Human Bacterial Pathogens Research Articles

The profile and persistence of clinically critical antibiotic resistance genes and human pathogenic bacteria in manure-amended farmland soils.

Microbial contamination in farmlands is usually underestimated and understudied. Different fertilization times and manure origins might introduce and change the microorganism diversity in farmland soils and thus might influence the abundance and persistence of microbial contamination including antibiotic resistance genes (ARGs), human bacterial pathogens (HBPs), and virulence factor genes (VFGs). A 0.5-/1.5-year fertilization experiment was performed, and metagenomic sequencing was conducted to quantify microbial contamination. The resistomes of soil samples revealed that ARGs against antibiotics which were extensively used in veterinary medicine as well as clinically critical ARGs (CCARGs) persisted in manure-amended soils. Here the extended-spectrum beta-lactamase and carbapenemase bla genes, the high-level mobilized colistin resistance gene mcr, the tigecycline resistance gene tet(X), and the vancomycin resistance gene van, all of which can circumvent the defense line of these "last-resort" antibiotics were selected to investigate CCARG pollution in farm environments. A total of 254 potential HBPs and 2106 VFGs were detected in soil samples. Overall, our results revealed that (1) farmland soils could serve as a reservoir of some important bla, mcr, tet(X), and van gene variants, (2) the diversity and relative abundance of HBPs and VFGs increased significantly with incremental fertilization times and were discrepant among different manureamended soils, and (3) most CCARGs and VFGs coexisted in HBPs. The results of this study suggested a biological risk of manure in spreading antimicrobial resistance and pathogenicity.

Antibacterial activity of seahare (Dolabella auricularia) against human bacterial pathogens

Antibacterial activity of seahare (Dolabella auricularia) against human bacterial pathogens

Characterization and biochemical activities of novel functional antimicrobial peptide (AMP) from Trichogramma chilonis

Introduction and Aim: The antimicrobial peptides (AMPs) are generally found in invertebrates, mammals, birds, plants and insects. AMPs produced by insect parasitoids contribute to innate immunity to resist infection due to lack of adaptive immunity. T. chilonis is one of the most effective endoparasitoid wasps for controlling lepidopterous insects. Several attempts have been made to isolate, characterize and develop a commercially viable product of AMPs from various insect sources. The present study aimed to characterize AMP from T. chilonis for potential antimicrobial and anti-cancer properties. Methods: AMP was identified through T. chilonis transcriptome sequence and designed in silico and synthesized. Its purity was quantified using RP-HPLC, and the mass identified by mass spectrophotometry. LC/MS-MS was employed to predict the sequence and the BLAST program used to compare the sequence. AMP was tested for haemolytic activity and antimicrobial activity. Two pathogenic bacteria and fungal strains were used and IC50 values and MIC values were predicted against microbial strains. Results: Synthetic peptide was found to be 95% homogenous with molecular weight of 3.48 kD. The peptide was identified to be a novel antimicrobial peptide consisting of 33 amino acid residues, and has a low computed instability index of -0.1.55 with high hydrophobic ratio of 27.27%. The antimicrobial activity revealed that T. chilonis antimicrobial peptide (TC-AMP) strongly inhibits the growth of selected human bacterial and fungal pathogens. While the haemolytic assay showed that the peptide did not obliterate human RBC in vitro. TC-AMP also showed an efficient inhibition of angiogenesis by in vivo model as evident by inhibition of vascularization. Conclusions: AMP derived from the parasitoid has a potent antibiotic and anti-angiogenesis property. The peptide can be used as a potential antimicrobial and anticancer drug in near future with more detailed studies on its targeted applications.

A Caenorhabditis elegans nck-1 and filamentous actin-regulating protein pathway mediates a key cellular defense against bacterial pore-forming proteins.

