Related Experiment Video

Updated: Jan 26, 2026

Studying Oxidative Stress Caused by the Mitis Group Streptococci in Caenorhabditis elegans
09:36

Studying Oxidative Stress Caused by the Mitis Group Streptococci in Caenorhabditis elegans

Published on: March 23, 2019

7.6K

Evaluation of Four Media for Recovery of Heat-Stressed Streptococci

C A Magnus1, A R McCURDY1, W M Ingledew1

  • 1Department of Applied Microbiology and Food Science, University of Saskatchewan, Saskatoon, Saskatchewan S7N 0W0.

Journal of Food Protection
|April 18, 2019
PubMed

Insights

Heat stress impacts Streptococcus survival differently across various growth media. All purpose tween agar demonstrated the highest recovery rates for heat-stressed Streptococcus faecium and Streptococcus faecalis cells.

Area of Science:

  • Microbiology
  • Food Science
  • Bacteriology

Background:

  • Streptococcus faecium and Streptococcus faecalis are common bacteria found in food products.
  • Heat treatment is a crucial method for food preservation, aiming to reduce microbial load.
  • Assessing bacterial survival under stress conditions is vital for food safety and quality control.

Purpose of the Study:

  • To investigate the influence of different agar media on the survival rates of heat-stressed Streptococcus species.
  • To compare the efficacy of various recovery media in detecting sublethally injured bacterial cells.

Main Methods:

  • Two strains of Streptococcus faecium and one strain of Streptococcus faecalis were subjected to heat stress in ham broth.
  • Bacterial recovery was performed on four different agar media: All Purpose Tween Agar, deMan-Rogosa-Sharpe (MRS) agar, Tryptone-Dextrose-Yeast Extract-Meat Extract-Peptone (TDYEMEP) agar, and Tryptic Soy Agar (TSA).
  • Survival curves were generated, and D values (decimal reduction times) were calculated to quantify heat resistance.

Main Results:

  • Significant differences in death rates (D values) were observed for each bacterial strain across the tested media.
  • All Purpose Tween Agar yielded the highest recovery of cells that had undergone sublethal heat treatment compared to MRS, TDYEMEP, and TSA.
  • The choice of recovery medium demonstrably affected the assessment of heat resistance in Streptococcus species.

Conclusions:

  • The recovery medium plays a critical role in evaluating the heat resistance of Streptococcus faecium and Streptococcus faecalis.
  • All Purpose Tween Agar is recommended for optimal recovery of sublethally heat-injured Streptococcus cells in food safety assessments.
  • Further research should explore the specific components in different media that influence bacterial recovery post-heat stress.

More Related Videos

Author Spotlight: Polysome Profiling Protocol for Studying Translational Regulation in Arabidopsis Under Heat Stress08:39

Author Spotlight: Polysome Profiling Protocol for Studying Translational Regulation in Arabidopsis Under Heat Stress

Published on: October 11, 2024

2.2K
Prevention of Heat Stress Adverse Effects in Rats by Bacillus subtilis Strain07:57

Prevention of Heat Stress Adverse Effects in Rats by Bacillus subtilis Strain

Published on: July 11, 2016

8.0K

Related Concept Videos

Responses to Heat and Cold Stress02:45

Responses to Heat and Cold Stress

Every organism has an optimum temperature range within which healthy growth and physiological functioning can occur. At the ends of this range, there will be a minimum and maximum temperature that interrupt biological processes.
14.7K
Quantifying Heat02:46

Quantifying Heat

Thermal Energy Microscopically, thermal energy is the kinetic energy associated with the random motion of atoms and molecules. Temperature is a quantitative measure of “hot” or “cold”, which depends on the amount of thermal energy. When the atoms and molecules in an object are moving or vibrating quickly, they have a higher average kinetic energy (KE) (or higher thermal energy), and the object is perceived as “hot”, or it is described as being at a higher temperature. When the...
61.8K
Specific Heat01:16

Specific Heat

The specific heat capacity of a substance refers to the energy required to increase the temperature of one gram of that substance by one degree Celcius. Specific heat capacity is often represented in calories (cal), grams (g), and degrees Celsius (oC), but can also be expressed in joules (J), kilograms (kg), and Kelvin (K), among other units.
For example, increasing the temperature of one gram of water by 1°C requires one calorie of heat energy and can be written as 1 cal/g-°C, or...
67.3K
Heat Flow and Specific Heat01:12

Heat Flow and Specific Heat

Heat is a type of energy transfer that is caused by a temperature difference, and it can change the temperature of an object. Since heat is a form of energy, its SI unit is the joule (J). Another common unit of energy often used for heat is the calorie (cal), which is defined as the energy needed to change the temperature of 1 g of water by 1 °C, specifically between 14.5 °C and 15.5 °C, since the energy needed shows a slight temperature dependence. Another commonly used unit is...
6.7K
Heating and Cooling Curves02:44

Heating and Cooling Curves

When a substance—isolated from its environment—is subjected to heat changes, corresponding changes in temperature and phase of the substance is observed; this is graphically represented by heating and cooling curves.
For instance, the addition of heat raises the temperature of a solid; the amount of heat absorbed depends on the heat capacity of the solid (q = mcsolidΔT). According to thermochemistry, the relation between the amount of heat absorbed or released by a substance, q, and its...
27.4K
Heat and Free Expansion01:24

Heat and Free Expansion

The work done by a thermodynamic system depends not only on the initial and final states but also on the intermediate states—that is, on the path. Like work, when heat is added to a thermodynamic system, it undergoes a change of state, and the state attained depends on the path from the initial state to the final state. Consider an ideal gas cylinder fitted with a piston. When the cylinder is heated at a constant temperature, the gas molecules absorb energy and expand slowly in a...
2.8K