查看更多>>摘要：Lactic acid bacteria that inhabit in the lung play important roles in maintaining the microbiome balance by interacting with the host immune system. Numerous metabolites (e.g., short chain fatty acids, bacteriocins, and hydrogen peroxide) produced by Lactobacillus sakei possess a special inhibitory spectrum against invading pathogens. In this research, the whole genome of L. sakei JD10 strain isolated from the porcine lung was sequenced and investigated. The whole size of the L. sakei JD10 chromosome was 1,989,921 bp, which encoded a total of 1951 predicted genes. Genome analyses revealed that many genes encoded carbohydrate-active enzymes (CAZymes) were predicted, which were responsible for the carbohydrate degradation and short chain fatty acids production. The metabolic profiles of short chain fatty acids in the L. sakei JD10 culture medium were measured by GC/TOFMS, and their regulatory effects on bacterial phagocytosis of RAW264.7 cells were also determined. The bacteriocin-producing genes of the L. sakei JD10 genome were also predicted, and a bacteriocin gene encoding carnocin was characterized and its molecular structure was analyzed. Two CRISPR-Cas system related genes were identified from the L. sakei JD10 genome, revealed that precise and efficient genome editing technologies could be applied for genetic engineering-manipulation. In all, investigation on the genomic features and metabolic features of L. sakei JD10 showed the potential probiotic traits to fight against pathogenic infection and regulate the host immune function.
Di Mento, GiuseppinaGona, FlorianaRusselli, GiovannaCuscino, Nicola...
8页
查看更多>>摘要：In this work, we assessed and characterized the epidemiological scenario of carbapenem-resistant Klebsiella pneumoniae strains (CR-Kp) at IRCCS-ISMETT, a transplantation hospital in Palermo, Italy, from 2008 to 2017. A total of 288 K. pneumoniae clinical isolates were selected based on their resistance to carbapenems. Molecular characterization was also done in terms of the presence of virulence and resistance genes. All patients were inpatients from our facility and clinical isolates were collected from several sources, either from infection or colonization cases. We observed that, in agreement with the Italian epidemiological scenario, initially only ST258 and ST512 clade II (but not from clade I) were identified from 2008 to 2011. From 2012 onwards, other STs have been observed, including the clinically relevant ST101 and ST307, but also others not previously observed in other Italian health settings, such as ST220 and ST753. The presence of genes involved in resistance and virulence was confirmed, and a heterogeneous genetic resistance profile throughout the years was observed. Our work highlights that resistance genes are rapidly disseminating between different and novel K. pneumoniae clones which, combined with resistance to multiple antibiotics, can derive into more aggressive and pathogenic multidrug-resistant strains of clinical importance. Our results stress the importance of continuous surveillance of CR Enterobacterales in health facilities so that novel STs carrying resistance and virulence genes that may become increasingly pathogenic can be identified and adequate therapies to adopted to avoid their dissemination and derived pathologies.
查看更多>>摘要：FlhF protein is critical for intact flagellar assembly in Campylobacter jejuni. It is a putative GTPase with B-, Nand G-domains. However, the role of the Band N-domains in flagella biosynthesis remains unclear in C. jejuni. This study demonstrated that both the Band N-domains are essential for flagellar synthesis, with the absence of B and/or N-domains showing truncated variants of FlhF by TEM. Point mutations in the Band N-domains (T13A, K159A, G231A) also induced flagella abnormalities. Furthermore, significant defects in GTPase activity and polar targeting of FlhF were triggered by point mutations of Band N-domains. Flagella gene expression and transcription were also significantly disrupted in flhF(T13A), flhF(K159A) and flhF(G231A) strains. This study initially explored the effects of Band N-domains on flagella synthesis. We speculated that Band N-domains may directly or indirectly cause flagella abnormalities by affecting flagellar gene expression or GTPase activity, which helps us better understand the function of FlhF in flagella synthesis.
Lopez-Espinoza, Jose UrielGarcia-Guerrero, Joel TohevarisAlfonso-Corrado, CeciliaClark-Tapia, Ricardo...
11页
查看更多>>摘要：The dynamic microbiota of the human palmar surface (PS) is related to the various hygienic habits of humans and can be transmitted or exchanged upon contact with objects of daily use, such as the indispensable touchscreen cell phone (TCP); this interaction could allow the development of drug-resistant bacteria. The objective was to determine the drug-resistant bacterial contamination between PSs and TCPs in an urban community. Among the total bacterial colonies isolated and molecular and phylogenetically characterized based on the V4-V6 regions of the 16S rRNA gene from PSs and TCPs, the genera present in both types of samples were Staphylococcus (53.3 and 43.5 %, respectively), Bacillus (37.8, 37 %), Atlantibacter (2.2, 10.8 %) and Micro-bacterium (2.2, 4.3 %). The genera present in only one type of sample were Rothia, Paenibacillus, Escherichia and Micrococcus (2.2 % each). Resistance to penicillins (35.6-93.5 %) and nonsusceptibility to cephalosporins (8.9-37 %) and nitrofurantoin (13.3 and 15.2 %) were observed. The percentage of multidrug antibiotic resis-tance was 15.4 %. The prevalence of drug-resistant and multidrug-resistant bacteria in PSs and TCPs in the community could give rise to human health problems, and hygiene measures are recommended.
