scholarly journals Effect of Temperature Treatments on the Viability of Clavibacter sepedonicus in Infected Potato Tissue

2021 ◽  
Author(s):  
L. H. Stevens ◽  
J. Y. Tom ◽  
P. S. van der Zouwen ◽  
O. Mendes ◽  
L. M. Poleij ◽  
...  
Keyword(s):  
Organic Matrix ◽  
Effect Of Temperature ◽  
Bacterial Cells ◽  
Stem Tissue ◽  
Potato Tubers ◽  
Potato Tissue ◽  
Potato Waste ◽  
Temperature Controlled

AbstractThe objective of the present study was to establish whether exposure to temperatures of 55-70 °C results in eradication of the pathogen Clavibacter sepedonicus (Cs) in colonised potato tissue, in order to evaluate the efficiency of composting for disinfection of Cs-infected potato waste. Pre-sprouted potato tubers were inoculated and planted to produce Cs-colonised stem and tuber material. After incubation in temperature-controlled water baths, the infected potato tissue was analysed for the presence of culturable and pathogenic Cs. Additional experiments were performed with Cs-colonised potato stem tissue crushed and deaerated, thus simulating macerated stem tissue in the compost heap. To enable a comparison with bacterial cells that are not enclosed by their natural organic matrix, temperature treatments were applied to non-infected stem tissue crushed and deaerated, and spiked with freshly prepared Cs-suspensions. Cs settled inside colonised potato tissue, as well as Cs present as Cs-suspensions supplemented to potato tissue, was eradicated by exposure to heat, even after a treatment of 1 h at 55 °C, with the exception of one case in which the pathogen present in intact stem material escaped a treatment of 6 h at 60 °C, indicating that incidentally stems may provide niches in which the pathogen is protected against heat.

A METHOD OF ISOLATING ACTINOMYCETES FROM SCABBY POTATO TISSUE AND SOIL WITH MINIMAL CONTAMINATION

1956 ◽  
Vol 34 (1) ◽  
pp. 44-47 ◽  
Author(s):  
C. H. Lawrence
Keyword(s):  
Culture Medium ◽  
Potato Tubers ◽  
Sodium Propionate ◽  
Potato Tissue ◽  
Treated Soil ◽  
Bacterial Contaminants ◽  
Fungal Contaminants

The isolation of actinomycetes from soil or from scabby potato tubers was facilitated by a 10-min. treatment of the material from which the isolations were to be made with phenol in dilution of 1: 140. This eliminated most bacterial contaminants and reduced fungal contaminants especially those of the spreading type. Treatment of the material with higher concentrations of phenol progressively decreased the number of actinomycetes until there was no growth after treatment with 1: 70 dilution of phenol. Optimum development and maximum numbers of actinomycetes occurred when phenol-treated material was cultured on media adjusted to pH 6.5. More actinomycetes developed on glucose-asparagine agar than on Czapek's agar inoculated with phenol-treated material from scab-infected potatoes. However, when phenol-treated soil suspensions were tested, Czapek's agar was more favorable to the development of actinomycete colonies. A comparison of the phenol method with another in which sodium propionate is incorporated into the culture medium showed that the phenol method was more efficient in reducing contaminants and in permitting a larger number of actinomycete colonies to develop.

scholarly journals Characterization of E coli phage isolated from sewage

2010 ◽  
Vol 9 (2) ◽  
pp. 45 ◽  
Author(s):  
G.A. Al-Mola, and I. H. Al-Yassari
Keyword(s):  
Statistical Analysis ◽  
Latent Period ◽  
Burst Size ◽  
Host Cells ◽  
Effect Of Temperature ◽  
Lytic Bacteriophage ◽  
Bacterial Cells ◽  
Dilution Factor ◽  
Countable Number ◽  
Phage Titre

