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Frontiers in Microbiology 2022Vorarlberger Bergkäse (VB) is an artisanal Austrian washed-rind hard cheese produced from alpine cows' raw milk without the addition of ripening cultures. Ripening time...
Vorarlberger Bergkäse (VB) is an artisanal Austrian washed-rind hard cheese produced from alpine cows' raw milk without the addition of ripening cultures. Ripening time is a key factor in VB, as it strongly influences the microbial communities present in the cheeses and the organoleptic properties of the product. In this study, the microbial and metabolic transcriptional profiles in VB rinds at different ripening times were investigated. VB products before (30 days of ripening) and after (90 days of ripening) selling were selected, RNA was extracted and subjected to shotgun metatranscriptomic sequencing. The analysis revealed some of the previously described abundant bacterial taxa of , , , , and to be highly active in VB rinds. Additionally, the investigation of most important metabolic pathways in cheese ripening clearly showed differences in the gene transcription profiles and the active microbiota between the two ripening points investigated. At 30 days of ripening, metabolic events related with the degradation of residual lactose, lactate, citrate, proteolysis, and lipolysis were significantly more transcribed and mainly associated with . On the other hand, genes involved in the degradation of smaller compounds derived from previous metabolism (i.e., metabolism of free amino acids and fatty acids) were significantly more expressed in VB rinds with 90 of ripening, and mainly associated with and . These latter metabolic activities are responsible of the generation of compounds, such as methanethiol and 2,3-butanediol, that are very important for the flavor and aroma characteristics of cheeses. This study shows the dynamic changes in the gene transcriptional profiles associated with energy substrates metabolism and the generation of organoleptic compounds during VB ripening and uncovers bacterial taxa as key drivers of the ripening process. These taxa might be the target for future studies toward an accelerated cheese ripening and the enhancement of its organoleptic properties.
PubMed: 35300479
DOI: 10.3389/fmicb.2022.813480 -
Journal of Biochemistry Apr 1985Phosphoenolpyruvate (PEP) carboxylases (PC) were purified from a wild strain and an aspartate-producing mutant of Brevibacterium flavum to electrophoretic homogeneity....
Phosphoenolpyruvate (PEP) carboxylases (PC) were purified from a wild strain and an aspartate-producing mutant of Brevibacterium flavum to electrophoretic homogeneity. The molecular weights of the enzymes were determined to be 4.1 X 10(5) by the gel-filtration technique. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the enzyme gave only one protein band with a molecular weight of 1.07 X 10(5). The enzyme was labile and stabilized by substrate PEP, activators, metallic cofactors, an allosteric inhibitor and ammonium sulfate. The mechanism for the PC reaction was rapid equilibrium random Bi Bi with a dead end complex, enzyme-bicarbonate-Pi. The KmS for PEP and bicarbonate were 2.5 and 0.63 mM, respectively, and the apparent KmS were not affected by the secondary substrate concentrations. Dissociation constants for Pi of enzyme-Pi and the dead end complex were 5.0 and 16 mM, respectively. Aspartate inhibition was completely competitive with both the substrates, PEP and bicarbonate, with an inhibitor constant of 0.044 mM. An activator, acetyl-CoA, did not alter the apparent Km for bicarbonate but decreased that for PEP. The activator constants for the enzyme-PEP complex and free enzyme were 6.3 and 40 microM, respectively. Double reciprocal plots of reaction rate against PEP concentration were not linear at lower PEP concentrations. Hill coefficients for PEP were 1.6 in the absence of any effectors, 1.0 in the presence of acetyl-CoA, and 2.3 in the presence of aspartate. As to the mutant enzyme, only the inhibitor constant for aspartate was increased, being 0.18 mM, but other constants, coefficients, as described above, and specific activity were almost the same as those of the wild-type enzyme.
Topics: Allosteric Regulation; Aspartic Acid; Brevibacterium; Carboxy-Lyases; Kinetics; Macromolecular Substances; Molecular Weight; Mutation; Phosphoenolpyruvate Carboxylase
PubMed: 4030719
DOI: 10.1093/oxfordjournals.jbchem.a135156 -
The Journal of Antimicrobial... May 2024Corynebacterium (C.) sp. 22KM0430 related to C. oculi and isolated from a dog exhibited resistance to tetracycline, and its WGS analysis revealed a putative resistance...
