H., M. C., T. E. D. M. A., J. A. L., M. C. D., A. Catherine, K. M. R., J. P. H., Y. J. Carl, G. Savannah, B. J. - L. C., et al., "Diversity and community structure of anaerobic gut fungi in the rumen of wild and domesticated herbivores", Applied and Environmental MicrobiologyApplied and Environmental Microbiology, vol. 90, issue 2: American Society for Microbiology, pp. e01492-23, 2024. AbstractWebsite
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Tag ElDein, M. A., N. G. Mohamed, Y. E. Shahein, L. Ziko, and N. A. Hussein, Altering Escherichia coli envelope integrity by mimicking the lipoprotein RcsF, , vol. 206, issue 1, pp. 12, 2023. AbstractWebsite

Escherichia coli cell envelope is crucial for stress sensing and signal transduction, mediated by numerous protein–protein interactions to enable adaptation and survival. Interfering with these interactions might affect envelope integrity leading to bacterial death. The outer membrane lipoprotein (RcsF) is the stress sensor of the regulator of capsule synthesis (Rcs) phosphorelay that senses envelope threats. RcsF interacts with two essential proteins, IgaA (repressing the Rcs system) and BamA (inserting β-barrel proteins in the outer membrane). Disturbing RcsF interactions may alter Rcs signaling and/or membrane integrity thus affecting bacterial survival. Here, we derived the sequence of a peptide mimicking RcsF (RcsFmim), based on the in silico docking of RcsF with IgaA. Expression of rcsFmim caused 3-to-4-fold activation of the Rcs system and perturbation of the outer membrane. Both effects result in decreased E. coli growth rate. We anticipate that RcsFmim present a candidate for future antibacterial peptide development.

Meili, C. H., A. L. Jones, A. X. Arreola, J. Habel, C. J. Pratt, R. A. Hanafy, Y. Wang, A. S. Yassin, M. A. Tag ElDein, C. D. Moon, et al., Patterns and determinants of the global herbivorous mycobiome, , vol. 14, issue 1, pp. 3798, 2023. AbstractWebsite

Despite their role in host nutrition, the anaerobic gut fungal (AGF) component of the herbivorous gut microbiome remains poorly characterized. Here, to examine global patterns and determinants of AGF diversity, we generate and analyze an amplicon dataset from 661 fecal samples from 34 mammalian species, 9 families, and 6 continents. We identify 56 novel genera, greatly expanding AGF diversity beyond current estimates (31 genera and candidate genera). Community structure analysis indicates that host phylogenetic affiliation, not domestication status and biogeography, shapes the community rather than. Fungal-host associations are stronger and more specific in hindgut fermenters than in foregut fermenters. Transcriptomics-enabled phylogenomic and molecular clock analyses of 52 strains from 14 genera indicate that most genera with preferences for hindgut hosts evolved earlier (44-58 Mya) than those with preferences for foregut hosts (22-32 Mya). Our results greatly expand the documented scope of AGF diversity and provide an ecologically and evolutionary-grounded model to explain the observed patterns of AGF diversity in extant animal hosts.

Tag ElDein, M. A., A. S. Yassin, O. El-Tayeb, and M. O. N. A. T. KASHEF, Chlorhexidine leads to the evolution of antibiotic-resistant Pseudomonas aeruginosa, , vol. 40, issue 11, pp. 2349 - 2361, 2021. AbstractWebsite

Antimicrobial resistance is a major public-health concern. We evaluate chlorhexidine role in selection of resistant Pseudomonas aeruginosa mutants and their antibiotic cross-resistance. Mutation frequency and mutation rate after short-term exposure to sub-inhibitory concentrations of chlorhexidine were compared to those after spontaneous chlorhexidine-exposure, in P. aeruginosa PAO1 strain. Chlorhexidine-resistant mutants were generated, either by serial passage in increasing chlorhexidine concentrations or by single exposure to lethal chlorhexidine concentration. The generated mutants were tested for cross-resistance to different antibiotics, by determination of minimum inhibitory concentrations (MIC). The accompanied phenotypic changes in membrane permeability, outer membrane proteins (OMP), and efflux function were evaluated. The effect of exposure to chlorhexidine on MexAB-OprM, MexEF-oprN, and MexXY efflux pumps expression was investigated. No significant change was recorded between the mutation frequencies and mutation rates after short-term exposure to sub-inhibitory concentrations of chlorhexidine and after spontaneous chlorhexidine-exposure, in P. aeruginosa PAO1 strain. Twelve stable mutants, with ≥ eight-fold increase in chlorhexidine MIC, were generated. Several mutants showed increase in the MIC of colistin, cefepime, ceftazidime, meropenem, ciprofloxacin, and amikacin; seven mutants expressed meropenem cross-resistance. This was accompanied by decreased outer membrane permeability and changes in OMP. Using efflux pump inhibitor, chlorhexidine resistance was reverted in most isolates. Exposure to sub-inhibitory concentration of chlorhexidine induced the expression of MexXY efflux pump. Some resistant mutants had overexpressed MexXY efflux pump. Chlorhexidine can select P. aeruginosa strains with antibiotic cross-resistance. This necessitates implementing special protocols for chlorhexidine use and re-evaluation of its benefit versus risk in personal-care products.

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