Pore-forming proteins (PFPs) comprise the largest single class of bacterial protein virulence factors and are expressed by many human and animal bacterial pathogens. Cells that are attacked by these virulence factors activate epithelial intrinsic cellular defenses (or INCEDs) to prevent the attendant cellular damage, cellular dysfunction, osmotic lysis, and organismal death. Several conserved PFP INCEDs have been identified using the nematode Caenorhabditis elegans and the nematicidal PFP Cry5B, including mitogen-activated protein kinase (MAPK) signaling pathways. Here we demonstrate that the gene nck-1, which has homologs from Drosophila to humans and links cell signaling with localized F-actin polymerization, is required for INCED against small-pore PFPs in C. elegans. Reduction/loss of nck-1 function results in C. elegans hypersensitivity to PFP attack, a hallmark of a gene required for INCEDs against PFPs. This requirement for nck-1-mediated INCED functions cell-autonomously in the intestine and is specific to PFPs but not to other tested stresses. Genetic interaction experiments indicate that nck-1-mediated INCED against PFP attack is independent of the major MAPK PFP INCED pathways. Proteomics and cell biological and genetic studies further indicate that nck-1 functions with F-actin cytoskeleton modifying genes like arp2/3, erm-1, and dbn-1 and that nck-1/arp2/3 promote pore repair at the membrane surface and protect against PFP attack independent of p38 MAPK. Consistent with these findings, PFP attack causes significant changes in the amount of actin cytoskeletal proteins and in total amounts of F-actin in the target tissue, the intestine. nck-1 mutant animals appear to have lower F-actin levels than wild-type C. elegans. Studies on nck-1 and other F-actin regulating proteins have uncovered a new and important role of this pathway and the actin cytoskeleton in PFP INCED and protecting an intestinal epithelium in vivo against PFP attack.

Genome-Wide Transposon Mutagenesis Screens Identify Group A Streptococcus Genes Affecting Susceptibility to β-Lactam Antibiotics.

Group A streptococcus (GAS) is a Gram-positive human bacterial pathogen responsible for more than 700 million infections annually worldwide. Beta-lactam antibiotics are the primary agents used to treat GAS infections. Naturally occurring GAS clinical isolates with decreased susceptibility to beta-lactam antibiotics attributed to mutations in PBP2X have recently been documented. This prompted us to perform a genome-wide screen to identify GAS genes that alter beta-lactam susceptibility in vitro. Using saturated transposon mutagenesis, we screened for GAS gene mutations conferring altered in vitro susceptibility to penicillin G and/or ceftriaxone, two beta-lactam antibiotics commonly used to treat GAS infections. In the aggregate, we found that inactivating mutations in 150 GAS genes are associated with altered susceptibility to penicillin G and/or ceftriaxone. Many of the genes identified were previously not known to alter beta-lactam susceptibility or affect cell wall biosynthesis. Using isogenic mutant strains, we confirmed that inactivation of clpX (Clp protease ATP-binding subunit) or cppA (CppA proteinase) resulted in decreased in vitro susceptibility to penicillin G and ceftriaxone. Deletion of murA1 (UDP-N-acetylglucosamine 1-carboxyvinyltransferase) conferred increased susceptibility to ceftriaxone. Our results provide new information about the GAS genes affecting susceptibility to beta-lactam antibiotics. IMPORTANCE Beta-lactam antibiotics are the primary drugs prescribed to treat infections caused by group A streptococcus (GAS), an important human pathogen. However, the molecular mechanisms of GAS interactions with beta-lactam antibiotics are not fully understood. In this study, we performed a genome-wide mutagenesis screen to identify GAS mutations conferring altered susceptibility to beta-lactam antibiotics. In the aggregate, we discovered that mutations in 150 GAS genes were associated with altered beta-lactam susceptibility. Many identified genes were previously not known to alter beta-lactam susceptibility or affect cell wall biosynthesis. Our results provide new information about the molecular mechanisms of GAS interaction with beta-lactam antibiotics.

Synthesis and characterization of cefixime loaded silver nanoparticles for antibacterial activity against staphylococcus aureus

In Recent year's medication obstruction is a quickly developing issue over the whole world in the treatment of infectious diseases. The widespread use of broad-spectrum antibiotics produced antibiotic resistance for many human bacterial pathogens. Anyways right now, nanotechnology research has been engaging more in restorative businesses with various advantages because of the way that surface area to volume proportion of Nanoparticles is quite large. In this exploration work, Silver Nanoparticles (AgNPs) are prepared by using a reducing agent like sodium borohydride and capping agent Polyvinylpyrrolidone. The prepared AgNPs and Cefixime-loaded AgNPs were subjected to characterization like particle size, FT-IR, X-ray diffraction. In addition, the AgNPs draw much interest in the account of their powerful antibacterial movement. The antibacterial activity of AgNPs and Cefixime-loaded AgNPs was checked against the bacterial culture of Staphylococcus Aureus. The zone of inhibition AgNPs was checked against microorganisms. The results of this study demonstrate the antibacterial activity of AgNPs and Cefixime-loaded Silver Nanoparticles against the bacterial culture of Staphylococcus Aureus with synergistic activity