BACKGROUND
Corynebacterium (C.) sp. 22KM0430 related to C. oculi and isolated from a dog exhibited resistance to tetracycline, and its WGS analysis revealed a putative resistance gene on a 35 562-bp plasmid also harbouring the MLSB resistance gene erm(X).
OBJECTIVES
To characterize the novel tetracycline resistance gene tet(65) and demonstrate its functionality by expression in C. glutamicum and Escherichia coli and plasmid curing of the host strain.
METHODS
tet(65) was cloned with and without its repressor tetR(65) and expressed in C. glutamicum DSM20300 and E. coli DH5α. Plasmid was cured by non-selective passages. Minimal inhibitory concentrations (MICs) of tetracyclines were determined according to CLSI guidelines. Association of tet(65) with efflux was shown by the addition of reserpine to MIC assays. Phylogenetic position and transmembrane structure of Tet(65) were analysed using MEGA11 and DeepTMHMM.
RESULTS
Tet(65) shows 73% amino acid identity with the closest related Tet(Z), contains 12 transmembrane domains and is structurally related to the Major Facilitator Superfamily. The tetracycline MICs decreased in the plasmid-cured strain and increased when tet(65) was expressed in C. glutamicum and in E. coli. The MICs of tetracycline decreased in the presence of reserpine indicating that tet(65) functions as an efflux pump. A GenBank search also identified tet(65) in C. diphtheriae and Brevibacterium (B.) casei and B. luteolum.
CONCLUSIONS
A novel tetracycline efflux gene tet(65) was identified in a C. oculi related species and was also present in the human pathogen C. diphtheriae and in Brevibacterium species indicating broader potential for dissemination.
Topics: Plasmids; Tetracycline Resistance; Microbial Sensitivity Tests; Anti-Bacterial Agents; Escherichia coli; Corynebacterium; Animals; Drug Resistance, Multiple, Bacterial; Phylogeny; Dogs; Tetracycline; Cloning, Molecular; Corynebacterium Infections; Dog Diseases
PubMed: 38497972
DOI: 10.1093/jac/dkae066 -
Frontiers in Microbiology 2018Eco-evolutionary dynamics of microbiotas at the macroscale level are largely driven by ecological variables. The diet and living environment of the oriental fruit fly, ,...
Eco-evolutionary dynamics of microbiotas at the macroscale level are largely driven by ecological variables. The diet and living environment of the oriental fruit fly, , diversify during development, providing a natural system to explore convergence, divergence, and repeatability in patterns of microbiota dynamics as a function of the host diet, phylogeny, and environment. Here, we characterized the microbiotas of 47 individuals from three distinct populations by 16S rRNA amplicon sequencing. A significant deviation was found within the larvae, pupae, and adults of each population. Pupae were characterized by an increased bacterial taxonomic and functional diversity. Principal components analysis showed that the microbiotas of larvae, pupae, and adults clearly separated into three clusters. , and were the predominant families in larval and adult samples, and PICRUSt analysis indicated that phosphoglycerate mutases and transketolases were significantly enriched in larvae, while phosphoglycerate mutases, transketolases, and proteases were significantly enriched in adults, which may support the digestive function of the microbiotas in larvae and adults. The abundances of (mainly ) and (mainly ) were significantly higher in pupae, and the antibiotic transport system ATP-binding protein and antibiotic transport system permease protein pathways were significantly enriched there as well, indicating the defensive function of microbiotas in pupae. Overall, differences in the microbiotas of the larvae, pupae, and adults are likely to contribute to differences in nutrient assimilation and living environments.
PubMed: 29449838
DOI: 10.3389/fmicb.2018.00114 -
Microbiology Resource Announcements Jun 2019Here, we report the genome sequence of LuckyBarnes, a newly isolated singleton siphovirus that infects ATCC 15728 and has a 50,774-bp genome with 67 predicted genes.
Here, we report the genome sequence of LuckyBarnes, a newly isolated singleton siphovirus that infects ATCC 15728 and has a 50,774-bp genome with 67 predicted genes.
PubMed: 31221644
DOI: 10.1128/MRA.00330-19 -
Frontiers in Microbiology 2016The microbial communities in cheeses are composed of varying bacteria, yeasts, and molds, which contribute to the development of their typical sensory properties. In...
