Chlorella, a genus of green algae, exhibits rapid growth and high lipid accumulation as self-defense against adverse conditions. This study aimed to identify optimal conditions for the growth and lipid accumulation of Chlorella sorokiniana in a two-stage process for biofuel production. In the first stage, C. sorokiniana grew best in BG-11 medium with 3 g L⁻¹ NaNO₃ and 10 g L⁻¹ glucose, achieving highest dry cell weight (DCW) of 2.87 ± 0.35 g L⁻¹ and lipid content of 23.25 ± 0.15 % DCW after 4 d of cultivation. The second stage cultivation reached a C. sorokiniana biomass concentration of 2.18 ± 0.08 g L⁻¹ and lipid content of 40.78 ± 0.61 % DCW with the addition of 30 g L⁻¹ NaCl, 6 g L⁻¹ NaHCO₃ and a light intensity of 150 µmol m⁻² s⁻¹ after 2 d cultivation in 1 L Erlenmeyer flasks. C. sorokiniana cultured in 20 L, 50 L, and 300 L closed photobioreactors (PBRs) achieved DCW ranging from 1.35 ± 0.06 to 1.94 ± 0.04 g L⁻¹ and lipid contents from 33.21 ± 0.67 % to 38.48 ± 0.76 % DCW, respectively, after 4 d in the first and 2 d in the second stage under optimal conditions of cultivation. Fatty acids profile, including C16:0, C18:2, and C18:3, indicated high-quality biodiesel, meeting 4-5 out of 5 parameters according to US and European standards. Therefore, C. sorokiniana is a potential feedstock for biodiesel.

Cellulose nanofibers (CNFs) are materials produced from cellulosic pulp derived from renewable woody biomass and fibrillated to the nano size in width, and is expected to be alternative to fossil-based plastic gas barrier packaging materials. There are many reports of gas barrier films made by coating with chemically modified CNFs such as a TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidized CNF, however low drying efficiency is one of the problems. On the other hand, although the mechanically nanofibrillated CNF has relatively high drying efficiency with chemically modified CNFs, there are few examples of its use as a gas barrier material. To produce the gas barrier thin films, a thin film transfer method based on the formation of wet paper of mechanically fibrillated CNF using paper-making technology was established, and the effect of CNF thin film on gas barrier properties were investigated. The paper-making technology was applied to the formation of a mechanically fibrillated CNF thin film with a basis weight of 7.5 g/m² and its transfer onto a filter paper substrate, enabling the formation of sheets with an oxygen barrier property. This study shows that thin films of mechanically fibrillated CNF with oxygen barrier properties can be fabricated by the papermaking method using paper as the base material. In addition, the fact that there were sheets with high oxygen barrier properties even when mixed with unfibrillated fibers suggests that the formation of mechanically treated CNF thin films by this method will lead to higher efficiency in the nanofibrillation, dewatering, and drying processes.