Nanoemulsions have small droplet size and are kinetically stable colloidal systems. They have enhanced functional properties in comparison to conventional emulsions. The composition and structure of the nanoemulsions can be controlled for the encapsulation and effective delivery of bioactive lipophilic compounds. Nanoemulsions have potential application in the food industry for the delivery of nutraceuticals, coloring and flavoring agents, and antimicrobials. The nanoemulsion formulations of active ingredients can be used for developing biodegradable coating and packaging films to enhance the quality, functional properties, nutritional value, and shelf life of foods. This review focuses on preparation of food grade nanoemulsions using high-energy methods and low-energy approaches and their characterization for physical properties, stability, and microstructure. The application of nanoemulsion formulations for sustainable food processing and improving the delivery of functional compounds, such as colorants, flavoring agents, nutraceuticals, and preservatives or antimicrobial agents in foods has been discussed.

Quorum sensing regulates violacein pigment production in C. violaceum.

In the present study, nanoparticles of gold, iron oxide and zinc oxide (ZnO) were studied for cytotoxicity in the colorectal cancer cell HT 29. The metallic nanoparticles in the range of <50 and <100 nm were screened for anticancer activity by MTT assay. The nanoparticles were tested at concentrations ranging from 0.5 to 50 µg/ml. Zinc oxide exhibited significant anti-cancer activity in comparison to other nanoparticles. It had an IC50 value of 17.12 µg/ml. The mechanism of action was studied by fluorescence microscopy with acridine orange, propidium iodide and DAPI staining techniques. The ROS production of ZnO nanoparticles was determined by DCFH-DA. The ZnO nanoparticles were conjugated with novel hydrophobic peptides and evaluated for anticancer activity. It was observed that the nanoparticles peptide complex showed better cytotoxicity than either peptide or nanoparticle alone. Thus, the ZnO nanoparticles tested in our study has anticancer activity against colon cancer cells. It can also be conjugated with peptides and used for targeting cancer cells with higher efficacy.

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Bacterial endophytes are found in the internal tissues of plants and have intimate associations with their host. However, little is known about the diversity of medicinal plant endophytes (ME) or their capability to produce specialised metabolites that may contribute to therapeutic properties. We isolated 75 bacterial ME from 24 plant species of the Western Ghats, India. Molecular identification by 16S rRNA gene sequencing grouped MEs into 13 bacterial genera, with members of Gammaproteobacteria and Firmicutes being the most abundant. To improve taxonomic identification, 26 selected ME were genome sequenced and average nucleotide identity (ANI) used to identify them to the species-level. This identified multiple species in the most common genus as Bacillus. Similarly, identity of the Enterobacterales was also distinguished within Enterobacter and Serratia by ANI and core-gene analysis. AntiSMASH identified non-ribosomal peptide synthase, lantipeptide and bacteriocin biosynthetic gene clusters (BGC) as the most common BGCs found in the ME genomes. Five of the ME isolates belonging to Bacillus, Serratia and Enterobacter showed antimicrobial activity against the plant pathogen Pectobacterium carotovorum. Using molecular and genomic approaches we have characterised a unique collection of endophytic bacteria from medicinal plants. Their genomes encode multiple specialised metabolite gene clusters and the collection can now be screened for novel bioactive and medicinal metabolites.

The results of the study showed that of all the tested nanoparticles, ZnO nanoparticles had significant antimicrobial activity against the drug resistant pathogens and could be used at concentrations less toxic to mammalian cells. Hence, ZnO nanoparticles have the potential for the design of novel antibacterial agents and therapeutics.

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