Microbial polysaccharides can serve as renewable sources for hydrocolloids used in food, pharmaceutical, and other industrial applications. Xanthan, gellan, dextran, and alginate are among the common microbial polysaccharides in current use. Although only limited numbers of microbial polysaccharides are commercialized, several approaches to modify microbial polysaccharides are laid out to improve their functional and technological properties via physical and chemical cross-linking reactions. This review discusses the properties of microbial polysaccharides as well as several methods of physical and chemical cross-linking for polysaccharides modification.

Here we report the draft genomes and annotation of four N-acyl homoserine lactone (AHL)-producing members from the family Sphingomonadaceae. Comparative genomic analyses of 62 Sphingomonadaceae genomes were performed to gain insights into the distribution of the canonical luxI/R-type quorum sensing (QS) network within this family. Forty genomes contained at least one luxR homolog while the genome of Sphingobium yanoikuyae B1 contained seven Open Reading Frames (ORFs) that have significant homology to that of luxR. Thirty-three genomes contained at least one luxI homolog while the genomes of Sphingobium sp. SYK6, Sphingobium japonicum, and Sphingobium lactosutens contained four luxI. Using phylogenetic analysis, the sphingomonad LuxR homologs formed five distinct clades with two minor clades located near the plant associated bacteria (PAB) LuxR solo clade. This work for the first time shows that 13 Sphingobium and one Sphingomonas genome(s) contain three convergently oriented genes composed of two tandem luxR genes proximal to one luxI (luxR-luxR-luxI). Interestingly, luxI solos were identified in two Sphingobium species and may represent species that contribute to AHL-based QS system by contributing AHL molecules but are unable to perceive AHLs as signals. This work provides the most comprehensive description of the luxI/R circuitry and genome-based taxonomical description of the available sphingomonad genomes to date indicating that the presence of luxR solos and luxI solos are not an uncommon feature in members of the Sphingomonadaceae family.

No abstract

Oscillatory and steady shear rheology of gellan (G) and dextran (D) solution individually, and in blends (G/D ratio 1:1, 1:2, and 1:3 w/v) with a total hydrocolloid concentration of 3 % (w/v) were studied at 25°C. Individually, 1.5 % dextran and 1.5 % gellan in solution exhibited Newtonian and non-Newtonian behavior, respectively. A blend of equal proportion of dextran and gellan (G/D=1:1) exhibits a distinct gel point (G′ = G″), and further addition of dextran in the blend (G/D=1:2 and 1:3) resulted predominating liquid-like (G″ > G′) behavior. A plot of G′ vs G″ distinctly showed the gradual transition of the blend. Shear stress (τ)-shear rate (γ ) data fitted well the Herschel-Bulkley model. The G/D blend exhibited shear thinning behavior with flow behavior index less than unity. The Cox-Merz rule did not fit well for the complex shear viscosity (η*) and apparent viscosity (η) of the blend.

Ice cream has been selected as a good carrier of beneficial effects through the health-promoting component incorporated into the product to meet the needs of functional food. The majority of people in the globe adore ice cream because it has distinct texture and sensory features. Ice cream is a promising carrier for the unhindered distribution of bioactive elements due to its composition, colloidal form, and low-temperature system. The development of functional ice cream has consolidated numerous health-promoting ingredients such as probiotics, prebiotic, synbiotic, and natural antioxidants (e.g., polyphenols). In this review, recent advances in the attempts of developing alternative ice cream formulation and functional ice cream (a product supplemented or fortified with bioactive substances) are presented: the highlighted contents encompass the aspects that include-defining the bioactive component with its beneficial effect, strategies for the successful integration with potential hurdles during the product manufacture, ideal consumption model with possible side-effect, and current scenario of the functional ice cream development.