scholarly journals The survival ofEscherichia coliin an aerosol at air temperatures of 15 and 30 °C and a range of humidities

1986 ◽  
Vol 97 (3) ◽  
pp. 489-496 ◽  
Author(s):  
C. M. Wathes ◽  
K. Howard ◽  
A. J. F. Webster
Keyword(s):  
Escherichia Coli ◽  
E Coli ◽  
Air Temperatures ◽  
Livestock Buildings ◽  
Two Phases

SUMMARYThe survival ofEscherichia coliin an aerosol was studied at several temperatures and over a range of relative humidities using a Henderson apparatus.Death occurred in two phases, the first lasting approximately 1 min; in the second the number of viable microorganisms declined exponentially.E. coliwas robust and remained viable for many hours. Death was most rapid at low humidities (< 50% r.h.) at 15 and 30 °C, with half-lives of 14 and 3 min respectively. In humid conditions the half-lives were much longer, approximately 83 and 14 min respectively.Based on this work, preliminary recommendations for the climate of livestock buildings can now be given to control the airborne spread ofE. coli.

Lactobacillus inhibitor production against Escherichia coli and coaggregation ability with uropathogens

1988 ◽  
Vol 34 (3) ◽  
pp. 344-351 ◽  
Author(s):  
Gregor Reid ◽  
Jacqueline A. McGroarty ◽  
Rosanne Angotti ◽  
Roger L. Cook
Keyword(s):  
Escherichia Coli ◽  
Defense Mechanism ◽  
Inhibitory Effect ◽  
Second Phase ◽  
Vitro Assay ◽  
E Coli ◽  
Host Defense Mechanism ◽  
Important Host ◽  
Two Phases

Previous investigations have shown that certain strains of lactobacilli can competitively exclude uropathogens from attaching to uroepithelial cells and from causing urinary tract infection in animals. The finding of an inhibitory effect produced by Lactobacillus casei ssp. rhamnosus GR-1 against the growth of uropathogens was investigated further using two Escherichia coli indicator strains Hu 734 and ATCC 25922. There were two phases to the inhibitor studies. The first one using an agar sandwich technique showed that the inhibitor activity was heat stable and inhibitory to the E. coli. The second phase showed that MRS broth provided optimum lactobacilli growth and inhibitor production. In addition, the inhibition was present under conditions buffering for acid and pH. The data indicated that the inhibitory effect was not due to bacteriophages or hydrogen peroxide. Strain GR-1 was found to coaggregate with E. coli ATCC 25922 in urine, a phenomenon that has not previously been reported for urogenital bacteria. An in vitro assay system was developed to study the coaggregation of various lactobacilli and uropathogens. The results demonstrated that highest coaggregation scores occurred after 4 h incubation at 37 °C with lactobacilli and two type-1 fimbriated E. coli strains. Of the nine lactobacilli strains tested, each was found to coaggregate with 2 or more of the 13 uropathogens. The dominance of inhibitor-producing lactobacilli on the urogenital epithelium and the ability of these organisms to interact closely with uropathogens would constitute an important host defense mechanism against infection.

Effect of 5-bromouracil on the growth of a thymine auxotroph of Escherichia coli K-12

1971 ◽  
Vol 17 (1) ◽  
pp. 87-93 ◽  
Author(s):  
Roosevelt J. Jones ◽  
Roger R. Hewitt
Keyword(s):  
Escherichia Coli ◽  
Cell Division ◽  
Solid Medium ◽  
Cell Number ◽  
Bacteriostatic Effect ◽  
E Coli ◽  
Static Phase ◽  
Two Phases ◽  
K 12 ◽  
Mass Increase

An atypical viability response to 5-bromouracil has been observed in a thymine auxotroph of E. coli K-12. The response occurs in two phases, the first reflecting tolerance to the analogue during continued exponential growth and cell division. The second is a static phase during which viable number remains constant, while cell number and mass increase at a diminishing rate.During the latter phase filamentous cells increase in number and length. Examination of the cloning potential of cells after 10 h of growth in 5-bromouracil indicated that filamentous cells continue extension on solid medium into non-septate coils that are sterile. Other cells, presumably static when plated, readily form microcolonies free of defective members.Observed responses to penicillin, potentially stabilizing media, or added thymine suggest that 5-bromouracil evokes a bimodal response in this strain. The analogue exerts a bacteriostatic effect on some cells which remain viable for several hours. The bacteriocidal effect, presumably on cells continuing growth, interferes with cell division by preventing septation.

