• Journal of Veterinary Science
• /
• 제23권3호
• /
• pp.37.1-37.8
• /
• 2022

Background: Avian pathogenic Escherichia coli (APEC) causes colibacillosis, resulting in significant economic losses in the poultry industry. Objectives: In this study, the molecular characteristics of two extended-spectrum beta-lactamase (ESBL)-producing APEC isolates were compared with previously reported ESBL-producing E. coli isolates. Methods: The molecular characteristics of E. coli isolates and the genetic environments of the ESBL genes were investigated using whole genome sequencing. Results: The two ESBL-producing APEC were classified into the phylogenetic groups C and B1 and ST410 and ST162, respectively. Moreover, the ESBL genes of the two isolates were harbored in different Inc plasmids. The EC1809182 strain, harboring the bla_CTX-M-55 gene on the plasmid, exhibited extensive homology to IncFIB (98.4%) and IncFIC(FII) (95.8%). The EC1809191 strain, harboring the bla_CTX-M-1 gene, was homologous to IncI1-I (Gamma) (99.3%). All chromosomes carried the multidrug transporter, mdf(A) gene. Mobile genetic elements, adjacent to CTX-M genes, facilitated the dissemination of genes in the two isolates, analogous to other ESBL-producing E. coli isolates. Conclusions: This study clarifies the transmission dynamics of CTX-M genes and supports strengthened surveillance to prevent the transmission of the antimicrobial-resistant genes to humans via the food chain.

• 한국미생물·생명공학회지
• /
• 제16권2호
• /
• pp.111-118
• /
• 1988

유기산 생산균인 L. casei Y, Str. faecium C, Str. faecalis, Cl. butyricum M, B. toyoi를 사료첨가제와 발효유로부터 분리 확인하여 이들 균주가 자돈의 대장균증 설사를 유발시키는 E. coli $A_2$, E. coli G$_7$에 대하여 in vitro에서는 어떤 항균효과를 나타내는지 조사한 결과를 요약하면 다음과 같다. 1. L. casei Y, Str. faecium C, Str. faecalis, B. toyoi Cl. butyricum M을 각각 배양한 BL broth 3일 배양액은 모두 E. coli $A_2$와 E. coli G$_7$에 대하여 항균효과를 나타내었고, 이들 배양액을 E. coli $A_2$와 E. coli G$_7$에 대한 발육 Disc 확산시험 결과 그 저지환 직경은 각각 15mm와 17mm, 14mm와 15mm, 13mm와 14mm, 11mm와 13 mm, 10mm와 12mm 였다. 2. 유기산 생산 능력이 우수한 균일수록 E. coli $A_2$와 E. coli G$_7$에 대한 항균력이 높게 관찰되었으며, L. casei Y와 Str. faecium C가 이들 두 대장균에 대하여 높은 항균력을 나타내었다. 3. 유기산 생성균과 대장균(E. coli $A_2$, E. coli G$_7$)을 BL broth 에 혼합 배양할 때 E. coli $A_2$와 E. coli G$_7$은 배양액의 pH가 5.0 이하일 때 생육억제 되었고, pH 4.5 이하였을 때 사멸되었다. 4. 생성된 유기산은 배양액의 pH를 저하시킴과 동시에 항균성 물질로 직접 작용하여 E. coli $A_2$와 E. coli G$_7$의 생육저해 또는 사멸을 유도하였다. 5. E. coli $A_2$가 E. coli G$_7$보다 유기산 생산균의 대사산물에 대하여 더 높은 내성을 갖고 있었다.

• 한국식품위생안전성학회지
• /
• 제12권4호
• /
• pp.367-378
• /
• 1997

• Parasites, Hosts and Diseases
• /
• 제49권4호
• /
• pp.349-356
• /
• 2011

The existence of symbiotic relationships between Acanthamoeba and a variety of bacteria is well-documented. However, the ability of Acanthamoeba interacting with host bacterial pathogens has gained particular attention. Here, to understand the interactions of Escherichia coli K1 and E. coli K5 strains with Acanthamoeba castellanii trophozoites and cysts, association assay, invasion assay, survival assay, and the measurement of bacterial numbers from cysts were performed, and nonpathogenic E. coli K12 was also applied. The association ratio of E. coli K1 with A. castellanii was 4.3 cfu per amoeba for 1 hr but E. coli K5 with A. castellanii was 1 cfu per amoeba for 1 hr. By invasion and survival assays, E. coli K5 was recovered less than E. coli K1 but still alive inside A. castellanii. E. coli K1 and K5 survived and multiplied intracellularly in A. castellanii. The survival assay was performed under a favourable condition for 22 hr and 43 hr with the encystment of A. castellanii. Under the favourable condition for the transformation of trophozoites into cysts, E. coli K5 multiplied significantly. Moreover, the pathogenic potential of E. coli K1 from A. castellanii cysts exhibited no changes as compared with E. coli K1 from A. castellanii trophozoites. E. coli K5 was multiplied in A. castellanii trophozoites and survived in A. castellanii cysts. Therefore, this study suggests that E. coli K5 can use A. castellanii as a reservoir host or a vector for the bacterial transmission.

