Due to diminishing petroleum reserves and deleterious environmental consequences of exhaust gases from fossil-based fuels, research on renewable and environment friendly fuels has received a lot of impetus in the recent years. However, the availability of the non-edible crops serve as the sources for biofuel production are limited and economically not feasible. Algae are a promising alternative source to the conventional feedstocks for the third generation biofuel production. There has been a considerable discussion in the recent years about the potential of microalgae for the production of biofuels, but there may be other more readily exploitable commercial opportunities for macroalgae and microalgae. This review, briefly describes the biofuels conversion technologies for both macroalgae and microalgae. The gasification process produces combustible gases such as H2, CH4, CO2 and ammonia, whereas, the product of pyrolysis is bio-oil. The fermentation product of algae is ethanol, that can be used as a direct fuel or as a gasohol. Hydrogen can be obtained from the photobiological process of algal biomass. In transesterification process, algae oil is converted into biodiesel, which is quite similar to those of conventional diesel and it can be blended with the petroleum diesel. This study, also reviewed the production of high value byproducts from macroalgae and microalgae and their commercial applications. Algae as a potential renewable resource is not only used for biofuels but also for human health, animal and aquatic nutrition, environmental applications such as CO2 mitigation, wastewater treatment, biofertilizer, high-value compounds, synthesis of pigments and stable isotope biochemicals. This review is mainly an attempt, to investigate the biorefinery concept applied on the algal technology, for the synthesis of novel bioproducts to improve the algal biofuels as even more diversified and economically competitive. The employment of a high-value, co-product strategy through the integrated biorefinery approach is expected to significantly enhance the overall commercial implementation of the biofuel from the algal technology.

Macroalgae and microalgae as a potential source for commercial applications along with biofuels production: A biorefinery approach

https://www.int-res.com/articles/meps/207/m207p225.pdf

Marine chemical ecology

Algal chemodiversity and bioactivity: sources of natural variability and implications for commercial application.

Chemical cues constitute much of the language of life in the sea. Our understanding of biotic interactions and their effects on marine ecosystems will advance more rapidly if this language is studied and understood. Here, I review how chemical cues regulate critical aspects of the behavior of marine organisms from bacteria to phytoplankton to benthic invertebrates and water column fishes. These chemically mediated interactions strongly affect population structure, community organization, and ecosystem function. Chemical cues determine foraging strategies, feeding choices, commensal associations, selection of mates and habitats, competitive interactions, and transfer of energy and nutrients within and among ecosystems. In numerous cases, the indirect effects of chemical signals on behavior have as much or more effect on community structure and function as the direct effects of consumers and pathogens. Chemical cues are critical for understanding marine systems, but their omnipresence and impact are inadequ...

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Marine chemical ecology: chemical signals and cues structure marine populations, communities, and ecosystems.

Cyanobacteria and algae having complex photosynthetic systems can channelize absorbed solar energy into other forms of energy for production of food and metabolites. In addition, they are promising biocatalysts and can be used in the field of “white biotechnology” for enhancing the sustainable production of food, metabolites and green energy sources such as biodiesel. In this review, an endeavour has been made to uncover the significance of various metabolites like phenolics, phytoene/terpenoids, phytols, sterols, free fatty acids, photoprotective compounds (MAAs, scytonemin, s, polysaccharides, halogenated compounds, etc.), phytohormones, cyanotoxins, biocides (algaecides, herbicides and insecticides) etc. Apart from this, the importance of these metabolites as antibiotics, immunosuppressant, anticancer, antiviral, anti-inflammatory agent has also been discussed. Metabolites obtained from cyanobacteria and algae have several biotechnological, industrial, pharmaceutical and cosmetic uses which have also been discussed in this review along with the emerging technology of their harvesting for enhancing the production of compounds like bioethanol, biofuel etc. at commercial level. In later sections, we have discussed genetically modified organisms and metabolite production from them. We have also briefly discussed the concept of bioprocessing highlighting the functioning of companies engaged in metabolites production as well as their cost effectiveness and challenges that are being addressed by these companies.

/pdf/uncovering-potential-applications-of-cyanobacteria-and-algal-590cp0xyry.pdf

Uncovering Potential Applications of Cyanobacteria and Algal Metabolites in Biology, Agriculture and Medicine: Current Status and Future Prospects

Summary


1
It is well understood that herbivory can cause plants to elevate production of defensive chemicals in their tissues. One of the key questions in understanding patterns of potential coevolutionary links between plant and herbivore is ‘what switches these induced plant defences on?’ Until cues are identified, understanding the evolutionary and ecological significance of defences in the context of the plant is difficult.

2
We induced host plant resistance in a marine macroalga (Ascophyllum nodosum) in the absence of herbivory by application of α-amylase, known to exist in mollusc saliva. There was a demonstrable change in the behaviour of a subsequent herbivore (Littorina obtusata) consistent with herbivore induction, i.e. reduced consumption, more but smaller meals and greater movement. We also produced a concomitant increase in the level of phlorotannins, compounds associated with defence against herbivory.

3
Such changes in herbivore behaviour and plant chemistry provide evidence that brown algae and higher plants utilize similar salivate-based signals in the induction of defence against herbivory. Thus the possibility that such responses could be either highly conserved or a convergent strategy is discussed.

A. J. Moody

Papers

An enzyme in snail saliva induces herbivore-resistance in a marine alga