Search

Staphylococcal infections and contaminations have elicited a growing and perennial concern in the medical and food industries. Meanwhile, the manifestation of antibiotic-resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA) beside the production of disinfectant-resistant biofilms makes the confrontation with the bacteria more cumbersome and challenging. Pomegranate peel as a waste product of juicing factories is a natural antibacterial agent. The pomegranate peel hydro-extract (PPHE), as a bio-friendly material, was prepared from an Iranian pomegranate cultivar, Rabab, and its phenolic compounds and antioxidant (via DPPH and FRAP assays) and anti-staphylococcal (anti-planktonic and anti-biofilm) properties were assessed. The Rabab PPHE inhibited planktonic cells and biofilm formation of three S. aureus. The Rabab PPHE produced large and obvious staphylococcal inhibition zones in which their diameters were significantly dose-dependent for the milk isolated S. aureus (p < 0.05). Despite the resistance of MRSA (ATCC 33591) to beta-lactam antibiotics, the minimum inhibitory concentration (MIC) of PPHE against its planktonic cells was only 3.75mg mL-1. Furthermore, Rabab PPHE inhibited bacterial biofilms formation in a dose-dependent manner. The MIC of Rabab PPHE against planktonic milk-isolated S. aureus, S. aureus (ATCC 29737), and MRSA prevented 47, 36, and 26% of their biofilm formation, respectively. This addresses the differences between the anti-planktonic and anti-biofilm activity of Rabab PPHE. The anti-planktonic and to a lesser extent the anti-biofilm forming activity of this water-based extract supports the notion of its effectiveness and salubrious application in food and pharmaceutical industries.

The limitations of rennin application in cheese crafting usually urge the discovery of novel proteases. The Withania coagulans fruits are well-known for their caseinolytic activity in cheese production. The study aims to evaluate some of the factors affecting the milk-clotting activity (MCA) of W. coagulans fruit enzymatic extract in even and odd-toed hoofed-mammals milk. The extracts were prepared by distilled water and normal saline and their protein content were evaluated. The time necessary for the appearance of discernible and discrete particles in the mare and cow milk by the two concentrations of saline and hydro W. coagulans extracts (SE and HE, respectively) was assessed at 35 and 40°C while exposing different levels of calcium chloride. The interaction of these factors on MCA was evaluated using mixed-design ANOVA. Three significant interaction patterns considering the maximum number of factors were revealed (p < 0.05). The higher extract concentration and incubation temperature (40°C) was always effective in producing the utmost MCA in these interactions. The SE was faster than HE in milk clot formation. The cow milk was a more suitable substrate than mare milk for the enzyme activity.