Enzymatic activities of non-starter lactic acid bacteria isolated from a traditional Portuguese cheese

Four strains of lactic acid bacteria, previously isolated from traditional Serra da Estrela cheese and duly identified as Lactobacillus paracasei ssp. paracasei, Leuconostoc mesenteroides ssp. dextranicum, Lactococcus lactis ssp. lactis and Enterococcus faecium, were tested for their aminotransferase, oxidase and dehydrogenase activities towards five amino acids in free form: two branched-chain (leucine and valine), one sulfur-containing (methionine) and two aromatic (phenylalanine and tryptophan) amino acids. For this purpose, both resting cells (RC) and crude cell-free extracts (CFE) were considered; their lyase and demethiolase activities (towards methionine and -keto- -methiolbutyric acid (KMBA), respectively) were also evaluated. Aminotransferase activity (AT) of RC was ca. 10-fold higher towards Met than towards Leu or Val. No AT activity was found in CFE, although these extracts displayed high dehydrogenase activity (DA) towards Phe, especially L. lactis ssp. lactis and E. faecium. In the case of L. paracasei ssp. paracasei and L. mesenteroides ssp. dextranicum, they showed high DA activity, which was ca. 10-fold higher towards Met than towards Leu or Val. E. faecium displayed high oxidase activity towards Met, and produced nine-fold more methanethiol from Met and five-fold more methanethiol from KMBA than the other three isolates under study

Relationships between flavour and microbiological profiles in Serra da Estrela cheese throughout ripening

Cheeses manufactured in certi"ed dairies in the Portuguese region of Serra da Estrela, using refrigerated and non-refrigerated raw sheep milk, were quantitatively evaluated in terms of indigenous micro#ora and volatile compounds during a ripening period of up to 6 mo. Viable counts were obtained for lactococci, lactobacilli, leuconostoc, enterococci, yeasts, Enterobacteriaceae and staphylococci; analyses of volatiles were performed by chromatography after solid-phase micro-extraction. Treatment of all analytical data produced by principal component analysis revealed correlations between the major microbial groups present in cheese and patterns of volatiles generated. End products resulting from the degradation of sugars, free amino acids and glycerides constituted the predominant volatiles of Serra da Estrela cheeses. Among volatile, short-chain carboxylic acids detected were acetic, propionic, iso-butyric and iso-valeric acids; these compounds are known to be breakdown products of Gly, Ala and Ser, of Thr, of Val, and of Ile, respectively, following oxidative deamination. Semi-volatile fatty acids and their corresponding ethyl esters appeared in the cheese, probably as a result of the activity of lipases produced by yeasts and Enterobacteriaceae. These ethyl esters, which are responsible for fruity #avours, were especially pronounced in cheeses manufactured from refrigerated milk

Storage and lyophilization effects of extracts of Cynara cardunculus on the degradation of ovine and caprine caseins

Clotting and proteolytic activities are important parameters when evaluating rennets for cheesemaking. Both these activities were determined for extracts of the plant Cynara cardunculus in fresh form and after lyophilization followed by reconstitution, either in water or in citrate buffer (pH 5.4) and stored for up to 4 weeks at 4°C. The patterns of degradation of ovine and caprine caseins were followed by urea polyacrylamide gel electrophoresis in attempts to qualitatively differentiate the activity of the enzyme extracts as storage time elapsed. Storage at 4°C significantly decreased the clotting power of the extracts but lyophilization retarded this decrease; β- and αs-casein breakdown generally increased with storage time, via patterns that depend on caseinate type and extract used, but lyophilized extracts reconstituted in citrate buffer were significantly less proteolytic than the other extracts. Therefore, it is suggested that lyophilized extracts (reconstituted with citrate buffer) of flowers of C. cardunculus be used rather than fresh extracts

Novel strategies for preventing dysbiosis in the oral cavity

Oral diseases affect over three billion people worldwide, making it one of the most common infections. Recent studies show that one approach to reducing the risk of chronic infections, such as caries, gingivitis, periodontitis, and halitosis, is to control the ecology of the oral microbiome instead of completely removing both the harmful and beneficial microorganisms. This is based on the knowledge that oral diseases are not caused by a single pathogen but rather by a shift in the homeostasis of the entire microbiota, a process known as dysbiosis. Consequently, it is of the utmost importance to implement strategies that are able to prevent and control oral dysbiosis to avoid serious complications, including heart, lung, and other systemic diseases. Conventional treatments include the use of antibiotics, which further disrupt the equilibrium in the oral microbiota, together with the mechanical removal of the decayed cavity area following its formation. Therefore, it is imperative to implement alternative strategies with the potential to overcome the disadvantages of the current therapy, namely, the use of broad-spectrum antibiotics. In this sense, probiotics and postbiotics have received particular attention since they can modulate the oral microbiota and decrease the dysbiosis rate in the oral cavity. However, their mechanisms of action need to be addressed to clarify and drive their possible applications as preventive strategies. In this sense, this review provides an overview of the potential of probiotics and postbiotics, focusing on their antimicrobial and antibiofilm activities as well as their ability to modulate the inflammatory response. Finally, it also showcases the main advantages and disadvantages of orodispersible films—a promising delivery mechanism for both probiotics and postbiotics to target oral dysbiosis.info:eu-repo/semantics/publishedVersio

