Learn vocabulary, terms, and more with flashcards, games, and other study tools. What is the importance of studying factors affecting. The influence of ph value and aeration on the growth of aerobacter aerogenes and. Their optimum growth temperature is between 5c and 15c. At the end of the experiment, the student must be able to. Microorganisms require growth factors such as amino acids, carbohydrates, lipids and nucleic acids for growth. Coli, enterococcus faecalis, bacillus, staphylococcus, saccharomyces cervisiase, serratia marcescens, pseudomonas and micrococcus.
Factors affecting microbial growth in food intrinsic factors environmental factors. Determine the effects of several chemical and physical factors on the growth of different microorganisms. In general bacteria grow fastest in the ph range 6. In nature, where many species coexist, fluctuating environmental conditions cause dramatic population shifts due to the varying growth rates of. Discussion questions for the bacterial growth experiment refer to the results from your bacterial growth experiment as you answer the following questions. Different organisms react to their environment in different ways. How do you explain the presence of bacteria on the plate. Physical conditions required for growth of bacteria. Pdf controlled factors for bacterial growth and culture media. Bacteria have a minimum, optimum, and maximum temperature for growth and can be divided into 3 groups based on their optimum growth temperature. Laboratory exercise 14 physical and chemical factors affecting growth objectives. Factors affecting rate of bacterial growth youtube. Little information is available on the factors affecting the growth of individual bacterial species in natural waters alexander 1986. The requirements for microbial growth can be divided into two main categories.
A value close to room temperature is obtained for dead cells while a much larger effective temperature is needed for live cells, showing that these. Many molds are osmotically tolerant and can grow at a a w value of 0. Fetal growth is exponential and during the last 20 weeks of gestation the fetus gains 95% of its weight. Independent effects of acetic acid and ph on survival of. Intrinsic or food related parameters are those parameters of plants and animal tissues which are inherent part of the tissue. This is why molds typically spoil cereal grains rather than bacteria. Microbial growth the microbial growth is the increase in number of cells rather than in size of individual cells.
Effects on soil respiration and bacterial and fungal growth rates. Vitamins and organic growth factors provided by meat and. Module nutrition and growth of bacteria microbiology 36 notes 3. Acidity inhibits most microbial growth and is used. Limiting factors for microbial growth and activity in soil horizon ird. Bacteria are divided into four groups according to oxygen requirement.
Although bacteria do increase in size before cell division, bacterial growth refers to an increase in the number of organisms rather than an increase in. Intrinsic factors are those that are characteristic of the food itself. Depending on the requirement of oxygenair for growth 2. Classify different bacterial species according to their response to various temperature, ph, oxygen and salinityosmolarity. Introduction bacteria normally reproduce by binary fission, forming two equalsized progeny cells and thus doubling their number with each division. Genetic, nutritional, environmental, uteroplacental, and fetal factors have been suggested to influence fetal growth. So, generally, bacteria require different environments from yeasts and. Some of the important factors affecting bacterial growth are. Factors affecting bacterial growth factors affecting bacterial growth are. Microorganisms show varying sensitivity to different types of factors. Factors affecting the growth of microorganisms in food. Physical factors affecting bacterial growthlesson 11. Factors affecting microbial growth physical factors ph temperature osmotic pressure hydrostatic pressure moisture. Saltsugar concentrations most microbes cannot survive environments in which there are such high concentrations of salt.
In addition, the inhibitory effects of oa can be modulated by factors other than ph. Factors affecting bacterial growth flashcards quizlet. Environmental factors that affect fuel system microbial growth pdf. Problems need to establish conditions for growth of the bacterium you want to pure culture, and organism of interest may be a minority in population andor dependent on another organisms for growth. Decrease in nutrient concentration decreases the growth rate. A variety of intrinsic and extrinsic factors determine whether microbial growth will preserve or spoil foods, as shown in table 3. H7 were over 1 ph unit apart, depending on whether acetic acid mic 5ph5. One indicator of microbial response is their taxonomic classification. Bacterial growth and factors affecting growth of bacteria with respect to humans, the term growth refers to an increase in size. Bacteria grow only in the presence of oxygen, called. Get a printable copy pdf file of the complete article 815k, or click on a page image below to browse page by page. Table 32 lists the approximate minimum a w values for the growth of selected microorganisms relevant to food. The rate of bacteria growth may be affected by environmental factors such as temperature, light, oxygen, moisture, etc.
