生物课实验报告参考

Exploration of the Bacteria Escherichia coli

Population Growth

at Different Temperatures

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BIO101, LAB-X

September 10, 2012

Jane Dow

BIO101, LAB-E

John Dow

September 10, 2012

Monitoring of the Bacteria Escherichia coli Population Growth

at Different Temperatures

Introduction:

Escherichia coli (E. coli) is a large and diverse group of bacteria, which normally lives in the intestines of people and warm-blood animals (defined by CDC, 2011). Because of E. coil’s rapid growing speed and low price, it is frequently used as a model organism in microbiology studies from several decants ago (Lederberg, J & Tatum E.L., 1946). In this laboratory report, a nonpathogenic strain of E. coli was used to study comparative growth tendency at different temperatures (25°C, 30°C, and 37°C) and for the same time intervals. It was hypothesized that the general growth tendency of E. coli bacteria would be consistent with the exponential growth model. Besides, compared to the other two temperatures, the bacteria E. coli would grow best at 37°C which is close to the body temperature of many mammals.

Methods:

Three 125 ml flasks were prepared with the same 25 ml L-Broth and 0.5ml E-coli inoculums in each. Three flasks should be put into three incubators separately. One flask was placed in the 25°C incubator, one flask was placed in the 30°C incubator, and one flask was placed in the 37°C incubator. Accordingly, the experimenters were divided into three groups (3or 4 teams in each group to save time) and every group was assigned one of the three culture flasks. Subsequently, every flask needed to be marked by the group name to distinguish.

Using sterile pipettes, each of the three groups took a 1 ml sample from their own culture flask at the same time and placed these samples in three experimental cuvettes. Afterwards, the flasks were returned to the incubators. Placing the cuvettes in the spectrophotometer, the groups took a reading of the light absorbance and recorded the time and absorbance on the sheet. After removals of cuvettes from the spectrophotometer, sample liquid was poured in the sink to dispose. Cuvettes were rinsed after every use.

At 20 or 25 minute intervals, the light absorbance of the culture was measured as indicated above. Finally, every lab group exchanges absorbance readings with all the other lab groups.

Results:

Based on the data collected for three lab groups, tables and graphs were built by Microsoft Excel. Table 1is the Group 1 Absorbance Measurements for E. coli Growth at Temperatures of 25° C

Work Cited

Lederberg, J & Tatum E.L., Gene recombination in E. coli":1946. Source from

/wiki/Escherichia_coli#Model_organism

CDC, Centers for Disease Control and Prevention(full name). E. coli (Escherichia coli): 2011.

Source from http://www.cdc.gov/ecoli/general/index.html

 

第二篇：水生物处理实验报告模板

实验名称 ：

一、实验目的

二、实验器材和药品

三、实验步骤

四、实验（观测）结果

五、实验讨论