Bacteriophage are viruses that infect bacterial cells. as with all viruses, phage are nonliving agents and thus require the use of the host‟s metabolic processes to replicate itself. in this study, the phage of interest are those that infect and lyses E. colt host cells. when phage are released from the ruptured host, distinct zones of clearing (plaques) form. the original E. colt host cells for this experiment came from a sample of raw sewage. in order to obtain the bacteriophage, a procedure of enrichment, isolation, dilution and seeding was followed, the presence of distinct plaques indicated that lytic bacteriophage had been successfully amplified, separated and grown.This study included determination of phage titre, latent period , rise period and the burst size of the phage and effect some of factor on phage titre such as (temperature, ether and chloroform) .for determination ofhage titre used series of dilutions(10-1, 10-2, 10-3, 10-4, 10-4, 10-6, 10-7, 10-8, 10-9) the dilution factor gave the best countable number of plaques is(103). this dilution factor was then used for all other experiments, the latent period , rise period and the burst size of the phage are determined by countable number of plaques and phage titre(titer: plaque-forming unit(p.f.u) during 10,20,30,40,50, and 60 minutes . it was (4.7x105 „ 5.3x105 and 6.0x105)during 1O,20and30minutes respectively in the latent period ,but it was (8.5x105 8.9x10‟ 9.3x105)during 40,50,and 60 minutes respectively in the rise period .then the burst size of the phage is counted by the ratio of the phage titer after rise period to that during the latent period it was(1.67).This study also included effect of temperature on phage titre the statistical analysis was significantly increase P<0.05 in phage titre at the temperature37 C° comparing with phage titre at the temperature 50 C° and phage titre at the temperature 65 C°. effects of ether and chloroform on number of plaques and phage titre during 5,10,15 ,20,25 ,30,35 and 40 minutes it was(0.7x105 , 0.3x105 , 0 , 0 , 0 , 0, 0 and 0) respectively in ether sensitivity, but the phage titre in chloroform sensitivity was completely inactivated by chloroform treatment, the statistical analysis (freedom degree ( 2,21 ) and F value=52.60 was high] significant increase (P<0.05) in phage titre in normal saline comparing with phage titre in ether and chloroform sensitivity

Inactivation Rates of Cronobacter spp. and Selected Other Bacterial Strains in Powdered Infant Formulae Stored at Different Temperatures

2010 ◽  
Vol 73 (5) ◽  
pp. 839-848 ◽  
Author(s):  
M. C. KANDHAI ◽  
M. W. REIJ ◽  
M. van SCHOTHORST ◽  
L. G. M. GORRIS ◽  
M. H. ZWIETERING
Keyword(s):  
Distribution Model ◽  
Effect Of Temperature ◽  
Powdered Infant Formula ◽  
Bacterial Cells ◽  
Bacterial Strains ◽  
Infant Formulae ◽  
Different Temperatures ◽  
D Values ◽  
Log Linear ◽  
Increasing Temperature

The aim of this study was to determine the survival of two strains of Cronobacter (Enterobacter sakazakii) and six other bacterial strains inoculated into dry powdered infant formula (PIF) stored for 22 weeks at several temperatures between 7 and 42°C. The experimental setup involved a relatively high initial concentration of bacteria, around 104 CFU/g of powder, and enumeration of survivors with a minimum detection level of 100 CFU/g. For all strains tested, it was found that the number of bacterial cells decreased faster with increasing temperature. Cronobacter spp. cells generally survived better at high temperatures (37 and 42°C) than the other bacteria, while such a difference in survival was not apparent at other temperatures. To describe the effect of temperature on survival, both the Weibull distribution model and the log-linear model were tested. At 22°C, decline rates of 0.011 and 0.008 log units per day were found for Cronobacter sakazakii ATCC 29544 and Cronobacter strain MC10, respectively. Assuming a linear relationship between log-transformed D-values and temperature, z-values estimated for C. sakazakii ATCC 29544 and Cronobacter MC10 were 13.3 and 23.5°C, respectively. Such differences found in resistance among Cronobacter spp. would be relevant to consider when establishing quantitative risk assessments on consumer risks related to PIF.

scholarly journals The effect of ambient temperature on the development of cotton bollworm (Helicoverpa armigera Hübner, 1808)

