Project description:Mitigation of N2O-emissions from soils is needed to reduce climate forcing by food production. Inoculating soils with N2O-reducing bacteria would be effective, but costly and impractical as a standalone operation. Here we demonstrate that digestates obtained after biogas production may provide a low-cost and widely applicable solution. Firstly, we show that indigenous N2O-reducing bacteria in digestates grow to high levels during anaerobic enrichment under N2O. Gas kinetics and meta-omic analysis show that the N2O respiring organisms, recovered as metagenome-assembled genomes (MAGs) grow by harvesting fermentation intermediates of the methanogenic consortium. Three digestate-derived denitrifying bacteria were obtained through isolation, one of which matched the recovered MAG of a dominant Dechloromonas-affiliated N2O reducer. While the identified N2O-reducers encoded genes required for a full denitrification pathway and could thus both produce and sequester N2O, their regulatory traits predicted that they act as N2O-sinks in the current system. Secondly, moving towards practical application, we show that these isolates grow by aerobic respiration in digestates, and that fertilization with these enriched digestates reduces N2O emissions. This shows that the ongoing implementation of biogas production in agriculture opens a new avenue for cheap and effective reduction of N2O emissions from food production.
Project description:Background:
- Some bacteria found in the large and small intestines help keep people healthy and aid digestion. They may also affect a person s risk of developing cancer. Researchers want to study the relationship between intestinal bacteria and breast cancer risk factors. They can do this by looking at stool and urine samples from postmenopausal women.
Objectives:
- To study intestinal bacteria and its relationship to urine-based markers of breast cancer risk in women.
Eligibility:
- Women between 55 and 69 years of age with a recent mammogram that showed no signs of cancer.
Design:
* Participants will be screened with a medical history and basic health questionnaire.
* At home, participants will complete questionnaires about cancer risk factors and food consumption.
* Participants will also collect urine and stool samples. They will send the samples to the designated labs for study.
* No treatment will be provided as part of this protocol.
Project description:Early detection of spoilage microorganisms and food pathogens is of major importance in preventing food recalls and foodborne outbreaks. Although constant effort is invested in developing sensitive methods for rapid microbial detection, none of the current methods enables the detection of food pathogens within a few hours; therefore, development of innovative early-warning food-testing strategies are needed. Herein, we assessed a novel strategy that harnesses the microbiome signature of a food product to determine deviations in the abundance of particular community members and detect production defects. Employing the production process of barbecued (BarBQ) pastrami as a model, we characterized the microbiome profiles of the product along the production line using next-generation sequencing of the 16S rRNA gene, concentrating on the live microbiota. Following the establishment of a microbiome dataset representing a properly produced product, we were able to identify shifts in the microbiome profile of a defective batch produced under potassium lactate deficiency. With the identification of Vibrio and Lactobacillus as potential indicator bacteria for potassium lactate deficiency, rapid qPCR assays were designed for their quantification. Aligned with the microbiome profiling results, these qPCR assays were effective for rapid identification of a defective production event. This implies the use of rapid quantification targeting microbiome profile-derived indicator bacteria for in-house detection of defective batches and identification of food-safety and quality events with results obtained on the same day. The suggested strategy should pave the way toward safer and more efficient food-production systems.
Project description:A prototype oligonucleotide microarray was designed to detect and identify viable bacterial species with the potential to grow of common beer spoilage microorganisms from the genera Lactobacillus, Megasphaera, Pediococcus and Pectinatus. Probes targeted the intergenic spacer regions (ISR) between 16S and 23S rRNA, which were amplified in a combination of reverse transcriptase (RT) and polymerase chain reaction (PCR) prior to hybridization. This method allows the detection and discrimination of single bacterial species in a complex sample. Furthermore, microarrays using oligonucleotide probes targeting the ISR allow the distinction between viable bacteria with the potential to grow and non-growing bacteria. The results demonstrate the feasibility of oligonucleotide microarrays as a contamination control in food industry for the detection and identification of spoilage microorganisms within mixed population. Keywords: microarray, oligonucleotide, species-specific, detection, beer spoilage bacteria
Project description:Post-transcriptional modifications are important for transfer RNAs (tRNAs) to be efficient and accurate in translation on the ribosome. The m1G37 modification on a subset of tRNAs in bacteria are generated by a conserved methyltransferase TrmD and is essential for bacterial growth. Previous studies showed that m1G37 has an important role in preventing translational frameshifting and also that this modification is coupled with aminoacylation of tRNAs for proline. Here we performed suppressor screening to isolate a mutant E. coli cell that lacks TrmD but is viable, and the whole-genome sequencing revealed several mutations on prolyl-tRNA synthetase (ProRS) gene conferring cell viability in the absence of TrmD. Biochemical assays confirmed uncoupling of m1G37 modification and aminoacylation, and cell-based assays uncovered the critical role of m1G37 in supporting Wobble decoding.
