ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
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.