2010 ◽  
Vol 42 (No. 4) ◽  
pp. 135-138 ◽  
Author(s):  
A. Barteková ◽  
J. Praslička
Keyword(s):  
Ambient Temperature ◽  
Helicoverpa Armigera ◽  
Cotton Bollworm ◽  
Effect Of Temperature ◽  
Thermal Constant ◽  
Thermal Threshold ◽  
Thermal Thresholds ◽  
Helicoverpa Armígera ◽  
Developmental Rates ◽  
Temperature Controlled

The development of individual cotton bollworm stages depending on the ambient temperature was studied in laboratory conditions. The effect of temperature on the development of all stages of <I style="mso-bidi-font-style: normal">Helicoverpa armigera</I> was studied at three constant temperatures of 20, 25, and 30°C in temperature-controlled chambers. The temperature dependence of the developmental rates and the thermal thresholds were established by means of linear regression. Our data has established following optimal temperatures: the lower thermal threshold for the development of&nbsp;the <I style="mso-bidi-font-style: normal">Helicoverpa armigera</I> eggs is 14.83°C, for the development of&nbsp;the larvae is 11.34°C and for the development of&nbsp;the pupae is 8.18°C. The termal constant for the development of&nbsp;the <I style="mso-bidi-font-style: normal">Helicoverpa armigera</I> eggs is 64.10 day-degrees, for the development of&nbsp;the larvae is 344.83 day-degrees and for the development of&nbsp;the pupae is 222.22 day-degrees. The lower thermal threshold for the total <I style="mso-bidi-font-style: normal">Helicoverpa armigera </I>development is 11.50�C and the thermal constant is 625.00 day-degrees.

THE INACTIVATION AND REACTIVATION OF A PROTEUS RETTGERI PHAGE IN SALT SOLUTIONS

1966 ◽  
Vol 12 (6) ◽  
pp. 1203-1212
Author(s):  
Robert B. Stewart ◽  
Sunil S. Gandhi ◽  
Francis H. Milazzo ◽  
Norman A. Hinton
Keyword(s):  
Salt Solution ◽  
Effect Of Temperature ◽  
Bacterial Cells ◽  
Salt Solutions ◽  
Concentrated Solutions ◽  
Two Stage

A phage isolated from a strain of Proteus rettgeri was studied with respect to its behavior in salt solutions. Infectivity was lost when phage was exposed to dilute salt solutions but regained when the phage was transferred to more concentrated solutions. Investigation of the effect of temperature on this phenomenon indicated that two inactivating mechanisms were involved; one associated with temperature was not reversible, whereas salt inactivation was reversible.Studies of phage attachment: showed a two-stage sequence, the first reversible the second irreversible. Phage inactivated in dilute salt solution was found to attach to bacterial cells, hence salt inactivation is not explained by inhibition of attachment.

scholarly journals Temperature-dependent development and mortality of Australian cockroach, Periplaneta australasiae (Fabricius) (Blattodea: Blattidae

2010 ◽  
Vol 40 (No. 1) ◽  
pp. 11-15 ◽  
Author(s):  
V. Stejskal ◽  
J. Lukáš ◽  
R. Aulický
Keyword(s):  
Development Rate ◽  
Effect Of Temperature ◽  
Thermal Constant ◽  
Pest Species ◽  
Temperature Dependent ◽  
Thermal Threshold ◽  
Dependent Development ◽  
Thermal Constants ◽  
Temperature Controlled ◽  
Periplaneta Australasiae

The effect of temperature on the development of the 1<SUP>st</SUP> instar of <I>Periplaneta australasiae</I> (Fabr.) was studied at the four constant temperatures of 21°C, 24°C, 27°C and 30°C in temperature-controlled chambers. Mortality was 50% at 30°C, and 10% at 21°C, 24° and 27°C. Thermal constants were established by plotting linear regression to development rate. The thermal threshold for the development was 17.1°C and the thermal constant for 1<SUP>st</SUP> instar larvae was 147.1 day-degrees. As “safe temperature” (<I>t<SUB>s</SUB></I>) – the temperature to be maintained in stores or food premises to prevent the development of a pest species – we recommend 16°C.

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