical testing methods for biotoxins in seafood. The tropical collection allows research into potential issues for New Zealand as the oceans warm, for example, the risks of ciguatera fish poisoning and palytoxins in seafood. Research results generated from isolates in the cyanobacterial collection have assisted national risk management regarding drinking water and informed the development of the New Zealand guidelines for managing cyanobacteria in recreational fresh waters. The actual living and cryopreserved micro-algae and cyanobacteria collection (without infrastructure) has a current estimated value of NZ

Optimising conditions for growth and xanthophyll production in continuous culture of Tisochrysis lutea using photobioreactor arrays and central composite design experiments

1.6 million.

Demonstration of the use of a photosynthetic microbial fuel cell as an environmental biosensor

ABSTRACT The production of valuable metabolites from microalgae represents a potentially sustainable source of a range of products that can be difficult to synthesise directly. Microalgae respond to the dynamic and often subtly shifting growth environment in a complex way. The optimal conditions for growth can be quite different to those needed for optimal product generation, depending on the nature of the biosynthesis of that product. This is especially so for secondary metabolites. A combination of a multi-vessel photobioreactor array, where certain growth conditions can be monitored and controlled precisely together with an experimental design matrix has been used to determine the optimal combination of temperature, irradiance and pH for a group of xanthophylls including fucoxanthin in the algae Tisochrysis lutea in continuous culture. Continuous culture as a mode is more suited for industrial production than batch mode in which the media constituents and algal population change dramatically over time. The central composite design experiment matrix has a range of set values for each parameter being investigated that bracket the optimal conditions. The three parameters investigated in this work (temperature, irradiance and pH) are major factors influencing algal growth. The method can be applied to other parameters that might affect growth or might affect production of a metabolite of interest, such as a nutrient level. The combined approach has been used previously to indicate optimal growth conditions for biomass generation and this work is one of the first to apply it to the generation of an algal product of interest.

Algal and cyanobacterial bioenergy and diversity

Microbial fuel cells (MFCs) are bioelectrochemical systems (BESs) that exploit biological catalytic processes for the generation of electrical power or the accumulation of useful compounds. Photosynthetic MFCs (pMFCs) are those that utilise photosynthetic microorganisms, such as algae and cyanobacteria, to provide reducing power at the anode. A reproducible light-dependent electrogenic effect occurs as algae or cyanobacteria convert light to electrical energy in the BES. In addition to the generation of electricity, the phenomenon may be useful in niche circumstances such as for bioelectrosynthesis or for use in environmental biosensors. In this study we measure the effect of common toxicants (copper, thallium, zinc and glyphosate) on the electrogenic activity of electrode surface-dwelling algae and cyanobacteria. We observed a decrease in the light-dependent electrical response via these photosynthetic microorganisms in our pMFC that was proportional to the concentration of toxicants. This demonstrates the utility of these BESs as potential environmental biosensors where the metabolism of photosynthetic microorganisms acts to sense signals from the environment.

Greenshell™ Mussels: A Review of Veterinary Trials and Future Research Directions

The current issue of the New Zealand Journal of Botany has its origins in a one-day meeting on different aspects of algal and cyanobacterial biomass accumulation, bioenergy and the production of commercially important bioproducts. The meeting was held at Otago University on 7 December 2012, and was jointly sponsored by the Cawthron Institute and the University of Otago. In addition, the Otago Energy Research Centre sponsored a public talk on the evening of 6 December 2012 by Professor Anthony Larkum (from the Global Climate Cluster at the University of Technology in Sydney, Australia) who spoke on: ‘Second and third generation microalgae for the bioenergy revolution’. Eleven papers have been submitted to this Special Issue representing the contributions of 38 authors from institutions across New Zealand. In addition to Otago University and the Cawthron Institute, these institutions include the University of Auckland, Waikato University, the University of Canterbury, Lincoln University, Lincoln Agritech Ltd, the National Institute of Water and Atmospheric Research (NIWA), Environmental Science and Research Limited (ESR) and Landcare Research. Visiting scientists from the University of Sydney and the Institute of Plant Biology at the Biological Research Centre of the Hungarian Academy of Sciences, in Szeged, Hungary attended the meeting and have also submitted contributions (Kiss et al. 2014; Torres et al. 2014). A full list of registered participants is given in Appendix 1 and a list of all presentations is given in Appendix 2. The work by Torres et al. (2014) explores the photosynthetic efficiency of two diatoms, Phaeodactylum tricornutum and Amphora coffeaeformis under different light regimes and demonstrates the flexibility of the photosynthetic systems of these algae and the high efficiency attained under optimal conditions. The contribution from Dr Imre Vass and colleagues at the Hungarian Academy of Sciences investigates the expression of the hox genes encoding the bidirectional hydrogenase in two cyanobacteria, Anabaena variabilis ATCC 29413 and Anabaena sp. PCC 7120, revealing a specific requirement for this enzyme in darkness both in the presence and absence of oxygen (Kiss et al. 2014). From Otago University, Morris et al. (2014) have sequenced two ‘wild-type’ strains of the cyanobacterium Synechocystis sp. PCC 6803, a widely used model organism for the study of photosynthesis and the response of cyanobacteria to different environmental conditions. Morris and co-workers report a number of unique mutations in these strains suggesting the need to know the genomic background of different laboratory strains when constructing targeted mutants. Commault et al. (2014) present a collaborative study between Lincoln Agritech Ltd, the University of Auckland and Landcare Research describing a photosynthetic bio-cathode in a sediment-type microbial fuel cell. Using their biofilm-coated carbon and stainless steel cathode, their system was able to produce 11 mWm over six months without feeding. The research reported by Craggs et al. (2014) from NIWA in Hamilton discusses the use of High Rate Algal pond systems for improving conventional wastewater treatment ponds incorporating energy recovery and biofuel production. The following study by Mabbitt et al. (2014) considers the Photosystem II assembly factor known as Psb27 in both cyanobacteria and green algae, and compares these proteins with the isoforms found in Arabidopsis thaliana. This work New Zealand Journal of Botany, 2014 Vol. 52, No. 1, 1–5, http://dx.doi.org/10.1080/0028825X.2013.877947