Nathália Fernandes

The SH-SY5Y human neuroblastoma cell line is widely used as an in vitro model of β-amyloid (Aβ) neurotoxicity in Alzheimer’s disease (AD). However, the lack of standardized protocols for assessing Aβ toxicity - including differentiation strategies for SH-SY5Y cells - limits the comparability of results across studies. To address these issues, we conducted a systematic review and meta-analysis to evaluate how methodological factors influence Aβ-induced toxicity in SH-SY5Y cells. We included 359 eligible studies encompassing 1,192 MTT-based comparisons of cell viability between Aβ-treated and control SH-SY5Y cells. A three-level meta-analysis estimated mean cell viability after Aβ exposure at 63% of control levels (95% CI [61.6; 64.3]), with very high heterogeneity (I²=99.6%). Meta-regression identified significant associations between increased toxicity and higher Aβ concentrations, longer exposure durations, and the use of peptide preparations described as fibrils. Conversely, differentiation protocols, duration, and cell density did not significantly influence toxicity outcomes. Reporting quality was often poor, with frequent omissions regarding cell line origin, authentication, contamination testing, Aβ preparation details and nature of the experimental unit. Overall, our findings show robust Aβ toxicity in SH-SY5Y cells, primarily driven by dose, exposure time, and Aβ aggregation state, but not cell differentiation status. Our conclusions highlight the critical need for better reporting of Aβ exposure parameters to enhance reproducibility and translational potential in AD research.

Concerns over the replicability and reproducibility of published research have grown in many research fields, but empirical data to inform policies are still scarce. Biomedical research in Brazil expanded rapidly over the last three decades, with no systematic assessment of the replicability of its findings. With this in mind, we set up the Brazilian Reproducibility Initiative, a multicenter replication of published experiments from Brazilian science using three common experimental methods: the MTT assay, the reverse transcription polymerase chain reaction (RT-PCR) and the elevated plus maze (EPM). A total of 56 laboratories performed 143 replications of 56 experiments; of these, 90 replications of 45 experiments were considered valid by an independent committee. Replication rates for these experiments varied between 20 and 44% according to five predefined criteria. In median terms, ratios between group means were 58% lower in replications than in original experiments, while coefficients of variation were 82% higher. Effect size decrease was smaller for MTT experiments, original results with less variability and those considered more challenging to replicate, while t values for replications were positively correlated with researcher predictions about replicability, and negatively correlated with the rate of publications by the original article’s last author. Deviations from preregistered protocols were very common in replications, most frequently due to reasons inherent to the experimental model or related to infrastructure and logistics. Our results highlight factors that limit the replicability of results published by researchers in Brazil and suggest ways by which this scenario can be improved.

Raw milk and traditional fermented foods such as artisanal cheese represent a natural source of lactic acid bacteria (LAB). They can produce antimicrobial compounds, such as bacteriocins and lactic acid, which may be exploited in dairy biopreservation. This study aimed to conduct a systematic review and meta-analysis to synthesize the inhibition diameter (ID) of LAB against L. monocytogenes, S. aureus, and Salmonella spp. Literature electronic searches were performed on PubMed, Scopus, and Web of Science, to identify articles that reported data on in-vitro antimicrobial activity by LAB isolated from dairy foods. A total of 1665 papers were retrieved, and 20 primary studies were selected according to the selection criteria, of which 397 observations were extracted. Random-effects meta-regression models were employed to describe the effects of LAB genus, pathogen concentration, susceptibility method, incubation time, inoculation volume, agar type and pH on the IDs for L. monocytogens, S. aureus, and Salmonella spp. L. monocytogens was the most susceptible pathogen (p < 0.05) to the LAB effects, followed by S. aureus and Salmonella spp. As a whole, LAB from the Lacticaseibacillus genus were the most effective (p < 0.05) in inhibiting L. monocytogens (21.49 ± 2.654 mm), followed by S. aureus (21.06 ± 2.056 mm). Salmonella spp. presented higher (p < 0.05) susceptibility to Lactobacillus genus (19.93 ± 2.456 mm). From the results, a general trend could be observed for the well-diffusion method to produce higher (p < 0.05) ID estimates than the spot and disk methods (30.73 ± 2.530 mm vs. 21.98 ± 1.309 mm vs. 13.39 ± 1.403 mm for L. monocytogenes; 22.37 ± 1.073 mm vs. 14.91 ± 2.312 mm vs. 20.30 ± 2.319 mm for Salmonella spp.), respectively. Among the tested moderators, the pathogen’s inoculum concentration, the in vitro susceptibility assay itself, incubation time and inoculation volume on agar are determinant parameters to be looked at when designing a robust and reproducible experimental plan. The in vitro results reinforced that LAB can be useful in controlling the development of pathogenic bacteria frequently found in the dairy industry.

