We assessed the antimicrobial activity of reuterin produced in vitro in glycerol aqueous solutions in situ by Lactobacillus reuteri ATCC 53608 as part of a fermented milk product against starter (Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus), spoilage (Penicillium expansum), pathogenic (Staphylococcus aureus Salmonella enterica ssp. enterica, and Listeria monocytogenes), and pathogen surrogate (Escherichia coli DH5α) microorganisms. We also assayed the influence of cold storage (28 d at 4°C) and reuterin on the color and rheology of the fermented milk product. We obtained maximum reuterin concentrations of 107.5 and 33.97 mM in glycerol aqueous solution and fermented milk product, respectively. Reuterin was stable throughout its refrigerated shelf life. Gram-positive microorganisms were more resistant to reuterin than gram-negative microorganisms. Penicillium expansum and Lactobacillus reuteri ATCC 53608 survived at concentrations up to 10 and 8.5 mM, respectively. Escherichia coli DH5α was the most sensitive to reuterin (0.9 mM). The presence of reuterin did not cause relevant changes in the quality parameters of the fermented milk product, including pH, acidity, soluble solids, color, and rheological aspects (storage and loss moduli and viscosity). This study demonstrated the viability of using Lactobacillus reuteri ATCC 53608 as a biopreservative in a fermented milk product through reuterin synthesis, without drastically modifying its quality parameters.

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En la actualidad, la mayoría de las actividades humanas dependen en gran medida del uso de los plásticos, cuya producción y consumo han aumentado considerablemente en las últimas décadas. La utilización de productos plásticos ha tenido impactos positivos para nuestro bienestar; sin embargo, los efectos negativos derivados de su disposición inapropiada son motivo de gran preocupación, especialmente durante la actual emergencia sanitaria provocada por la COVID-19, en la que el uso de plásticos por una ocasión ha aumentado drásticamente. A pesar de que algunos polímeros plásticos como el polietileno (PE) y el poliestireno (PS) pueden reciclarse, la alta demanda energética y tecnológica, el empleo de sustancias potencialmente tóxicas y la baja rentabilidad económica del proceso, vuelven a esta opción poco viable. Ante esta situación, el tratamiento biológico de plásticos a través de organismos degradadores del PE y del PS, como las larvas de la harina y de la cera, surge como una alternativa prometedora y ha llamado la atención de investigadores alrededor del mundo. El objetivo de esta revisión es sintetizar los avances más recientes en el campo de la biodegradación de plásticos por larvas de insectos y un análisis de las tendencias actuales y futuras en esta creciente área de investigación.

The influence of environmental factors such as glycerol concentration, time of production, presence of Escherichia coli, and two different strains of Lactobacillus reuteri (ATCC 55730 and ATCC 53608) on 3‐hydroxypropionaldehyde (3‐HPA) production was analyzed. Additionally, the influence of those factors on gene expression in the 3‐HPA production pathway was evaluated. The genes studied were GldC, cbiP, and Lreu_1734. The results of this study showed that the principal environmental factors that influence 3‐HPA production are glycerol concentration and Lactobacillus reuteri strain. As glycerol concentration increased, 3‐HPA content increased. The greatest 3‐HPA concentration (56.6 mM ±5.99) was achieved by L. reuteri ATCC 55730. Gene expression was also affected by environmental factors. Factor that showed the greatest influence were also strain and glycerol concentration. The genes cbiP, GldC, and Lreu_1734 had basal gene expression in glycerol absence; however, glycerol regulated its expression. Glycerol induced overexpression of cbiP and GldC genes (Strain ATCC 53608), probably to ensure its efficient utilization. On the contrary, glycerol concentration suppressed Lre_1734 expression in both analyzed strains, as a mechanism for 3‐HPA accumulation. Down‐regulation was observed in all the genes tested in strain ATCC 55730, probably due to feedback inhibition by 3‐HPA.