Large scale purification protocol for carnocin KZ 213 from Carnobacterium piscicola

Mass transfer process and separation mechanism of four 5'-ribonucleotides on a strong acid cation exchange resin

5'-ribonucleotides including adenosine 5'-monophosphate (AMP), cytidine 5'-monophsphate (CMP), guanosine 5'-monophosphate (GMP) and uridine 5'-monophosphate (UMP) have been widely used in the food and pharmaceutical industries. This work focused on the assessment of mass transfer process and separation mechanism of four 5'-ribonucleotides and counter-ion Na⁺ on the strong cation exchange resin NH-1. The intraparticle diffusion was determined as the rate-limiting step for the mass transfer of AMP, CMP, GMP, and Na⁺ on the resin NH-1 through the Boyd model. Meanwhile, a homogeneous surface diffusion model (HSDM) combing ion exchange and physical adsorption was proposed and tested against adsorption kinetic data in the batch adsorption systems. The fixed-bed film-surface diffusion model based on the HSDM was then developed and successfully predicted the concentration profiles of 5'-ribonucleotides and the change of pH at the outlet of the fixed-bed in the dynamic adsorption and separation process. Finally, the separation mechanism of 5'-ribonucleotides was presented combining model prediction and experimental results. The separation of UMP, GMP and CMP were mainly based on their differences in isoelectric points, while that of AMP and CMP were lied with the discrepancy of their physical adsorption binding capacity with the resin NH-1.

Recovery of a bacteriocin-like inhibitory substance from Pediococcus acidilactici Kp10 using surfactant precipitation

Bacteriocin is an important peptide which can be used as an anti-microbial agent in food. However, simpler and more cost-effective purification methods need to be developed compared to chromatography to enhance its commercial viability. Surfactant precipitation was employed for the first time to purify bacteriocin-like inhibitory substance (BLIS) from a fermentation broth of Pediococcus acidilactici Kp10, and the amount precipitated was investigated as a function of anionic surfactant (AOT) concentration, and pH. Protein recovery from the precipitate was accomplished using solvent extraction, and solvent type, NaCl concentration, and ionic strength of the final solution were optimised. Optimal conditions were; 1.05mM of AOT at pH 4 for precipitation, and acetone extraction (with 1mM NaCl), which resulted in an 86.3% yield, and 53.8 purification factor. This study highlighted the fact that surfactant precipitation can be used as a primary recovery method for BLIS from a complex fermentation broth.

Bacteriocin production and different strategies for their recovery and purification

Bacteriocins from lactic acid bacteria (LAB) are a diverse group of antimicrobial proteins/peptides, offering potential as biopreservatives, and exhibit a broad spectrum of antimicrobial activity at low concentrations along with thermal as well as pH stability in foods. High bacteriocin production usually occurs in complex media. However, such media are expensive for an economical production process. For effective use of bacteriocins as food biopreservatives, there is a need to have heat-stable wide spectrum bacteriocins produced with high-specific activity in food-grade medium. The main hurdles concerning the application of bacteriocins as food biopreservatives is their low yield in food-grade medium and time-consuming, expensive purification processes, which are suitable at laboratory scale but not at industrial scale. So, the present review focuses on the bacteriocins production using complex and food-grade media, which mainly emphasizes on the bacteriocin producer strains, media used, different production systems used and effect of different fermentation conditions on the bacteriocin production. In addition, this review emphasizes the purification processes designed for efficient recovery of bacteriocins at small and large scale.

A new thermodynamic model describes the effects of ligand density and type, salt concentration and protein species in hydrophobic interaction chromatography

A new thermodynamic model is derived that describes both loading and pulse-response behavior of proteins in hydrophobic interaction chromatography (HIC). The model describes adsorption in terms of protein and solvent activities, and water displacement from hydrophobic interfaces, and distinguishes contributions from ligand density, ligand type and protein species. Experimental isocratic response and loading data for a set of globular proteins on Sepharose resins of various ligand types and densities are described by the model with a limited number of parameters. The model is explicit in ligand density and may provide insight into the sensitivity of protein retention to ligand density in HIC as well as the limited reproducibility of HIC data.