Effects of trace PFOA on microbial community and metabolisms: Microbial selectivity, regulations and risks

Perfluorooctanoic acid (PFOA), a "forever chemical", is continuously discharged and mitigated in the environment despite its production and use being severely restricted globally. Due to the transformation, attachment, and adsorption of PFOA in aquatic environments, PFOA accumulates in the porous media of sediments, soils, and vadose regions. However, the impact of trace PFOA in the porous media on interstitial water and water safety is not clear. In this work, we simulated a porous media layer using a sand column and explored the effects of µg-level PFOA migration on microbial community alternation, microbial function regulation, and the generation and spread of microbial risks. After 60 days of PFOA stimulation, Proteobacteria became the dominant phylum with an abundance of 91.8%, since it carried 71% of the antibiotic resistance genes (ARGs). Meanwhile, the halogen-related Dechloromonas abundance increased from 0.4% to 10.6%. In addition, PFOA significantly stimulated protein (more than 1288%) and polysaccharides (more than 4417%) production by up-regulating amino acid metabolism (p< 0.001) and membrane transport (p < 0.001) to accelerate the microbial aggregation. More importantly, the rapidly forming biofilm immobilized and blocked PFOA. The more active antioxidant system repaired the damaged cell membrane by significantly up-regulating glycerophospholipid metabolism and peptidoglycan biosynthesis. It is worth noting that PFOA increased the abundance of antibiotic resistance genes (ARGs) and human bacterial pathogens (HBPs) in porous media by 30% and 106%. PFOA increased the proportion of vertical transmission ARGs (vARGs), and co-occurrence network analysis (r ≥ 0.8, p ≤ 0.01) verified that vARGs were mainly mediated by HBPs. A comprehensive understanding of PFOA interactions with its microecological environment is provided.

Effects of manure fertilization on human pathogens in endosphere of three vegetable plants

Pathogens can colonize plant endosphere and, be transferred into human beings through the food chain. However, our understanding of the influences of agricultural activities, such as fertilization, on endophytic microbial communities and human pathogens is still limited. Here, we conducted a microcosm experiment using the combination of 16 S rRNA gene amplicon sequencing and high-throughput qPCR array to reveal the effects of manure fertilization on microbiomes of soils and plants and how such impact is translated into endophytic pathogens. Our results showed that manure fertilization significantly altered soil microbiomes, whereas with less influence on endophytic microbial communities. Soil is a vital source of both bacterial communities and human pathogens for the plant endosphere. The abundance of pathogens was increased both in soils and endosphere under manure fertilization. These findings provide an integrated understanding of the impact of manure fertilization on endophytic pathogens.

Enhanced removal of antibiotic resistance genes and human bacterial pathogens during anaerobic digestion of dairy manure via addition of manure biochar.

In this study, the response of antibiotic resistance genes (ARGs), mobile gene elements (intI1), and human bacterial pathogens (HBPs) to addition of manure biochar (1-10g/L) was studied in anaerobic digestion (AD) at 20-55°C for treating dairy manure. Twelve ARGs comprising five tetracycline resistance genes, two sulfonamide resistance genes, two macrolide resistance genes, three β-lactam antibiotic resistance genes, and intI1 were analyzed by quantitative PCR. High-throughput sequencing data were matched against a database of putative 538 HBPs. Significant removal of ARGs (except for tetO and ermB) and intI1 was observed in all the samples. Manure biochar resulted in significant removal of ARGs and HBPs; however, negative effects were also observed in some conditions. This is the first study to provide to explore the fates of ARGs and HBPs by adding manure biochar to AD.

