Functional Analysis of SI10875 in the Regulation of PS I Activity in Synechocystis sp.PCC 6803 / 中国生物化学与分子生物学报

Phylloquinone is a unique cofactor of photosystem I (PS I ) , made up of a redox-active naphthoquinone ring attached to a partially saturated C-20 phytyl side chain.At present, the research on the biosynthesis of phylloquinone in cyanobacteria is mainly focused on the formation of naphthoquinone ring, while there was a shortage of reports in the biosynthesis of phytyl side chain.In this study, a highly homologous protein S110875 was found in Synechocystis sp.PCC 6803 by homologous sequence alignment with VTE6, a kinase involved in phylloquinone biosynthesis by converting phytyl-phosphate into phytyl- diphosphate in Arabidopsis thaliana.The resulting S110875 mutant, called As/Z0875, accumulates none phylloquinone and tocopherol, as well as low amounts of chlorophyll content (P<0.05).The mutant had retarded growth in the absence of added glucose.Chlorophyll fluorescence, P700 absorbance changes, 77 K fluorescence emission spectra and Western blot analyses showed that in As/Z0875, PS I function was impaired and accumulation of the PS I complex was reduced remarkably (P<0.01), indicating that phvlloquinone deficiency affected PS I function, thus hindering the normal growth of cyanobacteria.Our results provide the evidence that the phytol phosphorylation pathway is essential for phylloquinone biosynthesis in cyanobacteria for the first time, and a basis for further investigate the protein synthesis, assembly and stability of PS I complex in cyanobacteria.

Indoleacetic acid production and chromium reduction by cyanobacteria Synechocystis SP. P2A (Chroococcales) immobilized in alginate beads / Produção de ácido indolacético e redução do cromo por cianobactérias Synechocystis SP. P2A (Chroococcales) imobilizadas em esferas de alginato

A simple extrusion method was used to entrap Synechocystis sp.P2A in alginate beads. The viability, growth response and Indoleacetic acid (IAA) production at different pH were studied in alginate immobilized Synechocystis sp.P2A. 2.6% sodium alginate (w/v) and pH-7 was found to be optimum for growth of Synechocystis sp. P2A as well as IAA production (79µg/ml). To prepare effective formulation for plant inoculation, alginate beads were further modified by coating with chitosan or chitosan-polyethylene glycol. Effect of all formulations containing Synechocystis sp. P2A in free and immobilized form on growth of Triticumaestivum was evaluated. Soil inoculation of entrapped Synechocystis in alginate beads coated with chitosan resulted in 20% increase in root length and 14% increase in dry weight as compared to non-inoculated seedlings. Free and immobilized cyanobacteria were allowed to grow in BG11 medium supplemented with 100µg/ml K2CrO4 and chromium reduction was measured at variable pH. At pH 7 immobilized showed 5% more reduction than free form. The current study showed that alginate immobilized Synechocystis sp. P2A can accomplish viable functions including plant growth promoting hormone production and chromium reduction and therefore propose an efficient and convenient method for storage and use of cyanobacteria.

Um método de extrusão simples foi utilizado para aprisionar Synechocystis sp.P2A em esferas de alginato. A viabilidade, a resposta ao crescimento e a produção de ácido indolacético (IAA) a diferentes pH foram estudadas na Synechocystis sp.P2A imobilizada com alginato. Alginato de sódio a 2,6% (p/v) e pH-7 revelou-se ótimo para o crescimento de Synechocystis sp. P2A, bem como para a produção de IAA (79 µg/ml). Para preparar uma formulação eficaz para inoculação de plantas, as esferas de alginato foram adicionalmente modificadas por revestimento com quitosano ou quitosano-polietileno glicol. O efeito de todas as formulações contendo Synechocystis sp. P2A em forma livre e imobilizada no crescimento de Triticumaestivum foi avaliado. A inoculação no solo com Synechocystis aprisionado em esferas de alginato revestidas com quitosano resultou em um aumento de 20% no comprimento da raiz e aumento de 14% no peso seco em comparação com mudas não inoculadas. As cianobactérias livres e imobilizadas foram deixadas crescer em meio BG11 suplementado com 100 µg/ml de K2CrO4 e a redução do cromo foi medida a um pH variável. A um pH 7 a forma imobilizada apresentou 5% mais de redução do que a forma livre. O presente estudo mostrou que o alginato imobilizado de Synechocystis sp. P2A pode realizar funções viáveis, incluindo a produção de hormônio promotor do crescimento de plantas e redução de cromo e, portanto, propor um método eficiente e conveniente para armazenamento e uso de cianobactérias.

Formulation and evaluation of folic acid conjugated gliadin nanoparticles of curcumin for targeting colon cancer cells.

