Extremophilic fungi in arctic ice: a relationship between adaptation to low temperature and water activity

2003 ◽  
Vol 28 (28-32) ◽  
pp. 1273-1278 ◽  
Author(s):  
N. Gunde-Cimerman ◽  
S. Sonjak ◽  
P. Zalar ◽  
J.C. Frisvad ◽  
B. Diderichsen ◽  
...  
Keyword(s):  
Low Temperature ◽  
Water Activity ◽  
Arctic Ice ◽  
Extremophilic Fungi

Effect of Gamma Irradiation on the Survival of Pathogens in Kwamegi, a Traditional Korean Semidried Seafood

2003 ◽  
Vol 66 (11) ◽  
pp. 2093-2096 ◽  
Author(s):  
S. P. CHAWLA ◽  
D. H. KIM ◽  
C. JO ◽  
J. W. LEE ◽  
H. P. SONG ◽  
...  
Keyword(s):  
Low Temperature ◽  
Salmonella Typhimurium ◽  
Water Activity ◽  
Pathogenic Bacteria ◽  
Radiation Sensitivity ◽  
E Coli ◽  
Public Health Significance ◽  
Irradiation Treatment ◽  
Test Organisms ◽  
Health Significance

Kwamegi (semidried raw Pacific saury) is traditional seafood available in Korea. It has water activity in the range of 0.90 to 0.95. Spoilage and the growth of most pathogenic bacteria is retarded because of low water activity, low temperature, and packaging. However, it is contaminated with bacteria of public health significance and poses a hazard to the consumer because it is consumed raw without any cooking. The effectiveness of these hurdles in preventing the growth of Staphylococcus aureus, Bacillus cereus, Salmonella Typhimurium, and Escherichia coli and the efficacy of irradiation treatment in eliminating these bacteria from kwamegi using inoculated pack studies was examined. Radiation sensitivity of S. aureus, B. cereus, Salmonella Typhimurium, and E. coli in kwamegi was investigated. D10-values of these organisms in kwamegi were 590 ± 13.6, 640 ± 14.9, 560 ± 45.4, and 550 ± 8.6 Gy, respectively. The growth of all four test organisms inoculated into these foods during 4 weeks of storage at an ambient winter temperature (ranging from −5°C to +5°C) was recorded. All four pathogens (inoculated at 106 CFU/g) were eliminated by irradiation at 4 kGy. These studies unequivocally demonstrate that irradiation, with a combination of low water activity and low temperature, results in microbiologically safe kwamegi.

Differences Between Aspergillus flavus Strains in Growth and Aflatoxin B1 Production in Relation to Water Activity and Temperature

1977 ◽  
Vol 40 (11) ◽  
pp. 778-781 ◽  
Author(s):  
M. D. NORTHOLT ◽  
H. P. van EGMOND ◽  
W. E. PAULSCH
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Water Activity ◽  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Toxin Production ◽  
Fast Growth ◽  
Temperature Optimum ◽  
Agar Media ◽  
Stimulation Of

The optimum and limiting conditions of water activity (aw) and temperature for growth of and aflatoxin B1 production by various Aspergillus flavus strains were determined. Agar media were used in which the aw was adjusted by addition of sucrose or glycerine. Optimum temperatures for aflatoxin B1 production at high aw varied with the strain tested being 13–16, 16–24, or 31 C. Strains with a low temperature optimum for aflatoxin B1 production showed fast growth at 37 C without aflatoxin B1 production. A reduced aw (0.95 and less) together with a moderate or low temperature inhibited toxin production more than growth. However, at a high temperature one strain showed stimulation of aflatoxin B1 production on the glycerine medium at reduced aw No differences were noted between aflatoxinpositive and aflatoxin-negative strains with respect to growth under various conditions.

Survival and Recovery ofSalmonella entericaSerovar Typhimurium DT104 at Low Temperature and Water Activity in a Broth System

2006 ◽  
Vol 3 (4) ◽  
pp. 375-383 ◽  
Author(s):  
Kathleen J. Kinsella ◽  
Tara A. Rowe ◽  
Ian S. Blair ◽  
David A. McDowell ◽  
James J. Sheridan
Keyword(s):  
Low Temperature ◽  
Water Activity

scholarly journals Behaviour of Listeria monocytogenes and Natural Microflora during the Manufacture of Riojano Chorizo (Spanish Dry Cured Sausage)

2021 ◽  
Vol 9 (9) ◽  
pp. 1963
Author(s):  
Elena Gonzalez-Fandos ◽  
Maria Vazquez de Castro ◽  
Alba Martinez-Laorden
Keyword(s):  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Low Temperature ◽  
Water Activity ◽  
Low Temperatures ◽  
Production Method ◽  
Starter Cultures ◽  
Natural Microflora ◽  
Traditional Technologies ◽  
Traditional Production