查看更多>>摘要：The cassava-alcohol fermentation process employing cassava requires nitrogen source to maximize yields by a commercial strain of S. cerevisiae TG1348. In this study, a factorial experimental design was used to assess a suitable nitrogen source for growth and fermentative performance of S. cerevisiae in cassava-ethanol fermentation. The alcohol fermentation time was about 39 h for urea and ammonium acetate, which was 48 h for ammonium chloride and ammonium sulphate. The fermentation time was reduced by 19 % when using urea and ammonium acetate as nitrogen source. Ammonium acetate leaded to the highest alcohol yield, which was 4% higher than for ammonium sulphate. In addition, byproduct formation differed obviously between the nitrogen sources. The glycerol yields were similar for urea, ammonium sulphate and ammonium chloride but were 24 % lower for ammonium acetate. However, glycerol yield for ammonium carbonate was higher than for other nitrogen sources. Clearly, in batch cultures the ammonium acetate not only increased ethanol generation, but also decreased glycerol generation. In order to understand why ammonium acetate promotes alcohol fermentation, acetic acid was added to different nitrogen sources. The weight loss effect of ammonium sulphate adding acetic acid and ammonium acetate as nitrogen source was the same. The fermentation time was shortened by adding acetic acid. And pH was increased by addition of acetic acid when ammonium sulfate and urea were used as nitrogen sources. The results showed that the acetate root plays an important role in ammonium acetate. The results of this study could facilitate the development of new strategies to control fermentation performance.
查看更多>>摘要：Escherichia coli is one of the leading causes of bovine mastitis; it can cause sub-clinical, and clinical mastitis characterized by systemic changes, abnormal appearance of milk, and udder inflammation. E. coli pathogenicity in the bovine udder is due to the interaction between its virulence factors and the host factors; it was also linked to the presence of a new pathotype termed mammary pathogenic E. coli (MPEC). However, the presence of this pathotype is commonly debated. Its main virulence factor is the lipopolysaccharide (LPS) that is responsible for causing an endotoxic shock, and inducing a strong immune response by binding to the toll-like receptor 4 (TLR4), and stimulating the expression of chemokines (such as IL-8, and RANTES) and pro-inflammatory cytokines (such as IL-6, and IL-1 beta). This strong immune response could be used to develop alternative and safe approaches to control E. coli causing bovine mastitis by targeting pro-inflammatory cytokines that can damage the host tissue. The need for alternative treatments against E. coli is due to its ability to resist many conventional antibiotics, which is a huge challenge for curing ill animals. Therefore, the aim of this review was to highlight the pathogenicity of E. coli in the mammary gland, discuss the presence of the new putative pathotype, the mammary pathogenic E. coli (MPEC) pathotype, study the host's immune response, and the alternative treatments that are used against mastitis-associated E. coli.
查看更多>>摘要：Beneficial ecosystem services provided by arbuscular mycorrhizal fungi (AMF) are the outcome of their synergistic actions with diverse bacterial communities (AMF-associated bacteria; AAB) living in strict association with AMF hyphae and spores. Herein, bacterial diversity associated with 6 AMF species from 33 different co-cultures belonging to order Glomerales and Diversisporales were identified, using a combination of culture-dependent functional analyses and amplicon sequencing. Overall, 231 bacterial strains were isolated from the AMF spores and hyphae which covered 30 bacterial genera and 52 species. Hierarchical clustering based on plant growth promoting traits identified 9 clades comprising diverse bacterial genera with clades 7, 8 and 9 representing the most functionally rich AAB. High-throughput amplicon sequencing across a small subset of 8 AMF co cultures spread across 3 AMF genera identified Operational Taxonomic Units belonging to 118 bacterial genera. The study revealed a greater diversity of AAB from spores of in vitro transformed AMF root co-cultures rather than in situ, pot AMF cultures. Functionally active, culturable AABs with multiple plant growth promoting traits such as phosphate solubilisation, nitrogen fixation, biofilm formation, enzyme and plant growth regulator production along with biocontrol activity were identified. These properties could be utilized individually and/or as consortia with AMF, as biological growth enhancers.
