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Abstract: The genetic background and activities of the enzymes involved in H2 production were investigated from ten distinct H2 producing cyanobacteria, revealed by a recent screening. All strains are N2-fixing, filamentous and heterocystous. Southern hybridization revealed that the tested strains possess the genes encoding the conventional nitrogenase (nifHDK1), and lack the alternative nitrogenases. The high H2 production rate of these strains was shown not to be dependent on the presence of highly active nitrogenase or bidirectional hydrogenase enzymes. Moreover, most of the strains possessed a highly active uptake hydrogenase enzyme. We also examined the structure of the nif and hup operons encoding nitrogenase and uptake hydrogenase enzymes in the Calothrix 336/3 strain, the best H2 producer in the screening. We concluded that the ability of the cyanobacteria to produce high levels of H2 is not directly linked to the maximum capacities of the enzymes involved in H2 production. [Copyright &y& Elsevier]

Screening of 55 different cyanobacterial strains revealed that an extract from Nostoc XPORK14A drastically modifies the amplitude and kinetics of chlorophyll a fluorescence induction of Synechocystis PCC 6803 cells. After 2 d exposure to the Nostoc XPORK14A extract, Synechocystis PCC 6803 cells displayed reduced net photosynthetic activity and significantly modified electron transport properties of photosystem II under both light and dark conditions. However, the maximum oxidizable amount of P700 was not strongly affected. The extract also induced strong oxidative stress in Synechocystis PCC 6803 cells in both light and darkness. We identified the secondary metabolite of Nostoc XPORK14A causing these pronounced effects on Synechocystis cells. Mass spectrometry and nuclear magnetic resonance analyses revealed that this compound, designated as M22, has a non-peptide structure. We propose that M22 possesses a dual-action mechanism: firstly, by photogeneration of reactive oxygen species in the presence of light, which in turn affects the photosynthetic machinery of Synechocystis PCC 6803; and secondly, by altering the in vivo redox status of cells, possibly through inhibition of protein kinases. [ABSTRACT FROM AUTHOR]

Recently, biodiesel is gaining significant importance due to eco-friendly nature and development of large-scale production methodologies. Biodiesel is a mixture of mono-alkyl esters of fatty acids (FA). During transesterification, the long-chain FAs are combined with methanol to produce fatty acid methyl ester (FAME), the principle component of biodiesel. The biodiesel fuel properties are determined by structural components of FAs such as chain length, degree of unsaturation, and branching of the carbon chain. The fuel quality of biodiesel are evaluated by assessing the properties such as cetane number (CN), iodine value (IV), cold filter plugging point (CFPP), higher heating value (HHV), cloud point (CP), pour point (PP) etc., of FAME. The amount of lipid or fat produced may vary from organism to organism. A particular species may have high biomass with low lipid content and vice versa. So the selection of suitable species/genus by decision analysis software is much needed. Besides various multi-criteria decision analyses, Preference Ranking Organization Method for Enrichment of Evaluation (PROMETHEE) and Graphical Analysis for Interactive Aid (GAIA) analysis is considered as the most promising tool in selecting the prominent biodiesel producing strain. Here we describe the method of evaluating the fuel quality parameters for the produced FAME and selecting the prominent strain through PROMETHEE-GAIA algorithm.

An ever increasing energy demand and fast depletion of fossil fuels have led to increased consideration of bacterial lipids as a renewable biofuel source. Many methods are available for both physical and chemical extraction of bacterial lipids. The method of choice will depend on the nature of sample to be analyzed, combinations of solvent systems preferred, content and quality of the lipid to be analyzed, types of equipment available, and time of the extraction procedures employed. Here we describe the most reliable, routine method of extracting bacterial lipids and evaluating the growth kinetic parameters like biomass and lipid productivity and lipid content. We also describe the method of comparing bacterial fatty acid methyl ester peaks with standard peaks for analysis.

We announce the draft genome sequence of Calothrix strain 336/3, an N2-fixing heterocystous filamentous cyanobacterium isolated from a natural habitat. Calothrix 336/3 produces higher levels of hydrogen than Nostoc punctiforme PCC 73102 and Anabaena strain PCC 7120 and, therefore, is of interest for potential technological applications., (Copyright © 2015 Isojärvi et al.)