ABSTRACT
Samples of nitrogen-starved Parachlorella kessleri containing intact cells (IC), cells ground by bead milling (BM), and cells subjected to high-pressure cell disruption (HPD), together with their supernatants after centrifugation, were compared for granulometry and lipid profiles. The effects of disruption on the lipid profile and organisation were evaluated. The quantity of lipids available for extraction increased with disruption, and up to 81% could be recovered in supernatants after centrifugation, but a marked reorganization occurred. The proportion of amphiphilic free fatty acids and lysophosphatidylcholine increased during disruption due to their release or owing to lipid degradation by enzymes or physical conditions. This effect was more marked in HPD than in BM. Lipids contained in the aqueous phase, after disruption and centrifugation, were enriched in unsaturated fatty acids, BM leading to larger droplets than HPD. The larger liquid lipid droplet would be easier to recover in the following downstream processing.
Subject(s)
Biomass , Microalgae , Chlorophyta , Fatty Acids , LipidsABSTRACT
A study of cell disruption by bead milling for two microalgae, Nannochloropsis oculata and Porphyridium cruentum, was performed. Strains robustness was quantified by high-pressure disruption assays. The hydrodynamics in the bead mill grinding chamber was studied by Residence Time Distribution modeling. Operating parameters effects were analyzed and modeled in terms of stress intensities and stress number. RTD corresponded to a 2 CSTR in series model. First order kinetics cell disruption was modeled in consequence. Continuous bead milling was efficient for both strains disruption. SI-SN modeling was successfully adapted to microalgae. As predicted by high pressure assays, N. oculata was more resistant than P. cruentum. The critical stress intensity was twice more important for N. oculata than for P. cruentum. SI-SN modeling allows the determination of operating parameters minimizing energy consumption and gives a scalable approach to develop and optimize microalgal disruption by bead milling.
Subject(s)
Biotechnology/methods , Microalgae/cytology , Porphyridium/cytology , Stramenopiles/cytology , Biomass , Hydrodynamics , Microalgae/chemistry , Models, Theoretical , Porphyridium/chemistry , Pressure , Stramenopiles/chemistryABSTRACT
Acute postoperative negative pressure pulmonary edema with hemoptysia as a complication of general anesthesia is seldom. Its is related to an obstacle on airway, with important negative intrathoracic depression during inspiration leading to pulmonary edema and hemoptysia. Physiopathology and treatment of such complication have been discussed.
