Outdoor cultivation and metabolomics exploration of Chlamydomonas engineered for bisabolene production.

Demonstrating outdoor cultivation of engineered microalgae at considerable scales is essential for their prospective large-scale deployment. Hence, this study focuses on the outdoor cultivation of an engineered Chlamydomonas reinhardtii strain, 3XAgBs-SQs, for bisabolene production under natural dynamic conditions of light and temperature. Our preliminary outdoor experiments showed improved growth, but frequent culture collapses in conventional Tris-acetate-phosphate medium. In contrast, modified high-salt medium (HSM) supported prolonged cell survival, outdoor. However, their subsequent outdoor scale-up from 250 mL to 5 L in HSM was effective with 10 g/L bicarbonate supplementation. Pulse amplitude modulation fluorometry and metabolomic analysis further validated their improved photosynthesis and uncompromised metabolic fluxes towards the biomass and the products (natural carotenoids and engineered bisabolene). These strains could produce 906 mg/L bisabolene and 54 mg/L carotenoids, demonstrating the first successful outdoor photoautotrophic cultivation of engineeredC. reinhardtii,establishing it as a one-cell two-wells biorefinery.

Multi-Fold Enhancement of Tocopherol Yields Employing High CO2 Supplementation and Nitrate Limitation in Native Isolate Monoraphidium sp.

Tocopherols are the highly active form of the antioxidant molecules involved in scavenging of free radicals and protect the cell membranes from reactive oxygen species (ROS). In the present study, we focused on employing carbon supplementation with varying nitrate concentrations to enhance the total tocopherol yields in the native isolate Monoraphidium sp. CABeR41. The total tocopherol productivity of NRHC (Nitrate replete + 3% CO2) supplemented was (306.14 µg·L-1 d-1) which was nearly 2.5-fold higher compared to NRVLC (Nitrate replete + 0.03% CO2) (60.35 µg·L-1 d-1). The best tocopherol productivities were obtained in the NLHC (Nitrate limited + 3% CO2) supplemented cells (734.38 µg·L-1 d-1) accompanied by a significant increase in cell biomass (2.65-fold) and total lipids (6.25-fold). Further, global metabolomics using gas chromatography-mass spectrometry (GC-MS) was done in the defined conditions to elucidate the molecular mechanism during tocopherol accumulation. In the present study, the Monoraphidium sp. responded to nitrogen limitation by increase in nitrogen assimilation, with significant upregulation in gamma-Aminobutyric acid (GABA). Moreover, the tricarboxylic acid (TCA) cycle upregulation depicted increased availability of carbon skeletons and reducing power, which is leading to increased biomass yields along with the other biocommodities. In conclusion, our study depicts valorization of carbon dioxide as a cost-effective alternative for the enhancement of biomass along with tocopherols and other concomitant products like lipids and carotenoids in the indigenous strain Monoraphidium sp., as an industrial potential strain with relevance in nutraceuticals and pharmaceuticals.

Comparison of propofol versus propofol-ketamine combination for sedation during spinal anesthesia in children: randomized clinical trial of efficacy and safety.

OBJECTIVES: This study was designed to compare the efficacy and safety of propofol vs propofol-ketamine combination for sedation during pediatric spinal anesthesia. METHODS: Forty children, aged 3-8 undergoing spinal anesthesia for lower abdominal surgeries were included. Participants were randomly assigned into two groups. Group 1 received propofol bolus of 2 mg.kg(-1) followed by an infusion of 4 mg.kg(-1).h(-1). Group 2 received a combination of 1.6 mg.kg(-1) propofol and 0.4 mg.kg(-1) ketamine followed by an infusion of 3.2 mg.kg(-1).h(-1) and 0.8 mg.kg(-1).h(-1), respectively. The infusion rate was titrated to keep the child sedated at University of Michigan Sedation Score of 3. The heart rate, blood pressure, respiratory rate and oxygen saturation were recorded every 5 min. The episodes of spontaneous body movements and requirement of supplemental sedation were recorded. The postoperative recovery was assessed by modified Aldrette score. RESULTS: Seventeen patients in group 1 and four patients in group 2 (P < 0.001) required extra boluses of study drug to prevent movements during lumbar puncture. Four patients experienced respiratory depression and three airway obstruction in group 1 when compared to one patient each in group 2 (P < 0.05). The recovery time was similar in both groups. None of the patient had postoperative nausea/vomiting or psychomimetic reactions. CONCLUSIONS: Propofol-ketamine combination provided better quality of sedation with lesser complications than propofol alone and thus can be a good option for sedation during spinal anesthesia in children.