Project description:Objectives: Colistin remains a last-line treatment for multidrug-resistant Acinetobacter baumannii and combined use of colistin and carbapenems has shown synergistic effects against multidrug-resistant strains. In order to understand the bacterial responses to these antibiotics we analysed the transcriptome of A. baumannii following exposure to each.
Project description:Many clinically relevant bacterial pathogens are encapsulated, as exemplified by Salmonella enterica serovar Typhi. S. Typhi, the causative agent of the life-threatening systemic disease enteric fever, expresses Vi as the outermost surface glycan that protects the bacteria from host immune responses. Multidrug-resistant (MDR) and extensively drug-resistant (XDR) S. Typhi strains, as well as Vi variants, are widespread globally. Our WGS analyses indicate that almost all S. Typhi clinical isolates are susceptible to rifamycins and azithromycin. Rifampin, even at sub-MIC levels, eliminates the protective capsule Vi, a process referred to as ‘decapsulation’, thereby enhancing bacterial clearance. Antibiotic-mediated decapsulation of S. Typhi appears specific to rifamycins, since azithromycin does not decapsulate S. Typhi. Rifampin mediated decapsulation occurs at the transcriptional level, where both high AT content and specific RpoB residues play a crucial role. Rifampin also effectively decapsulates Vi variants, which accounts for 1 in 5 S. Typhi isolates at the global level. A mechanistic explanation for rifampin mediated decapsulation of S. Typhi appears to be applicable to other encapsulated pathogens, including S. Paratyphi C.
Project description:The leaf surface, known as the phylloplane, represents the initial point of contact for plants in their interaction with the aboveground environment. Although prior research has assessed how leaves respond to external pH variations, particularly in the context of acid rain, there remains a limited understanding of the molecular mechanisms through which plants detect, respond to, and mitigate cellular damage. To look at plant responses to external pH changes, we measured the phylloplane pH for five species with variable phylloplane pH that ranged in the dry control. Moreover, we investigated the phylloplane pH in response to three pH treatments (pH 6.5, 4, and 2) and found that plants can modify their phylloplane pH, and this buffering ability is species-specific. Among the species analyzed, only Gossypium displayed a strong buffering ability. For treatments where leaves were exposed to either pH 6.5 or pH 4, Gossypium alkalinized the phylloplane pH slightly higher than the dry control pH. Remarkably, when leaves were exposed to pH 2, Gossypium was able to buffer the pH to 6 within five minutes. Furthermore, our transcriptional analysis indicated that the responses to external pH changes varied among species, highlighting differentially expressed genes associated with calcium (Ca2+) signaling pathways, as well as Ca2+ and H+-ATPases pumps. These findings also suggest that pH stress negatively impacts photosynthesis, and that both wetness and moderate pH shifts may trigger additional abiotic and biotic stress signaling pathways.
Project description:Biofilm lifestyle is critical for bacterial pathogens to colonize and protect themselves from host immunity and antimicrobial chemicals in plants and animals. The formation and regulation mechanism of phytobacterial biofilm are still obscure. Here, we found that Ralstonia solanacearum Resistance to ultraviolet C (RuvC) is highly abundant in biofilm and positively regulates pathogenicity by governing systemic movement in tomato xylem. RuvC protein accumulates at the later stage of biofilm and specifically targets the Holliday junction (HJ) like structures to disrupt biofilm extracellular DNA (eDNA) lattice, thus facilitating biofilm dispersal. Recombinant RuvC protein can resolve extracellular HJ prevent bacterial biofilm formation. Heterologous expression of R. solanacearum or Xanthomonas oryzae pv. oryzae RuvC with plant secretion signal in tomato or rice confers resistance to bacterial wilt or bacterial blight disease, respectively. Plant chloroplast localized HJ resolvase monokaryotic chloroplast 1 (MOC1) which is structural similar to bacterial RuvC shows a strong inhibit effect on bacterial biofilm formation. Re-localization of SlMOC1 to apoplast in tomato roots leads to increase resistance to bacterial wilt. Our novel finding reveals a critical pathogenesis mechanism of R. solanacearum and provides an efficient biotechnology strategy to improve plant resistance to bacteria vascular disease.
Project description:This study evaluated the transcriptomic profiles of Arabidopsis thaliana (Col-0) plants grown along bacterial isolates whose interactions induce root morhology changes in the plant
Project description:Polymyxin B is considered as a last-resort antibiotic for multidrug-resistant or extensively drug-resistant gram-negative bacterial infections. Addressing Salmonella resistance to polymyxin B is crucial for global public health. In this study, transcriptomic detection and analysis were used to clarify the mechanisms by which CpxA-deleted S.typhimurium is involved in resistance to polymyxin B stress, which may be related to processes such as increased assembly of bacterial flagella.
Project description:Tomato is one of the most important crops for human consumption. Unfortunately, its production is affected by diseases caused by pathogens such as the actynomicete Clavibacter michiganensis subsp. michiganens (Cmm). This pathogen is the causal agent of the bacterial canker of tomato, considered one of the most devastating tomato diseases. To date, there are not resistant varieties of commercial tomato against Cmm. However, there are wild tomato species resistant to Cmm. Using massive sequencing, we obtained the transcriptomes of the wild tomato species Solanum arcanum LA2157 and the commercial tomato Solanum lycopersicum cv. Ailsa Craig at 8 and 24 hours after Cmm challenge. We identified potential tomato tolerance-related genes by three approaches: mapping the reads to S. lycopersicum reference genome SL3.0, performing a semi de novo transcriptome assembly and a de novo transcriptome assembly. Some functional groups such as oxylipin biosynthetic process response to wounding, response to cytokinin among others, were enriched in both tomato species, suggesting a similar response, however, genes that encode proteins such as the Polyphenol oxidase E, Ankyrin and Leucine Rich Repeat receptors were overexpressed mainly in the wild tomato species, suggesting a possible role in the defense response. Here, we uncovered new candidate genes potentially related to bacterial canker tomato defense.