The double bond in anaerobic unsaturated fatty acid (UFA) biosynthesis is introduced by the FabA dehydratase/isomerase of the bacterial type II fatty acid biosynthetic pathway. A AfabA mutant of Pseudomonas aeruginosa grew aerobically, but required a UFA supplement for anaerobic growth. Wild-type cells produced 18:1A11 as the principal UFA, whereas the AfabA strain produced only 16:1Δ9. The double bond in the 16:1A9 was introduced after phospholipid formation and was localized in the sn-2 position. Two predicted membrane proteins, DesA and DesB, possessed the conserved histidine clusters characteristic of fatty acid desaturases. The AfabAAdesA double mutant required exogenous fatty acids for growth but the AfabAdesB double mutant did not. Exogenous stearate was converted to 18:1A9 and supported the growth of AfabAAdesA double mutant. A ΔfabAΔdesAdesB triple mutant was unable to desaturate exogenous stearate and was an UFA auxotroph. We detected a 2.5-fold increase in desA expression in AfabA mutants, whereas desB expression was derepressed by the deletion of the gene encoding a transcriptional repressor DesT. These data add two aerobic desaturases to the enzymes used for fatty acid metabolism in proteobacteria: DesA, a 2-position phospholipid A9-desaturase that supplements the anaerobic FabA pathway, and DesB, an inducible acyl-CoA A9-desaturase whose expression is repressed by DesT.

Two aerobic pathways for the formation of unsaturated fatty acids in Pseudomonas aeruginosa. Commentary

A review of ultrasound-assisted extraction for plant bioactive compounds: Phenolics, flavonoids, thymols, saponins and proteins.

Electrospun pullulan/PVA nanofibers integrated with thymol-loaded porphyrin metal-organic framework for antibacterial food packaging.

Essential oils have been investigated for their potential application as a natural ingredient in food preservation. However, the low solubility in the aqueous phase, high volatility, and low long-term stability are limiting factors for its use as a natural preservative to replace traditionally used preservatives. With the advancement of nanotechnology, the development of essential oil nanoemulsions has become a promising alternative. Nanoemulsions have unique characteristics due to their nanometric size, which include increased contact surface area and increased physicochemical stability. Meat matrices have a complex chemical composition that can interact with the compounds present in EO and reduce their bioactivity. The essential oil nanoemulsified is a conservation alternative to pure oil, with the ability to improve the interaction with specific targets in meat and exert antimicrobial and antioxidant activity. This paper summarizes the essential characteristics of nanoemulsions and presents the main advances in the application of essential oil nanoemulsified in meat and meat products for preservation. According to what is available so far from studies with essential oil nanoemulsified in meat, the application can extend the shelf life of meat and meat products, with improved bioactivity compared to pure oils. Bioactivity is directly associated with particle size, and both high and low-energy methods can be used to prepare of nanoscale emulsions and achieve droplet sizes ≤100 nm. Therefore, nanoemulsions can be a technological alternative to overcome the limitations of pure oils and be used in meat and meat products as a natural preservative. 

Essential oil nanoemulsions: Properties, development, and application in meat and meat products

Mg-coordinated self-assembly of MgO-doped ordered mesoporous carbons for selective recovery of phosphorus from aqueous solutions

MgO/carboxymethyl chitosan nanocomposite improves thermal stability, waterproof and antibacterial performance for food packaging.

The nano antibacterial composite film carboxymethyl chitosan/gelatin/nano ZnO improves the mechanical strength of food packaging.

Essential oils have attracted increasing attentions due to their broad-spectrum antimicrobial activities and generally recognized as safe (GRAS) regulatory status. However, their low-solubility in water and reduced effectiveness in food matrices limit the commercial application in food industry. In this study, we used ultrasonic emulsification, medium-chain triacylglycerol (MCT) and phosphate-buffered saline (PBS) to formulate a highly stable and water-dispersible litsea cubeba essential oil (LCEO) nanoemulsions. After emulsification, a minimizing droplet size of LCEO nanoemulsions was achieved at approximately 100 nm in diameter, resulting in an increase in the water solubility and better stability at 4 °C and 25 °C. Furthermore, the bioactivities (antibacterial, antioxidant and antibiofilm properties) of LCEO nanoemulsions were greatly improved after emulsification, suggesting that nano-emulsification is beneficial for the value development of various essential oils and the LCEO nanoemulsions could be used as a novel food preservative for controlling bacterial growth and preventing oxidative deterioration in foods.

Nano-emulsification improves physical properties and bioactivities of litsea cubeba essential oil

Ultrasonic pre-treatment modifies the pH-dependent molecular interactions between β-lactoglobulin and dietary phenolics: Conformational structures and interfacial properties.

Congnan Cen

Papers

MgO/carboxymethyl chitosan nanocomposite improves thermal stability, waterproof and antibacterial performance for food packaging.

The nano antibacterial composite film carboxymethyl chitosan/gelatin/nano ZnO improves the mechanical strength of food packaging.

Nano-emulsification improves physical properties and bioactivities of litsea cubeba essential oil

Ultrasonic pre-treatment modifies the pH-dependent molecular interactions between β-lactoglobulin and dietary phenolics: Conformational structures and interfacial properties.

Transcription factors FabR and FadR regulate cold adaptability and spoilage potential of Shewanella baltica.