Project description:Humans and microorganisms, both symbiotic and pathogenic, have evolved means to communicate through the dissemination of biological signals. In addition to small molecules and proteins, mobile small RNAs (sRNAs) have recently emerged as signal molecules that mediate inter-species crosstalk by functional RNA interference (RNAi). However, the trafficking of sRNAs between humans and microorganisms, as well as the resulting biological consequences, remains unexplored. Here, we report that human cells secrete exosomes to deliver sRNAs into bacteria and induce bacterial gene silencing. The unprecedented RNAi in bacteria is accomplished primarily through translational repression without mRNA degradation, for which the participation of human AGO2 proteins co-transferred with sRNAs is essential. Exosome-mediated bacterial RNAi was further applied to fight superbug infection by targeting drug-resistance genes in a mouse model. Our discovery of this unique exosome-mediated sRNA delivery and gene silencing in bacteria paves the way to understanding and manipulating the cross-kingdom communication between human hosts and intestinal microbiota, as well as between humans and pathogenic bacteria.
Project description:To explore the circulating miRNA expression after subcutaneous injection of Gram negative and positive bacteria in the mice The recombinant specific Gram negative pathogens Escherichia coli (xen14) and Gram positive pathogens Staphyllococcus aureus (xen29) were purchased from the Caliper (Caliper, Princeton, NJ, USA). 1M-CM-^W108 Escherichia coli or Staphyllococcus aureus pathogen in 100 M-NM-<l PBS was injected subcutaneously with Fr. 25 needle into the back of the mice to cause bacterial infection of the mice. An extra group of animals was inoculated with PBS to serve as a negative control. The mice had access to food and water ad libitum both before and after bacteria injection. The mice were killed at the indicated time points (4, 8, and 24 h) after the bacteria injection, and whole blood was drawn.
Project description:Biogenic amine-producing bacteria are responsible for the production of basic nitrogenous compounds, such as histamine, cadaverine, tyramine and putrescine, after foods spoil due to microorganisms. In the present work, we applied a shotgun proteomics approach to quickly and easily characterize 15 different foodborne strains of biogenic amine-producing bacteria. A total of 10673 peptide spectrum matches (PSMs) belonging to 4081 nonredundant peptides and corresponding to 1811 annotated proteins were identified. With the results, relevant functional pathways were determined and the strains were differentiated into different Euclidean hierarchical clusters. Moreover, a predicted protein‒protein interaction network of biogenic amine foodborne strains was created. The whole confidence network contains 260 nodes and 1973 interactions. Most of the identified proteins were related to pathways and networks of energy, putrescine metabolism and host‒virus interaction. In addition, a total of 556 nonredundant peptides were identified as virulence factors, and most of these peptides corresponded to functions such as toxins, antimicrobial compound production, antimicrobial resistance, additional resistances and tolerances, host colonization and immune evasion, ABC transporters, phage proteins, and alternative virulence factors and proteins involved in horizontal transfer. Potential species-specific peptide biomarkers were screened. Thus, 77 species-specific peptide biomarkers belonging to 64 different proteins were proposed to identify 10 species (Enterobacter aerogenes, Enterobacter cloacae, Hafnia alvei, Klebsiella oxytoca, Morganella morganii, Proteus mirabilis, Proteus penneri, Proteus vulgaris, Raoutella planticola, Stenotrophomonas maltophilia). All of these results constitute the first major dataset of peptides and proteins of seafood biogenic amine-producing strains. This repository may be useful for further studies, for the development of new therapeutic treatments for food intoxication and for tracking microbial sources in foodstuffs.