The physicochemical and microbiological properties of traditional Portuguese ready-to-eat dry fermented sausage chouriça de carne samples from 14 regional producers were analysed and subjected to multivariate analysis to determine the relationships between them and to evaluate how the quality and safety of these sausages is affected by these properties. Producer-mean values for physicochemical analyses were quite variable, with intervals of 4.87–6.11 for pH, 0.803–0.965 for a_w, moisture 19.5–48.5%, protein 32.0–60.1% (db), fat 22.0–53.3% (db), ash 3.52–9.69% (db), and carbohydrates 1.66–13.5% (db). Mesophilic counts varied (5.61–8.68 log CFU/g), while lactic acid bacteria were generally high (MRS: 8.21–10.2; M17: 7.66–10.0 log CFU/g). S. aureus was enumerated in levels up to 2.55 log CFU/g, while presumptive C. perfringens never surpassed 2 log CFU/g. Salmonella spp. and Listeria spp. were also detected in the samples tested. Principal component (PC) analysis yielded a three-dimension solution that explained 60% of the data variation; PC1 (26%) characterized chorizo formulations with more meat, while PC2 (19.3%) described sausages with longer/rapid fermentation, and PC3 (14.5%) highlighted chouriços with poorer hygiene. Cluster analysis identified three quality groups: (i) chorizos with high moisture, high protein content, and lowest pH; (ii) sausages with low moisture, high fat content, and elevated pH; and (iii) chouriças with high moisture and high protein but lower fat contents, low pH, and improved hygiene. Lastly, factor analysis yielded a varimax-rotated three-factor solution that explained 65% of the data, with similar results to PCA; factor 1 (23.5%) depicted chorizos with low pH but high moisture, factor 2 (20.8%) described sausages with more meat in the formulation, and factor 3 (20.6%) longer or rapid fermentation. Overall, the results evidenced the great variability in the quality attributes of Portuguese chorizo sausages, very likely to arise from multiple recipes, ingredients, and manufacturing practices. The definition of quality clusters is expected to play a crucial role for the self-denominated “artisanal” food companies to benchmark their chouriço sausages against the proper artisanal quality group.

Fresh meat is highly perishable, presenting challenges in spoilage mitigation and waste reduction globally. Despite the efforts, foodborne outbreaks from meat consumption persist. Biopreservation offers a natural solution to extend shelf life by managing microbial communities. However, challenges include the effective diffusion of bacteriocins through the meat matrix and the potential inhibition of starter cultures by bacteriocins targeting closely related lactic acid bacteria (LAB). LAB, predominant in meat, produce bacteriocins – small, stable peptides with broad antimicrobial properties effective across varying pH and temperature conditions. This review highlights the recent advances in the optimization of bacteriocin use, considering its structure and mode of action. Moreover, the strengths and weaknesses of different techniques for bacteriocin screening, including novel bioengineering methods, are described. Finally, we discuss the advantages and limitations of the modes of application of bacteriocins toward the preservation of fresh, cured, and novel meat products.

This systematic review and meta-analysis compile the in vitro antimicrobial efficacy of lactic acid bacteria (LAB) supernatants against three common pathogenic bacteria found in dairy products: Salmonella spp., L. monocytogenes, and Staphylococcus aureus. After screening and analysis of full papers, identified by searches in PubMed, Scopus, and Web of Science databases, thirty-nine studies were regarded as relevant, and a total of 510 observations were recorded. The effects of moderators on inhibition diameters were assessed by adjusting three pathogen-specific meta-regression models. Results showed that, in general terms, strains from the Enterococcus genus displayed the highest inhibition values against L. monocytogenes (15.90 ± 2.138 mm), whereas Lacticaseibacillus strains were more effective against S. aureus (11.89 ± 0.573 mm). The well diffusion test outperformed the spot and disk diffusion tests, and more acidic LAB supernatants resulted in higher measurements of inhibition diameters (p < 0.001). Meta-regression models incorporating LAB genus, pathogen concentration, and incubation time explained 33.8%, 52.3%, and 19.8% of the total variance in inhibition diameters for L. monocytogenes, Salmonella spp., and S. aureus, respectively. None of the three models showed evidence of publication bias. This meta-regression study demonstrated that LAB strains present in dairy products possess a variable capacity to inhibit any of the three foodborne pathogens. Overall, L. monocytogenes was found to exhibit greater susceptibility than Salmonella spp. and S. aureus; thus, the antilisterial capacity of the selected LAB strains could be exploited in developing biocontrol strategies for cheese-making.

