Growth Dynamics of E. coli in Varying Concentrations of Nutrient Broths, pH, and
in the Presence of an Antibiotic
Abstract
The purpose in this experiment of growth dynamics of E. coli in varying media
was to determine which media produces the maximum number of cells per unit time.
First a control was established for E. coli in a 1.0x nutrient broth. This was
used to compare the growth in the experimental media of 0.5x and 2.0x, nutrient
broths; nutrient broths with an additional 5.0mM of glucose and another with
5.0mM lactose; nutrient broths of varying pH levels: 6.0, 7.0, and 8.0; and
finally a nutrient broth in the presence of the drug/antibiotic chloramphenicol.
A variety of OD readings were taken and calculations made to determine the
number of cells present after a given time. Then two graphs were plotted, Number
of cells per unit volume versus Time in minutes and Log of the number of cells
per unit volume versus Time growth curve. The final cell concentration for the
control was 619,500 cells/mL. Four media, after calculations, produced fewer
cells than that of the control, these were: Chloramphenicol producing 89,3 01
cells/ml; glucose producing 411,951 cells/mL; lactose producing 477,441 cells/mL
and finally pH 6.0 producing 579,557cells/mL. The remaining four media, after
calculations, produced cell counts greater than the control: 2X with 1,087,009
cells/mL; 0.5X with 2,205,026 cells/mL; pH 8 with 3,583,750 cells/mL and finally
pH 7.0 with 8,090,325 cells/mL. From these results the conclusion can be made
that the environment is a controlling factor in the growth dynamics of E. coli.
This was found through the regulation of pH and nutrient concentrations. In the
presence of the drug/antibiotic, chloramphenicol, cell growth was minimal.
Introduction
E. coli grows and divides through asexual reproduction. Growth will continue
until all nutrients are depleted and the wastes rise to a toxic level. This is
demonstrated by the Log of the number of cells per unit volume versus Time
growth curve. This growth curve consists of four phases: Lag, Exponential,
Stationary, and finally Death. During the Lag phase there is little increase in
the number of cells. Rather, during this phase cells increase in size by
transporting nutrients inside the cell from the medium preparing for
reproduction and synthesizing DNA and various enzymes needed for cell division.
In the Exponential phase, also called the log growth phase, bacterial cell
division begins. The number of cells increases as an exponential function of
time. The third phase, Stationary, is where the culture has reached a phase
during which there is no net increase in the number of cells. During the
In this lab project, the microbiology students were given 2 unknown bacteria in a mixed broth each broth being numbered. The goal of this project is to determine the species of bacteria in the broth. They had to separate and isolate the bacteria from the mixed broth and ran numerous tests to identify the unknown bacteria. The significance of identifying an unknown bacteria is in a clinical setting. Determining the exact bacteria in order to prescribe the right treatment for the patient. This project is significant for a microbiology students because it gives necessary skills to them for future careers relating to clinical and research work.
ABSTRACT: Water samples from local ponds and lakes and snow runoff were collected and tested for coliform as well as Escherichia coli. Humans as well as animals come into contact with these areas, some are used for recreational activities such as swimming and some are a source of drinking water for both animals and humans The main goal of this experiment was to see which lakes, snow run off and ponds tested positive for coliform or Escherichia coli and to come up with some reasoning as to why. It was found that the more remote pond with less contact contained the most Escherichia coli. However, another lake that many swim in and use as their drinking water indeed tested positive for a small amount of Escherichia coli. The two samples from the snow showed negative results for both coliform and Escherichia coli and the two more public ponds that aren’t as commonly used as a source of human drinking water but animal drinking water tested in the higher range for coliforms but in the little to no Escherichia coli range. It was concluded that the remote pond should be avoided as it’s not a safe source of drinking water for humans or animals. Other than that, the the other ponds are likely to be safe from Escherichia coli, but coliforms are a risk factor.
The fetus in utero may show signs of slow growth and organs may not develop correctly. After birth there can be physical defects evidenced by a smooth skin surface between upper lip and nose, the nose may be upturned, wide set eyes and an extremely thin upper lip. The head may be small in circumference and brain size, deformities of the joints, vision and hearing problems, heart defects and problems with bones and kidneys. There may be problems with the central nervous system and brain, including poor memory and judgement, learning disorders, delayed development, poor coordination and/or balance and hyperactivity or jitteriness, and mood swings. Children born with FAS may have difficulty is school, have poor social skills, have trouble adapting to change, lack impulse control, unable to stay on task and find it hard to plan or work towards a goal. The severity and negative effects range from subtle to serious, they are always
Pregnant women who drink often miscarry or have low-birth weight infants, and are at a much greater risk of having a child who has fetal alcohol syndrome. Fetal Alcohol Syndrome can include heart defects, poor coordination, hyperactive behavior; learning and developmental disabilities, and mental retardation. These problems are long term and also come with physical deformities like a narrow head, smaller eyes, and stunted growth. These effects are more common to women who are either heavy drinkers or binge drinkers.
