Cellular disruption and its influence over the drying kinetics of brewer’s spent yeast biomass

Spent yeast biomass is one of the residues of brewing. It is specifically the second-largest residue from brewing industry. Most of the spent yeast is sold at low prices, or disposed as waste or used as animal feed. Spent yeast biomass is predominantly composed of proteins, and it has a high biological value, being an excellent source of high-quality protein, comparable in value with soy protein. Therefore, spent yeast biomass has great potential for use in foodstuffs for human consumption. The objective of this work was to evaluate the influence of cell rupture over the drying kinetics of spent yeast biomass using mathematical models (Lewis and Page). Also, to verify the influence of cell rupture method over the amount of protein. The cellular rupture was performed by two methods (chemical method and physical method: ultrasound). The drying process was performed by freeze-drying, and the parameters of the models were obtained using the non-linear regression (Generalized Reduced Gradient Nonlinear Optimization Code). Mathematical models of drying kinetics showed a strong correlation with the experimental data, R² > 0.96. The disruption process did not significantly affect the drying time and protein content. But the cellular autolysis improves the protein digestibility since the proteins will be totally available to the digestive enzymes and also increase the bioavailability of nutrients.

Investigation of a Gas Hydrate Dissociation-Energy-Based Quick-Freezing Treatment for Sludge Cell Lysis and Dewatering

A gas Hydrate dissociation-energy-based Quick-Freezing treatment (HbQF) was applied for sewage sludge cell rupture and dewatering. Carbon dioxide (CO2) and water (H2O) molecules in sewage create CO2 gas hydrates, and subsequently the sludge rapidly freezes by releasing the applied pressure. Cell rupture was observed through a viability evaluation and leachate analysis. The decreased ratios of live cell to dead cells, increased osmotic pressure, and increased conductivity showed cell lysis and release of electrolytes via HbQF. The change in physicochemical properties of the samples resulting from HbQF was investigated via zeta potential measurement, rheological analysis, and particle size measurement. The HbQF treatment could not reduce the sludge water content when combined with membrane-based filtration post-treatment because of the pore blocking of fractured and lysed cells; however, it could achieve sludge microbial cell rupture, disinfection, and floc disintegration, causing enhanced reduction of water content and enhanced dewatering capability via a sedimentation post process. Furthermore, the organic-rich materials released by the cell rupture, investigated via the analysis of protein, polysaccharide, total organic carbon, and total nitrogen, may be returned to a biological treatment system or (an) aerobic digester to increase treatment efficiency.

Calpain drives pyroptotic vimentin cleavage, intermediate filament loss, and cell rupture that mediates immunostimulation

Pyroptosis is an inflammatory form of programmed cell death following cellular damage or infection. It is a lytic process driven by gasdermin D-mediated cellular permeabilization and presumed osmotic forces thought to induce swelling and rupture. We found that pyroptotic cells do not spontaneously rupture in culture but lose mechanical resilience. As a result, cells were susceptible to rupture by extrinsic forces, such as shear stress or compression. Cell analyses revealed that all major cytoskeleton components were disrupted during pyroptosis and that sensitivity to rupture was calpain-dependent and linked with cleavage of vimentin and loss of intermediate filaments. Moreover, while release of lactate dehydrogenase (LDH), HMGB1, and IL-1β occurred without rupture, rupture was required for release of large inflammatory stimuli—ASC specks, mitochondria, nuclei, and bacteria. Importantly, supernatants from ruptured cells were more immunostimulatory than those from nonruptured cells. These observations reveal undiscovered cellular events occurring during pyroptosis, define the mechanisms driving pyroptotic rupture, and highlight the immunologic importance of this event.

Towards sustainable microalgal biomass processing: anaerobic induction of autolytic cell-wall self-ingestion in lipid-rich Nannochloropsis slurries

Incubating Nannochloropsis slurries in darkness at 38 °C activated auto-fermentation metabolism that thinned cell walls and led to increased cell rupture.

Discrete element modelling of tomato tissue deformation and failure at the cellular scale

In this work, a 3D micro-mechanical plant tissue model that is able to model cell rupture and inter-cellular debonding and thus provide more insight in the micro-mechanics was developed.