查看更多>>摘要：The ability to cope with environmental abiotic stress and biotic stress is crucial for the survival of plants and microorganisms, which enable them to occupy multiple niches in the environment. Previous studies have shown that transcription factors play crucial roles in regulating various biological processes including multiple stress tolerance and response in eukaryotes. This work identified multiple critical transcription factor genes, metabolic pathways and gene ontology (GO) terms related to abiotic stress response were broadly activated by analyzing the transcriptome of phytopathogenic fungus Alternaria alternata under metal ions stresses, oxidative stress, salt stresses, and host-pathogen interaction. We investigated the biological functions and regulatory roles of the bZIP transcriptional factor (TF) genes in the phytopathogenic fungus A.alternata by analyzing targeted gene disrupted mutants. Morphological analysis provides evidence that the bZIP transcription factors (Gcn4, MeaB, Atf1, the ER stress regulator Hac1, and the all development altered-1 gene Ada1) are required for morphogenesis as the colony morphology of these gene deletion mutants was significantly different from that of the wild-type. In addition, bZIPs are involved in the resistance to multiple stresses such as oxidative stress (Ada1, Yap1, MetR) and virulence (Hac1, MetR, Yap1, Ada1) at varying degrees. Transcriptome data demonstrated that the inactivation of bZIPs (Hac1, Atf1, Ada1 and Yap1) significantly affected many genes in multiple critical metabolism pathways and gene ontology (GO) terms. Moreover,the delta Hac1 mutants displayed reduced aerial hypha and are hypersensitivity to endoplasmic reticulum disruptors such as tunicamycin and dithiothreitol. Transcriptome analysis showed that inactivation of Hac1 significantly affected the proteasome process and its downstream unfolded protein binding, indicating that Hac1 participates in the endoplasmic reticulum stress response through the conserved unfolded protein response. Taken together, our findings reveal that bZIP transcription factors function as key regulators of fungal morphogenesis, abiotic stress response and pathogenesis, and expand our understanding of how microbial pathogens utilize these genes to deal with environmental stresses and achieve successful infection in the host plant.
查看更多>>摘要：Though carbon catabolite repression (CCR) has been intensively studied in some more characterised organisms, there is a lack of information of CCR in thermophiles. In this work, CCR in the thermophile, Parageobacillus thermoglucosidasius DSM 2542 has been studied during growth on pentose sugars in the presence of glucose. Physiological studies under fermentative conditions revealed a loosely controlled CCR when DSM 2542 was grown in minimal medium supplemented with a mixture of glucose and xylose. This atypical CCR pattern was also confirmed by studying xylose isomerase expression level by qRT-PCR. Fortuitously, the pheB gene, which encodes catechol 2, 3-dioxygenase was found to have a cre site highly similar to the consensus cataboliteresponsive element (cre) at its 3 ' end and was used to confirm that expression of pheB from a plasmid was under stringent CCR control. Bioinformatic analysis suggested that the CCR regulation of xylose metabolism in P. thermoglucosidasius DSM 2542 might occur primarily via control of expression of pentose transporter operons. Relaxed control of sugar utilization might reflect a lower affinity of the CcpA-HPr (Ser46-P) or CcpA-Crh (Ser46P) complexes to the cre(s) in these operons.
查看更多>>摘要：Salinity stress is one of the most harmful abiotic stresses that inhibit crop growth and grain yield. In this study, a salt-tolerant bacterium was isolated from the soil of the rice rhizosphere and named Myroides sp. JIL321, based on the results of the phylogenetic tree analysis. The strain JIL321 tolerated up to 1, 283.37 mM of NaCl and exhibited positive plant growth-promoting traits, such as the production of indole acetic acid (IAA) and 1-aminocyclopropane-1-carboxylate (ACC) deaminase. Therefore, the effects of JIL321 on rice (Oryza sativa L.) under salinity stress were determined. The inoculation of strain JIL321 significantly increased the chlorophyll content and the accumulation of osmotic adjustment substances, such as proline and soluble sugars, in rice expose to salt stress. Additionally, strain JIL321 inoculation significantly enhanced the activities of some enzymes commonly found in soil, such as urease, invertase and catalase. Moreover, the production of hydrogen sulfide (H2S), a pivotal signaling molecule, was also induced in rice by salt stress. Treatment with sodium hydrogen sulfide (NaHS, H2S donor) improved salt stress tolerance of the rice, while treatment with hypotaurine (HT, H2S scavenger) significantly suppressed it. Interestingly, NaHS treatment also improved the production of IAA and ACC deaminase in strain JIL321 under 0 mM and 150 mM salt concentrations. The combined treatment of JIL321 and NaHS could further improve the growth of salt-stressed rice seedlings, most likely due to the interaction effect between H2S and strain JIL321. To our knowledge, this study is the first to demonstrate that the combined use of H2S and plant growth-promoting bacteria could alleviate the adverse effects of salt stress on rice plants, and further verifies the novel role of H2S as a signaling molecule that enhance the tolerance of plant to abiotic stresses.
NSTL
Elsevier