Survival of Selected Organisms During Spray Drying of Skim Milk and Storage of Nonfat Dry Milk1

1978 ◽  
Vol 41 (1) ◽  
pp. 16-19 ◽  
Author(s):  
S. S. THOMPSON ◽  
L. G. HARMON ◽  
C. M. STINE
Keyword(s):  
Escherichia Coli ◽  
Bacillus Subtilis ◽  
Moisture Content ◽  
Spray Drying ◽  
Skim Milk ◽  
Drying Temperature ◽  
E Coli ◽  
Air Temperatures ◽  
And Storage ◽  
Spray Dried

Pasteurized concentrated skim milk containing 35 to 40% total solids was inoculated with cultures of Bacillus subtilis, Micrococcus flavus, or Escherichia coli to contain 1 × 106 organisms per g and spray-dried to determine the effect of exit air temperatures of 93.3, 82.2, and 71.1 C on survival of the organisms and moisture content of the finished product. The numbers of survivors increased as the drying temperature decreased. The percent survivors varied from 27.57 in the product made from milk inoculated with M. flavus and dried at 71.1 C to 0.02 in the product made from milk inoculated with E. coli and dried at 93.3 C. The organism most resistant to drying and most persistent during storage was B. subtilis, followed by M. flavus and E. coli, with the latter showing low survival during drying and abrupt die-off during the first 4 weeks of storage. The moisture content of the dry milks varied from 2.75 to 4.80% with low moisture associated with high drying temperature.

29 Live Yeast and Yeast Extracts with and Without Pharmacological Levels of Zinc on Nursery Pig Growth Performance and Fecal Escherichia coli Antimicrobial Resistance

2021 ◽  
Vol 99 (Supplement_1) ◽  
pp. 28-29
Author(s):  
Jenna A Chance ◽  
Joel M DeRouchey ◽  
Jordan T Gebhardt ◽  
Raghavendra G Amachawadi ◽  
Victor Ishenhoma ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Resistance ◽  
Phase 1 ◽  
Dilution Method ◽  
Phase 2 ◽  
Fecal Samples ◽  
E Coli ◽  
Nursery Pig ◽  
Two Phases ◽  
Dietary Treatments

Abstract A total of 360 barrows (DNA 200×400; initially 5.6 kg) were used to evaluate yeast-based probiotics (Phileo by Lesaffre, Milwaukee, WI) in diets with or without pharmacological levels of Zn on growth and fecal Escherichia coli antimicrobial resistance (AMR). There were 5 pigs/pen and 18 pens/treatment. Dietary treatments were arranged in a 2×2 factorial with main effects of yeast pre- and probiotics (0 vs. 0.10% Actisaf Sc 47 HR+, 0.05% SafMannan, and 0.05% Nucleosaf in phase 1 then concentrations were lowered by 50% in phase 2) and pharmacological levels of Zn (110 vs. 3,000 mg/kg in phase 1 and 2,000 mg/kg in phase 2 provided by zinc oxide). Treatments were fed in two phases from d 0 to 7 and 7 to 21 with a common diet fed from d 21 to 42 post-weaning. There were no probiotics×Zn interactions. From d 0 to 21, pigs fed pharmacological Zn had increased (P &lt; 0.001) ADG and ADFI; however, there were no effects of added pre- and probiotics. Fecal samples were collected on d 4, 21, and 42 from the same three pigs/pen for AMR profiles and fecal dry matter (DM). On d 4, pigs fed pharmacological Zn had greater fecal DM (P = 0.043); however, no differences were observed on d 21 or 42. E. coli was isolated from fecal samples and species confirmation was accomplished by PCR detection of uidA and clpB genes. Microbroth dilution method using SensititreTM CMV3AGNF panel was used to determine antimicrobial susceptibilities of E. coli isolates to 14 different antimicrobials. There was no evidence for differences in AMR of fecal E. coli isolates to antibiotics by added pre- and probiotics or Zn. Results suggest that pharmacological levels of Zn stimulate intake and growth and improve fecal consistency in the nursery with no statistical response from added pre- and probiotics.

Sites of Adsorption of the Bacteriophages T3 and T5 on the Wall of Escherichia Coli B.

