Large-scale production of microalgae and their bioactive compounds has steadily increased in response to global demand for natural compounds. Spirulina, in particular, has been used due to its high nutritional value, especially its high protein content. Promising biological functions have been associated with Spirulina extracts, mainly related to its high value added blue pigment, phycocyanin. Phycocyanin is used in several industries such as food, cosmetics, and pharmaceuticals, which increases its market value. Due to the worldwide interest and the need to replace synthetic compounds with natural ones, efforts have been made to optimize large-scale production processes and maintain phycocyanin stability, which is a highly unstable protein. The aim of this review is to update the scientific knowledge on phycocyanin applications and to describe the reported production, extraction, and purification methods, including the main physical and chemical parameters that may affect the purity, recovery, and stability of phycocyanin. By implementing different techniques such as complete cell disruption, extraction at temperatures below 45 °C and a pH of 5.5–6.0, purification through ammonium sulfate, and filtration and chromatography, both the purity and stability of phycocyanin have been significantly improved. Moreover, the use of saccharides, crosslinkers, or natural polymers as preservatives has contributed to the increased market value of phycocyanin.

Salmonellosis remains one of the most frequent foodborne zoonosis, constituting a worldwide major public health concern. The most frequent sources of human infections are food products of animal origin, being pork meat one of the most relevant. Currently, particular pig food production well-adapted and persistent Salmonella enterica serotypes (e.g., Salmonella Typhimurium, Salmonella 1,4,[5],12:i:-, Salmonella Derby and Salmonella Rissen) are frequently reported associated with human infections in diverse industrialized countries. The dissemination of those clinically-relevant Salmonella serotypes/clones has been related to the intensification of pig production chain and to an increase in the international trade of pigs and pork meat. Those changes that occurred over the years along the food chain may act as food chain drivers leading to new problems and challenges, compromising the successful control of Salmonella. Among those, the emergence of antibiotic resistance in non-typhoidal Salmonella associated with antimicrobials use in the pig production chain is of special concern for public health. The transmission of pig-related multidrug-resistant Salmonella serotypes, clones and/or genetic elements carrying clinically-relevant antibiotic resistance genes, frequently associated with metal tolerance genes, from pigs and pork meat to humans, has been reported and highlights the contribution of different drivers to the antibiotic resistance burden. Gathered data strengthen the need for global mandatory interventions and strategies for effective Salmonella control and surveillance across the pig production chain. The purpose of this review was to provide an overview of the role of pig and pork meat in human salmonellosis at a global scale, highlighting the main factors contributing to the persistence and dissemination of clinically-relevant pig-related Salmonella serotypes and clones.

The mcr-1 gene was found in 11 isolates from a Portuguese Salmonella collection (n = 1,010; 58 serotypes; 2002–15) of clinical samples, foodstuff, food-animals and water. Mcr-1 has been located on different plasmids (IncX4/IncHI2) in pig-associated multidrug-resistant, copper-tolerant S.1,4,[5],12:i:-/ST34 and S. Rissen/ST469 clones from human and pork products since at least 2011. Our data highlight dissemination of mcr-1 by successful resistant clones in Europe and raise questions about the efficacy of copper-based interventions to reduce colistin use.

We studied the occurrence of diverse copper (Cu) tolerance genes from Gram-positive bacteria and their co-transfer with antibiotic resistance genes among Enterococcus from diverse sources. Enterococcus (n = 922) of several species and from human, animal, environment and food samples were included. Antimicrobial and CuSO₄ susceptibility and conjugation assays were performed by standard procedures, bacterial screening of Cu and antibiotic resistance genes by PCR, and clonality by PFGE/multilocus sequence typing. tcrB and cueO genes occurred in 15% (n = 137/922) and 14% (n = 128/922) of isolates, respectively, with the highest occurrence in piggeries (P < 0.05). They were more frequent among Enterococcus faecium (tcrB: 23% versus 8% in Enterococcus faecalis and 12% in other species; cueO: 25% versus 5% and 9%, respectively; P < 0.05). A correlation between phenotypic and genotypic assays was observed for most E. faecium (CuSO₄ MIC₅₀ = 24 mM in tcrB/cueO⁺ versus CuSO₄ MIC₅₀ = 12 mM in tcrB/cueO⁻), but not for other species. Co-transfer of Cu tolerance (associated with tcrB, cueO or an unknown mechanism) with erythromycin, tetracycline, vancomycin, aminoglycosides or ampicillin resistance was demonstrated. A variety of PFGE types was detected among isolates carrying Cu tolerance mechanisms, some identified in sequence types (STs) often linked to human infections (E. faecium from ST18 and ST78 clonal lineages and E. faecalis clonal complex 2). Cu tolerance might contribute to the selection/maintenance of multidrug-resistant Enterococcus (including resistance to first-line antibiotics used to treat enterococcal infections) due to the use of Cu compounds (e.g. antiseptics/animal feed supplements). The distribution of the multicopper oxidase cueO and the co-transfer of ampicillin resistance along with Cu tolerance genes are described for the first time.