Active extracellular substances of Bacillus thuringiensis ITRI-G1 induce microalgae self-disruption for microalgal biofuel.

Microalgal cultures are a clean and sustainable means to use solar energy for CO2 fixation and fuel production. Microalgae grow efficiently and are rich in oil, but recovering that oil is typically expensive and consumes much energy. Therefore, effective and low-cost techniques for microalgal disruption and oil or lipid extraction are required by the algal biofuel industry. This study introduces a novel technique that uses active extracellular substances to induce microalgal cell disruption. A bacterium indigenous to Taiwan, Bacillus thuringiensis, was used to produce the active extracellular substances, which were volatile compounds with high thermal stability. Approximately 74% of fresh microalgal cells were disrupted after a 12-h treatment with the active extracellular substances. Algal lipid extraction efficiency was improved and the oil extraction time was decreased by approximately 37.5% compared with the control treatment. The substances effectively disrupted fresh microalgal cells but not dehydrated microalgal cells. An analysis of microalgal DNA from fresh cells after disruption treatment demonstrated typical DNA laddering, indicating that disruption may have resulted from programmed cell death. This study revealed that biological treatments are environmentally friendly methods for increasing microalgal lipid extraction efficiency, and introduced a microalgal cell self-disruption mechanism.

Continuous lipid extraction of microalgae using high-pressure carbon dioxide.

Sequestering carbon, purifying water, and creating biofuel materials using microalgae are of global interest in the R&D field. However, extracting algal oil consumes a high amount of energy, which is an obstacle for the biofuel market. Nontoxic and recyclable high-pressure CO2 extraction processes are being developed by numerous researchers; however, most of these processes use batch operations mixed with a large amount of co-solvent and require improvement. We fabricated a continuous high-pressure CO2 extraction system, evaluating the optimal parameters for the extraction process. The various parameter tests included temperature, pressure, pretreatment methods, ratio, and the species of co-solvent. We integrated the optimal parameters from previous tests, using a 5-d continuous operation. Compared with traditional solvent extraction, a 90.56% extraction yield ratio was achieved using this continuous extraction method. This shows the stable, high extraction yields of this continuous high-pressure CO2 extraction system.

A fermentation strategy for producing docosahexaenoic acid in Aurantiochytrium limacinum SR21 and increasing C22:6 proportions in total fatty acid.

During the fermentation process, dissolved oxygen values and carbon-to-nitrogen ratios are critical factors influencing DHA productivity. This study employed an intermittent oxygen feeding method to maintain a 50% dissolved oxygen level and produced a dissolved oxygen fluctuation environment to facilitate both Aurantiochytrium limacinum SR21 growth and lipid accumulation. Study results indicated that at a 1.25 C:N ratio and medium composition of 100gL(-1) glycerol, 40gL(-1) yeast extract, and 40gL(-1) peptone, A. limacinum SR21 achieved biomass at 61.76gL(-1), lipid content at 65.2%, DHA concentration at 20.3gL(-1), and DHA productivity at 122.62mgL(-1)h(-1), this result were better than most similar researches. Dissolved oxygen fluctuation environment also altered the fatty acid composition of A. limacinum SR21. In the late period of the fermentation process, C16:0 fatty acid ratios decreased significantly to below 5%, and C22:6 fatty acid ratios increased to 70%.

(+)-N-[2-(4-Chloro-phen-yl)propano-yl]bornane-10,2-sultam.

In the mol-ecular structure of the title compound, C(19)H(24)ClNO(3)S, the six-membered ring of the bornane unit shows a boat form, while the five-membered ring of the sultam unit adopts a twist form. Intra-molecular C-H⋯N and C-H⋯O inter-actions are observed. In the crystal structure, mol-ecules are connected by inter-molecular C-H⋯O hydrogen bonds into a chain running along the b axis. The crystal was a partial inversion twin with a twin ratio of 0.73 (1):0.27 (1).

N-[2-(4-Chloro-phen-yl)propano-yl]-1-methyl-bornane-10,2-sultam.

In the mol-ecular structure of the title compound, C(20)H(26)ClNO(3)S, the six-membered ring of the bornane unit shows a boat conformation, while the five-membered ring of the sultam unit adopts a twist conformation. In the crystal structure, mol-ecules are connected by inter-molecular C-H⋯O hydrogen bonds into a chain running along the b axis. Intramolecular C-H⋯O and C-H⋯N hydrogen bonds are also present.