1967 ◽  
Vol 25 ◽  
pp. 96-97
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Electron Microscope ◽  
Uranyl Acetate ◽  
E Coli ◽  
Receptor Sites ◽  
Rigid Cell Wall ◽  
Host Cell Surface ◽  
Bacterial Viruses ◽  
Escherichia Coli B

Bacterial viruses adsorb specifically to receptors on the host cell surface. Although the chemical composition of some of the cell wall receptors for bacteriophages of the T-series has been described and the number of receptor sites has been estimated to be 150 to 300 per E. coli cell, the localization of the sites on the bacterial wall has been unknown.When logarithmically growing cells of E. coli are transferred into a medium containing 20% sucrose, the cells plasmolize: the protoplast shrinks and becomes separated from the somewhat rigid cell wall. When these cells are fixed in 8% Formaldehyde, post-fixed in OsO4/uranyl acetate, embedded in Vestopal W, then cut in an ultramicrotome and observed with the electron microscope, the separation of protoplast and wall becomes clearly visible, (Fig. 1, 2). At a number of locations however, the protoplasmic membrane adheres to the wall even under the considerable pull of the shrinking protoplast. Thus numerous connecting bridges are maintained between protoplast and cell wall. Estimations of the total number of such wall/membrane associations yield a number of about 300 per cell.

The Influence of Glycosylation on the Catalytic and Fibrinolytic Properties of Pro-Urokinase

1992 ◽  
Vol 68 (05) ◽  
pp. 539-544 ◽  
Author(s):  
Catherine Lenich ◽  
Ralph Pannell ◽  
Jack Henkin ◽  
Victor Gurewich
Keyword(s):  
Escherichia Coli ◽  
Mammalian Cell ◽  
Human Gene ◽  
Culture Media ◽  
Mammalian Cell Culture ◽  
Glycosylation Site ◽  
Clot Lysis ◽  
Cell Culture Media ◽  
E Coli ◽  
The Uk

SummaryWe previously found that human pro-UK expressed in Escherichia coli is more active in fibrinolysis than recombinant human pro-UK obtained from mammalian cell culture media. To determine whether this difference is related to the lack of glycosylation of the E. coli product, we compared the activity of E. coli-derived pro-UK [(-)pro-UK] with that of a glycosylated pro-UK [(+)pro-UK] and of a mutant of pro-UK missing the glycosylation site at Asn-302 [(-) (302) pro-UK]. The latter two pro-UKs were obtained by expression of the human gene in a mammalian cell. The nonglycosylated pro-UKs were activated by plasmin more efficiently (≈2-fold) and were more active in clot lysis (1.5-fold) than the (+)pro-UK. Similarly, the nonglycosylated two-chain derivatives (UKs) were more active against plasminogen and were more rapidly inactivated by plasma inhibitors than the (+)UK.These findings indicate that glycosylation at Asn-302 influences the activity of pro-UK/UK and could be the major factor responsible for the enhanced activity of E. coli-derived pro-UK.

Usefulness of a Multiplex PCR for Detection of Diarrheagenic Escherichia coli in a Diagnostic Microbiology Laboratory Setting

2016 ◽  
Vol 1 (2) ◽  
pp. 38-42 ◽  
Author(s):  
Khairun Nessa ◽  
Dilruba Ahmed ◽  
Johirul Islam ◽  
FM Lutful Kabir ◽  
M Anowar Hossain
Keyword(s):  
Escherichia Coli ◽  
Multiplex Pcr ◽  
Clinical Laboratory ◽  
Proteinase K ◽  
Microbiology Laboratory ◽  
Pcr Assay ◽  
E Coli ◽  
Diarrheagenic Escherichia Coli ◽  
Multiplex Pcr Assay ◽  
Diagnostic Microbiology

A multiplex PCR assay was evaluated for diagnosis of diarrheagenic Escherichia coli in stool samples of patients with diarrhoea submitted to a diagnostic microbiology laboratory. Two procedures of DNA template preparationproteinase K buffer method and the boiling method were evaluated to examine isolates of E. coli from 150 selected diarrhoeal cases. By proteinase K buffer method, 119 strains (79.3%) of E. coli were characterized to various categories by their genes that included 55.5% enteroaggregative E. coli (EAEC), 18.5% enterotoxigenic E. coli (ETEC), 1.7% enteropathogenic E. coli (EPEC), and 0.8% Shiga toxin-producing E. coli (STEC). Although boiling method was less time consuming (<24 hrs) and less costly (<8.0 US $/ per test) but was less efficient in typing E. coli compared to proteinase K method (41.3% vs. 79.3% ; p<0.001). The sensitivity and specificity of boiling method compared to proteinase K method was 48.7% and 87.1% while the positive and negative predictive value was 93.5% and 30.7%, respectively. The majority of pathogenic E. coli were detected in children (78.0%) under five years age with 53.3% under one year, and 68.7% of the children were male. Children under 5 years age were frequently infected with EAEC (71.6%) compared to ETEC (24.3%), EPEC (2.7%) and STEC (1.4%). The multiplex PCR assay could be effectively used as a rapid diagnostic tool for characterization of diarrheagenic E. coli using a single reaction tube in the clinical laboratory setting.Bangladesh J Med Microbiol 2007; 01 (02): 38-42