Bacterial growth experiment office of science education. For example, reported ph values for the inhibition of growth lio157. Biofilm maturity affects the succession of species present i. Pdf the growth of microorganisms is greatly affected by the. These factors are obviously different from microorganism to microorganism. To establish growth curves for an unknown bacterial species and observe the different phases of growth to demonstrate skill and knowledge in the use of the spectrophotometer.
There are many factors that affect bacterial growth. A complex interplay of individual with cooperative or competitive factors thus exists. They are usually found in the arctic and antarctic regions and in streams fed by glaciers. Factor affecting bacterial growth online biology notes. The wildtype exhibited the expected infection dynamics at the cellular level, with low numbers of bacteria per cell at 72 h post infection p. Depending on the optimum temperatures for growth 3. The rate of growth or death of a particular microbial species is influenced by a variety of physical factors in its environment including temperature, osmotic pressure, ph, and oxygen concentration.
The 1imiting effect of one factor is aftcn strongly affected by athers present. Early stage development photosynthetic biofilms have a high proportion of eps and bacteria compared to algae and cyanobacteria. Generally,an increase in temperature will increase enzyme activity. Nutritional factors that influence microbial growth by. Compare the bacterial growth on the two plates from the parental culture plates 1 and 2. Factors affecting the growth of bacterial colonies on agar. Environmental factors have tremendous influence on the growth. Anaerobic or facultatively anaerobic sporeformers are most likely to grow in canned foods. When a bacterial cell reaches a certain size, it divides to form two daughter cells.
The initial exponential growth of the single cell is soon replaced by a phase in which the radius of the developing colony is linearly related to the time of incubation. Compounds affecting microbial enzymes oxidative agents, chelating agents, heavy metals. Factors affecting the survival and growth of bacteria. By learning about such factors, we can control the growth of bacteria in the direction that is more beneficial for us.
Depending on the requirement of water and salt for growth. This can be, and is on a regular basis, used to the advantage of the microbiologist andor the clinician. Before we go over these factors we must however understand the bacterial growth curve. Here, we show that biofilm formation is strongly affected by the flows in thin layers of bacterial suspensions. The interval of time between two cell divisions, or the time required for a. Factors affecting microbial growth physical factors ph temperature osmotic pressure hydrostatic pressure. A detailed study has been made of the growth of single colonies. Acidophiles are acidloving bacteria which grow best at a ph between 0. Understanding environmental factors affecting the attachment and the early stages of the biofilm development will help develop methods of controlling the biofilm growth. On the other hand, lowering temperature will decrease enzyme activity. The growth of microorganisms, like that of human beings, is affected by the environment in which they are subsiding. But if temperatures get too high, enzyme activity will diminish and the protein the enzyme will denature. The microbial growth is the increase in number of cells rather than in size of individual cells. Kinetics of microbial growth factors determining growth.
Uteroplacental and umbilical blood flow and transplacental glucose and fetal insulin are major determinants of fetal growth. If culture media is rich in growth promoting substance, growth of bacteria occurs faster. Factors that influence bacterial growth biology libretexts. Surface waves control bacterial attachment and formation. Nutrient requirements of certain butyl alcoholproducing bacteria.
The survival and growth of a microbe is a function of a myriad of different activities. Bacterial growth and factors affecting growth of bacteria. Edward lawrie tatum, harland goff wood, 2 and william harold peterson. Factors affecting microbial growth airtek environmental. Neutrophiles are neutralloving bacteria which grow best at a ph between 5. Factors affecting the survival and growth of bacteria introduced into. Alkalinophiles are alkalinebaseloving bacteria which grow best at a ph between 7. The results indicate that the model system may be a suitable means of estimating the growth of bacteria on. Formation of bacterial biofilms on solid surfaces within a fluid starts when bacteria attach to the substrate. Growth of bacteria is affected by many factors such as nutrition concentration and other environmental factors. Not all bacteria observed in nature have been pure cultured. Some of the environmental factors influencing growth of bacteria are.
How do bacteria reproduce and what factors affect their. Microaerophilic bacteria are most likely to grow in vacuum packed foods since they have low oxygen tension. Get a printable copy pdf file of the complete article 1. If given the appropriate elements and an energy source, e. Physical and chemical factors affecting microbial growth. Energy sources organisms harvest energy either from sunlight or chemical compounds phototrophs. The activities of microorganisms are greatly affected by the chemical and physical conditions of their environments. Some researchers refer to this as conditioning of the biofilm growth surface fig. Vitamin b 1, a growth stimulant for propionic acid bacteria. Factors affecting rates of change in soil bacterial. Factors affecting microbial growth john songponnopachon 12 november 2014 bio 402.
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