Analyzing and optimizing the carbon utilization and lipid yield at different light intensities for Scenedesmus arcuatus

Microalgae, the photosynthetic microorganism growing abundantly in marine and aquatic ecosystems, are potential source for biological sequestration of CO2. The carbon uptake differs in the presence of other nutrients, light intensity etc. The biomass yield of Scenedesmus arcuatus var capitatus was studied based on the Face Centred Central Composite design (FCCD) of Response Surface Methodology (RSM) for nitrate, phosphate and carbonate under different conditions (laboratory, room and sunlight conditions). Various pre-treatments (osmotic shock, autoclaving, microwave and ultrasonication) were employed to find the best method for maximum lipid yield. The biomass yield reached a maximum of 1 g/L under sunlight conditions of nitrate concentration 500 ppm and carbonate 2000 ppm. The laboratory conditions resulted in a biomass yield of 0.59 g/L at 500 ppm nitrate, 1000 ppm carbonate and 250 ppm phosphate. Under room conditions, the yield was very low (0.11 g/L). Osmotic shock resulted in higher lipid yield than the other pre-treatment methods. The ability of Scenedesmus arcuatus to uptake high carbon under sunlight conditions and to adapt to high light intensity and fluctuations in light intensity concludes that this species is suitable for large-scale open pond cultivation for CO2 sequestration and production of metabolites.

Effect of Photosynthetic Microorganism on Lime Plant Growing and Fruiting

Lime plant has an absolute requirement of nutrients for growing. The microbial application can facilitate in addressing limited access to chemical fertilizer concern. Moreover, the photosynthetic microorganism community can contribute together in nutrient availability for plant growing and fruiting. The objectives of this research were analyzed the growth rate of photosynthetic microorganism in a fermented juice within three months. A fermented juice was analyzed in terms of MLSS, COD, and nutrient. The efficiencies of fermented juice of lime plant growing, and fruiting was also investigated. The lime plant growth rate was collected in terms of plant height, and fruiting. The experimental results showed that the concentration of microbes in a fermented juice was maintained approximately 1,063 ± 135 mg/L on average (n=5). The photosynthetic microorganism concentration and nutrients concentration in fermented juice was a significant promotion of productivity of lime plant growing and fruiting.

Ecotoxicological Studies of ZnO and CdS Nanoparticles on Chlorella vulgaris Photosynthetic Microorganism in Seine River Water

Seine river water was used as natural environmental medium to study the ecotoxicological impact of ZnO and CdS nanoparticles and Zn2+ and Cd2+ free ions using Chlorella vulgaris as a biological target. It was demonstrated by viability tests and photosynthetic activity measurements that free Zn2+ (IC50 = 2.7 × 10−4 M) is less toxic than free Cd2+ and ZnO nanoparticles (IC50 = 1.4 × 10−4 M). In the case of cadmium species, free Cd2+ (IC50 = 3.5 × 10−5 M) was similar to CdS nanoparticles (CdS-1: IC50 = 1.9 × 10−5 M and CdS-2: IC50 = 1.9 × 10−5 M), as follows: CdS > Cd2+ > ZnO > Zn2+. Adenosine-5’-triphosphate (ATP) assay and superoxide dismutase (SOD) enzymatic activity confirmed these results. Transmission electron microscopy (TEM), coupled with energy-dispersive X-ray spectroscopy (EDS), confirmed the internalization of CdS-1 nanoparticles after 48 h of contact with Chlorella vulgaris at 10−3 M. With a higher concentration of nanoparticles (10−2 M), ZnO and CdS-2 were also localized inside cells.