Riojano chorizo is a dry cured sausage manufactured with traditional technologies without adding starter cultures at low temperatures. Its characteristics differ from other types of chorizo since sugars and nitrites are no added and processing temperatures are low- This work evaluates the behaviour of Listeria monocytogenes during the processing of inoculated Riojano chorizo as well as the natural microflora that can play a technological role or be of interest as indicators. The sausage mixture was inoculated with a cocktail of three selected strains of L. monocytogenes (CECT 932, CECT 934 and CECT 4032) (4 log10 CFU/g) and after processed following the traditional production method. Samples were taken before inoculation, after inoculation, after stuffing (day 0) and on days 6, 13, 21 and 28 of processing. L. monocytogenes, mesophiles, Micrococcaceae, lactic acid bacteria, Enterobacteriaceae, S. aureus, sulfite-reducing clostridia and molds and yeast counts were evaluated. Furthermore, pH, water activity and humidity were determined. No growth of L mocytogenes was observed during the first 6 days, when the temperature of processing was 4 °C. The low temperature in the initial stages was a relevant hurdle to control L. monocytoegenes growth. A significant decrease (p ≤ 0.05) in L. monocytogenes counts was observed on day 13 compared to the initial counts. During drying (days 6 to 21) a reduction in this pathogen of 1.28 log CFU/g was observed. The low water activity below 0.92 on day 13 and 0.86 on day 21 seems to be critical for the reduction of L. monocytogenes.

scholarly journals Low temperature and limited water activity reveal a pathway to magnesite via amorphous magnesium carbonate

2020 ◽  
Vol 56 (81) ◽  
pp. 12154-12157
Author(s):  
Sebastian T. Mergelsberg ◽  
Sebastien N. Kerisit ◽  
Eugene S. Ilton ◽  
Odeta Qafoku ◽  
Christopher J. Thompson ◽  
...  
Keyword(s):  
Low Temperature ◽  
Water Activity ◽  
Reaction Pathway ◽  
Magnesium Carbonate

Experiments at low H2O activity and 25 °C reveal a new reaction pathway to magnesite via amorphous magnesium carbonate during the thin H2O film carbonation of forsterite in water-bearing liquid CO2.

Exsolution and inversion in pigeonite from the Whin Sill, Northern England

1978 ◽  
Vol 36 (1) ◽  
pp. 474-475
Author(s):  
P.P.K. Smith
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Homogeneous Nucleation ◽  
Silicate Mineral ◽  
Antiphase Boundaries ◽  
Two Phase ◽  
Primitive Form ◽  
The Core ◽  
Nucleation Mechanisms ◽  
And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

Low temperature x-ray microanalysis of frozen-hydrated tobacco leaves

1984 ◽  
Vol 42 ◽  
pp. 284-285
Author(s):  
S. Edith Taylor ◽  
Patrick Echlin ◽  
May McKoon ◽  
Thomas L. Hayes
Keyword(s):  
Low Temperature ◽  
Lemna Minor ◽  
Root Tips ◽  
Tobacco Leaves ◽  
X Ray ◽  
Whole Cells ◽  
Carbon Coated ◽  
The Right ◽  
Beam Currents ◽  
The University

Low temperature x-ray microanalysis (LTXM) of solid biological materials has been documented for Lemna minor L. root tips. This discussion will be limited to a demonstration of LTXM for measuring relative elemental distributions of P,S,Cl and K species within whole cells of tobacco leaves.Mature Wisconsin-38 tobacco was grown in the greenhouse at the University of California, Berkeley and picked daily from the mid-stalk position (leaf #9). The tissue was excised from the right of the mid rib and rapidly frozen in liquid nitrogen slush. It was then placed into an Amray biochamber and maintained at 103K. Fracture faces of the tissue were prepared and carbon-coated in the biochamber. The prepared sample was transferred from the biochamber to the Amray 1000A SEM equipped with a cold stage to maintain low temperatures at 103K. Analyses were performed using a tungsten source with accelerating voltages of 17.5 to 20 KV and beam currents from 1-2nA.

Bulk standards for low-temperature biological x-ray microanalysis

1984 ◽  
Vol 42 ◽  
pp. 282-283
Author(s):  
P. Echlin ◽  
M. McKoon ◽  
E.S. Taylor ◽  
C.E. Thomas ◽  
K.L. Maloney ◽  
...  
Keyword(s):  
Phase Separation ◽  
Low Temperature ◽  
Analytical Method ◽  
Salt Solutions ◽  
Absolute Concentration ◽  
Cooling Process ◽  
X Ray ◽  
The Absolute ◽  
Analytical Procedures ◽  
Electrical Conductors

Although sections of frozen salt solutions have been used as standards for x-ray microanalysis, such solutions are less useful when analysed in the bulk form. They are poor thermal and electrical conductors and severe phase separation occurs during the cooling process. Following a suggestion by Whitecross et al we have made up a series of salt solutions containing a small amount of graphite to improve the sample conductivity. In addition, we have incorporated a polymer to ensure the formation of microcrystalline ice and a consequent homogenity of salt dispersion within the frozen matrix. The mixtures have been used to standardize the analytical procedures applied to frozen hydrated bulk specimens based on the peak/background analytical method and to measure the absolute concentration of elements in developing roots.

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