Saman Shalibeik, Fereshte Ghandehari, Ali-Mohammad Ahadi, Ali-Asghar Rastegari, Mojgan Ghiasian,
Volume 16, Issue 3 (May-Jun 2022)
Abstract
Background and objectives: Bacteriocins are generally active antimicrobial peptides effective against bacteria closely related to the producer. Escherichia coli produce two bacteriocins: colicins and microcins. Microcin J25 (Mcc J25) is an antibacterial peptide that inhibits bacterial transcription by disrupting the nucleotide-uptake channel of bacterial RNA polymerase. The objective of this study was to evaluate antimicrobial activity of MccJ25 produced by the bacteriocinogenic E. coli.
Methods: In this experimental study, 120 clinical specimens were selected from private diagnostic laboratories in Isfahan (Iran) in 2020. Antagonistic activity of isolates was tested by adopting agar plug method. Total DNA was extracted from clinical specimens and polymerase chain reaction (PCR) was performed using specific primers for amplification of the complete sequence of MccJ25 gene. Accuracy of the PCR products was confirmed by direct sequencing. Homology analysis was performed by using BLAST. Data were analyzed with Chromasv2.1.1 software.
Results: Overall, 120 E. coli strains were isolated from the clinical specimens. The antibiotic activity of Mcc J25 was mainly directed at Enterobacteriaceae, including several pathogenic E. coli strains of which 25 had positive well test samples, and about 5 (20%) of the collected clinical samples that were infected with E. coli had the MccJ25 gene.
Conclusions: Based on the results, Mcc J25 has favorable antibacterial potential, which can be further exploited as an alternative to chemical antibiotics.
Fereshteh Hematyar Tabatabaie , Ali Asghar Moshtaghie, Ali Asghar Rastegari, Hashem Nayeri,
Volume 18, Issue 2 (Mar-Apr 2024)
Abstract
Background: Certain trace elements, like cerium, have the potential to disrupt iron metabolism. This study explored the impact of cerium on intestinal iron absorption, focusing on the initial stage of iron metabolism. We employed the rat everted gut sac (EGS) segments to assess the interference caused by cerium. The primary objectives of this study were to examine the absorption of cerium in the intestines and to compare iron absorption in the presence and absence of cerium.
Methods: For the EGS experiment, segments of the rat's duodenum, ileum, or jejunum were promptly excised, cut into 5-6 cm segments, and rinsed with a physiological solution. These freshly prepared rat EGS segments were then incubated in Earle's medium containing iron (III) and/or cerium (III). We examined the impact of ascorbic acid, glucose, and different time intervals on the intestinal absorption of cerium and iron. Specifically, we investigated how glucose (5 mM) and ascorbic acid (2.8 mM) affected the absorption of cerium and iron at various concentrations (ranging from 0 to 200 mg/L). Additionally, we assessed the interfering effect of cerium on iron absorption.
Results: The results indicated that the maximum intestinal absorption of Fe (III) and Ce (III) occurred at a concentration of 200 mg/L. Furthermore, it was observed that their uptake increased following the reduction by ascorbic acid. The absorption of these elements also rose in the presence of glucose, suggesting energy-dependent transport. Additionally, a consistent cerium concentration was found to decrease iron absorption by 24.3% (P ≤ 0.05).
Conclusion: Based on the results, cerium likely reduces iron uptake by competing with iron. Cerium can also disrupt iron metabolism and lead to iron-related metabolic disorders. However, further studies at the molecular and intracellular levels are needed to gain a better understanding of this mechanism.
