Quantcast
Factors influencing the growth of microorganisms - Preservation of Foods

Share on Google+Share on FacebookShare on LinkedInShare on TwitterShare on DiggShare on Stumble Upon
Custom Search
 
  
 
(3)  By control of one or more unfavorable environmental conditions such as
nutrients, moisture, pH, or temperature. The greater the number of conditions that are
unfavorable means the longer the delay of the beginning of cell growth.
(4)
By damage to organisms through processing methods such as heat or
irradiation.
1-17. FACTORS INFLUENCING GROWTH OF MICROORGANISM
There are several factors that influence the growth of microorganisms: nutrition,
oxygen, pH, temperature, and moisture. Lack of food retards bacterial growth, and
growth is favored by a sufficient quantity of the proper kind of food. Moisture is required
to carry foods in solution into the cell, to carry wastes in solution away from the cell, and
to maintain the moisture content of the cytoplasm. Temperature has a profound
influence on the growth rate of microorganisms. Microorganisms subjected to adverse
temperatures are either destroyed or are not able to multiply. The optimum temperature
of a microorganism is the temperature that provides for the most rapid growth of that
microorganism. The pH of the medium in which microorganisms grow exerts a
considerable influence on their rate of growth. All microorganisms have an optimum pH
at which they grow best. Most species of bacteria have an optimum pH between 6.0
and 8.5. Molds will grow in a pH range between 2.0 to 8.5. Yeasts have an optimum
pH range from 5.5 to 6.5.
1-18. NUTRITION
Nutrients or foods are substances which are outside the cell and which, upon
entering a cell after passing across the cell membrane, can be used by the cell for
building material or for obtaining energy. Food requirements of bacteria show great
variations from species to species. Some organisms can obtain all their food
requirements from inorganic matter while others need many complex organic
compounds. Although any one species may be able to use only a small number of
materials as sources of food, bacteria as a group are able to utilize all the naturally
occurring organic compounds as well as many inorganic substances.
a. Requirements. Bacteria require foods for the same purposes, as do other
forms of life, namely, as sources of material for cellular synthesis and for energy in
order to perform these synthetic processes. Requirements include carbohydrates
(sugar, starches, and celluloses), a source of nitrogen, vitamins, water, and a source of
energy.
b. Sources. The majority of bacteria species use naturally occurring organic
materials such as carbohydrates, proteins, fats, and so forth, not only as sources of carbon,
hydrogen, oxygen, and nitrogen but also for the energy needed to synthesize these
materials into protoplasm (that material referred to as the physical basis of life and
which is common to all living cells). The requirements of most bacteria for inorganic
materials can be satisfied by salts containing sodium, potassium, calcium, magnesium,
MD0703
1-16



Medical News
Research explores health care support for young adults with ASD
How difficult would it be to abruptly be plopped down...
medicalxpress.com
Evidence points to potential benefits of polypill for heart health
(Medical Xpress)—Taking one pill instead of three could be a...
medicalxpress.com
Saudi Arabia reports three more deaths from MERS virus
Saudi Arabia's health ministry says three more patients who contracted...
medicalxpress.com
Study finds codeine often prescribed to children, despite available alternatives
Despite its potentially harmful effects in children, codeine continues to...
medicalxpress.com
Make the Diagnosis: Itchy rash
(MedPage Today) -- A previously healthy 24-year-old student developed sharp...
medpagetoday.com
AMA examines economic impact of physicians
(HealthDay)—Physicians who mainly engage in patient care contribute a total...
medicalxpress.com
Less-schooled whites lose longevity, study finds
Barbara Gentry slowly shifts her heavy frame out of a...
medicalxpress.com
How to keep your fitness goals on track
(HealthDay)—The New Year's resolutions many made to get fit have...
medicalxpress.com
Low tolerance for pain? The reason may be in your genes
Researchers may have identified key genes linked to why some...
medicalxpress.com
Navy OKs changes for submariners' sleep schedules
The U.S. Navy has endorsed changes to submarine sailors' schedules...
medicalxpress.com
10 Questions: Dave Mittman, PA
(MedPage Today) -- How can medical professionals avoid burnout? Be...
medpagetoday.com
HTN Guidance Takes Center Stage at NKF
(MedPage Today) -- Guidelines on hypertension management, particularly the recent...
medpagetoday.com
Team identifies source of most cases of invasive bladder cancer
A single type of cell in the lining of the...
medicalxpress.com
Researchers uncover link between Down syndrome and leukemia
Although doctors have long known that people with Down syndrome...
medicalxpress.com
'Chaperone' compounds offer new approach to Alzheimer's treatment
A team of researchers from Columbia University Medical Center (CUMC),...
medicalxpress.com
Cancer stem cells linked to drug resistance
Most drugs used to treat lung, breast and pancreatic cancers...
medicalxpress.com
Improving newborns' bacterial environment could fend off infections, animal study suggests
Mothers give a newborn baby a gift of germs—germs that...
medicalxpress.com
How To Get Medicare To Cover A Spa Trip
(MedPage Today) -- Good news for doctors who think their...
medpagetoday.com
Biggest Insurer Shocked with Hep C Costs
(MedPage Today) -- UnitedHealth Group spent $100 million on hepatitis...
medpagetoday.com
The WeekAhead: NKF, SGIM, and JAMA Does Neurology
(MedPage Today) -- This week MedPage Today staff head to...
medpagetoday.com
   


Privacy Statement - Copyright Information. - Contact Us

comments powered by Disqus

Integrated Publishing, Inc.
9438 US Hwy 19N #311 Port Richey, FL 34668

Phone For Parts Inquiries: (727) 755-3260
Google +