E coli growth curve - Lab Report Example

Growth depends on several environmental factors and we analyzed with the affect of pH on the growth curve for the population since pH is an important factor for microbial growth (Rousk et al, 2009). It is known that the optimal pH conditions for E.coli is around 7 and therefore a decrease in the pH would alter the normal growth pattern and lead to reduction in the growth rate of the bacterial population. For this experiment we took 2 flasks filled with LB. In one of the flasks 20ml of E.coli culture was transferred and this flask was marked as CONTROL and incubated .

To test the affect pH had on the bacterial growth curve, we made the broth acidic in nature and this flask was marked EXPERIMENTAL. This flask was also incubated. At regular intervals of 20 minutes spectrophotometric readings were taken of both the CONTROL as well as the EXPERIMENTAL at 660nm. We see that the doubling time for both the cultures is not same and this is because the rate of growth has been affected in some way. The resulst show that the doubling time for CONTROL is about 41 minutes while that for the EXPERIMENTAL is 277.

25 minutes. Analyzing both the data it is seen that the EXPERIMENTAL culture does not go through all the phases because of the altered pH conditions and drastic reduction in the rate of growth. Another reason is that time restrictions did not allow the cultures to be observed through all the expected phases. The CONTROL was absolutely necessary to understand what affect modified pH had on the same E.coli. This comparison between the CONTROLand EXPERIMENT shows that when the pH factor is differed the growth is reduced and rate of growth is also reduced.

This also proves the fact that microbes requires an optimal pH in which they can grow without inhibition. Microbial growth is of major concern for public health (Roszak and Colwell, 1987, p.365). Since experimental evidence show the