Lipid droplets (LDs) are multi-functional organelles consisting of a neutral lipid core surrounded by a phospholipid monolayer, and exist in organisms ranging from bacteria to humans. Here we study the functions of LDs in the oleaginous bacterium Rhodococcus jostii. We show that these LDs bind to genomic DNA through the major LD protein, MLDS, which increases survival rate of the bacterial cells under nutritional and genotoxic stress. MLDS expression is regulated by a transcriptional regulator, MLDSR, that binds to the operator and promoter of the operon encoding both proteins. LDs sequester MLDSR, controlling its availability for transcriptional regulation. Our findings support the idea that bacterial LDs can regulate nucleic acid function and facilitate bacterial survival under stress.

with neither expansion nor contraction in response to different temperatures is urgently demanded in several fields, particularly in highly advanced modern applications such as telescopes, satellites, and semiconductors. [2,4] Thus far, ZTE materials such as Mn-based antiperovskites, [11,12] R 2 Fe 17 -based magnets, [13,14] LaFe 13−x Si x hydrides, [15] SnO 2 nanowires, [16] PbTiO 3 -Bi(Co,Ti)O 3 ferroelectric solid solutions, [17] and Tb(Co,Fe) 2 magnets [18] with different mechanisms have demonstrated excellent physical properties and unique advantages in practical applications. However, manipulation to obtain excellent NTE and ZTE within a broad temperature range is still challenging and limited for broad applications. Magnetic transition has been regarded as the desired mechanism for manipulating NTE based on a tunable magnetoelastic effect. The optimized NTE, but not yet yielding ZTE in Hf 1−x Ta x Fe 2 (Hf-Ta-Fe) magnets with excellent mechanical properties, [19][20][21][22][23] is obtained owing to the cell volume shrinkage during the ferromagnetic to antiferromagnetic (FM-AFM) transition. The induced weak PTE has exhibited magnetoelastic coupling; however, has not yet garnered considerable attention. Furthermore, Zero-thermal-expansion (ZTE) alloys, as dimensionally stable materials, are urgently required in many fields, particularly in highly advanced modern industries. In this study, high-performance ZTE with a negligible coefficient of thermal expansion a v as small as 2.4 ppm K −1 in a broad temperature range of 85-245 K is discovered in Hf 0.85 Ta 0.15 Fe 2 C 0.01 magnet. It is demonstrated that the addition of trace interstitial atom C into Ta-substituted Hf 0.85 Ta 0.15 Fe 2 exhibits significant capability to tune the normal positive thermal expansion into high-performance ZTE via enhanced magnetoelastic coupling in stabilized ferromagnetic structure. Moreover, direct observation of the magnetic transition between ferromagnetic and triangular antiferromagnetic states via Lorentz transmission electron microscopy, along with corresponding theoretical calculations, further uncovers the manipulation mechanism of ZTE and negative thermal expansion. A convenient and effective method to optimize thermal expansion and achieve ZTE with interstitial C addition may result in broadened applications based on the strong correlation between the magnetic properties and crystal structure.

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