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BackgroundLactic acid bacteria (LAB) can be isolated from traditional milk products. LAB that secrete substances that inhibit pathogenic bacteria and are resistant to acid, bile, and pepsin but not vancomycin may have potential in food applications.ResultsLAB isolated from a range of traditional fermented products were screened for the production of bacteriocin-like inhibitory substances. A total of 222 LAB strains were isolated from fermented milk products in the form of fresh curds, dried curds, and ghara (a traditional flavor enhancer prepared from whey), and fermented cocoa bean. Eleven LAB isolates that produced antimicrobial substances were identified as Lactococcus lactis, Lactobacillus plantarum, and Pediococcus acidilactici strains by biochemical methods and 16S rDNA gene sequencing. Of these, the cell-free supernatant of Kp10 (P. acidilactici) most strongly inhibited Listeria monocytogenes. Further analysis identified the antimicrobial substance produced by Kp10 as proteinaceous in nature and active over a wide pH range. Kp10 (P. acidilactici) was found to be catalase-negative, able to produce β-galactosidase, resistant to bile salts (0.3%) and acidic conditions (pH 3), and susceptible to most antibiotics.ConclusionTraditionally prepared fermented milk products are good sources of LAB with characteristics suitable for industrial applications. The isolate Kp10 (P. acidilactici) shows potential for the production of probiotic and functional foods.

A simplex centroid mixture design was used to study the interactions between two chosen solvents, dichloromethane (DCM) and acetone (ACT), as organic-phase components in the formation and physicochemical characterization and cellular uptake of astaxanthin nanodispersions produced using precipitation and condensation processes. Full cubic or quadratic regression models with acceptable determination coefficients were obtained for all of the studied responses. Multiple-response optimization predicted that the organic phase with 38% (w/w) DCM and 62% (w/w) ACT yielded astaxanthin nanodispersions with the minimum particle size (106 nm), polydispersity index (0.191), and total astaxanthin loss (12.7%, w/w) and the maximum cellular uptake (2981 fmol/cell). Astaxanthin cellular uptake from the produced nanodispersions also showed a good correlation with their particle size distributions and astaxanthin trans/cis isomerization ratios. The absence of significant (p > 0.05) differences between the experimental and predicted values of the response variables confirmed the adequacy of the fitted models.

In recent year, aqueous two-phase system (ATPS) has become a proven tool used in separation and purification technology. The application of ATPSs in clarification, partitioning and partial purification of biomolecules and bioproducts had showed the rapid development. This method is able to give high recovery yield and high purity in a single step. The ATPS shows characteristics of high selectivity and is easily to scale up. Therefore, ATPS offers an attractive alternative that meets the requirements of the high demand in industry processes and it is also beneficial in terms of economic and environmental protection. In the past, a lot of works and researches have been done in order to develop feasible separation processes using different types of ATPSs and their applications in numerous product separations. This paper aims to review on the recent literature works in the development of different type of ATPSs and their applications in novel separations and purifications of biomaterials.