Bacillus amyloliquefaciens is a potential surrogate for Clostridium botulinum in validation studies involving bacterial spore inactivation by pressure-assisted thermal processing. Spores of B. amyloliquefaciens Fad 82 were inoculated into egg patty mince (approximately 1.4 x 10(8) spores per g), and the product was treated with combinations of pressure (0.1 to 700 MPa) and heat (95 to 121 degrees C) in a custom-made high-pressure kinetic tester. The values for the inactivation kinetic parameter (D), temperature coefficient (zT), and pressure coefficient (zP) were determined with a linear model. Inactivation parameters from the nonlinear Weibull model also were estimated. An increase in process pressure decreased the D-value at 95, 105, and 110 degrees C; however, at 121 degrees C the contribution of pressure to spore lethality was less pronounced. The zP-value increased from 170 MPa at 95 degrees C to 332 MPa at 121 degrees C, suggesting that B. amyloliquefaciens spores became less sensitive to pressure changes at higher temperatures. Similarly, the zT-value increased from 8.2 degrees C at 0.1 MPa to 26.8 degrees C at 700 MPa, indicating that at elevated pressures, the spores were less sensitive to changes in temperature. The nonlinear Weibull model parameter b increased with increasing pressure or temperature and was inversely related to the D-value. Pressure-assisted thermal processing is a potential alternative to thermal processing for producing shelf-stable egg products.

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Osteosarcoma exhibits marked patient-to-patient heterogeneity, but little is known about heterogeneity within individual tumors. This study focuses on the roles that phenotypic plasticity and clonal selection play as tumors adapt to primary and metastatic microenvironments. We show that osteosarcomas have a high degree of transcriptional heterogeneity, like osteoblasts, that is retained even after prolonged cell culture or adaptation to changing microenvironments. We find that both cell lines and PDXs grown in cell culture or as flank tumors adopt markedly different transcriptional profiles when grown as primary bone tumors or metastatic lung lesions. By combining lineage tracing with single-cell transcriptomics, we find that very little clonal selection occurs when tumors grow in the tibia, but significant expansion of select clones occurs when grown as experimental metastases in the lung. Interestingly, the selective pressures that drive clonal expansion do not cause narrowing of transcriptional phenotypes. By comparing the phenotypes from transcriptional clusters in orthotopic/metastatic tumor pairs, we identify a transcriptional signature that is shared among clusters that become enriched during lung colonization. This includes responses to IFNG, TNF, PDGF, previously unidentified IL1B, and a shift away from genes associated with glycolysis and toward those associated with oxidative metabolism. The metastatic microenvironment enriches for phenotypically diverse clones that each display metabolic properties that engender fitness within the metastatic microenvironment. Together, these data suggest that an underlying program, possibly a developmental program retained from the tissue of origin, maintains phenotypic heterogeneity, even during adaptation to changing microenvironmental conditions.