Year-round sustainable biomass production potential of Nannochloris sp. in outdoor raceway pond enabled through strategic photobiological screening.

Microalgae cultivation utilizes the energy of sunlight to reduce carbon dioxide (CO2) for producing renewable energy feedstock. The commercial success of the biological fixation of carbon in a consistent manner depends upon the availability of a robust microalgae strain. In the present work, we report the identification of a novel marine Nannochloris sp. through multiparametric photosynthetic evaluation. Detailed photobiological analysis of this strain has revealed a smaller functional antenna, faster relaxation kinetics of non-photochemical quenching, and a high photosynthetic rate with increasing light and temperatures. Furthermore, laboratory scale growth assessment demonstrated a broad range halotolerance of 10-70 parts per thousand (PPT) and high-temperature tolerance up to 45 °C. Such traits led to the translation of biomass productivity potential from the laboratory scale (0.2-3.0 L) to the outdoor 50,000 L raceway pond scale (500-m2) without any pond crashes. The current investigation revealed outdoor single-day peak areal biomass productivity of 43 g m-2 d-1 in summer with an annual (March 2019-February 2020) average productivity of 20 g m-2 d-1 in seawater. From a sustainability perspective, this is the first report of successful round-the-year (> 347 days) multi-season (summer, monsoon, and winter) outdoor cultivation of Nannochloris sp. in broad seawater salinity (1-57 PPT), wide temperature ranges (15-40 °C), and in fluctuating light conditions. Concurrently, outdoor cultivation of this strain demonstrated conducive fatty acid distribution, including increased unsaturated fatty acids in winter. This inherent characteristic might play a role in protecting photosynthesis machinery at low temperatures and in high light stress. Altogether, our marine Nannochloris sp. showed tremendous potential for commercial scale cultivation to produce biofuels, food ingredients, and a sustainable source for vegetarian protein.

Evaluation of various waste substrates for biofilm formation and subsequent use in aerobic packed-bed reactor for secondary treatment of domestic wastewater.

Immobilization of bacterial cells on suitable substrates is of utmost importance in the secondary treatment of wastewater using fixed-film reactors. Therefore, screening of efficient and cheaper materials for bacterial surface immobilization was carried out. Eleven waste materials were used as substrates, packed in a column, and bacterial surface immobilization was carried out using cow dung slurry/MLSS mixture. All the chosen substrates were screened for bacterial immobilization/biofilm formation by standard bacterial enumeration technique. The substrate with the highest biofilm-forming ability was used for secondary treatment of raw domestic wastewater. The results showed that high-density polyethylene and aluminium foil sheets have poor immobilizing characteristics with 2.2 × 108 and 2.4 × 108 CFU/cm2 respectively, whereas jute fibres were observed to be the most efficient among the substrates with 5.1 × 1023 CFU/cm2. The column packed with jute fibres was used for wastewater treatment. Various physico-chemical parameters were analyzed before and after treatment and there was a significant reduction in major parameters after treatment. The bacteria-immobilized jute fibres showed maximum immobilization potential and were highly efficient in wastewater treatment, and therefore these findings offer immense promise in the synthesis of composite polymers for bacterial immobilization and subsequent secondary treatment.

Degradation of indulin, a kraft pine lignin, by Serratia marcescens.

Serratia marcescens isolated from decaying coconut pith exhibited high lignolytic activity. Growth on indicator medium, analysis of residual indulin, and infra-red spectroscopic analysis indicated the lignolytic potential of the isolate. Ortho-Coumaric acid, ferulic acid, 2,3-dihydroxy cinnamic acid and protocatechuic acid were identified as intermediates involved in indulin degradation by S. marcescens. Qualitative confirmation and quantitative estimation of the intermediates were carried out by high performance thin layer chromatography (HPTLC).

Low shear stress preferentially enhances IKK activity through selective sources of ROS for persistent activation of NF-kappaB in endothelial cells.

NF-kappaB signaling pathway has been known to play a major role in the pathological process of atherogenesis. Unlike high shear stress, in which the NF-kappaB activity is transient, our earlier studies have demonstrated a persistent activation of NF-kappaB in response to low shear stress in human aortic endothelial cells. These findings partially explained why low shear regions that exist at bifurcations of arteries are prone to atherosclerosis, unlike the relatively atheroprotective high shear regions. In the present study, we further investigated 1) the role of NF-kappaB signaling kinases (IKKalpha and beta) that may be responsible for the sustained activation of NF-kappaB in low shear stress and 2) the regulation of these kinases by reactive oxygen species (ROS). Our results demonstrate that not only is a significant proportion of low shear-induced-kinase activity is contributed by IKKbeta, but it is also persistently induced for a prolonged time frame. The IKK activity (both alpha and beta) is blocked by apocynin (400 microM), a specific NADPH oxidase inhibitor, and diphenyleneiodonium chloride (DPI; 10 microM), an inhibitor of flavin-containing oxidases like NADPH oxidases. Determination of ROS also demonstrated an increased generation in low shear stress that could be blocked by DPI. These results suggest that the source of ROS generation in endothelial cells in response to low shear stress is NADPH oxidase. The DPI-inhibitable component of ROS is the primary regulator of specific upstream kinases that determine the persistent NF-kappaB activation selectively in low shear-induced endothelial cells.

A new approach for enhanced multiplication of arbuscular mycorrhizal fungi and isolation of ITS regions from Glomus deserticola and Laccaria fraterna.

Rootlets induced from the petiole base of L. purpureus, using IAA and kinetin was used for enhanced multiplication of arbuscular mycorrhizal (AM) fungus, G. deserticula. Using conserved short arbitrary oligonucleotides, as specific primers, we amplified the ITS-region, a molecular marker for fungal identification, from the genomic DNA extracted from cultured spores of G. deserticola, and genomic DNA extracted from the mycelium of L. fraterna. The capacity of fungal colonization and subsequent spore formation of G. deserticola, compared with the natural root system was evaluated. This technology would provide a simple way to multiply AM fungi and to produce spores without microbial contamination useful for further molecular characterization.