The microbial communities in cheeses are composed of varying bacteria, yeasts, and molds, which contribute to the development of their typical sensory properties. In situ studies are needed to better understand their growth and activity during cheese ripening. Our objective was to investigate the activity of the microorganisms used for manufacturing a surface-ripened cheese by means of metatranscriptomic analysis. The cheeses were produced using two lactic acid bacteria (Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus), one ripening bacterium (Brevibacterium aurantiacum), and two yeasts (Debaryomyces hansenii and Geotrichum candidum). RNA was extracted from the cheese rinds and, after depletion of most ribosomal RNA, sequencing was performed using a short-read sequencing technology that generated ~75 million reads per sample. Except for B. aurantiacum, which failed to grow in the cheeses, a large number of CDS reads were generated for the inoculated species, making it possible to investigate their individual transcriptome over time. From day 5 to 35, G. candidum accounted for the largest proportion of CDS reads, suggesting that this species was the most active. Only minor changes occurred in the transcriptomes of the lactic acid bacteria. For the two yeasts, we compared the expression of genes involved in the catabolism of lactose, galactose, lactate, amino acids, and free fatty acids. During ripening, genes involved in ammonia assimilation and galactose catabolism were down-regulated in the two species. Genes involved in amino acid catabolism were up-regulated in G. candidum from day 14 to day 35, whereas in D. hansenii, they were up-regulated mainly at day 35, suggesting that this species catabolized the cheese amino acids later. In addition, after 35 days of ripening, there was a down-regulation of genes involved in the electron transport chain, suggesting a lower cellular activity. The present study has exemplified how metatranscriptomic analyses provide insight into the activity of cheese microbial communities for which reference genome sequences are available. In the future, such studies will be facilitated by the progress in DNA sequencing technologies and by the greater availability of the genome sequences of cheese microorganisms.
PubMed: 27148224
DOI: 10.3389/fmicb.2016.00536 -
Frontiers in Microbiology 2016Marine Actinobacteria, particularly coral-associated Actinobacteria, have attracted attention recently. In this study, the abundance and diversity of Actinobacteria...
Marine Actinobacteria, particularly coral-associated Actinobacteria, have attracted attention recently. In this study, the abundance and diversity of Actinobacteria associated with three types of coral thriving in a thermally stressed coral reef system north of the Arabian Gulf were investigated. Coscinaraea columna, Platygyra daedalea and Porites harrisoni have been found to harbor equivalent numbers of culturable Actinobacteria in their tissues but not in their mucus. However, different culturable actinobacterial communities have been found to be associated with different coral hosts. Differences in the abundance and diversity of Actinobacteria were detected between the mucus and tissue of the same coral host. In addition, temporal and spatial variations in the abundance and diversity of the cultivable actinobacterial communities were detected. In total, 19 different actinobacterial genera, namely Micrococcus, Brachybacterium, Brevibacterium, Streptomyces, Micromonospora, Renibacterium, Nocardia, Microbacterium, Dietzia, Cellulomonas, Ornithinimicrobium, Rhodococcus, Agrococcus, Kineococcus, Dermacoccus, Devriesea, Kocuria, Marmoricola, and Arthrobacter, were isolated from the coral tissue and mucus samples. Furthermore, 82 isolates related to Micromonospora, Brachybacterium, Nocardia, Micrococcus, Arthrobacter, Rhodococcus, and Streptomyces showed antimicrobial activities against representative Gram-positive and/or Gram-negative bacteria. Even though Brevibacterium and Kocuria were the most dominant actinobacterial isolates, they failed to show any antimicrobial activity, whereas less dominant genera, such as Streptomyces, did show antimicrobial activity. Focusing on the diversity of coral-associated Actinobacteria may help to understand how corals thrive under harsh environmental conditions and may lead to the discovery of novel antimicrobial metabolites with potential biotechnological applications.
PubMed: 26973601
DOI: 10.3389/fmicb.2016.00204 -
Frontiers in Microbiology 2022Plant-associated microbes play important roles in plant health and disease. is often found in the plant rhizosphere, and its possible functions are not well known,...
