Cooperative effects of fatty acids and n-butanol on lipid membrane phase behavior.

Biodiesel-derived crude glycerol can be fermented to produce n-butanol, which is a platform chemical for biorefining and a biofuel. One limitation to crude glycerol fermentation is the presence of long-chain fatty acids (FAs) that can partition into cellular membranes, leading to membrane fluidization and interdigitation, which can inhibit cellular function. In this work, we have examined the phase behavior of dipalmitoylphosphatidylcholine (DPPC, C16:0) membranes and the membrane partitioning of n-butanol as a function of FA degree of unsaturation (steric, oleic, and linoleic acids) using differential scanning calorimetry (DSC) and monolayer surface pressure studies.

Homeoviscous response of Clostridium pasteurianum to butanol toxicity during glycerol fermentation.

Clostridium pasteurianum ATCC 6013 achieves high n-butanol production when glycerol is used as the sole carbon source. In this study, the homeoviscous membrane response of C. pasteurianum ATCC 6013 has been examined through n-butanol challenge experiments.

n-Butanol partitioning into phase-separated heterogeneous lipid monolayers.

Cellular adaptation to elevated alcohol concentration involves altering membrane lipid composition to counteract fluidization. However, few studies have examined the biophysical response of biologically relevant heterogeneous membranes. Lipid phase behavior, molecular packing, and elasticity have been examined by surface pressure-area (π-A) analysis in mixed monolayers composed of saturated dipalmitoylphosphatidylcholine (DPPC) and unsaturated dioleoylphosphatidylcholine (DOPC) as a function of DOPC and n-butanol concentration.

Role of ionic strength on n-butanol partitioning into anionic dipalmitoyl phosphatidylcholine/phosphatidylglycerol vesicles.

Bacteria adjust their membrane lipid composition to counteract the fluidizing effects of alcohol and to adapt to elevated alcohol concentrations during fermentation. Bacterial membranes are rich in anionic phosphatidylglycerols (PGs), but little is known regarding alcohol partitioning into anionic membranes, particularly for n-butanol. This work examines the effects of lipid charge on n-butanol partitioning into anionic membrane vesicles composed of dipalmitoyl phosphatidylcholine (DPPC) and dipalmitoyl phosphatidylglycerol (DPPG) in the absence and presence of salt (phosphate-buffered saline, PBS; 0.

n-Butanol partitioning and phase behavior in DPPC/DOPC membranes.

Membrane phase behavior and fluidization have been examined in heterogeneous membranes composed of dipalmitoylphosphatidylcholine (DPPC, a saturated lipid) and dioleoylphosphatidylcholine (DOPC, an unsaturated lipid) at n-butanol concentrations below and above the interdigitation threshold of DPPC. Our results show that the presence of DOPC did not influence the interdigitation concentration of n-butanol on DPPC (0.1-0.

Impact of impurities in biodiesel-derived crude glycerol on the fermentation by Clostridium pasteurianum ATCC 6013.

During the production of biodiesel, crude glycerol is produced as a byproduct at 10% (w/w). Clostridium pasteurianum has the inherent potential to grow on glycerol and produce 1,3-propanediol and butanol as the major products. Growth and product yields on crude glycerol were reported to be slower and lower, respectively, in comparison to the results obtained from pure glycerol.