Secondary metabolite from Nostoc XPORK14A inhibits photosynthesis and growth of Synechocystis PCC 6803.

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 PCC6803 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 dualaction 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.

Qualitative and Quantitative Estimation of Bacterial Lipid Production.

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.

Assessment of Fuel Quality Parameters and Selection of Bacteria Using PROMETHEE-GAIA Algorithm.

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.

Growth kinetic and fuel quality parameters as selective criterion for screening biodiesel producing cyanobacterial strains.

The efficiency of cyanobacterial strains as biodiesel feedstock varies with the dwelling habitat. Fourteen indigenous heterocystous cyanobacterial strains from rice field ecosystem were screened based on growth kinetic and fuel parameters. The highest biomass productivity was obtained in Nostoc punctiforme MBDU 621 (19.22mg/L/day) followed by Calothrix sp. MBDU 701 (13.43mg/L/day). While lipid productivity and lipid content was highest in Nostoc spongiaeforme MBDU 704 (4.45mg/L/day and 22.5%dwt) followed by Calothrix sp. MBDU 701 (1.54mg/L/day and 10.75%dwt). Among the tested strains, Nostoc spongiaeforme MBDU 704 and Nostoc punctiforme MBDU 621 were selected as promising strains for good quality biodiesel production by Preference Ranking Organization Method for Enrichment Evaluation (PROMETHEE) and Graphical Analysis for Interactive Assistance (GAIA) analysis.

Unraveling the presence of multi-class toxins from Trichodesmium bloom in the Gulf of Mannar region of the Bay of Bengal.

Trichodesmium is an enigmatic bloom forming, non-heterocystous cyanobacterium reported most frequently in the coastal waters of India. However, the toxigenic potential of this globally significant N2 fixing cyanobacterium has not been characterized. In this study, we report for the first time the presence of potent multi-class neurotoxins such as Anatoxin-a, Saxitoxins, Gonyautoxin and hepatotoxins like MC-LR, MC-YA from a bloom material of Trichodesmium sp. MBDU 524 collected at the Gulf of Mannar region. Toxins were determined using liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) analysis of HPLC purified aqueous and solvent fractions. Molecular phylogenetic analysis through 16S rRNA gene sequencing showed the close relationship with Trichodesmium erythraeum clade. The toxigenic potential was validated through brine shrimp toxicity assay and showed 100% mortality after 48 h of incubation. The results suggest the potential toxigenic and environmental impacts of Trichodesmium bloom sample from the Gulf of Mannar region.

Draft genome sequence of calothrix strain 336/3, a novel h2-producing cyanobacterium isolated from a finnish lake.

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.

Nodularin uptake and induction of oxidative stress in spinach (Spinachia oleracea).

The bloom-forming cyanobacterium Nodularia spumigena produces toxic compounds, including nodularin, which is known to have adverse effects on various organisms. We monitored the primary effects of nodularin exposure on physiological parameters in Spinachia oleracea. We present the first evidence for the uptake of nodularin by a terrestrial plant, and show that the exposure of spinach to cyanobacterial crude water extract from nodularin-producing strain AV1 results in inhibition of growth and bleaching of the leaves. Despite drastic effects on phenotype and survival, nodularin did not disturb the photosynthetic performance of plants or the structure of the photosynthetic machinery in the chloroplast thylakoid membrane. Nevertheless, the nodularin-exposed plants suffered from oxidative stress, as evidenced by a high level of oxidative modifications targeted to various proteins, altered levels of enzymes involved in scavenging of reactive oxygen species (ROS), and increased levels of α-tocopherol, which is an important antioxidant. Moreover, the high level of cytochrome oxidase (COX II), a typical marker for mitochondrial respiratory protein complexes, suggests that the respiratory capacity is increased in the leaves of nodularin-exposed plants. Actively respiring plant mitochondria, in turn, may produce ROS at high rates. Although the accumulation of ROS and induction of the ROS scavenging network enable the survival of the plant upon toxin exposure, the upregulation of the enzymatic defense system is likely to increase energetic costs, reducing growth and the ultimate fitness of the plants.