Bacteria grow in very diverse conditions, which explains why they are found nearly everywhere on Earth. Although bacteria are good at adapting to their environments, certain conditions promote bacterial growth more than others. These conditions include temperature, moisture, pH and environmental oxygen. Understanding the optimal conditions for bacterial growth can potentially help you reduce your risk for bacterial infections and food poisoning.
Most disease-causing bacteria thrive in warm temperatures, especially those close to body temperature. The human body, therefore, provides an ideal environment for many types of bacteria to grow. Certain strains of bacteria, however, can grow at lower or higher temperatures. Since ideal temperature is crucial for the growth of any given species of bacteria, food must be handled appropriately to avoid food poisoning. In most cases -- but not all -- refrigerating or freezing food is sufficient to suppress the growth disease-causing bacteria, such as Staphylococcus. Thoroughly cooking meats and poultry to the correct internal temperature is also important to kill harmful bacteria that may be present in the food, such as Salmonella and E. coli.
- Most disease-causing bacteria thrive in warm temperatures, especially those close to body temperature.
- In most cases -- but not all -- refrigerating or freezing food is sufficient to suppress the growth disease-causing bacteria, such as Staphylococcus.
Bacteria That Grow in the Refrigerator
Bacteria need water to grow and die without a water source. Moist areas are particularly prone to bacterial growth, such as bathrooms and kitchens. Water content in food also provides an excellent environment for many types of bacteria to grow. Certain foods can be dehydrated or freeze-dried, which removes most of the water and can allow for longer storage without bacterial growth. Moist tissues in the body, such as the mouth and nose, provide an excellent source of moisture for bacteria and are particularly prone to bacterial growth.
- Bacteria need water to grow and die without a water source.
- Moist tissues in the body, such as the mouth and nose, provide an excellent source of moisture for bacteria and are particularly prone to bacterial growth.
The pH of an environment -- a measure of its acidity or alkalinity -- is important for bacterial growth. Most strains of disease-causing bacteria prefer to grow in conditions with a near neutral pH, similar to the pH of the human body. Some strains of bacteria, however, can live in more acidic or more alkaline conditions. Cleaning solutions are typically highly acidic or basic, which kills bacteria, because they cannot survive at these extremes of pH.
The acidity of food is also an important factor affecting bacterial growth 1. More acidic foods can typically be stored longer without spoiling. Preserving agents that increase the acidity of food, such as citric acid, are commonly added to help prevent bacterial growth and allow for longer storage. Vinegar and lemon juice have a similar effect.
- The pH of an environment -- a measure of its acidity or alkalinity -- is important for bacterial growth.
- Preserving agents that increase the acidity of food, such as citric acid, are commonly added to help prevent bacterial growth and allow for longer storage.
How Does UV Light Kill Bacteria?
The presence of oxygen can greatly affect the growth of bacteria. Many types of disease-causing bacteria grow best in an oxygen-rich environment or require oxygen to grow. This is why many commercial foods are vacuum-sealed. Vacuum sealing -- also known as reduced oxygen packaging -- inhibits the growth of many types of bacteria and fungi that cause food spoilage. Once the vacuum seal is broken, exposure to the environment and oxygen limits the shelf life. Keeping food properly sealed while during storage is a good preventive measure against bacterial growth because it restricts the amount of oxygen. Proper sealing is also important when doing home canning for similar reasons.
While reduced oxygen inhibits the growth of many types of bacteria that can spoil food, there are others that thrive in the absence of oxygen. Two important examples are Clostridium botulinum -- the bacteria responsible for botulism -- and Listeria monocytogenes, another food-borne bacteria that is particularly harmful to pregnant women, newborns and people with a weakened immune system.
Reviewed and revised by: Tina M. St. John, M.D.
- The presence of oxygen can greatly affect the growth of bacteria.
- Keeping food properly sealed while during storage is a good preventive measure against bacterial growth because it restricts the amount of oxygen.
Bacteria That Grow in the Refrigerator
How Does UV Light Kill Bacteria?
Botulism Risk of Canned Beans
How to Prevent Bacterial Growth in Food
Side Effects of Eating Thawed Then Refrozen Food
How Do Preservatives Prevent Mold?
Mayonnaise & Food Poisoning
How Does a Food Dehydrator Work?
Antiseptic Vs. Disinfectant
The Effects of Temperature on E. Coli
- U.S. Food and Drug Administration: Bacterial Pathogen Growth and Inactivation
- Centers for Disease Control and Prevention: Listeria (Listeriosis)
- Todar's Online Textbook of Bacteriology: Bacterial Pathogens of Humans
- Gut Bacteria in Health and Disease
- Probiotics and Colon Cancer
- Influence of High-Fat-Diet on Gut Microbiota: A Driving Force for Chronic Disease Risk
- Adaptation of the Gut Microbiota to Modern Dietary Sugars and Sweeteners | Advances in Nutrition | Oxford Academic
- Influence of diet on the gut microbiome and implications for human health
- Connection Between BMI-Related Plasma Metabolite Profile and Gut Microbiota - PubMed
- Organophosphorus pesticide chlorpyrifos intake promotes obesity and insulin resistance through impacting gut and gut microbiota | Microbiome | Full Text
- Food Chemicals Disrupt Human Gut Microbiota Activity And Impact Intestinal Homeostasis As Revealed By In Vitro Systems | Scientific Reports
- Looking at the Effects of Antibiotic Use on Childhood Obesity and Growth -- The PCORnet® Antibiotics Study | PCORI
- Associations of Prenatal and Childhood Antibiotic Use with Child Body Mass Index at Age Three Years
- Dynamics of Human Gut Microbiota and Short-Chain Fatty Acids in Response to Dietary Interventions with Three Fermentable Fibers | mBio
- Commercial Probiotic Products: A Call for Improved Quality Control. A Position Paper by the ESPGHAN Working Group for Probiotics and Prebiotics - PubMed
- Frontiers | Probiotic Supplements: Hope or Hype? | Microbiology
- Choosing an appropriate probiotic product for your patient: An evidence-based practical guide
- A review of probiotic supplementation in healthy adults: helpful or hype? - PubMed
Noelle Thompson has extensive experience with health and scientific research, including in the biotechnology/pharmaceutical industry. She graduated from the University of California, Santa Barbara, with a B.S. in cell and developmental biology. Thompson then went on to earn a Ph.D. in biological chemistry, with an emphasis on stem cell biology, from the University of California, Irvine.