Biofunctionalization of Cork with Moringa oleifera Seeds and Use of PMA Staining and qPCR to Detect Viability of Escherichia coli

Abstract

Cork matrices biofunctionalized with Moringa oleifera seed extracts (MoSe) have potential for use as a biofilter with antibacterial properties to reduce waterborne pathogens. The aim of this study was to evaluate the effect of cork biofunctionalized with active antimicrobial compounds of MoSe (f-cork) on the inhibition of Escherichia coli (InhEc). The LacZ gene from a strain of E. coli was used as the target sequence using viability quantification Polymerase Chain Reaction (qPCR) and differentiation of viable and dead bacteria through selective cell viability PMA staining. To perform this, a 27−4 fractional factorial design and a biofiltration system were used to evaluate the effect of the active protein in MoSe immobilized in granulated cork on InhEc. We found that the potential for antimicrobial activity increased with f-cork for an effective maximal bacterial reduction (99.99%; p < 0.05). The effect of f-cork functionalized with MoSe on E. coli viability was of 0.024% and 0.005% for the cells exposed to PMA, respectively, being the relevant conditions in treatment 2: (0 L/min) without aeration, (5%) MoSe and (5 mm) cork particle. In conclusion, the f-cork functionalized with MoSe presented biosorbent and antibacterial properties that effectively reduced the E. coli growth.

Sono-Enzymatically Embedded Antibacterial Silver-Lignin Nanoparticles on Cork Filter Material for Water Disinfection

“…In a previous work, XPS and FTIR analyses revealed that the mild conditions used at the present work (i.e., low temperature and mild-alkaline pH) during AgLNP synthesis ensure a low extent of lignin oxidation, preserving the phenolic moieties required for the laccase-assisted NPs immobilization onto the cork [ 43 ]. All the results herein obtained for AgLNP characterization were in agreement with those previously reported in other works from our group [ 28 , 41 , 43 , 44 ].…”

“…Therefore, this method is a fast and eco-friendly approach to obtain nanocomposite materials with durable and efficient coatings. On the other hand, the enzymatic immobilization is a very complex process that involves different interactions/reactions between the cork surface and the AgLNP, such as electrostatic interactions, hydrogen bonds, and covalent bonds between laccase-activated cork residues and the AgLNP [ 44 ]. Cork chemical composition can vary according to its origin in the range of 40–60% suberin, 10–50% lignin, 5–15% polysaccharides, and 10–25% extractable components (e.g., waxes and tannins).…”

“…Herein, the phenolic moieties in cork provides bonding sites for covalent immobilization of AgLNP imparting a permanent modification of the material and a more durable antibacterial effect. Our group previously undertook the laccase assisted functionalization of cork with AgNP at standard reaction conditions (e.g., chemical reduction of Ag + to elemental Ag 0 using NaBH 4 under vigorous stirring) [ 43 , 44 ]. However, it is a method that requires much more time compared to the ultrasound functionalization used at the present study.…”

Improving the Efficiency of Viability-qPCR with Lactic Acid Enhancer for the Selective Detection of Live Pathogens in Foods

“…DNA intercalating dyes are able to enter dead cells without damaging their membrane integrity and intercalate with DNA using their photo-inducible azide groups, preventing PCR-induced DNA amplification [7,8]. Viable qPCR assays with PMA have been successfully optimized to detect major foodborne pathogens, including E. coli O157:H7, Salmonella spp., and Listeria monocytogenes [11][12][13][14][15][16][17].…”