Microbial Physiology and Genetics - Assignment Example

? Microbial physiology and genetics MPG1: Batch culture of Escherichia Aim The prime purpose of this experiment was to consoli the understanding of the bacteria batch culture. In this respect, at the end of the experiment, learners would be able to give a description of key features in a laboratory system of fermentation. The student would also be able to monitor biomass using viable and absorbance counting. The students would also be able to present and analyse the batch data and the calculation of the specific lag time and growth rate. Introduction A batch culture is a technique of feeding a nutrient substrate of growth limiting to a culture. Batch strategy is normally used in processes of bioindustry in realizing high density of cells within a bioreactor. In many cases, the solution feed is normally highly concentrated in order to avoid the bioreactor dilution. The addition that is controlled has a direct influence on the culture’s growth rate, helping it to avoid metabolisms that are over flown. This means that the side metabolite formation, especially acetate, which is used for Escherichia coli would occur. The limitations of substrate give out the chance of controlling the rates of reaction in order to avoid the limitations of technology that are normally connected to the reactor’s cooling and transfer of oxygen (Maaloe, 2004). The limitation of substrate could provide an allowance for the control of metabolism. This helps in avoiding osmotic effects, overflow metabolism, and catabolise repression of the side products. There are varied processes that can be used in controlling the batch growth process. In order to understand the batch culture, an experiment was set to investigate the characteristics of a bacteria batch culture. Method In the first week, each group of students was given a fermenter batched having 800 cubic centimetres oxoid half strength broth nutrient at 37 degrees Celsius. The demonstrator informed the students about the inoculation fermenter time. A stock culture was inoculated by a nutrient agar slope and incubated for a period of twenty four hours at a temperature of 37 degrees Celsius. The slope biomass was washed into a 250 cubic centimetre flask having 50 cubic centimetres broth of nutrient that was incubated at 37 degrees Celsius and shaking at 250 rpm for duration of 14 hours (Maaloe, 2004). About 25cubic centimetres of the leading culture were utilized inoculating a 250 cubic centimetres flask of shake having 25 cubic centimetres of broth nutrient incubated at 37 degrees Celsius and shaking at 250rpm for a period of an hour. Each fermenter had been inoculated with 20cubic centimetres of the obtained culture. After this, the students picked a sample from a fermenter and recorded the absorbance at approximately 660 nm versus water blank. The samples were returned to the tubes and discarded in the vessel of discarding. The spectrophotometer tube was sterilized with a seventy percent IMS and allowed to dry. The sampling procedure was repeated after fifteen minutes. Whenever an absorbance increase was observed, the fermenter was aerated by the demonstrator at a rate of 800 cubic centimetres per minute. After this, viable counts were made and measurements of the absorbance taken. The viable counts were made continuously for the alternate sample. The group decided on the viable count method determination and discussed the method with the demonstrator. The vessel was sampled continuously until the phase of stationery was realized. In the second week, the viable counts of the tested samples were recorded. The students completed the proforma that was given and submitted it for assessment. Results All the data collected were recorded in a tabula proforma as in table 1. Table 1. Time Absorbance at 660nm 0 0.209 15 0.209 30 0.250 45 0.332 60 0.375 75 0.411 90 0.449 105 0.503 Data analysis Discussion The obtained graph is a smooth curve with a positive gradient. This is a clear indication that Escherichia coli have a potential of growing on different carbon substrate in a similar manner as other bacteria. Whenever bacteria are set to grow in different batch cultures on substrates, an exponential growth is normally observed as in the graph displayed in this experiment. This graph has characteristics rates for the specific substrate (Mahler, 2002). External limitation towards the exponential growth rate does not exist thus the existing rates of growth are inherent towards the metabolism of bacteria. In cultures that are chemostatic, the control of the experiment is done by the rate of growth. In this case, a dilution rate of the chemostat is set. This experiment supports the idea that specific rate of growth of batch cultures is limited to specific rates of respiration and the concomitant generation rate of ATP through oxidative phosphorylation. For a system that is well adapted, the general rate of growth needs to be determined through physical limits in which pathways are developed and adjusted. These limits could be of different nutrients rates, and maximum content of cells. MPG2: Continuous culture Aim In this section of the experiment, the key aim was to show out the continuous culture dynamic equilibrium. After completion of this experiment, the learners gave out the description of the kinetic wash out in a culture that is continuous. The learners were able to give a description of the growth kinetics in a culture that is continuous. The learners were also able to calculate ?max out of the washout data. Introduction Continuous culture is a method that is extremely vital in microbiology. It is a technique which occurs under conditions that are steady. This means that the method may take place at a constant rate of metabolic products, nutrients concentration, and oxygen that change in the period of growing the batch culture. The characteristics of this technique make it be unique and vital since it gives out many merits in terms of the economic technique of production in the microbiologist industry (Kreyazig, 2007). In attempts to understand this technique, an experiment is set to investigate the properties of continuous culture. Method The participants were given mock continuous system culture and a culture that was continuous of the Escherichia coli. The participants worked in groups of five individuals. The demonstrator explained the methodology that was to be used and asked the subjects to record it in their logs. The crystal violet dye washout was observed from the continuous culture mock system. The data were presented in a suitable graphical form. The biomass was monitored in the E coli continuous fermenter as displayed (Kessler, 2004). Each group compared the generated data with the system of mock and found a conclusion concerning the description of kinetic of growth in a culture that is continuous. After this, rate of dilution of the continuous culture was increased. The biomass was monitored, and the obtained data plotted. ?max was calculated. Results All the data that was collected was recorded in table 2. Table 2. Replicate Count small squares N=10 Total=177 Mean=17.7 Count cm-3 =17.7x2x107 =3.54 x 108 cells per count 1 14 2 16 3 19 4 20 5 20 6 14 7 16 8 21 9 21 Data Analysis Counts per cubic centimetres = 3.54 x 108 cm-3 Plots = 0.1 cm3 Ratio=0.375/0.163= 2.3 Our count= 3.54 x 108 x 2.3 = 8.142 x 108 Discussion From the results of the experiment, it is evidenced that a continuous flow has some reactors for which reactants move at a rate that is steady and where products germinate. This operation is governed by the manner in which the materials pass by the reactor, and the reaction’s kinetics. Many reactors are found in the extremes of a tank, and in different situations in piston flow (Beek, 2008). For a piston flow that is ideal, all particles would have an equal time of residence, which is equal to the average time of residence. References Beek, C., 2008. Pattern of enzymes and Aerobic growth. New York: Oxford publishers. Kessler, P., 2004. Escherichia coli growth. New York: Jack and sons publishers. Kreyazig, E., 2007. Continuous Culture. New York: John Willy & sons press. Maaloe, O., 2004. Microbial synthesis. New York : Benjamin. Inc. Mahler, R., 2002. Biological chemistry. New York: Harper & Row Press. Read More