Comparison of ethanol tolerance between potential cyanobacterial production hosts

Cyanobacteria are photosynthetic prokaryotes that have been extensively studied as potential autotrophic biotechnological hosts for the production of different carbon-based end-products directly from atmospheric CO2. While commercially competitive applications do not yet exist, the production of ethanol in cyanobacteria is the most mature technology, endorsed by relatively high production yields and established status of ethanol in the global biofuel market. Within this concept, the aim here was to systematically compare ethanol tolerance of different commonly used cyanobacterial strains and substrains, in order to assess their relative potential for biotechnological production platforms. The comparison revealed clear strain-specific differences in ethanol toxicity, with growth inhibition GI(50 )values ranging between 3 gL(-1) (0.4% V/V) and 28 g L-1 (3.5% V/V). The most tolerant wild-type strains were Synechocystis sp. PCC 6803 (substrain A) and Synechococcus sp. PCC 7002, which did not show any apparent effect in growth below ethanol concentrations 9.2 gL(-1 )(1.2% V/V). In comparison to typical biotechnological yeast strains used for ethanol fermentation, these values are clearly lower but still around the same order of magnitude. The results also underlined the challenges in direct number-based comparison between cyanobacterial strains and culture conditions due to inconsistencies in respect to chlorophyll content, cell morphology and optical properties

Faecalibacterium prausnitzii Treatment Improves Hepatic Health and Reduces Adipose Tissue Inflammation in High-fat Fed Mice

Faecalibacterium prausnitzii is considered as one of the most important bacterial indicators of a healthy gut. We studied the effects of oral F. prausnitzii treatment on high-fat fed mice. Compared to the high-fat control mice, F. prausnitzii-treated mice had lower hepatic fat content, aspartate aminotransferase and alanine aminotransferase, and increased fatty acid oxidation and adiponectin signaling in liver. Hepatic lipidomic analyses revealed decreases in several species of triacylglycerols, phospholipids and cholesteryl esters. Adiponectin expression was increased in the visceral adipose tissue, and the subcutaneous and visceral adipose tissues were more insulin sensitive and less inflamed in F. prausnitzii-treated mice. Further, F. prausnitzii treatment increased muscle mass that may be linked to enhanced mitochondrial respiration, modified gut microbiota composition and improved intestinal integrity. Our findings show that F. prausnitzii treatment improves hepatic health, and decreases adipose tissue inflammation in mice and warrant the need for further studies to discover its therapeutic potential.</p

A Calorimetric Study of Binary Mixtures of Dihydrosphingomyelin and Sterols, Sphingomyelin, or Phosphatidylcholine

The thermotropic properties of binary mixtures of D-erythro-n-palmitoyl-dihydrosphingomyelin (16:0-DHSM), D-erythro-n-palmitoyl-sphingomyelin (16:0-SM), cholesterol, lathosterol, and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) were studied by differential scanning calorimetry. Addition of sterol to 16:0-DHSM and 16:0-SM bilayers resulted in a progressive decrease in both the T(m) and the enthalpy of the main transition. The sterol-induced broad components in 16:0-DHSM endotherms had markedly lower enthalpies than those induced in 16:0-SM. Pretransitions recorded in 16:0-DHSM and 16:0-SM membranes responded differently to low concentrations of cholesterol. The presence of 5 mol % cholesterol increased the pretransition temperature in 16:0-SM bilayers, whereas it decreased the temperature in 16:0-DHSM membranes. Lathosterol behaved in general as cholesterol with regard to its effects on the thermotropic behavior of both sphingolipids, but it appeared to form more stable sterol-rich domains, as seen from the higher T(m) of the broad component, in comparison to cholesterol. Thermograms recorded on binary mixtures of 16:0-SM:16:0-DHSM and DPPC:16:0-DHSM showed that 16:0-SM mixed nearly ideally with 16:0-DHSM, whereas DPPC mixing was less ideal in a 16:0-DHSM membrane. In conclusion, we observed that 16:0-DHSM interactions with sterols differed from that seen with 16:0-SM, and that 16:0-DHSM mixed better with 16:0-SM than DPPC, which indicates that DHSM could function as a membrane organizer within laterally condensed domains

Properties of Palmitoyl Phosphatidylcholine, Sphingomyelin, and Dihydrosphingomyelin Bilayer Membranes as Reported by Different Fluorescent Reporter Molecules

The properties of vesicle membranes prepared from 16:0-SM, 16:0-DHSM, or DPPC were characterized using steady-state and time-resolved fluorescence spectroscopy and different fluorescent reporter molecules. The acyl-chain region was probed using free and phospholipid-bound 1,6-diphenyl-1,3,5-hexatriene. 16:0-DHSM was found to be the more ordered than both DPPC and 16:0-SM 5°C below and above melting temperature. Interfacial properties of the phospholipid bilayers were examined using 6-dodecanoyl-2-dimethyl-aminonaphthalene (Laurdan), 6-propionyl-2-dimethyl-amino-naphthalene (Prodan), and dansyl-PE. Laurdan and Prodan reported that the two sphingomyelin (SM) membrane interfaces were clearly different from the DPPC membrane interface, whereas the two SM membrane interfaces had more similar properties (both in gel and liquid-crystalline phase). Prodan partition studies showed that membrane resistance to Prodan partitioning increased in the order: 16:0-SM < DPPC < 16:0-DHSM. The degree to which dansyl-PE is exposed to water reflects the structural properties of the membrane-water interface. By comparing the lifetime of dansyl-PE in water and deuterium oxide solution, we could show that the degree to which the dansyl moiety was exposed to water in the membranes increased in the order: 16:0-SM < DPPC < 16:0-DHSM. In conclusion, this study has shown that DHSM forms more ordered bilayers than acyl-chain matched SM or phosphatidylcholine, even in the liquid-crystalline state

Faecalibacterium prausnitzii treatment improves hepatic health and reduces adipose tissue inflammation in high-fat fed mice

Faecalibacterium prausnitzii is considered as one of the most important bacterial indicators of a healthy gut. We studied the effects of oral F. prausnitzii treatment on high-fat fed mice. Compared to the high-fat control mice, F. prausnitzii-treated mice had lower hepatic fat content, aspartate aminotransferase and alanine aminotransferase, and increased fatty acid oxidation and adiponectin signaling in liver. Hepatic lipidomic analyses revealed decreases in several species of triacylglycerols, phospholipids and cholesteryl esters. Adiponectin expression was increased in the visceral adipose tissue, and the subcutaneous and visceral adipose tissues were more insulin sensitive and less inflamed in F. prausnitzii-treated mice. Further, F. prausnitzii treatment increased muscle mass that may be linked to enhanced mitochondrial respiration, modified gut microbiota composition and improved intestinal integrity. Our findings show that F. prausnitzii treatment improves hepatic health, and decreases adipose tissue inflammation in mice and warrant the need for further studies to discover its therapeutic potential.peerReviewe