Evaluation of Bioactive Secondary Metabolites from Ponyfish Associated Bacteria (&lt;i&gt;Photobacterium leiognathi&lt;/i&gt;)

The marine environment continues to surprise us by producing novel bioactive substances with a wide range of benefits for humans. Materials and Methods: Marine bioluminescent bacteria Photobacterium leiognathi was isolated from pony fish, Secutorruconius which was confirmed with microscopic and molecular characterization. The secondary metabolite of the isolated bacteria was extracted with dichloromethane. The chemical fingerprinting of the isolated metabolite was analyzed through TLC, FT-IR, and HPLC. The nature of the compound present in the metabolite was identified in the gas chromatography-mass spectrometry analysis (GC - MS). The isolated extract was investigated for its antibacterial property against 10 human pathogenic bacteria and also its antioxidant activity using different assays such as 1, 1-Diphenyl-2-picrylhydrazyl, Phosphomolybdenum, Metal chelating, Hydroxyl radical scavenging and hydrogen peroxide scavenging activity. Results: The Presence of functional groups including phenols, sugars, and amino acids in the extracts were identified by TLC. Totally, nine peaks were obtained for the crude extract through the FTIR spectrum range of 400 to 4000 cm-1 for the active sample. The DCM extract showed a broad spectrum of antibacterial activity against the six human bacterial pathogens. Secondary metabolites from the bioluminescent bacteria, P. leiognathi, have strong antioxidant properties. These results will be instrumental in developing novel products with biosensors and bio-imaging applications using P. leiognathi.

INHIBITORY ACTIVITY OF THERMO-RESISTANT METABOLITES PRODUCED BY Streptomyces SP. CACIS-1.16CA AGAINST HUMAN AND PLANT PATHOGENIC BACTERIA

For many decades, members in the genus Streptomyces have been considered the principal microbial producers of secondary metabolites with antibiotic activity. In this study, we evaluated the inhibitory activity of a cell-free supernatant produced by Streptomyces sp. CACIS-1.16CA against human and plant bacterial pathogens. We also assessed the thermal stability of the compounds. An initial screening to evaluate the antibacterial activity of compounds diffused from a CACIS-1.16CA culture into agar discs found inhibitory effects against Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, Bacillus pumilus, and Pectobacterium carotovorum. A cell-free supernatant from cultured CACIS-1.16CA confirmed the inhibition effects on the susceptible pathogens. Thermally treating the supernatant did not significantly affect the inhibitory activity, indicating Streptomyces sp. CACIS-1.16CA produces some thermally stable antibacterial metabolites. This antibacterial activity is consistent with the detection of biosynthetic gene clusters for polyketide synthase Types I and II and non-ribosomal peptide synthase.

Removal of clinically significant antibiotics from aqueous solutions by applying unique high-throughput continuous-flow plasma pencil and plasma brush systems

High demands of medical and husbandry sectors led to a massive annual production of 100,000 tonnes of various antibiotics on a global scale. Considering that an access to sublethal doses of these pharmaceuticals causes subsequent increase in resistance of virulent human bacterial pathogens, there is a substantial need for development of novel methods and techniques for degradation of antibiotics from aqueous solutions. Here, high-throughput continuous flow plasma pencil and plasma brush methodologies were developed and verified for their applicability for removal of antibiotics from solutions, as estimated by high-performance liquid chromatography coupled with diode-array detection (HPLC-DAD) or ultraperformance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). The removal efficiency of drugs treated by the plasma pencil was in the range from 3 to 24%, and was corresponded to with 1.39% to 10.76% losses in the antibacterial properties of the plasma-treated solutions. However, application of a unique plasma brush increased the antibiotics degradation rates significantly, now falling in the range from 29 to 67% that led to 12.06–81.59% decrease in the antimicrobial properties of the plasma-exposed antibiotics solutions. The deviations in the effectiveness of the plasma pencil and the plasma brush methods were assigned with the types and amounts of generated species. Various intermediate degradation products were also detected in the post-plasma solutions, which derived from the oxygen attack to nucleophilic sides of the antibiotic molecules. We assume that such novel high-throughput, continuous flow methodological setups may find application in hospitals as an end-of-pipe technology for routine elimination of pollutants before reaching municipal sewage treatment plants.

