A Comparative Study Between the Antibacterial Effect of Nisin and Nisin-Loaded Chitosan/Alginate Nanoparticles on the Growth of Staphylococcus aureus in Raw and Pasteurized Milk Samples

Abstract

The aim of this study was to evaluate the antibacterial effect of nisin-loaded chitosan/alginate nanoparticles as a novel antibacterial delivery vehicle. The nisin-loaded nanoparticles were prepared using colloidal dispersion of the chitosan/alginate polymers in the presence of nisin. After the preparation of the nisin-loaded nanoparticles, their physicochemical properties such as size, shape, and zeta potential of the formulations were studied using scanning electron microscope and nanosizer instruments, consecutively. FTIR and differential scanning calorimetery studies were performed to investigate polymer-polymer or polymer-protein interactions. Next, the release kinetics and entrapment efficiency of the nisin-loaded nanoparticles were examined to assess the application potential of these formulations as a candidate vector. For measuring the antibacterial activity of the nisin-loaded nanoparticles, agar diffusion and MIC methods were employed. The samples under investigation for total microbial counts were pasteurized and raw milks each of which contained the nisin-loaded nanoparticles and inoculated Staphylococcus aureus (ATCC 19117 at 10(6) CFU/mL), pasteurized and raw milks each included free nisin and S. aureus (10(6) CFU/mL), and pasteurized and raw milks each had S. aureus (10(6) CFU/mL) in as control. Total counts of S. aureus were measured after 24 and 48 h for the pasteurized milk samples and after the time intervals of 0, 6, 10, 14, 18, and 24 h for the raw milk samples, respectively. According to the results, entrapment efficiency of nisin inside of the nanoparticles was about 90-95%. The average size of the nanoparticles was 205 nm, and the average zeta potential of them was -47 mV. In agar diffusion assay, an antibacterial activity (inhibition zone diameter, at 450 IU/mL) about 2 times higher than that of free nisin was observed for the nisin-loaded nanoparticles. MIC of the nisin-loaded nanoparticles (0.5 mg/mL) was about four times less than that of free nisin (2 mg/mL). Evaluation of the kinetic of the growth of S. aureus based on the total counts in the raw and pasteurized milks revealed that the nisin-loaded nanoparticles were able to inhibit more effectively the growth of S. aureus than free nisin during longer incubation periods. In other words, the decrease in the population of S. aureus for free nisin and the nisin-loaded nanoparticles in pasteurized milk was the same after 24 h of incubation while lessening in the growth of S. aureus was more marked for the nisin-loaded nanoparticles than the samples containing only free nisin after 48 h of incubation. Although the same growth reduction profile in S. aureus was noticed for free nisin and the nisin-loaded nanoparticles in the raw milk up to 14 h of incubation, after this time the nisin-loaded nanoparticles showed higher growth inhibition than free nisin. Since, generally, naked nisin has greater interactions with the ingredients present in milk samples in comparison with the protected nisin. Therefore, it is concluded that the antibacteri...

Streptomycin-loaded PLGA-alginate nanoparticles: preparation, characterization, and assessment

“…The results of similar research had agreement with other researcher results (Slütter et al 2010;Witschi and Doelker 1998). Results also showed that from four concentrations 0.5 % due to electrostatic stability and charge, balance was stable and observable under microscope (Zohri et al 2010). In formulations 0.1, 0.2 and 1 % concentrations, nanoparticles were not formed or were not stable for observation under SEM.…”

“…The structure of the nanoparticles is compact and their stability/solubility is greatly dependent on the pH. Release of streptomycin is a pH-dependent factor with attention to the in vitro release results, about 90-95 % release, in the medium with pH of 7.4 (because this pH leads to the more positive charge of nisin and consequently, more partitioning of streptomycin into the release medium) (Zohri et al 2010). It was shown that the nanoparticles have the same level of antimicrobial activity as the free drug.…”

“…These carriers are new vehicles which can cause deliver encapsulant to their right and appropriate place. Also, these systems allow protection of sensitive ingredient from unwanted reaction that lead to structural changes and emerging unpleasant taste or odor (Zohri et al 2010). Another benefit of these systems is the control release property that can increases functional properties of food.…”

Interaction of Nanomaterials with Plants: What Do We Need for Real Applications in Agriculture?

“…Again, compounds allowing synthesis of carriers in the nanoscale, innocuous for living organisms and with biodegrading traits are very good candidates. As pointed out previously, chitosan and alginate are ideal materials for this task, being already used in the food industry due to their lack of toxicity, biodegradability and edibility (Zohri et al, 2010;Azevedo et al, 2014).…”

Synthesis and Characterization of Nisin Loaded TPP Cross Linked Chitosan Nanoparticles

“…CS-TPP nanoparticles were synthesized using ionotropic gelation between positively charged amino groups of chitosan and negatively charged TPP, as reported previously by Krauland and Alonso [21]. Briefly, chitosan (0.1%), TPP (0.1%) and Nisin 10 mg/ml were prepared and filtered with 0.22-µm filter.…”