This systematic review and meta-analysis compile the in vitro antimicrobial efficacy of lactic acid bacteria (LAB) supernatant against three common dairy product pathogenic bacteria. After screening and analysis of full papers, identified by searches in PubMed, Scopus, and Web of Science databases, thirty-nine studies were regarded as relevant, and a total of 510 were extracted thereof. The effects of moderators, namely, pathogen’s concentration, susceptibility test method, agar type, incubation time and temperature, LAB supernatant pH and aliquot volume, on inhibition diameters were assessed by adjusting three pathogen-specific meta-regression models. Results showed that, in general terms, strains from the Enterococcus genus (15.90 ± 2.138 mm) displayed the highest inhibition values against L. monocytogenes, whereas Lacticaseibacillus strains were more effective against Staphylococcus aureus (11.89 ± 0.573 mm). Whereas the well diffusion test outperformed spot and disk diffusion tests; the pH of LAB supernatant resulted in high measurements of inhibition diameters (p

Alheira is a naturally fermented meat sausage traditionally made in the Portuguese region of Trás-os-Montes. Lactic acid bacteria (LAB) are the dominant microorganisms in alheira and can endow it with various technological properties. This study aimed (1) to characterize technological features and in vitro antimicrobial activity of LAB isolated from alheira, and (2) to reveal associations between such phenotypic characteristics and the isolates species identified through amplification and sequencing of the 16S ribosomal gene. Sixty-two LAB isolates were identified and Enterococcus (E.) faecium corresponded to 32.3% of isolates, followed by Leuconostoc (L.) mesenteroides (19.4%) and Latilactobacillus (Lb.) sakei (17.7%), aligning with previous research on traditional Portuguese fermented meat sausages. The phenotypic analysis of LAB isolates indicated diverse acidification capacities, proteolytic activities, and inhibitory effects against foodborne pathogens Listeria (L.) monocytogenes, Salmonella (S.) Typhimurium and Staphylococcus (S.) aureus. Overall, lactobacilli displayed high inhibition activity against the pathogens S. aureus, L. monocytogenes, and S. Typhimurium. Although the mechanisms for the inhibition of pathogen growth need to be further elucidated, these findings enhance our understanding of LAB diversity and functionality in alheira sausages, contributing to product safety and quality.

Alheira is a naturally fermented meat sausage traditionally made in the Portuguese region of Trás-os-Montes. Lactic Acid Bacteria (LAB) have been found to be the dominant microorganisms in alheira. This study aimed: 1) to characterize technological features and in vitro antimicrobial activity of LAB isolates; and 2) to reveal associations between such phenotypic characteristics and the isolates genotypically identified to species level through amplification and sequencing of the 16S ribosomal gene. Sixty-two LAB isolates were identified and Enterococcus faecium was the most prevalent (32.3%), followed by Leuconostoc mesenteroides (19.4%) and Latilactobacillus sakei (17.7%), aligning with previous research on traditional Portuguese fermented meat sausages. The phenotypic analysis of LAB isolates indicated diverse acidification capacities, proteolytic activities, and inhibitory effects against foodborne pathogens. Comprising the technological attributes, L. paracasei and L. mesenteroides had higher proteolytic activity (3.46 and 3.43 mm), whereas E. faecium and L. paracasei stood out for their acidifying capacity, with mean pH after 6 h of 5.78 and 6.03, respectively. Overall, lactobacilli presented higher inhibition diameter against the pathogens Staphylococcus aureus, Listeria monocytogenes and Salmonella Typhimurium. Although the mechanisms for inhibition of pathogen growth needs to be further elucidated, these findings enhance our understanding of LAB diversity and functionality in alheira sausages, contributing to product safety and quality assessment.