Revista Argentina de microbiologia最新文献

The microbial communities within honey bee colonies contribute to the defense against pathogens. The goal of this study was to isolate, identify, and lyophilize lactic acid bacteria and bifidobacteria from the gut of nurse bees and bee bread in Apis mellifera colonies. Bacterial cultures from the intestinal content were conducted, and subsequently identified, sequenced, and lyophilized. Cross-antagonism among them was also assessed. Studies based on 16 S rRNA gene Sanger sequencing revealed that the MC3 strain had 100% identity with Bifidobacterium choladohabitans, the PP2B strain showed 99.16% similarity with Enterococcus faecium, while the PP1 strain exhibited 99.49% similarity with Lacticaseibacillus sp. and the PP1B strain showed 99.32% similarity with Lacticaseibacillus sp. There was no evidence of cross-antagonism among the strains, and the lyophilization process showed good stability and conservation. This is the first report of the isolation of B. choladohabitans from honey bee gut in Argentina, and also associates the presence of E. faecium with bee bread.

In recent years the relationship between the intestinal microbiota, the host and chronic non-communicable diseases has brought interest into the study of its formation and maintenance in the host. Lactic acid bacteria (BAL) are Gram-positive bacteria with probiotic activity, which have been associated with many health benefits, such as decreased body fat mass and lower risk of type II diabetes mellitus. One of the main colonization mechanisms and bacteria survival strategies is the production of biofilms and the use of prebiotics as substrates to achieve a balance within intestinal microbiota. However, there is not enough evidence to demonstrate the biofilm formation in the presence of agave fructans (AF). This study aimed to evaluate in vitro the biofilm formation in a consortium of lactic acid bacteria: Lactobacillus delbrueckii ssp. lactis, Lactobacillus delbrueckii ssp. bulgaricus y Streptococcus thermophilus in the presence of AF at different concentrations: 0%, 0,1%, 4%, 8% y 16%. The addition of 0,1% of AF correlates with the best capacity for biofilm formation. The findings imply the possibility of modulating the biofilm formation of lactic acid bacteria with AF. These results can contribute positively to the host, by generating intestinal homeostasis, colonization resistance, stability to food digestion and chemical modifications of drugs and carry out beneficial functions to the health.

Cildáñez stream (in Matanza-Riachuelo basin, Buenos Aires) is one of the most polluted watercourses of Argentina, containing a mixed contamination from agricultural and industrial wastes. The application of water bioremediation processes for this kind of effluent will require microorganisms with a high tolerance to contamination. In this sense, obtaining higher contaminant-resistant microalgae lines is widely desired. In this study, adaptive laboratory evolution (ALE) and random mutagenesis were used to obtain Chlorella vulgaris LMPA-40 strains adapted to grow in polluted water from the Cildáñez stream. The ALE process was performed by 22 successive subcultures under selective pressure (Cildáñez wastewater alone or with the addition of phenol or H₂O₂) while random mutagenesis was performed with UV-C radiation at 275 nm. Not all the cell lines obtained after ALE could adapt enough to overcome the stress caused by the Cildáñez wastewater, indicating that the process is quite random and depends on the stressor used. The best results were obtained for the Cildáñez wastewater adapted cells (Cild 3 strain) that were more resistant than the original strain. The concentration of protein, Chlorophyll A, Chlorophyll B, and carotenoids in the Cild 3 ALE evolved strain was higher than that of the control strain. However, this strain exhibited half of the lipid content compared to the same control strain. Interestingly, these alterations and the acquired tolerance may be reversed over time during storage. These findings suggest that the acquisition of novel cell lines could not be permanent, a fact that must be considered for future trials.

The first autochthonous case of rickettsiosis is reported here. The case occurred in the Costanera Sur Ecological Reserve, a protected area of the City of Buenos Aires, in August 2022, where 4 species of ticks were found, namely Amblyomma aureolatum, Ixodes auritulus sensu lato, Rhipicephalus sanguineus sensu stricto and Amblyomma triste.

The epidemiological, ecological, clinical and laboratory aspects that allowed timely diagnosis and appropriate treatment are also described.

Human listeriosis is an infectious disease caused by Listeria monocytogenes. The invasive form of this disease leads to a high rate of hospitalizations and fatality. The main mode of transmission is through contaminated ready-to-eat foods such as dairy, vegetables and meat products. The knowledge of the diversity and population dynamics of isolates collected from human and food sources is essential for the detection of clusters and the identification of common sites of infection. The aim of this study was the molecular characterization of L. monocytogenes isolates in Argentina. We sequenced a total of 63 isolates, 35 from human and 28 from food sources, collected between 2018 and 2023. Our genomic study divided the isolates into two lineages, four serogroups, 17 sequence types and 15 clonal complexes (CCs). The hypervirulent clone CC1 (lineage I; serogroup IVb) predominated in human and food samples. The phylogenomic analysis showed a high and possible epidemiological relationship between isolates from human and/or food sources, suggesting the presence of transmission chains in our country. These findings highlight the need to strengthen genomic surveillance of L. monocytogenes in Argentina. The identification of geographic distribution and characteristics of predominant and emerging clones from human and food sources might help to focus action plans and public health policies better directed at the control and prevention of listeriosis.