Plant-associated microbes play important roles in plant health and disease. is often found in the plant rhizosphere, and its possible functions are not well known, especially in medical plants. isolated from ginseng soil was used to investigate its effects on plant disease. The promoting properties and interactions with rhizospheric microorganisms were investigated in a medium. Further, a pot experiment was conducted to explore its effects on ginseng root rot disease. Physicochemical properties, high-throughput sequencing, network co-occurrence, distance-based redundancy analysis (db-RDA), and correlation analysis were used to evaluate their effects on the root rot pathogen. The results showed that YW25 had a high indoleacetic acid production capacity, and the maximum yield was 141.37 mg/L at 4 days. The growth of YW25 was inhibited by some probiotics (, , , , etc.) and potential pathogens (, , etc.), but it did not show sensitivity to the soil-borne pathogen . Pot experiments showed that could significantly alleviate the diseases caused by , and increased the available nitrogen and phosphorus content in rhizosphere soil. In addition, it enhanced the activities of soil sucrase and acid phosphatase. High-throughput results showed that the inoculation of with changed the microbial community structure of ginseng, stimulated the plant to recruit more plant growth-promoting bacteria, and constructed a more stable microbial network of ginseng root. In this study, we found and proved the potential of as a biocontrol agent against , providing a new idea for controlling soil-borne diseases of ginseng by regulating rhizosphere microorganisms.
PubMed: 35633727
DOI: 10.3389/fmicb.2022.850917 -
Biocontrol Science 2021In the present study, the antifungal activity of metabolites produced by Bacillus atrophaeus B5 and a new Brevibacterium strain against Alternaria alternata was...
Effect of Metabolites Produced by Bacillus atrophaeus and Brevibacterium frigoritolerans Strains on Postharvest Biocontrol of Alternaria alternata in Tomato (Solanum lycopersicum L.).
In the present study, the antifungal activity of metabolites produced by Bacillus atrophaeus B5 and a new Brevibacterium strain against Alternaria alternata was evaluated. Assays in vitro and in vivo on tomato fruit during postharvest were made. Based on the 16S rDNA gene sequence analysis, the new strain (strain B7) was identified as Brevibacterium frigoritolerans. Metabolites produced by both bacterial strains reduced the spore germination of A. alternata in vitro and decreased the severity of the alternaria rot disease on tomato fruit during postharvest. This is the first report that demonstrates the potential of B. frigoritolerans B7 as a biocontrol agent against this fungal phytopathogen. The use of metabolites produced by B. atrophaeus B5 and B. frigoritolerans B7 represents a new approach to reduce the use of chemical pesticides and control fungal decay during the postharvest stage.
Topics: Alternaria; Bacillus; Brevibacterium; Fruit; Solanum lycopersicum; Plant Diseases
PubMed: 34092716
DOI: 10.4265/bio.26.67 -
Poultry Science Dec 2023Efforts to achieve sustainable phosphorus (P) inputs in broiler farming which meet the physiological demand of animals include nutritional intervention strategies that...
Efforts to achieve sustainable phosphorus (P) inputs in broiler farming which meet the physiological demand of animals include nutritional intervention strategies that have the potential to modulate and utilize endogenous and microbiota-associated capacities. A temporal P conditioning strategy in broiler nutrition is promising as it induces endocrinal and transcriptional responses to maintain mineral homeostasis. In this context, the current study aims to evaluate the composition of the jejunal microbiota as a functional entity located at the main absorption site involved in nutrient metabolism. Starting from a medium or high P supply in the first weeks of life of broilers, a depletion strategy was applied at growth intervals from d 17 to 24 and d 25 to 37 to investigate the consequences on the composition of the jejunal microbiota. The results on fecal mineral P, calcium (Ca), and phytate contents showed that the diets applied to the depleted and non-depleted cohorts were effective. Microbial diversity in jejunum was represented by alpha diversity indices which appeared unaffected between dietary groups. However, chickens assigned to the dietary P depletion groups showed significantly higher abundances of Facklamia, Lachnospiraceae, and Ruminococcaceae compared to non-depleted control groups. Based on current knowledge of microbial function, these microorganisms make only a minor contribution to the birds' adaptive mechanism in the jejunum following P depletion. Microbial taxa such as Brevibacterium, Brachybacterium, and genera of the Staphylococcaceae family proliferated in a P-enriched environment and might be considered biomarkers for excessive P supply in commercial broiler chickens.
Topics: Animals; Phosphorus; Jejunum; Chickens; Minerals; Diet; Microbiota; Animal Feed; Dietary Supplements; Animal Nutritional Physiological Phenomena
PubMed: 37797492
DOI: 10.1016/j.psj.2023.103096