ASSESSMENT OF QUORUM QUENCHING ACTIVITY OF SERRATIA SPP. ISOLATED FROM PLANT RHIZOSPHERE AGAINST QUORUM SENSING CONTROLLED BIOFILM-FORMING PATHOGENS

Quorum quenching is the process of blocking quorum sensing activity that can be used as an effective way to control quorum sensing dependent virulence in pathogens. Quorum quenching mechanisms prevent the development of antibiotic resistance in biofilm-forming microorganisms. Rhizospheric bacteria shows great diversity along with complex intra species interactions. Within this diversified environment many bacterial species with quorum sensing and quorum quenching ability are found in close vicinity. In this study rhizospheric soil of different plants was used to screen potential quorum quenchers. The rhizospheric bacterial isolates were tested for their ability to degrade/inactivate N-hexanoyl-l-homoserine lactone (C6HSL) molecules. Pigment inhibition bioassays were performed using Chromobacterium violaceum CV026 and C. violaceum 2656 to screen bacterial isolates possessing quorum quenching activity. The biofilm formation inhibition by six screened isolates was studied against different human pathogens such as Vibrio parahaemolyticus MTCC451, V. cholerae MTCC3906 and Pseudomonas aeruginosa PA01. Results revealed that biofilms were efficiently inhibited. Significant biofilm inhibition was revealed by two isolates and identified as S. marcescens subsp. sakuensis KRED, and S. nematodiphila using 16S rRNA gene sequencing technique. The partial purification of C6HSL inactivating quorum quenching molecule resulted in maximum pigment inhibition of C. violaceum 2656 at 80% saturation of ammonium sulphate. These findings revealed that S. marcescens subsp. sakuensis KRED and S. nematodiphila are found to be potential candidates to control biofilms in bacterial human pathogens.

Gut and Gill-Associated Microbiota of the Flatfish European Plaice (Pleuronectes platessa): Diversity, Metabolome and Bioactivity against Human and Aquaculture Pathogens.

Similar to other marine holobionts, fish are colonized by complex microbial communities that promote their health and growth. Fish-associated microbiota is emerging as a promising source of bioactive metabolites. Pleuronectes platessa (European plaice, plaice), a flatfish with commercial importance, is common in the Baltic Sea. Here we used a culture-dependent survey followed by molecular identification to identify microbiota associated with the gills and the gastrointestinal tract (GIT) of P. platessa, then profiled their antimicrobial activity and metabolome. Altogether, 66 strains (59 bacteria and 7 fungi) were isolated, with Proteobacteria being the most abundant phylum. Gill-associated microbiota accounted for higher number of isolates and was dominated by the Proteobacteria (family Moraxellaceae) and Actinobacteria (family Nocardiaceae), whereas Gram-negative bacterial families Vibrionaceae and Shewanellaceae represented the largest group associated with the GIT. The EtOAc extracts of the solid and liquid media cultures of 21 bacteria and 2 fungi representing the diversity of cultivable plaice-associated microbiota was profiled for their antimicrobial activity against three fish pathogens, human bacterial pathogen panel (ESKAPE) and two human fungal pathogens. More than half of all tested microorganisms, particularly those originating from the GIT epithelium, exhibited antagonistic effect against fish pathogens (Lactococcus garvieae, Vibrio ichthyoenteri) and/or human pathogens (Enterococcus faecium, methicillin-resistant Staphylococcus aureus). Proteobacteria represented the most active isolates. Notably, the solid media extracts displayed higher activity against fish pathogens, while liquid culture extracts were more active against human pathogens. Untargeted metabolomics approach using feature-based molecular networking showed the high chemical diversity of the liquid extracts that contained undescribed clusters. This study highlights plaice-associated microbiota as a potential source of antimicrobials for the control of human and the aquaculture-associated infections. This is the first study reporting diversity, bioactivity and chemical profile of culture-dependent microbiota of plaice.

Green Synthesis and Antibacterial Activity of Ag/Fe2O3 Nanocomposite Using Buddleja lindleyana Extract.