In vitroAnticancer Evaluation of Saponins Obtained From Spirulina platensis on MDA, HepG2, and MCF7 Cell Lines

Introduction: Microalgae are known for their bioactive compounds with potential applications as antimicrobial, antiaging, and anticancer activities. Spirulina platensis (S. platensis) is a filamentous and photosynthetic microorganism that has 25 kinds of vitamins and minerals that contain many compounds with biotic activity such as alkaloids, phenolic compounds, terpenoids, and saponins. Saponins are mainly present in plants; while there are few studies about their role in microalgae. This study aims to investigate the anticancer potential of extracted saponins from S. platensis. Methods: Saponins were extracted; using distilled water and n-butanol. The total extracted saponin was dried and weighed. The cellular viability of HepG2, MCF-7, and MDA- MB-123 cell lines was evaluated; using MTT assay after 24 h treatment with 0.02-2 mg/ ml of saponins extracted from S. platensis. Morphology of cell lines was evaluated by invert microscopy. Results: Total saponin extracted from S. platensis was estimated at 28±0.0005 mg/g dry wt. Thin-layer chromatography profiles showed four bands for saponins with Rf values of 0.44, 0.48, 0.50, and 0.55. The cytotoxic activity after 24 h treatment with 0.02-2 mg/ml of saponins was a concentration-dependent manner. The highest toxicity of saponins with IC50=0.22 mg/ml was observed in MDA-MB-123 cells. In HepG2 and MCF-7 cells IC50 value was obtained in 0.35 mg/ml and 0.4 mg/ml, respectively. Conclusions: This is the first report to evaluate the anticancer effects of saponins from S. platensis in liver and breast cancers. The result showed that saponins from Spirulina decrease cancer cellular viability. Therefore, these compounds can be a candidate for anticancer agents.

Modular engineering for efficient photosynthetic biosynthesis of 1-butanol from CO2 in cyanobacteria

Systematic modular engineering of a photosynthetic microorganism resulted in cells with significant levels and rates of 1-butanol production directly from CO2.

Enhancement of COD, ammonia, phosphate and sulfide simultaneous removal by the anaerobic photosynthetic bacterium of Ectothiorhodospira magna in batch and sequencing batch culture

An anaerobic photosynthetic bacterium, with chemical oxygen demand (COD), ammonia nitrogen (NH3-N), total phosphorus (TP) and sulfide (S2−) simultaneous removal ability, strain SU6, was isolated and identified as belonging to Ectothiorhodospira magna. Its removal efficiencies were simultaneously evaluated in batch culture and influenced in sequencing batch culture. The maximum COD, NH3-N, TP and S2− removal rates of 93.04%, 86.70%, 37.55% and 99.99% were obtained in batch culture with an initial pH 8.0 at 35 °C after 72 h. The simultaneous removal efficiency was enhanced in sequencing batch culture, and 789.27 mg/L COD, 68.91 mg/L NH3-N, 70.20 mg/L S2− and 5.26 mg/L TP were removed by the end of the last cycle within 24 h. This was the first time of reporting contaminants' simultaneous removal by a pure-cultured photosynthetic bacterium. The experimental results demonstrate that E. magna can efficiently serve as a good candidate in anaerobic wastewater contaminants' simultaneous removal, and maybe as another model anaerobic photosynthetic microorganism for water purification investigations.

Genome Rearrangement ShapesProchlorococcusEcological Adaptation

ABSTRACTProchlorococcusis the most abundant and smallest known free-living photosynthetic microorganism and is a key player in marine ecosystems and biogeochemical cycles.Prochlorococcuscan be broadly divided into high-light-adapted (HL) and low-light-adapted (LL) clades. In this study, we isolated two low-light-adapted clade I (LLI) strains from the western Pacific Ocean and obtained their genomic data. We reconstructedProchlorococcusevolution based on genome rearrangement. Our results showed that genome rearrangement might have played an important role inProchlorococcusevolution. We also found that theProchlorococcusclades with streamlined genomes maintained relatively high synteny throughout most of their genomes, and several regions served as rearrangement hotspots. Backbone analysis showed that different clades shared a conserved backbone but also had clade-specific regions, and the genes in these regions were associated with ecological adaptations.IMPORTANCEProchlorococcus, the most abundant and smallest known free-living photosynthetic microorganism, plays a key role in marine ecosystems and biogeochemical cycles.Prochlorococcusgenome evolution is a fundamental issue related to howProchlorococcusclades adapted to different ecological niches. Recent studies revealed that the gene gain and loss is crucial to the clade differentiation. The significance of our research is that we interpreted theProchlorococcusgenome evolution from the perspective of genome structure and associated the genome rearrangement with theProchlorococcusclade differentiation and subsequent ecological adaptation.