Preparation of folic acid (FA) conjugated (FA-CUR-GNPs) and non-conjugated (CUR-GNPs) gliadin nanoparticles of curcumin were successfully formulated by desolvation method for oral delivery of drug for targeting colon cancer cell. F1, F3, F5 (conjugated) and F2, F4, F6 (Non-conjugated) were formulated using various drug-polymer ratio (1:2). They were further characterized by FTIR, Mass spectroscopy, NMR, solubility studies, entrapment efficiency, TEM, particle size, surface charge, In-vitro release studies, In vivo toxicity studies and simultaneously evaluated. F3 (curcumin 10mg, gliadin 20mg and FA 5mg) and F4 (curcumin 10mg and gliadin 20 mg) were found as the optimized formulation among both the categories. For F3 and F4 formulations; average particle size (168.1 and 195.7nm), zeta potential (-16.5 and -24.4mV), cumulative % drug release (92.92 and 94%) and In vivo toxicity studies were conducted and compared with the control (phosphate-buffer saline, pH 6.8) reveals no toxicity. From the characterization and evaluation studies it was identified that F4 (FA-CUR-GNPs) had better solubility, In vitro release profile and no specified In-vivo toxicity than F3 (CUR-GNPs) formulation with nano-range particle size throughout the experiment. Improved bioavailability and increase targeting capacity toward colon cancer tumor cells were successfully achieved.

Evaluation of microalgae’s (Chlorella sp. and Synechocystis sp.) pollutant removal property: Pig effluent as a live stock discharge.

The ability of microalgae to remove nitrogen and phosphorus from wastewater has been used in recent years as an alternative treatment for discharges from livestock slurry, which generate a negative environmental impact on vulnerable ecosystems. With this background and the feasibility of using microalgae, we have evaluated the effect of Chlorella sp. and Synechocystis sp., in removing contaminants from the pig manure collected from El Prado ESPE. Slurry samples were collected, filtered and autoclaved, and the supernatant was further diluted to three different concentrations of 40%, 60% and 80%. The microalgal growth and pollutants removal property was evaluated up to 15 days in batch culture. The cell density was determined by counting in a Neubauer hemocytometer, and the pollutants removal was analyzed by standard colorimetric methods. The microalgae Chlorella sp. showed a maximum cell growth of 1.70 ± 0.09 x107 cells/mL at 60% effluent concentration on day 6. While Synechocystis sp. showed a maximum growth of 1.04 ± 0.05 x107 cells/mL, at 60% concentration on day 9. On the other hand, there exists a competition when microalgae used as a consortium. The cell growth of Chlorella sp. was higher at all concentrations compared to Synechocystis sp.. Overall, efficiency of pollutant removal were between 40% and 90%, which demonstrate the feasibility of using microalgae in tertiary swine wastewater treatment.

Statistical evaluation of nutritional components impacting phycocyanin production in Synechocystis SP

Alkaliphilic cyanobacterial cultures were isolated from Lonar lake (MS, India). Among the set of cultures, Synechocystis sp, was studied for phycocyanin production. A maximum yield was obtained in BG-11 medium at optimized conditions (pH 10 and 16 h light). In order to increase the phycocyanin yield media optimization based on the eight media components a Plackett-Burman design of the 12 experimental trials was used. As per the analysis CaCl2.2H2O and Na2CO3 have been found to be the most influencing media components at 95% significance. Further the optimum concentrations of these components were estimated following a Box Wilson Central Composite Design (CCD) with four star points and five replicates at the center points for each of two factors was adopted for optimization of these two media components. The results indicated that there was an interlinked influence of CaCl2.2H2O and Na2CO3 on 98% significance. The maximum yield of phycocyanin (12% of dry wt) could be obtained at 0.058 g/l and 0.115 g/l of CaCl2.2H2O and Na2CO3, respectively.

Identification of a Pair of Toxin-antitoxin (TA) Gene in the Chromosome of Cyanobacteria Synechocystis sp. PCC6803 / 微生物学通报

Chromosomally encoded toxin–antitoxin (TA) systems are thought to result in growth arrest and eventual cell death upon exposure to environmental stress in E. coli. In the chromosome of cyanobacteria Synechocystis sp. PCC6803, the genetic organization of a 360 bp open reading frame (ORF), slr0664, and another small ORF of 256 bp, ssr1114, is similar to that of TA system. The predicted protein encoded by slr0664 is homologous to RelE, but neither homologue of ssr1114 nor ssr1114-encoding protein was found in TA system. To see whether slr0664 encodes a toxin protein, ssr1114 encodes an antitoxin, an expressing plasmid containing promoter Plac and PBAD, was constructed. In this construct, Both slr0664 and ssr1114 were controlled by Plac and PBAD, respectively. Expression of slr0664 in Escherichia coli results in the inhi-bition of bacterial growth, the expression of ssr1114 neutralize the toxicity of slr0664 expression. These re-sults show that slr0664 is toxin gene and ssr1114 is antitoxin gene, both ssr1114 and slr0664 constitute achromosomal TA system in Synechocystis sp. PCC6803.