In the study reported in this manuscript, silver/iron oxide nanocomposites (Ag/Fe2O3) were phytosynthesized using the extract of Buddleja lindleyana via a green, economical and eco-friendly strategy. The biosynthesized Ag/Fe2O3 nanocomposites were characterized using UV-Vis spectrophotometry, FTIR, XRD, TEM, DLS and SEM-EDX analyses. The particulates showed a triangular and spherical morphology having sizes between 25 and 174 nm. FTIR studies on the nanoparticles showed functional groups corresponding to organic metabolites, which reduce and stabilize the Ag/Fe2O3 nanocomposite. The antimicrobial efficacy of the phytosynthesized Ag/Fe2O3 against bacterial pathogens was assessed. In addition, Ag/Fe2O3 exhibited broad spectrum activities against B. subtilis, S. aureus, E. coli, and P. aeruginosa with inhibition zones of 23.4 ± 0.75, 22.3 ± 0.57, 20.8 ± 1.6, and 19.5 ± 0.5 mm, respectively. The Ag/Fe2O3 composites obtained showed promising antibacterial action against human bacterial pathogens (S. aureus, E. coli, B. subtilis and P. aeruginosa), making them candidates for medical applications.

Metagenomic insights into resistome coalescence in an urban sewage treatment plant-river system

The effluents of sewage treatment plants (eSTP) are one of the critical contributors of antibiotic resistiome in rivers. Recently, community coalescence has been focused as the entire microbiome interchanges with one another. While works have reported the prevalence of antibiotic resistance genes (ARGs) in eSTP and their effects on river resistome, little research has investigated the extent of resistome coalescence in the environment. In the study, we have addressed the issue and focused on the resistome coalescence of eSTP in an urban river with a typical effluent/river coalescence model, by utilizing high-throughput sequencing (HTS)-based metagenomic assembly analysis. In all, a total of 609 ARGs were found in the eSTP-river system, conferring resistance to 30 antibiotic classes and including some emerging ARGs such as mcr-type, tetX and carbapenemase genes. Statistical analyses including linear discriminant analysis effect size (LEfSe) showed the coalescence of STP effluents increased the diversity and abundance of river resistome, indicating its low resistance to disturb the invasion of resistome community in eSTP. After coalescence in the river, the imprints of STP-derived ARGs presented a temporary increase and gradually decreased trend along the flow path. Further, an innovative fast expectation-maximization microbial source tracking (FEAST) method was used to quantitatively apportion the coalescence event, and demonstrated the contribution of eSTP on river resistome and its attenuation dynamics in the downstream. Notably, correlation-based network analysis and contig-based co-occurrence analysis showed the coalesced resistome in the downstream river co-occurred with human bacterial pathogens, mobile genetic elements and virulence factor genes, indicating potential resistome dissemination risk in the environment. This study provides more profound understanding of resistome coalescence between engineered and natural contexts, which is helpful for optimizing strategies to prevent and control resistome risk in aquatic environment.

Hybrid antigens expressing surface loops of BauA from Acinetobacter baumannii are capable of inducing protection against infection

Acinetobacter baumannii is a human bacterial pathogen of increasing concern in clinical settings due to the emergence of antibiotic resistant strains and the lack of effective therapeutics. Researchers have been exploring new treatment options such as novel drug candidates and vaccines to prevent severe infections and mortality. Bacterial surface antigens that are essential to A. baumannii for acquiring micronutrients (e.g. iron, zinc) from nutrient restricted environments are being considered as targets for vaccines or immunotherapy due to their crucial role for growth and pathogenesis in the human host. BauA, the outer membrane receptor for the siderophore acinetobactin was targeted for vaccine development in this study. Due to challenges in the commercial production of membrane proteins for vaccines, a novel hybrid antigen method developed by our group was used. Exposed loops of BauA were selected and displayed on a foreign scaffold to generate novel hybrid antigens designed to elicit an immune response against the native BauA protein. The potential epitopes were incorporated into a scaffold derived from the C-lobe of Neisseria meningitidis transferrin binding protein B (TbpB), named the loopless C-lobe (LCL). Hybrid proteins displaying three selected loops (5, 7 and 8) individually or in combination were designed and produced and evaluated in an A. baumannii murine sepsis model as vaccine antigens. Immunization with the recombinant BauA protein protected 100% of the mice while immunization with hybrid antigens displaying individual loops achieved between 50 and 100% protection. The LCL scaffold did not induce a protective immune response, enabling us to attribute the observed protection elicited by the hybrid antigens to the displayed loops. Notably, the mice immunized with the hybrid antigen displaying loop 7 were completely protected from infection. Taken together, these results suggest that our hybrid antigen approach is a viable method for generating novel vaccine antigens that target membrane surface proteins necessary for bacterial growth and pathogenesis and the loop 7 hybrid antigen can be a foundation for approaches to combat A. baumannii infections.