Antagonistic activity of Bacillus subtilis strains isolated from various sources

2018 ◽  
Vol 8 (2) ◽  
pp. 354-364
Author(s):  
A. N. Irkitova ◽  
A. V. Grebenshchikova ◽  
A. V. Matsyura
Keyword(s):  
Escherichia Coli ◽  
Bacillus Subtilis ◽  
Wild Strain ◽  
Fish Farming ◽  
Antagonistic Activity ◽  
Antagonistic Effect ◽  
E Coli ◽  
Long Period ◽  
Test Culture ◽  
Agar Media

<p>An important link in solving the problem of healthy food is the intensification of the livestock, poultry and fish farming, which is possible only in the adoption and rigorous implementation of the concept of rational feeding of animals. In the implementation of this concept required is the application of probiotic preparations. Currently, there is an increased interest in spore probiotics. In many ways, this can be explained by the fact that they use no vegetative forms of the bacilli and their spores. This property provides spore probiotics a number of advantages: they are not whimsical, easily could be selected, cultivated, and dried. Moreover, they are resistant to various factors and could remain viable during a long period. One of the most famous spore microorganisms, which are widely used in agriculture, is <em>Bacillus subtilis</em>. Among the requirements imposed to probiotic microorganisms is mandatory – antagonistic activity to pathogenic and conditional-pathogenic microflora. The article presents the results of the analysis of antagonistic activity of collection strains of <em>B. subtilis</em>, and strains isolated from commercial preparations. We studied the antagonistic activity on agar and liquid nutrient medias to trigger different antagonism mechanisms of <em>B. subtilis</em>. On agar media, we applied three diffusion methods: perpendicular bands, agar blocks, agar wells. We also applied the method of co-incubating the test culture (<em>Escherichia coli</em>) and the antagonist (or its supernatant) in the nutrient broth. Our results demonstrated that all our explored strains of <em>B. subtilis</em> have antimicrobial activity against a wild strain of <em>E. coli</em>, but to varying degrees. We identified strains of <em>B. subtilis</em> with the highest antagonistic effect that can be recommended for inclusion in microbial preparations for agriculture.</p><p><em><br /></em><em></em></p>

NGHIÊN CỨU KHẢ NĂNG BẤT HOẠT ESCHERICHIA COLI TRONG NƯỚC BẰNG TIA CỰC TÍM VỚI SỰ HỖ TRỢ CỦA THIẾT BỊ TẠO MÀNG CHẤT LỎNG

2020 ◽  
Vol 129 (4B) ◽  
Author(s):  
Đặng Thị Thanh Lộc ◽  
Lê Văn Tuấn
Keyword(s):  
Escherichia Coli ◽  
E Coli

Công nghệ khử trùng nước không tạo ra các sản phẩm phụ độc hại ngày càng thu hút nhiều quan tâm nghiên cứu trong những năm gần đây. Nghiên cứu này trình bày kết quả khử trùng Escherichia coli trong nước bằng tia UV kết hợp với thiết bị tạo màng chất lỏng (LFFA). Sự nhạy cảm của vi khuẩn với sự khử trùng bằng UV hoặc UV/LFFA được xác định tại các điều kiện khác nhau của liều UV, tốc độ sục khí và mật độ ban đầu của vi khuẩn. Kết quả nghiên cứu cho thấy khử trùng bằng tia UV kết hợp với LFFA mang lại hiệu quả khử trùng cao hơn so với UV thông thường. Cụ thể, sự kết hợp của UV (liều UV = 20,83 mJ/cm2 và nhiệt độ phòng) và LFFA (tốc độ sục khí = 1,5 L/phút) đã bất hoạt hoàn toàn 5,4 log E. coli trong vòng 60 phút. Trong khi tại cùng một liều UV tương tự, khử trùng bằng tia UV chỉ giảm được 4,3 log vi khuẩn sau 75 phút. Nghiên cứu này hứa hẹn một khả năng áp dụng phương pháp hiệu quả để tăng cường hoạt tính diệt khuẩn của tia UV, nhằm giải quyết các mối quan tâm gần đây trong khử trùng nước.

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