Lab #6: Microbes Rules: Their function and importance

Transcription

1 Lab #6: Microbes Rules: Their function and importance to life on Earth Name: Date: Goals The main goal of this lab is to understand the function and importance of microbes in the cycle of life on the Earth and the role of Microbiology in what we already know about them. Introduction A 5000x scanning electron microscope image of E. Coli bacteria. Image Credit: The Centre for Microscopy and Microanalysis, The University of Queensland, Australia. Microbes have been living on the Earth for billions of years. As far as we know, they were one of the first forms of life appearing in the early stage of our evolutionary past. According to Wikipedia, a microorganism or microbe is an organism that is so small that it is microscopic (invisible to the naked eye). Microorganisms are often illustrated using single-celled, or unicellular, organisms; however, some unicellular protists are visible to the naked eye, and some multicellular species are microscopic. Microorganisms have played an important role in our evolution and it is not exaggerating to say that life on the Earth depends on these invisible forms of life. The subfield of Biology dedicated to the study of microorganisms is called microbiology. A very common mistake in regards to microbes is to consider them to be synonymous with germs and as causal agents of dangerous diseases. In specific cases this is true, some microbes are effectively causal agents of diseases, some fatal. In reality, however, our body is home for numerous microbes, as is the soil, air and water surrounding us. In fact we need them in order to survive. In addition, microbes have a great ability to adapt and can survive in almost any known and extreme environment. Some of them have been found perfectly adapted to survive in environments with extremely high temperatures and others in extremely low. Also, they are fundamental to processing food and critical to the function of various cycles in our environment. That is the reason why some microbes are used in industry, especially for food processing. In this lab you will be performing experimental activities to observe microorganisms and classify them according to their taxonomy. Also, you will observe and compare procedures for maintaining an environment clean of potentially dangerous microorganisms, especially those related to clean water and safe food. Environmental Science Laboratory 110L New Mexico State University, Department of Agronomy and Horticulture 1

2 Pre-lab Questions and Resources What kind of microorganisms can be found in our environment? In what sense are some of them dangerous and others beneficial to human life? How do they influence the natural equilibrium of our planet? Wikipedia: The free Encyclopedia Exploratorium: Microscope Imaging Station Microbe World Identify some industrial activities which are intimately related with microorganisms. Are these activities important to our current way of life? Why and in what sense (cultural, economical, social, political)? Microbe World: Microbes in Everyday Products Key Words Microbes, microbiology, clean water, safe food Objectives 1. Understand the definitions of microbe, microbiology, clean water, and safe food. 2. Observe and identify some microorganisms that can live in water and food. 3. Compare different samples of water to determine the presence of microorganisms. 4. Apply and compare different procedures for cleaning water of microorganisms. 5. Understand why microorganisms are important for life on Earth. Environmental Science Laboratory 110L New Mexico State University, Department of Agronomy and Horticulture 2

3 Procedure Materials Laboratory with microscopes Samples of water and food Kit to analyze water quality UV equipment to purify water Selected websites Books Articles from scientific magazines and newspapers Laboratory handouts First activity: Observing microorganisms in food 1. Open the samples of food (bread) provided by the instructor and carefully take a small amount of each sample to the microscope for observation. 2. Draw a picture of the different microorganisms that you can distinguish. 3. Based on the information previously explored, try to identify the microorganisms observed with their specific scientific names. 4. The three samples that you observed where maintained under the same conditions for one week. Try to come up with a hypothesis explaining the differences observed among them. Second activity: Observing microorganisms in the water 5. Take the three samples of water given by the instructor labeled as A, B, and C, respectively. 6. Observe each sample carefully under the microscope and compare what you observe with your control sample. 7. Based on your observations label the samples identifying which of them is water, bottle water, and pond water. Give support to your decisions based on your observations. Third activity: Purifying water (optional) 8. Take three samples of pond water and label them as A, B, and C. 9. Observe under the microscope the control sample and assume that this is the purest water that you can have. 10. Observe each sample under the microscope and give an estimation of the level of purity of the water (100% absolutely pure, 0% absolutely contaminated) compared with the control sample. Environmental Science Laboratory 110L New Mexico State University, Department of Agronomy and Horticulture 3

4 10. Apply to each sample one of the following purification methods: UV light, Chlorine or Boil. 11. Observe under the microscope what happens with the water after the purification process. 12. Compare the results to determine which purification method is the best. Calculations and Data Presentation Record your observations of different microorganisms here. Environmental Science Laboratory 110L New Mexico State University, Department of Agronomy and Horticulture 4

5 Sample Label A B C Sample Purification method Purity level without treatment (P i ) Purity level with treatment (P f ) Difference ( P= P f - P i ) A B C Control Make a graph comparing the purity level for each sample before and after the treatment. Make a graph showing the difference of purity ( P) for each sample of water. Discuss the results drawing reasonable conclusions from both graphs and your own lab records. Questions As a group discuss the following questions. You need to address these questions in your lab report which is, however, individual. 1. Based on the information sources analyzed, explain briefly why microbes are important for maintaining life on the Earth and why it is a big mistake to confuse germs with microbes. Environmental Science Laboratory 110L New Mexico State University, Department of Agronomy and Horticulture 5

6 2. What kind of microbes can be found in a pond? What do you recommend to a child who is trying to drink clear water from a nice pond in a really hot summer day? What would you explain to his parents? The parents are so concerned because the child is really thirsty and there is no other water source near. 3. Based on the discussion of your group and the information of your graphs, is there a difference among the different purification methods? Is P an appropriate measure to compare how well a specific method works? Why? 4. What method would you recommend as the best? Why? Justify based on your data. Important information Do not forget to submit your Full lab report by 5 p.m. on Friday DATE to TA NAME: TA ADDRESS Environmental Science Laboratory 110L New Mexico State University, Department of Agronomy and Horticulture 6