Amanda R. Stiles

Magnetic Flocculant for High Efficiency Harvesting of Microalgal Cells

Magnetic flocculant was synthesized for the highly efficient recovery of microalgal cells. The highest flocculation was achieved using the magnetic flocculant synthesized with iron oxide and 0.1 mg/mL cationic polyacrylamide (CPAM). This resulted in a recovery efficiency of more than 95% within 10 min using a dosage of 25 mg/L for Botryococcus braunii and 120 mg/L for Chlorella ellipsoidea. For both species, the adsorption isotherm data fit the Freundlich model better than the Langmuir model, indicating that the adsorption process was a heterogeneous multilayer. The maximum adsorption capacity was 114.8 and 21.4 mg dry cells/mg-particles at pH 7 for B. braunii and C. ellipsoidea, respectively. The primary flocculation mechanism was bridging, which was assisted by the electrostatic interactions between the microalgal cells and the magnetic flocculant under acidic conditions. These results provide new opportunities and challenges for understanding and improving the harvesting of microalgae using magnetic separation.

Microalgae cultivation in photobioreactors: An overview of light characteristics

There is increasing commercial interest in the cultivation of microalgae for the production of biofuels, foods, pharmaceuticals, and wastewater treatment. Light is one of the most important factors for the growth and product yield from photosynthetic cells. In this review, light transfer and photosynthesis in algal cells, and the issues of light utilization in the cultivation of microalgae in photobioreactor (PBR) are discussed. Research progress on the improvement of light utilization in microalgae cultivation is outlined. In addition, PBR design assisted by computational fluid dynamics and a strong focus on improving the light characteristics in the scale‐up of PBRs is emphasized.

Scale-up cultivation of Chlorella ellipsoidea from indoor to outdoor in bubble column bioreactors

The cultivation of Chlorella ellipsoidea in bubble column bioreactors was investigated at different scales under indoor and outdoor conditions. The algal cells were able to quickly adapt to the outdoor conditions and achieved a growth rate of 31.55mg L(-1)day(-1). Due to differences in light and temperature, the outdoor culture produced a higher percentage of unsaturated fatty acids compared to the indoor cultures, while the amino acid composition was unaffected. The overall cost of the biomass produced by the 200L outdoor cultivation (58.70US

Hairy Root Culture: Bioreactor Design and Process Intensification

/kg-dry weight) was estimated to be more than 7 times lower than that of the 20L indoor cultivation (431.39US

Botryococcus braunii cells: Ultrasound-intensified outdoor cultivation integrated with in situ magnetic separation

/kg-dry weight). Together these results provide a basis for the cultivation of C. ellipsoidea for the large-scale production of biofuels, high-value nutrients and/or recombinant proteins.

Dark preincubation improves shoot organogenesis from Rhodiola crenulata leaf explants

The cultivation of hairy roots for the production of secondary metabolites offers numerous advantages; hairy roots have a fast growth rate, are genetically stable, and are relatively simple to maintain in phytohormone free media. Hairy roots provide a continuous source of secondary metabolites, and are useful for the production of chemicals for pharmaceuticals, cosmetics, and food additives. In order for hairy roots to be utilized on a commercial scale, it is necessary to scale-up their production. Over the last several decades, significant research has been conducted on the cultivation of hairy roots in various types of bioreactor systems. In this review, we discuss the advantages and disadvantages of various bioreactor systems, the major factors related to large-scale bioreactor cultures, process intensification technologies and overview the mathematical models and computer-aided methods that have been utilized for bioreactor design and development.

Ionic liquids for biofuel production: Opportunities and challenges

An integrated system combining ultrasound-intensified outdoor cultivation of Botryococcus braunii with in situ magnetic harvesting of the algal cells was developed. The algal cells were cultivated in 200 L plastic bag reactors, and seven five-minute ultrasonic treatments at a four-day interval using a fixed frequency of 40 kHz and a total power of 300 W improved algal cell biomass and hydrocarbon productivity. The algal cells were harvested using functional magnetic particles and a magnetic separator, and a recovery efficiency of 90% was obtained under continuous operation at a flow rate of 100mL/min using the in situ magnetic separation system. The overall production cost using the integrated system was US

Harvesting microalgae by magnetic separation: A review

25.14 per kilogram of B. braunii dry biomass. The system developed in this study provides a base for the industrial production of B. braunii.

Gibberellic Acid Increases Secondary Metabolite Production in Echinacea purpurea Hairy Roots

An efficient in vitro plant regeneration system has been developed using dark preincubated leaf explants of Rhodiola crenulata, a traditional Tibetan medicinal plant. The leaf explants, preincubated in the dark for 5 d, developed an average of 9.1 shoots per explant on a medium containing 15 μM N6-benzyladenine (BA) and 2.5 μM gibberellic acid (GA3). The biochemical mechanism underlying dark-induced shoot organogenesis was investigated by measuring polyphenol oxidase (PPO) activity. Dark preincubation significantly reduced PPO activity in leaf explants during the initial period of shoot organogenesis and reduced browning compared to explants cultured in the light. Up to 88.4 % of the regenerated shoots formed roots and developed into complete plantlets on a medium containing 5 μM indoleacetic acid (IAA) within 25 d. Approximately 82 % of the regenerated plantlets survived transplantation and grew vigorously in the greenhouse.