Sustainability is a key principle in natural resource management, and it involves operational efficiency, minimisation of environmental impact and socio-economic considerations; all of which are interdependent. It has become increasingly obvious that continued reliance on fossil fuel energy resources is unsustainable, owing to both depleting world reserves and the green house gas emissions associated with their use. Therefore, there are vigorous research initiatives aimed at developing alternative renewable and potentially carbon neutral solid, liquid and gaseous biofuels as alternative energy resources. However, alternate energy resources akin to first generation biofuels derived from terrestrial crops such as sugarcane, sugar beet, maize and rapeseed place an enormous strain on world food markets, contribute to water shortages and precipitate the destruction of the world's forests. Second generation biofuels derived from lignocellulosic agriculture and forest residues and from non-food crop feedstocks address some of the above problems; however there is concern over competing land use or required land use changes. Therefore, based on current knowledge and technology projections, third generation biofuels specifically derived from microalgae are considered to be a technically viable alternative energy resource that is devoid of the major drawbacks associated with first and second generation biofuels. Microalgae are photosynthetic microorganisms with simple growing requirements (light, sugars, CO 2 , N, P, and K) that can produce lipids, proteins and carbohydrates in large amounts over short periods of time. These products can be processed into both biofuels and valuable co-products. This study reviewed the technologies underpinning microalgae-to-biofuels systems, focusing on the biomass production, harvesting, conversion technologies, and the extraction of useful co-products. It also reviewed the synergistic coupling of microalgae propagation with carbon sequestration and wastewater treatment potential for mitigation of environmental impacts associated with energy conversion and utilisation. It was found that, whereas there are outstanding issues related to photosynthetic efficiencies and biomass output, microalgae-derived biofuels could progressively substitute a significant proportion of the fossil fuels required to meet the growing energy demand.

/pdf/biofuels-from-microalgae-a-review-of-technologies-for-1t1wwr5e69.pdf

Biofuels from microalgae—A review of technologies for production, processing, and extractions of biofuels and co-products

The rise of harmful cyanobacteria blooms: The potential roles of eutrophication and climate change

Cultural eutrophication has become the primary water quality issue for most of the freshwater and coastal marine ecosystems in the world. However, despite extensive research during the past four to five decades, many key questions in eutrophication science remain unanswered. Much is yet to be understood concerning the interactions that can occur between nutrients and ecosystem stability: whether they are stable or not, alternate states pose important complexities for the management of aquatic resources. Evidence is also mounting rapidly that nutrients strongly influence the fate and effects of other non-nutrient contaminants, including pathogens. In addition, it will be important to resolve ongoing debates about the optimal design of nutrient loading controls as a water quality management strategy for estuarine and coastal marine ecosystems.

/pdf/eutrophication-science-where-do-we-go-from-here-2t1fz6ng64.pdf

Eutrophication science: where do we go from here?

Plant secondary metabolites are unique sources for pharmaceuticals, food additives, flavors, and industrially important biochemicals. Accumulation of such metabolites often occurs in plants subjected to stresses including various elicitors or signal molecules. Secondary metabolites play a major role in the adaptation of plants to the environment and in overcoming stress conditions. Environmental factors viz. temperature, humidity, light intensity, the supply of water, minerals, and CO2 influence the growth of a plant and secondary metabolite production. Drought, high salinity, and freezing temperatures are environmental conditions that cause adverse effects on the growth of plants and the productivity of crops. Plant cell culture technologies have been effective tools for both studying and producing plant secondary metabolites under in vitro conditions and for plant improvement. This brief review summarizes the influence of different abiotic factors include salt, drought, light, heavy metals, frost etc. o...

https://www.tandfonline.com/doi/pdf/10.4161/psb.6.11.17613

Influence of abiotic stress signals on secondary metabolites in plants

Cyanobacteria are the Earth's oldest known oxygen-evolving photosynthetic microorganisms, and they have had major impacts on shaping our current atmosphere and biosphere. Their long evolutionary history has enabled cyanobacteria to develop survival strategies and persist as important primary producers during numerous geochemical and climatic changes that have taken place on Earth during the past 3.5 billion years. Today, some cyanobacterial species form massive surface growths or 'blooms' that produce toxins, cause oxygen depletion and alter food webs, posing a major threat to drinking and irrigation water supplies, fishing and recreational use of surface waters worldwide. These harmful cyanobacteria can take advantage of anthropogenically induced nutrient over-enrichment (eutrophication), and hydrologic modifications (water withdrawal, reservoir construction). Here, we review recent studies revealing that regional and global climatic change may benefit various species of harmful cyanobacteria by increasing their growth rates, dominance, persistence, geographic distributions and activity. Future climatic change scenarios predict rising temperatures, enhanced vertical stratification of aquatic ecosystems, and alterations in seasonal and interannual weather patterns (including droughts, storms, floods); these changes all favour harmful cyanobacterial blooms in eutrophic waters. Therefore, current mitigation and water management strategies, which are largely based on nutrient input and hydrologic controls, must also accommodate the environmental effects of global warming.

