Influence of light intensity and photoperiod on the pigment and, lipid production of Dunaliella tertiolecta and Nannochloropsis oculata under three different culture medium

Optimization of lipid production in Tetradesmus dimorphus using response surface methodology using tannery wastewater for biodiesel production

The management of industrial wastewaters and generation of sustainable energy resources are the two major challenges concerned with the global population and depleting fossil fuels. Tannery wastewater (TWW) is a major source of environmental pollution and human health hazardous if released without adequate treatment. The microalgal treatment of TWW among other approaches seems to be beneficial and effective as microalgae use TWW as nutrient source offering wastewater treatment while producing large biomass for biofuel production. Biomass and lipid content are the adequate criteria for higher biodiesel yield. In present study, Tetradesmus dimorphus was grown in TWW with an objective to treat TWW along with the generation of large biomass for biodiesel production and Response Surface Methodology (RSM) was used to optimize the biodiesel production taking into count the parameters such as wastewater concentrations, pH and photoperiod. Results showed that highest biomass and lipid content produced were 1.63 ± 0.02 g/L and 487 ± 11 mg/L, respectively with 213.80 ± 7 mg/L of biodiesel production. Gas Chromatography-Flame Ionization Detection (GC-FID) analysis of biodiesel obtained from Tetradesmus dimorphus lipids showed that it was made up of more than 40 % Methyl decanoate (C11:0) and Methyl erucate (C22:1). The interrelationships between selected parameters like STTWW concentrations, pH and photoperiods reflected the positive impact on lipid productivity as 3D contour depicted the maximum yield at 80 % wastewater concentration, pH 8 and 14 h of photoperiod. Study showed that microalgal treatment of TWW among the other approaches seems beneficial and effective to harness wastewater nutrients while producing valuable biomass for biodiesel production.

Effect of carbon dots supplementation in Chlorella vulgaris biomass production and its composition

Microalgae cultures have an excellent ability to capture CO2 and produce high, medium, and low valuable biocompounds such as proteins, carbohydrates, lipids, pigments, and polyhydroxyalkanoates; those compounds have shown excellent properties in the pharmaceutical, cosmetic, food, and medical industries. Recently, the supplementation of carbon dots (CDs) in autotrophic microalgae cultures has been explored as a new strategy to increase light capture and improve photoluminescence, which in turn enhances biomass growth and biocompounds production. In this work, we synthesized CDs through a simple carbonization method using orange juice as a natural precursor. The green synthesized CDs were analyzed in detail through characterization techniques such as Fourier-transform infrared spectroscopy (FTIR), UV–visible, fluorescence spectroscopy, and ζ potential analysis. Moreover, CDs were added to Chlorella vulgaris to analyze the response under different photoperiod cycles and CDs dosages. The optimal results were obtained with the addition of 0.5 mg l−1 of CDs under a photoperiod cycle of 16 h:8 h (light:dark). In these conditions, a maximum biomass production of 2.12 g l−1 was observed, which represents an enhancement of 112% and 17% in comparison to the control samples under the photoperiod of 12 h:12 h and 16 h:8 h (light/dark), respectively. Furthermore, the production of lipids, proteins, and carbohydrates was significantly increased to 249 mg g−1, 285 mg g−1, and 217 mg g−1 dry weight, respectively. These results suggest that the addition of CDs enhances cell growth and increases the production of lipids and proteins, being a strategy with great potential for the food and pharmaceutical industries.

Transcriptome Analysis of Intermittent Light Induced Early Bolting in Flowering Chinese Cabbage

In flowering Chinese cabbage, early booting is one of the most important characteristics that is linked with quality and production. Through fixed light intensity (280 μmol·m-2·s-1) and fixed intermittent lighting in flowering Chinese cabbage, there was early bolting, bud emergence, and flowering. Moreover, the aboveground fresh weight, blade area, dry weight of blade, and quantification of the leaves in flowering Chinese cabbage were significantly reduced, while the thickness of tillers, tillers height, dry weight of tillers, and tillers weight were significantly increased. The chlorophyll contents and soil-plant analysis and development (SPAD) value decreased in the early stage and increased in the later stage. The nitrate content decreased, while the photosynthetic rate, vitamin C content, soluble sugar content, soluble protein content, phenolic content, and flavonoid content increased, and mineral elements also accumulated. In order to explore the mechanism of intermittent light promoting the early bolting and flowering of '49d' flowering Chinese cabbage, this study analyzed the transcriptional regulation from a global perspective using RNA sequencing. A total of 17,086 differentially expressed genes (DEGs) were obtained and 396 DEGs were selected that were closely related to early bolting. These DEGs were mainly involved in pollen wall assembly and plant circadian rhythm pathways, light action (34 DEGs), hormone biosynthesis and regulation (26 DEGs), development (21 DEGs), and carbohydrate synthesis and transport (6 DEGs). Three hub genes with the highest connectivity were identified through weighted gene co-expression network analysis (WGCNA): BrRVE, BrLHY, and BrRVE1. It is speculated that they may be involved in the intermittent light regulation of early bolting in flowering Chinese cabbage. In conclusion, intermittent light can be used as a useful tool to regulate plant growth structure, increase planting density, enhance photosynthesis, increase mineral accumulation, accelerate growth, and shorten the breeding cycle.