Application of chitosan in the control of fungal infections by dermatophytes

Dermatophytes are a group of fungi that can invade keratinized tissues of humans and other animals and produce an infection called Dermatophytosis. As chitosan possesses antimicrobial activity, it can potentially be used to treat dermatophytic infections. The main objective of this work was therefore, to evaluate the antifungal activity of chitosan upon some dermatophytes, namely Microsporum canis and Trychophyton rubrum. In view of this, Minimum Inhibitory (MICs) and Minimum Fungicidal Concentrations (MFCs) of chitosans upon the fungi were determined. Moreover, in order to understand the effect of chitosan on fungal activity, hair was infected with these fungi in the presence and absence of chitosan and Scanning Electron Microscopy (SEM) images were obtained and analyzed. Lastly, keratin-azure was used as substrate to evaluate the effect of chitosan on keratin degradation by M. canis and T. rubrum. The results showed that chitosan possesses antifungal activity against T. rubrum and M. canis, presenting MICs and MFCs ranging from 1.1 to 2.2 mg/mL. The antifungal activity of chitosan is concentration dependent. The analysis of SEM images of hair infected with these dermatophytes revealed that chitosan seems to have a protective effect on the hair, reducing the extent of damage when compared to the control. Chitosan also displayed important activity in preventing proteases’ action and in preventing hair damage. Based on the obtained results, it’s possible to conclude that chitosan showed relevant antifungal activity against dermatophytes, which opens good prospects to the use of chitosan as an alternative for the conventional fungal treatmentsinfo:eu-repo/semantics/publishedVersio

Immune response: the Achilles’ heel of the stem cell-based regenerative therapies

Besides trauma, several pathological conditions which directly affect the normal functioning of organs, require new therapeutic strategies to repair damaged or diseased tissues. Tissue regeneration is a complex and spatiotemporal process involving a plethora of cell types, including various immune cells and stem cells in a synchronized relationship. However, individual parameters, namely ageing, obesity, diabetes, and chronic conditions, have been intrinsically correlated with poor regenerative properties of adult tissues. While vast progress has been made regarding stem cell-based therapy to direct self-healing, the immune response is still the Achilles’ heel of such strategies. Whereas the role of effector immune cells has been well defined along the regenerative process, an understanding of the behavior of the main adult stem cells, namely mesenchymal stem cells (MSCs) and hematopoietic stem and progenitor cells (HSPCs), along the different phases of the regenerative process could clarify how these stem cells can be used to positively influence the immune response. In this scope, this review highlights the main interactions between these stem cells and immune cells during tissue repair, exploring the most important regenerative properties of stem cells and correlating them with the modulation of the immune response during tissue regeneration. Furthermore, the utmost strategies used to explore how the behavior and stem cell fate are affected by specific microenvironments and/or stimuli usually found during a regenerative process, are emphasized. This clarification may provide critical insight into the molecular mechanisms by which stem cells modulate the immune response in a positive feedback loop toward tissue repair

Insights into the biocompatibility and biological potential of a chitosan nanoencapsulated textile dye

Traditionally synthetic textile dyes are hazardous and toxic compounds devoid of any biological activity. As nanoencapsulation of yellow everzol textile dye with chitosan has been shown to produce biocompatible nanoparticles which were still capable of dyeing textiles, this work aims to further characterize the biocompatibility of yellow everzol nanoparticles (NPs) and to ascertain if the produced nanoencapsulated dyes possess any biological activity against various skin pathogens in vitro assays and in a cell infection model. The results showed that the NPs had no deleterious effects on the HaCat cells’ metabolism and cell wall, contrary to the high toxicity of the dye. The biological activity evaluation showed that NPs had a significant antimicrobial activity, with low MICs (0.5–2 mg/mL) and MBCs (1–3 mg/mL) being registered. Additionally, NPs inhibited biofilm formation of all tested microorganisms (inhibitions between 30 and 87%) and biofilm quorum sensing. Lastly, the dye NPs were effective in managing MRSA infection of HaCat cells as they significantly reduced intracellular and extracellular bacterial counts.info:eu-repo/semantics/publishedVersio

Amino acid and soluble nitrogen evolution throughout ripening of Serra da Estrela cheese

Four batches of Serra da Estrela cheese originating from as many dairy farms were sampled throughout the ripening period, and assayed for the evolution of free amino acid (FAA) content, total nitrogen content (TN), water-soluble nitrogen content (WSN), trichloroacetic acid-soluble nitrogen content (TCASN) and phosphotungstic acid-soluble nitrogen content (PTASN). The WSN content increased from 1% (on the day of manufacture) up to 43% of TN by 180 d of ripening, thus reflecting the intense proteolytic activity of the enzymes contributed by the plant coagulant utilized. The TCASN was also found to be high in this cheese by the end of ripening (16–20%), which suggests a high extent of FAA release throughout maturation. The major FAA by 180 d of ripening were Glu, Val, Leu and Lys, representing 56–70% of the total in all four dairies sampled. Cheeses produced from refrigerated milk possessed higher amounts of g-amino-n-butyric acid (Gaba) and lower amounts of Glu when compared with those manufactured withnon-refrigerated milk