Pseudomonas aeruginosa and Bacillus cereus Isolated from Brazilian Cerrado Soil Act as Phosphate-Solubilizing Bacteria.

The phosphate-solubilizing microorganism is essential for soil quality and plant development and can serve as an alternative to reduce such Brazilian needs for importing phosphate overseas. Here, we isolated and selected bacteria from Brazilian Cerrado soils capable of solubilize phosphate. We obtained 53 bacteria isolates, of which 23 could solubilize phosphate at a pH of 7.0, 17 could solubilize phosphate at a pH of 6.0, and 8 could solubilize at a pH of 5.5. Using 16S rRNA gene sequences, we identified nine bacteria species clustered in four groups: Bacillus sp., Pseudomonas sp., Priestia sp., and Klebsiella sp. Our results revealed that the UFT01 (P. aeruginosa) and UFT42 (B. cereus) isolates exhibited the best phosphate solubilization performance at all tested pH values. We further recorded higher levels of solubilization and phosphate availability six days after the soil inoculation with P. aeruginosa, and enzymatic analysis of the soil samples revealed that the P. aeruginosa-inoculated samples resulted in four-fold higher enzymatic activities when compared to non-inoculated soils. The B. cereus soil inoculation increased ß-glucosidase activities and resulted in reduced the activities of arylsulfatase. Altogether, our findings demonstrated that P. aeruginosa and B. cereus isolated from Cerrado soils showed high phosphate solubilization potential.

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

Microbial starter cultures are used in the production of many cheeses around the world, such as Parmigiano-Reggiano, in Italy, Époisses, in France, and Canastra, in Brazil, providing many of the unique features of these cheeses. Bacteriophages (phages) are ubiquitous and well known to modulate the structure of bacterial communities, and recent data indicate that cheeses contain a high abundance of naturally occurring phages. Here, we analyze the viral and bacterial metagenomes of Canastra cheese: a traditional artisanal Brazilian cheese produced using an endogenous starter culture and raw milk. Over 1,200 viral operational taxonomic units were recovered using both isolated viral-like particles and complete metagenomic DNA. Common viral families identified included Siphoviridae and Myoviridae, with 40% of putative phage genomes unidentified at the family level of classification. We observed very high phage diversity, which varied greatly across different cheese producers, with 28% of phage genomes detected in only one producer. Several metagenome-assembled genomes were recovered for lactic acid-producing bacteria, as well as nonstarter bacterial species, and we identified several phage-bacterium interactions, at the strain level of resolution, varying across distinct cheese producers. We postulate that at least one bacterial strain detected could be endogenous and unique to the Canastra cheese-producing region in Brazil and that its growth seems to be modulated by autochthonous phages present in this artisanal production system. This phage-host relationship is likely to influence the fermentation dynamics and ultimately the sensorial profile of these cheeses, with implications for other similar cheese production systems around the world. IMPORTANCE Our work demonstrated a dynamic yet stable microbial ecosystem during cheese production using an endogenous starter culture. This was observed across several distinct producers and was marked by genomic evidence of continued phage-bacterium interactions, such as the presence of bacterial defense mechanisms. Furthermore, we provide evidence of unique microbial signatures for each individual cheese producer studied in the region, a fact that may have profound consequences on product traceability. This was the first effort to describe and understand the bacteriophage composition and ecological dynamics within the Brazilian Canastra cheese production system. The study of this prototypical backslopping production system provides a solid background for further mechanistic studies of the production of many cheeses around the world.

Genomic and functional characterization of bacteriocinogenic lactic acid bacteria isolated from Boza, a traditional cereal-based beverage.

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 Pediococcus 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 to 12,800 AU/ml recorded against L. monocytogenes 104, 637 and 711, measured at 24 h of incubation at 37 °C. All bacteriocins remained active after incubation at pH 2.0-10.0. 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 ß-galactosidase assay, indicating a pore formation mechanism as a mode of action. The present study highlights the importance of combining genomic analyses and traditional microbiological approaches as way of characterizing microbial interactions in fermented foods.

Bacterial diversity in deep-sea sediments under influence of asphalt seep at the São 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 method. Sampling was performed at North São 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 2456 to 2728 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 Alphaproteobacteria (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 São Paulo Plateau, since these bacterial classes contain bacteria that possess the capability of metabolizing hydrocarbon compounds.

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 of 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 hypotheses, (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. 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.

HABEBEE: habitability of eyeball-exo-Earths.

Extrasolar Earth and super-Earth planets orbiting within the habitable zone of M dwarf host stars may play a significant role in the discovery of habitable environments beyond Earth. Spectroscopic characterization of these exoplanets with respect to habitability requires the determination of habitability parameters with respect to remote sensing. The habitable zone of dwarf stars is located in close proximity to the host star, such that exoplanets orbiting within this zone will likely be tidally locked. On terrestrial planets with an icy shell, this may produce a liquid water ocean at the substellar point, one particular "Eyeball Earth" state. In this research proposal, HABEBEE: exploring the HABitability of Eyeball-Exo-Earths, we define the parameters necessary to achieve a stable icy Eyeball Earth capable of supporting life. Astronomical and geochemical research will define parameters needed to simulate potentially habitable environments on an icy Eyeball Earth planet. Biological requirements will be based on detailed studies of microbial communities within Earth analog environments. Using the interdisciplinary results of both the physical and biological teams, we will set up a simulation chamber to expose a cold- and UV-tolerant microbial community to the theoretically derived Eyeball Earth climate states, simulating the composition, atmosphere, physical parameters, and stellar irradiation. Combining the results of both studies will enable us to derive observable parameters as well as target decision guidance and feasibility analysis for upcoming astronomical platforms.