Biology subjects

Queiroz, L. L.

Publications and source records attributed to Queiroz, L. L..

5 recordsLinked to original sources

bioRxiv2021

Bacteriocinogenic lactic acid bacteria in the traditional cereal-based beverage Boza: a genomic and functional approach

Boza is a traditional low-alcohol fermented beverage from the Balkan Peninsula, frequently explored as a functional food product. The product is rich in Lactic Acid Bacteria (LAB) and some of them can produce bacteriocins. In this study, a sample of Boza from Belogratchik, Bulgaria, was analyzed for the presence of bacteriocinogenic LAB, and after analyses by RAPD-PCR, three representative isolates were characterized by genomic analyses, using whole genome sequencing. Isolates identified as Pediococcus pentosaceus ST75BZ and Pediococcus pentosaceus ST87BZ contained operons encoding for bacteriocins pediocin PA-1 and penocin A, while isolate identified as P. acidilactici ST31BZ contained only the operon for pediocin PA-1 and a CRISPR/Cas system for protection against bacteriophage infection. The antimicrobial activity of bacteriocins produced by the three isolates was inhibited by treatment of the cell-free supernatants with proteolytic enzymes. The produced bacteriocins inhibited the growth of Listeria monocytogenes, Enterococcus spp. and some Lactobacillus spp., among other tested species. The levels of bacteriocin production varied from 3200 AU/ml to 12800 AU/ml recorded against L. monocytogenes 104, 637 and 711, measured at 24 h of incubation at 37{degrees}C. All bacteriocins remained active after incubation at pH 2.0 to 10.0. The activity mode of the studied bacteriocins was bactericidal, as determined against L. monocytogenes 104, 637 and 711. In addition, bactericidal activity was demonstrated using a cell leakage {beta}-galactosidase assay, indicating a pore formation mechanism as a mode of action. The present study highlights the importance of combining metagenomic analyses and traditional microbiological approaches as way of characterizing microbial interactions in fermented foods.

microbiology↗

bioRxiv2021

High Level of Interaction between Phages and Bacteria in an Artisanal Raw Milk Cheese Microbial Community

Endogenous starter cultures are used in the production of several cheeses around the world, such as Parmigiano-Reggiano, in Italy, Epoisses, in France, and Canastra, in Brazil. These microbial communities are responsible for many of the intrinsic characteristics of each of these cheeses. Bacteriophages are ubiquitous around the world, well known to be involved in the modulation of complex microbiological processes. However, little is known about phage-bacteria growth dynamics in cheese production systems, where phages are normally treated as problems, as the viral infections can negatively affect or even eliminate the starter culture during production. Furthermore, a recent metagenomic based meta-analysis has reported that cheeses contain a high abundance of phage-associated sequences. Here, we analyse the viral and bacterial metagenomes of Canastra cheese, a tradition artisanal cheese produced using an endogenous starter culture. We observe a very high phage diversity level, mostly composed of novel sequences. We detect several metagenomic assembled bacterial genomes at strain level resolution, and several putative phage-bacteria interactions, evidenced by the recovered viral and bacterial genomic signatures. We postulate that at least one bacterial strain detected could be endogenous to the Canastra region, in Brazil, and that its growth seems to be modulated by native phages present in this artisanal production system. This relationship is likely to influence the fermentation dynamics and ultimately the sensorial profile of these cheeses, with implication for all cheeses that employ similar production processes around the world.

microbiology↗

bioRxiv2021

Cold adapted desiccation-tolerant bacteria isolated from polar soils presenting high resistance to anhydrobiosis

Life on Earth is strictly dependent on liquid water. In polar terrestrial environments, water exists in solid state during almost the entire year. Polar microorganisms have not only to adjust their metabolism to survive at subzero temperatures, but also need to cope with extremely dry conditions. We investigated the presence of desiccation-adapted bacteria in Arctic permafrost and Antarctic surface soils and characterized their survivability to dryness. We selected desiccation tolerant cells by treating the soils with chloroform prior to cultivation, in order to mimic the stress of low water activity for long periods. From over 1000 colonies from different samples, 23 unique strains were selected and identified as members of phyla Firmicutes, Proteobacteria and Actinobacteria. About 60% of the strains survived after 50 days in anhydrobiosis. The competence to withstand desiccation varied between close related strains isolated from different locations, bringing the question if environmental conditions may play a role in the observed desiccation tolerance. Survivability was also affected by the solution in which the cells were suspended before drying; R2B medium being more protective than water. This is the first time that chloroform was used to select desiccation tolerant microorganisms from polar soils. The collection of polar microorganisms described herein opens the possibility of further experiments aiming to investigate the resistance mechanisms of polar anhydrobionts. Desiccation tolerance is fundamental to the survivability of microorganisms to the space environment and at the surface of thin-atmosphere planets like Mars. Therefore, the selected strains may open a road to better understand the limits of cold adapted life on Earth and beyond, and compare mechanisms of resistance with anhydrobionts from divergent extreme environments.

microbiology↗

bioRxiv2019

Bacterial diversity in deep-sea sediments under influence of asphalt seep at the Sao Paulo Plateau

Here we investigated the diversity of bacterial communities from deep-sea surface sediments under influence of asphalt seeps at the Sao Paulo Plateau using next-generation sequencing (NGS) method. Sampling was performed at North Sao Paulo Plateau using the human occupied vehicle Shinkai 6500 and her support vessel Yokosuka. The microbial diversity was studied at two surficial sediment layers (0-1 and 1-4 cm) of five samples collected in cores in water depths ranging from 2,456-2,728 m. Bacterial communities were studied through sequencing of 16S rRNA gene on the Ion Torrent platform and clustered in operational taxonomic units. We observed high diversity of bacterial sediment communities as previously described by other studies. When we considered community composition, the most abundant classes were Alphaprotebacteria (27.7%), Acidimicrobiia (20%), Gammaproteobacteria (11.3%) and Deltaproteobacteria (6.6%). Most abundant OTUs at family level were from two uncultured bacteria from Actinomarinales (5.95%) and Kiloniellaceae (3.17%). The unexpected high abundance of Alphaproteobacteria and Acidimicrobiia in our deep-sea microbial communities may be related to the presence of asphalt seep at North Sao Paulo Plateau, since these bacterial classes contain bacteria that possess the capability of metabolizing hydrocarbon compounds.

microbiology↗

bioRxiv2018

Dynamics of microbial contaminants is driven by selection during ethanol production

Brazil is the second largest ethanol producer in the World and largest using sugarcane feedstock. Bacteria contamination is one the most important issues faced by ethanol producers that seek to increase production efficiency. Each step of production is a selection event due to the environmental and biological changes that occur. Therefore, we evaluated the influence of the selection arising from the ethanol production process on diversity and composition of Bacteria. Our objectives were to test two hypothesis, (1) that species richness will decrease during the production process and (2) that Lactic Acid Bacteria will become dominant with the advance of ethanol production due to selection. Bacterial community assemblage was accessed using 16S rRNA gene sequencing from 19 sequential samples. Temperature is of great importance in shaping microbial communities. Species richness increased between the Decanter and Must steps of the process. Low Simpson index values were recorded at the fermentation step, indicating a high dominance of Lactobacillus. Interactions between Lactobacillus and yeast may be impairing the efficiency of industrial ethanol production.

microbiology↗