Climate change: A catalyst for global expansion of harmful cyanobacterial blooms

An in vitro propagation system was developed for Echinacea purpureaL. (purple coneflower), a medicinal plant commonly used in the treatment of colds, flu and related ailments. Root organogenesis from Echinacea purpurea hypocotyl explants was effectively induced by indolebutyric acid. Indoleacetic acid was found to be less effective than indolebutyric acid while treatments with naphthaleneacetic acid were ineffective for induction of root organogenesis. The results of this study have established a micropropagation system for Echinacea purpurea that will provide axenic plant material for further investigations into medicinally active biochemicals and the mass production of high-quality Echinacea purpurea root tissues for the commercial market.

Regeneration of echinacea purpurea: induction of root organogenesis from hypocotyl and cotyledon explants

Melatonin is an indoleamine neurotransmitter that has recently become well established as an important multi-functional signalling molecule in plants. These signals have been found to induce several important physiological responses that may be interpreted as behaviours. The diverse processes in which melatonin has been implicated in plants have expanded far beyond the traditional roles for which it has been implicated in mammals, which include sleep, tropisms and reproduction. These functions, however, appear to also be important melatonin mediated processes in plants, though the mechanisms underlying these functions have yet to be fully elucidated. Mediation or redirection of plant physiological processes induced by melatonin can be summarised as a series of behaviours including, among others: herbivore defence, avoidance of undesirable circumstances or attraction to opportune conditions, problem solving and response to environmental stimulus. As the mechanisms of melatonin action are elucidated, its involvement in plant growth, development and behaviour is likely to expand beyond the aspects discussed in this review and hold promise for applications in diverse fundamental and applied plant sciences including conservation, cryopreservation, morphogenesis, industrial agriculture and natural health products.

Melatonin in plant signalling and behaviour.

Peanut seeds germinated on media supplemented with thidiazuron [TDZ: N-phenyl-N′-(1,2,3-thiadiazol-yl)urea], formed somatic embryos at the hypocotyledonary notch region by Day 35 of the culture period. Supplementation of the culture media with proline, thioproline, or glutamine reduced the total number of embryos formed, but the resulting embryos were larger, greener and had a more synchronous development than the regenerants formed on media containing TDZ alone. Analysis of the endogenous amino acid content of the germinating seeds during the induction phase of somatic embryogenesis revealed accumulation of proline to 6% of the dry seed weight. Concurrent with the emergence of the radicle, the proline concentration remained significantly elevated throughout the expression phase of embryogenesis. Several other amino acids including alanine, aspartate, asparagine, glutamate, glutamine, γ-aminobutyrate (GABA), hydroxyproline, isoleucine, threonine and valine accumulated to peak values approximately 10-fold higher than those of the controls. These results indicate that proline plays a key role in directing the route of TDZ-induced somatic embryogenesis and that TDZ effectively stimulates a cascade of metabolic events resulting in the production of specific metabolites, including amino acids, required for the regenerative process.

The role of proline in thidiazuron-induced somatic embryogenesis of peanut

β-methylamino-l-alanine (BMAA) is a naturally occurring nonprotein amino acid originally discovered in cycad seeds and traditional foods of the Chamorro people of Guam. Recent research has implicated BMAA as a potential factor in neurodegenerative disease and described the production of BMAA in cyanobacteria, but conflicting results have complicated the interpretation of data. We hypothesized that the reactivity of BMAA with metal ions in the sample matrix and the formation of metal adducts in electrospray ionization mass spectrometry (MS) analysis confound results. Dilute solutions of TCA, MgCl2, NaCl, CuCl2, ZnCl2 (0.01 M), or artificial ocean water (Instant Ocean, 3.5 g/L) reduced the signal attributable to the BMAA M + H+ peak by 78–99.7%. The degree of adduct formation was significantly affected by MS settings such as induction voltage. A number of the detected ion peaks in BMAA standards were consistent with the formation of metal–BMAA complexes in addition to the adduct formation. A standard of Zn(...

Susan J. Murch

Papers

Regeneration of echinacea purpurea: induction of root organogenesis from hypocotyl and cotyledon explants

Melatonin in plant signalling and behaviour.

The role of proline in thidiazuron-induced somatic embryogenesis of peanut

Reactivity of β-Methylamino-l-alanine in Complex Sample Matrixes Complicating Detection and Quantification by Mass Spectrometry

Plant regeneration from mesophyll protoplasts of the Egyptian medicinal plants Artemisia judaica L. and Echinops spinosissimus Turra