• 한국동물위생학회지
• /
• 제15권2호
• /
• pp.134-143
• /
• 1992

The present study was conducted to investigate the biochemical characteristics and anti-biotic resistance of Escherichia coli(E. coli) isolated from piglets with diarrhea in Kyongbuk province during the Period from February to November 1991. 368 E. coli strains were isolated from 382 piglets with diarrhea and the biochemical and cultural reaction were compared with the classification criteria of Edwards and Ewing. Tetracycline and sulfadimethoxine were found to be highly ineffective at in vitro inhibition of the E. coli of piglets origin. The majority of E. coli were susceptible to amikacin, chloramphenicol and gentamicine. 89 (89.0%) of 100 strains of E. coil were resistant to one or more drugs. The organisms resistant to 20 or 3 drugs were 54(60.6%) of 89 strains, whereas 16(17.9%) strains were found to be resistant to one drug. 55(61.8%) out of 89 drug resistance strains carried R factors($R^+$) which were transfer-able to the recipients by conjugation.

• 미생물학회지
• /
• 제23권1호
• /
• pp.49-55
• /
• 1985

The survival of Escherichia coli in river water was comparatively studied by laboratory and in sity study methods. The survival by two methods was evaluated as a function of E. coli strain, indigeneous predator, level of water pollution, and water temperature in different season. The survival rate of E. coli examined by laboratory method was lower than that by in situ method. That was found to be due to the fact that higher number of predator was maintained in labortory study than in in situ study. The survival rates of E. coli in gradually polluted river waters could be differentiated by in situ study, but not by laboratory study. Therefore, an in situ method rather than labortory method was thought to be a choice of study method for the survival of E. coli in river waters.

• Journal of Microbiology and Biotechnology
• /
• 제9권6호
• /
• pp.722-725
• /
• 1999

Filamentation-suppressed recombinant Escherichia coli strain harboring the Alcaligenes latus polyhydroxyalkanoate (PHA) biosynthesis genes and the E. coli ftsZ gene was constructed and cultivated for the production of poly(3-hydroxybutyrate) [P(3HB)] with high concentration and high content. By the pH-stat fed-batch culture of this recombinant E. coli strain XL1-Blue(pJC5), the final cell concentration and P(3HB) concentration obtained in 44.25h were 172.2g cell dry weight/l and 141.9g P(3HB)/l, respectively, resulting in productivity of 3.21g P(3HB)/l-h. More importantly, the P(3HB) content obtained was 82.4 wt %, which was significantly higher than that obtained with the recombinant E. coli harboring only the PHA biosynthesis genes.

• 미생물학회지
• /
• 제27권2호
• /
• pp.147-154
• /
• 1989

Vibrio vulnificus Lipopolysaccharide (LPS) was extracted, performed chemical analysis, tested its biological activities, and compared to those of Escherichia coli LPS and Salmonella typhimurium LPS. The lethal activity of V. vulnificus LPS was 138.6138.6 mg/kg in mouse, but this was lower than thowe of E. coli LPS (56.3 mg/kg) and S. typhimurium LPS (37.5 mg/kg). The result of fatty acid analysis showed that V. vulnificus LPS had more saturated fatty acid than E. coli LPS and S. typhimurium LPS. Above results indicated that V. vulnificus LPS did not have much effect on the lethality. The results of biological responses of enzymes and blood cells by LPSs showed that V. vulnificus LPS had slightly greater activity than E. coli LPS and S. typhimurium LPS. V. vulnificus LPS was recommendavle for stimulant on interferon induction because of adequate stimulation and safety for host and cell lines.

• Journal of Microbiology and Biotechnology
• /
• 제16권9호
• /
• pp.1448-1452
• /
• 2006

The effects of amplifying the gluconeogenic phosphoenolpyruvate carboxykinase of Escherichia coli ($pck_{Ec}$) on succinic acid production in E. coli were examined under anaerobic condition. No significant increase in succinic acid production was observed in E. coli overexpressing the $pck_{Ec}$ gene without supplementing $NaHCO_{3}$ or $MgCO_{3}$. On the other hand, succinic acid production was enhanced as the $NaHCO_{3}$ concentration was increased. When 20 g/l of $NaHCO_{3}$ was added, succinic acid production in recombinant E. coli overexpressing PCK was 2.2-fold higher than that observed in the wild-type strain. It was concluded that the gluconeogenic $pck_{Ec}$ overexpression enabled E. coli to enhance succinic acid production only under the high bicarbonate supplementation condition.

• Journal of Microbiology and Biotechnology
• /
• 제21권3호
• /
• pp.252-255
• /
• 2011

Both Escherichia coli (E. coli) and Salmonella enterica serovar Typhimurium (S. Typhimurium) have a tdc operon that encodes enzymes involved in a metabolic pathway for the degradation of L-serine and L-threonine. However, S. Typhimurium does not have the tdcR gene, which is a positive regulator in E. coli. In the present study, transcriptional analysis revealed that tdcA expression in E. coli is higher under anaerobic than aerobic growth conditions, but the opposite is true in S. Typhimurium. Interestingly, a tdcR mutant strain of E. coli showed a similar expression pattern to that observed in S. Typhimurium and was also induced by anaerobic shock. These results suggest that the induction of tdcA expression by anaerobic conditions is observable when tdcA expression is low owing to the absence of TdcR.