There are three major factors that must be addressed in the diagnosis of FASD in an individual: (1) physical growth, development, and structural defects (for example, dysmorphology); (2) cognitive function and neurobehavior; and (3) maternal exposure and risk (May & Gossage, 2011a).
The exact way that alcohol causes the characteristics of FASD has not been clearly identified. One theory is that it enters freely into the placenta but does not leave as freely. Another that is because alcohol is a teratogenic, it disrupts developmental growth, that it disrupts nerve cell activity. Even in fairly small amounts the presence of alcohol alters the neurotransmission which then suppresses and disrupts nerve cell activity. (Kinney, 2012). This disrupts the normal fetal nerve development which causes neural cells to turn on themselves; it is believed that a million brain cells are lost because of this disruption.
In 2004, the term “Fetal Alcohol Spectrum Disorders” was agreed upon by a group of national experts to be used as an umbrella term to encompass all the disorders caused by prenatal alcohol exposure. When signs of brain damage appear following fetal alcohol exposure in the absence of other indications of FAS, the conditio...
Merrick J, Merrick E, Morad M, Kandel I. (2006). Fetal alcohol syndrome and its long-term effects. National Institute of Child Health and Human Development, Faculty of Health Sciences Jun;58(3):211-8.
According to Seaver, Fetal Alcohol Syndrome (FAS) is birth defects causing learning, and behavioral problems in individuals whose mothers drank alcohol during pregnancy. This disorder is very serious, yet it is recognized as one of the most preventable. This causes major issues, when something so serious could be prevented but is not. Fetal Alcohol Syndrome is a problem because it leaves a permanent effect on the unborn child, but some solutions could be educating women and putting up more informational posters and warning labels on products.
The severity that the disorder may have on a fetus depends on the amount of alcohol that was consumed and the time of consumption when the fetus was in uetero. FAS does not always result from high amounts of alcohol ingested by the mother, but possibly when it was consumed. The most critical time of fetal development in pregnancy is throughout the first trimester when the fetal body systems and organs are in the most vital stages of development, and are at risk for being severely altered, effecting every individual diagnosed in different ways. The central nervous system and brain are most affected, leading to developmental and cognitive alterations as well as physical changes of the child that is born with FAS. (Ismail, Buckley, Budacki, Jabbar, & Gallicano, 2010)
Alcohol, also known as ethanol, is a legal substance, which causes a person to become relaxed and “care-free”. Once alcohol is consumed, it is released into the bloodstream, which causes the brain to react, causing side effects. When a woman drinks alcohol while being pregnant, it can cause some physical and mental damage to the fetus. When a fetus is affected by alcohol exposure, it is called Fetal Alcohol Spectrum Disorder (FASD). If the affects are severe, it is then termed Fetal Alcohol Syndrome (FAS). The abnormalities occur in the central nervous system, facial structure, growth, and neurobehavioral development of the child. Severity of the damage depends on the amount of consumption, frequency, and timing of the consumption (Ungerer, Knezovich and Ramsay, 2013). Approximately 1 in 100 births have FASD effects. In the United States, 2-7 out of 1000 births are affected by FAS. 2-5% of young children in the United States and Western Europe are affected by FASD, while in Italy, the rate of FASD is 20.3-40.5 per 1000 births (Riley, Infante, Warren, 2011). These results are happening because 10-20% of women in the United States, 40% in Uruguay, and 50% of Italy consume alcohol while pregnant (Valenzuela, Morton and Diaz, 2012).
and physically, daily for as long as they can last in this entrapment. Each year there is an
Previous investigations have reported that bacterial growth increases in space flight; however, the underlying physical mechanisms responsible for these changes have not been fully determined. As bacteria consume nutrients, they excrete by-products whose presence can influence the onset of exponential growth and affect final cell population density. It is assumed that these metabolic processes create a reduced-density fluid zone and/or a solute gradient around each cell. On Earth, this density difference may result in local buoyancy-driven convection of the excreted by-products. The absence of convection and sedimentation in the low-gravity space flight environment, however, can be expected to alter the fluid dynamics surrounding the cells
First named and treated in the 1960’s, the condition results from the toxic effect of alcohol consumption and its chemical factors on a developing fetus. FAS is the leading cause of mental retardation in one out of every seven hundred fifty births. This number changes drastically if the mother is a heavy, habitual alcoholic, as high as twenty nine children out of every one thousand births. The ultimate sadness of this disease is that is one hundred percent
In effect, the permanent damage that alcohol leaves behind to the baby during conception and after birth is developmental disabilities. Prenatal alcohol exposure attacks the fetal brain structure and function causing FAS (Mattson, Schoenfled, & Riley, n.d.). Mothers who drink an unhealthy amount of alcohol during her pregnancy can hurt the baby’s corpus callosum, which is a significant part of the brain. The corpus callosum is the part of the brain that has a large amount of nerve fibers connecting each side of the hemisphere together, this allows for the right and left side of the brain to communicate with one another (Mattson, et.al., n.d.). People born with FAS’s corpus callosum is out of proportion and they struggle with reading, learning, and have deficits in attention (Mattson, et. al, n.d.). Individuals that are born with