Biodegradable polymers offer a potential solution to marine pollution caused by plastic waste. The marine biofilms that formed on the surfaces of poly(lactide acid) (PLA) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were studied. Bioplastics were exposed for 6 months to marine conditions in the Mediterranean Sea, and the biofilms that formed on their surfaces were assessed. The presence of specific PLA and PHBV degraders was also studied. PHBV showed extensive areas with microbial accumulations and this led to higher microbial surface densities than PLA (4.75 vs. 5.16 log CFU/cm²). Both polymers’ surfaces showed a wide variety of microbial structures, including bacteria, fungi, unicellular algae and choanoflagellates. A high bacterial diversity was observed, with differences between the two polymers, particularly at the phylum level, with over 70% of bacteria affiliated to three phyla. Differences in metagenome functions were also detected, revealing a higher presence of proteins involved in PHBV biodegradation in PHBV biofilms. Four bacterial isolates belonging to the Proteobacteria class were identified as PHBV degraders, demonstrating the presence of species involved in the biodegradation of this polymer in seawater. No PLA degraders were detected, confirming its low biodegradability in marine environments. This was a pilot study to establish a baseline for further studies aimed at comprehending the marine biodegradation of biopolymers.

The study was aimed at evaluating the presence of antibiotic-resistant Staphylococcus aureus in retailed raw chicken meat from retail stores intended for human consumption. The presence, characterization, and antibiotic susceptibility of S. aureus from 38 retail raw chicken meat samples was performed using a standard microbiological method involving mannitol salt agar (MSA) and Mueller-Hinton agar (MHA). All the samples were positive for Staphylococcus species, of which 34 (89.5%) were positive for S. aureus. The S. aureus isolates were most resistant to tetracycline (88.24%), erythromycin (82.35%), and chloramphenicol (61.77%). Nevertheless, decreased resistance towards gentamycin (23.53%) and cotrimoxazole (38.24%) were recorded. All the S. aureus isolates in this study were resistant to cloxacillin, amoxicillin, and augmentin (amoxicillin + clavulanic acid). The present findings show how the raw chicken meat samples could be a potential source of multidrug-resistant S. aureus strains dissemination. Therefore, this study suggests high-level contamination of meat with multidrug-resistant S. aureus and highlights the public health consequences of consuming such products. Undoubtedly, uncontrolled drugs in food animal production as growth stimulators or medicinal treatment present a possible consequence to people’s health. Having the aforementioned in mind, there is a necessity to control the use of drugs and monitor any residues left in the food intended for human consumption.

Four formulations have been used to produce different poly(2-hydroxyethyl methacrylate) (PHEMA) thin films, containing singlet oxygen photosensitizer Rose Bengal (RB). The polymers have been characterized employing Thermogravimetric Analysis (TGA), Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) and UV-vis Absorption Spectroscopy. When irradiated with white light (400–700 nm) films generated singlet oxygen (¹O₂), as demonstrated by the reactivity with ¹O₂ trap 9,10-dimethylanthracene (DMA). Material with the highest RB loading (polymer A4, 835 nmol RB/g polymer) was able to perform up to ten cycles of DMA oxygenation reactions at high conversion rates (ca. 90%). Polymer A4 was also able to produce the complete eradication of a Pseudomonas aeruginosa planktonic suspension of 8 log₁₀ CFU/mL, when irradiated with white light (total dose 72 J/cm²). The antimicrobial photodynamic effect was remarkably enhanced by adding potassium iodide (100 mM). In such conditions the complete bacterial reduction occurred with a total light dose of 24 J/cm². Triiodide anion (I₃⁻) generation was confirmed by UV-vis absorption spectroscopy. This species was detected inside the PHEMA films after irradiation and at concentrations ca. 1 M. The generation of this species and its retention in the matrix imparts long-lasting bactericidal effects to the RB@PHEMA polymeric hydrogels. The polymers here described could find potential applications in the medical context, when optimized for their use in everyday objects, helping to prevent bacterial contagion by contact with surfaces.

A series of poly(2-hydroxyethyl methacrylate) (PHEMA) thin films entrapping photosensitizer Rose Bengal (RB) and tetrabutylammonium iodide (TBAI) have been synthetized. The materials have been characterized by means of Thermogravimetric Analysis (TGA), Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) and UV-vis Absorption spectroscopy. Irradiation of the materials with white light led to the generation of several bactericidal species, including singlet oxygen (¹O₂), triiodide anion (I₃⁻) and hydrogen peroxide (H₂O₂). ¹O₂ production was demonstrated spectroscopically by reaction with the chemical trap 2,2′-(anthracene-9,10-diylbis(methylene))dimalonic acid (ABDA). In addition, the reaction of iodide anion with ¹O₂ yielded I₃⁻ inside the polymeric matrix. This reaction is accompanied by the formation of H₂O₂, which diffuses out the polymeric matrix. Generation of both I₃⁻ and H₂O₂ was demonstrated spectroscopically (directly in the case of triiodide by the absorption at 360 nm and indirectly for H₂O₂ using the xylenol orange test). A series of photodynamic inactivation assays were conducted with the synthesized polymers against Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa. Complete eradication (7 log₁₀ CFU/mL) of both bacteria occurred after only 5 min of white light irradiation (400–700 nm; total energy dose 24 J/cm²) of the polymer containing both RB and TBAI. The control polymer without embedded iodide (only RB) showed only marginal reductions of ca. 0.5 log₁₀ CFU/mL. The main novelty of the present investigation is the generation of three bactericidal species (¹O₂, I₃⁻ and H₂O₂) at the same time using a single polymeric material containing all the elements needed to produce such a bactericidal cocktail, although the most relevant antimicrobial activity is shown by H₂O₂. This experimental approach avoids multistep protocols involving a final step of addition of I⁻, as described previously for other assays in solution.

Triarylpyridinium cations are presented as broad-spectrum antimicrobial agents effective against pathogenic Gram-positive and Gram-negative bacteria, as well as fungi.