Protein dynamics and thermodynamics crossover at 10 °C: Different roles of hydration at hydrophilic and hydrophobic groups

Influence of surface properties on the adhesion of bacteria onto different casings

Bacteria adhere to the surfaces of sausage casing and form biofilms, which causes food spoilage and quality deterioration. However, bacterial adhesion to the casing surfaces has not received enough attention and has not been extensively studied. In this study, the effect of the physicochemical properties of casing surfaces on bacterial initial adhesion were investigated with Leuconostoc mesenteroides as model bacteria. The adhesion of Leuconostoc mesenteroides onto 5 types of casings were systematically investigated, including animal casings, collagen casings, cellulose casings, fiber casings, and nylon casings, which are the most frequently encountered casings in sausage processing. It was found that the number of viable cells on the casings following the trend as: animal casings > collagen casings > fiber casings > cellulose casings > nylon casings after 4 h of incubation time. This phenomenon might be due to the different physicochemical properties of the different casings. Therefore, physicochemical factors, including zeta potential, hydrophobicity and roughness of casings, zeta potential and hydrophobicity of Leuconostoc mesenteroides, were further characterized. In terms of hydrophobic interactions, the results showed that the number of bacteria attached to the casings did not conform to the trend of hydrophobic interaction. In terms of electrostatic interactions, the results showed that the number of bacteria attached to the casings did not conform to the trend of hydrophobic interaction. The casings with different surface roughnesses in a range of 1.67-20.83 μm, the variation of bacterial adhesion quantity was in good agreement with the variation trend of casing roughness, the result showed that the surface roughness was the key factor dominating the bacterial adhesion rate compared with the surface hydrophobicity and zeta potential. The results give new insights to explore the mechanism of bacterial adhesion on casings and prevent sausage spoilage.

Insights on protein thermal stability: a graph representation of molecular interactions

Motivation

Understanding the molecular mechanisms of thermal stability is a challenge in protein biology. Indeed, knowing the temperature at which proteins are stable has important theoretical implications, which are intimately linked with properties of the native fold, and a wide range of potential applications from drug design to the optimization of enzyme activity.

Results

Here, we present a novel graph-theoretical framework to assess thermal stability based on the structure without any a priori information. In this approach we describe proteins as energy-weighted graphs and compare them using ensembles of interaction networks. Investigating the position of specific interactions within the 3D native structure, we developed a parameter-free network descriptor that permits to distinguish thermostable and mesostable proteins with an accuracy of 76% and area under the receiver operating characteristic curve of 78%.

Availability and implementation

Code is available upon request to edoardo.milanetti@uniroma1.it

Supplementary information

Supplementary data are available at Bioinformatics online.