High-throughput sequencing comparative analyses of bacterial communities and human pathogens during the mesophilic anaerobic fermentation of swine feces

Manure as a resource is a major issue in the agricultural sector. Mesophilic anaerobic fermentation is the most common treatment modality for livestock manure, but it cannot completely eliminate human pathogens. Recently several reports characterized bacteria and human pathogens after manure treatment by mesophilic anaerobic fermentation. In this study, we used high-throughput sequencing to analyze bacterial and pathogen composition and diversity in fecal samples and digestates using three mesophilic anaerobic fermentation methods. The three methods altered composition and diversity, with the traditional fermentation method having the least effect on composition and diversity. In contrast, mesophilic anaerobic treatments plus extra bacteria displayed the greatest effects. We established a large-scale primary screening method for human pathogens at the genus level based on the mesophilic anaerobic fermentation system, and investigated pathogen survival rates at the species level. We provide a method for the preliminary evaluation and treatment of manure and we provide insights on the rational use of manure. • A large-scale primary screening method for human pathogens in the harmless treatment of livestock manure was established in this study. • Mesophilic anaerobic fermentation is difficult to control the abundance of Acinetobacter , Corynebacterium , Enterococcus , Pseudomonas and Streptococcus in fecal samples. • A method of traditional mesophilic anaerobic fermentation with extra bacteria was best to control potential human pathogen.

Predators of Soil Bacteria in Plant and Human Health

Soil bacterial predators that use the biomass of bacterial hosts for growth (multiplication), energy, or replication have the potential to reduce bacterial populations in the wide variety of terrestrial ecosystems in which they are found. Bacterial predators, including bacteria-feeding nematodes, protists, bacteria ( Bdellovibrio and like organisms, Lysobacter, and myxobacteria), and bacteriophages are responsible for bacterial turnover in soils that lead to many ecosystem services. The demonstrated breadth and specificity of bacterial host ranges for these predators make them interesting targets for the management of bacterial plant and human pathogens. However, there remain significant gaps in knowledge that will need to be filled in order to effectively utilize these predators for disease management. Here, we compared predatory strategies of the major groups of soil bacterial predators and outlined the gaps in knowledge or techniques that are limiting research. We offered specific needs and next steps for integrating analyses of predator identity and impact into studies of soil ecosystems in natural and applied settings.

The Helicobacter pylori UvrC Nuclease Is Essential for Chromosomal Microimports after Natural Transformation.

ABSTRACTHelicobacter pylori is a Gram-negative bacterial carcinogenic pathogen that infects the stomachs of half of the human population. It is a natural mutator due to a deficient DNA mismatch repair pathway and is naturally competent for transformation. As a result, it is one of the most genetically diverse human bacterial pathogens. The length of chromosomal imports in H. pylori follows an unusual bimodal distribution consisting of macroimports with a mean length of 1,645 bp and microimports with a mean length of 28 bp. The mechanisms responsible for this import pattern were unknown. Here, we used a high-throughput whole-genome transformation assay to elucidate the role of nucleotide excision repair pathway (NER) components on import length distribution. The data show that the integration of microimports depended on the activity of the UvrC endonuclease, while none of the other components of the NER pathway was required. Using H. pylori site-directed mutants, we showed that the widely conserved UvrC nuclease active sites, while essential for protection from UV light, one of the canonical NER functions, are not required for generation of microimports. A quantitative analysis of recombination patterns based on over 1,000 imports from over 200 sequenced recombinant genomes showed that microimports occur frequently within clusters of multiple imports, strongly suggesting they derive from a single strand invasion event. We propose a hypothetical model of homologous recombination in H. pylori, involving a novel function of UvrC, that reconciles the available experimental data about recombination patterns in H. pylori.