http://aem.asm.org/content/86/2/e02353-19.abstract Abstract: Steryl esters (SEs) are important storage compounds in many eukaryotes and are often prominent Actino Proteobacteria components of intracellular lipid droplets. Here, we demonstrate that selected - and growing on sterols are also able to synthesize SEs and to sequester them in cytoplasmic lipid droplets. We Rhodococcus Mycobacterium found cholesteryl ester (CE) formation in members of the actinobacterial genera , , Amycolatopsis Cellvibrionales and , as well as several members of the proteobacterial order. CEs maximally accumulated under nitrogen-limiting conditions, suggesting that steryl ester formation plays a crucial role for storing excess energy and carbon under adverse conditions. Rhodococcus jostii RHA1 was able to synthesize phytosteryl and cholesteryl esters, the latter reaching up to 7%of its cellular dry weight and 69% of its lipid droplets. Purified lipid droplets from RHA1 contained CEs, free cholesterol, and triacylglycerols. In addition, we found formation of CEs in Mycobacterium tuberculosis when it was grown with cholesterol plus an additional fatty acid substrate. This study provides a basis for the application of bacterial whole-cell systems in the biotechnological production of SEs for use in functional foods and cosmetics. Importance: Oleaginous bacteria exhibit great potential for the production of high-value neutral lipids, such as triacylglycerols and wax esters. This study describes the formation of steryl esters (SEs) as neutral lipid storage compounds in sterol-degrading oleaginous bacteria, providing a basis for biotechnological production of SEs using bacterial systems with potential applications in the functional food, nutraceutical, and cosmetic industries. Actino Proteobacteria We found cholesteryl ester (CE) formation in several sterol-degrading - and under nitrogen-limiting conditions, suggesting an important role of this process in storing energy and carbon under adverse conditions. In addition, Mycobacterium tuberculosis grown on cholesterol accumulated CEs in the presence of an additional fatty acid substrate.

Holliday, V.T., Bartlein, P.J., Scott, A.C., Marlon, J.R., 2020. Extraordinary biomass-burning episode and impact ∼ winter triggered by the Younger Dryas cosmic impact 12,800 years ago, Parts 1 and 2: A discussion. The Journal of Geology 128, 69-94.

https://www.journals.uchicago.edu/doi/abs/10.1086/706264 Wolbach et al. published two papers on the Younger Dryas Impact Hypothesis (YDIH) - the paleoenvironmental effects of a purported cosmic impact at the beginning of the Younger Dryas Chronozone (YDC). Part 1 includes a selective summary of previous discussions of the YDIH but leaves out key reviews, uncritically accepts previous interpretations of purported impact, and fails to take into account abundant criticisms and contradictory data. A discussion of ice-core evidence focuses only on the beginning of the YDC rather than on a longer interval that would allow the context of claimed impact indicators to be evaluated. The exceptionalism claimed for many of the key data points is the result of exaggerations, and the graphical analyses themselves are not reproducible. Part 2 presents data from sedimentary records. The authors assume that impacts triggered widespread fires, but the evidence for such a link between extraterrestrial impacts and wildfires is weak. The presence of charcoal at the beginning of the YDC (YDB) fails to unambiguously support the hypothesis of impact-related fires because there is also a large peak at the end of the YDC. Stratigraphic markers used to argue for widespread burning, such as the Usselo soil of northwest Europe and the black mat of the southwestern United States, were shown by their original investigators to have no plausible link to an impact event. Human population decline in North America is not supported by abundant published archaeological, geochronological, and stratigraphic evidence. Late Pleistocene megafauna extinctions varied in time for individual species across the Americas, Europe, and Asia and thus cannot be accounted for by a single impact. If there was some sort of extraterrestrial YDB-age event, it apparently had negligible terrestrial impact. Discussion of: Wolbach, W.S., Ballard, J.P., Mayewski, P.A., Adedeji, V., Bunch, T.E., Firestone, R.B., French, T.A., Howard, G.A., Israde-Alcántara, I., Johnson, J.R., Kimbel, D., Kinzie, C.R., Kurbatov, A., Kletetschka, G., LeCompte, M.A., Mahaney, W.C., Melott, A.L., Maiorana-Boutilier, A., Mitra, S., Moore, C.R., Napier, W.M., Parlier, J., Tankersley, K.B., Thomas, B.C., Wittke, J.H., West, A., Kennett, J.P., 2018. Extraordinary biomass-burning episode and impact winter triggered by the Younger Dryas cosmic impact ∼ 12,800 years ago. 1. Ice cores and glaciers. The Journal of Geology 126, 165-184.