Browsing by Author "Mateus, Cristiana"
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- Natural Transformation as a Mechanism of Horizontal Gene Transfer in Aliarcobacter butzleriPublication . Bonifácio, Marina; Mateus, Cristiana; Alves, Ana R.; Maldonado, Emanuel; Duarte, Ana Paula; Domingues, Fernanda; Oleastro, Mónica; Ferreira, SusanaAliarcobacter butzleri is an emergent enteropathogen, showing high genetic diversity, which likely contributes to its adaptive capacity to different environments. Whether natural transformation can be a mechanism that generates genetic diversity in A. butzleri is still unknown. In the present study, we aimed to establish if A. butzleri is naturally competent for transformation and to investigate the factors influencing this process. Two different transformation procedures were tested using exogenous and isogenic DNA containing antibiotic resistance markers, and different external conditions influencing the process were evaluated. The highest number of transformable A. butzleri strains were obtained with the agar transformation method when compared to the biphasic system (65% versus 47%). A. butzleri was able to uptake isogenic chromosomal DNA at different growth phases, and the competence state was maintained from the exponential to the stationary phases. Overall, the optimal conditions for transformation with the biphasic system were the use of 1 µg of isogenic DNA and incubation at 30 ◦C under a microaerobic atmosphere, resulting in a transformation frequency ~8 × 10−6 transformants/CFU. We also observed that A. butzleri favored the transformation with the genetic material of its own strain/species, with the DNA incorporation process occurring promptly after the addition of genomic material. In addition, we observed that A. butzleri strains could exchange genetic material in co-culture assays. The presence of homologs of well-known genes involved in the competence in the A. butzleri genome corroborates the natural competence of this species. In conclusion, our results show that A. butzleri is a naturally transformable species, suggesting that horizontal gene transfer mediated by natural transformation is one of the processes contributing to its genetic diversity. In addition, natural transformation can be used as a tool for genetic studies of this species.
- Prevalence of Arcobacter: From farm to retail – A systematic review and meta-analysisPublication . Mateus, Cristiana; Martins, Rodrigo; Luís, Ângelo; Oleastro, Mónica; Domingues, F.C.; Pereira, L.; Ferreira, SusanaArcobacter is a group of bacteria widely distributed in several habitats and throughout the food chain. Considering the pathogenic potential of some species within this group, it is important to understand their distribution along the food chain, as well as the possible routes of transmission. Aiming this, a systematic review and meta-analysis-based method was used to investigate the prevalence of Arcobacter species throughout the food chain, from farm to fork, using the worldwide available data. Database search was performed using related keywords and considering studies up to March 2020. The pooled prevalence of Arcobacter in food chain was 30% (0.300; 95% CI: 0.262–0.342), ranging from 0.5 to 99.4%. The highest prevalence of Arcobacter was observed in Belgium (0.575; 95% CI:0.427–0.710) and the lower in Ireland (0.031; 95% CI:0.022–0.042). Oceania continent (0.409; 95% CI:0.173–0.697) and the countries with high income level (0.342; 95% CI:0.293–0.394) presented the highest prevalence when considering the analysis of subgroups. Arcobacter spp. presented the highest prevalence at the processing stage (0.335; 95% CI:0.270–0.406), when compared with primary and retail stage. Also, data points to the relevance of environmental sources in food contamination. Arcobacter seems to be more frequently found in animal origin products, with the highest prevalence observed for poultry-associated products (0.404; 95% CI: 0.338–0.473), being Arcobacter butzleri the most frequently found species. The results of this meta-analysis highlight the high prevalence and distribution of Arcobacter along the food chain, suggesting a high risk to human health, and the relevance of taking preventive actions in order to reduce the burden of this pathogen in food sector.