Status: AVAILABLE |
In order to read or download safety report assessment manual ebook, you need to create a FREE account.
Download Now! |
eBook includes PDF, ePub and Kindle version
| ✔ Register a free 1 month Trial Account. |
| ✔ Download as many books as you like (Personal use) |
| ✔ Cancel the membership at any time if not satisfied. |
| ✔ Join Over 80000 Happy Readers |
I hate science with a passion but something felt different when I walked in the first day hope he's doing well. He is funny and very knowledgable. I really enjoyed this class. Labs are very easy. Quizzes are easy and tests are fair. If you study his notes well, you will do great. No need to read the book. Respected Clear grading criteria EXTRA CREDIT 0 0 PHYSIOLOGY1 ?? awesome Dec 5th, 2019 Quality 5.0 Difficulty 4.0 PHYSIOLOGY1 ?? awesome Dec 5th, 2019 For Credit: Yes Attendance: Mandatory Would Take Again: Yes Grade: Not sure yet Textbook: No Highly recommend this professor because he knows what he is talking about. The textbook is not required but it helps. He has his own notes(studyguide) that you print out and study for quizzes and exams. He is extremely hilarious and will answer any questions you have. Physiology is not easy but he explains things with stories and drawings. Love him Get ready to read Skip class. You won't pass. Lecture heavy 0 0 BIO3 ?? awesome May 30th, 2019 Quality 4.0 Difficulty 3.0 BIO3 ?? awesome May 30th, 2019 For Credit: Yes Attendance: Mandatory Would Take Again: Yes Grade: C Textbook: Yes Show up to class and read print out power points before lecture. His power points are the study guides. The lectures are a bit boring. As long as you do all labs, and do good on the quizzes you should pass.I did horrible on the 4 exams but managed to barley pass. Get ready to read Lecture heavy 0 0 ANATOMY1 ?? awesome Dec 8th, 2018 Quality 5.0 Difficulty 3.0 ANATOMY1 ?? awesome Dec 8th, 2018 Attendance: Mandatory Would Take Again: Yes Textbook: Yes Professor Reynolds is the best instructor I've ever had. He is extremely knowledgeable and caring. I've taken this class a few years ago and I have to say I have learned so much that what I've learned from his class has helped me through nursing school till the very end. He really prepares you for the future and I'm so glad I had professor Reynolds Inspirational Hilarious Caring 0 3 ANA01 ??
http://www.tc-muehlacker.de/data/tcmuehlacker/userfiles/image/da5400es-manual.xml
average May 24th, 2018 Quality 3.0 Difficulty 3.0 ANA01 ?? average May 24th, 2018 For Credit: Yes Would Take Again: Yes Textbook: No He reads the slides and draw on the board. He tells you what going to be on the test but i feel like his test are based on what he says. He can be rude sometimes, if you have a question sometimes he doesn't know what you are asking. The labs are really easy but when it comes to lecture test it can be hard. Quizzes are easy remember what he says. Get ready to read Skip class. You won't pass. TEST HEAVY 4 2 ANATOMY1 ?? awesome May 14th, 2018 Quality 5.0 Difficulty 3.0 ANATOMY1 ?? awesome May 14th, 2018 For Credit: Yes Attendance: Mandatory Would Take Again: Yes Textbook: No He is hands down the most caring professor that I have ever taken. He is very clear and fair when it comes to his exams, and he doesn't make anatomy harder than it needs to be. His lab exams are super easy because he tells you exactly what will be on them. His lectures are interesting and easy to follow. All the quizzes and tests were based off the powerpoints he goes over for lecture. The lab is aso really easy. He also gives a lot of extra credit to make sure you can pass the class. Get ready to study, study, study. Not an easy class, but what do you expect nursing pre reqs are NOT easy. I enjoyed his class and going to take his physiology class next semester. Wished he taught all science classes. Would make my life so much better. He encourages you to read and study alot. He gives you hints on what might be one the test. He gives many opportunities for easy points. His practicals are easy if you study. His grading is simple and clear. Respected Get ready to read Amazing lectures 2 0 PHYSIO1 ?? awesome Mar 8th, 2017 Quality 5.0 Difficulty 4.0 PHYSIO1 ??
http://www.jafra-com.at/userfiles/da50es-sony-manual.xml
awesome Mar 8th, 2017 For Credit: Yes Attendance: Mandatory Would Take Again: Yes Textbook: Yes The day of our first test class was cancelled and the next class meeting we found out he was being replaced by a substitute who finished teaching the remainder of the semester. We never found out why he suddenly disappeared but for the time we had him it was a pleasure attending his class. He's very clear on what you need to know. Studying is key. Get ready to read Skip class. You won't pass. Hilarious 0 0 ANATOMY1 ?? awesome Mar 8th, 2017 Quality 5.0 Difficulty 4.0 ANATOMY1 ?? awesome Mar 8th, 2017 For Credit: Yes Attendance: Mandatory Would Take Again: Yes Grade: A Textbook: Yes I took Anatomy with Professor Reynolds in spring 2016. While the class was tough it was mostly memorization that is taught during lecture and reviewed in lab with hands on work. Respected Get ready to read Skip class. The whole time spent in class is lectures and it's best to print out the slides because its exactly like the tests. The labs are easy, you turn in a take home worksheet from the lab manual. I dropped this class half way through because I CAN'T Tough Grader TEST HEAVY LECTURE HEAVY 0 3 BIO3 ?? awesome Oct 11th, 2016 Quality 5.0 Difficulty 3.0 BIO3 ?? awesome Oct 11th, 2016 For Credit: Yes Attendance: Mandatory Would Take Again: Yes Textbook: No What a guy Professor Reynolds is. He's a very interesting teacher but he makes class a lot of fun. I took him for bio 3 with the lab and it's not an easy class but he explains everything pretty well and he tries to explain it in ways we can all understand. I personally really enjoyed his class and would recommend taking him. Hilarious Clear grading criteria Caring 0 0 ANATOMY1 ?? awesome Aug 8th, 2016 Quality 4.0 Difficulty 5.0 ANATOMY1 ??
http://ninethreefox.com/?q=node/14056
awesome Aug 8th, 2016 For Credit: Yes Attendance: Mandatory Would Take Again: Yes Grade: B Textbook: Yes Anatomy was the hardest class i have ever taken but this professor has a special way of helping you remember this subject. I will admit, his tests and quizzes are very hard and it almost seems like he should give us a study guide based on the difficulty of his tests. His lecture is long but that is not his fault. Take him, he is great. 1 0 ANA1 ?? awesome Jun 3rd, 2016 Quality 4.0 Difficulty 3.0 ANA1 ?? awesome Jun 3rd, 2016 For Credit: Yes Attendance: Mandatory Would Take Again: Yes Grade: Not sure yet Textbook: No He is the best!! His tests are based off the lecture notes and stuff he mentions during lecture. Theres about 8 quizzes. His labs are fast and easy. Practicals are easy if you study. Anatomy is a hard class but an A is possible. He made Anatony a breeze. Always was able to ask him questions and get clear answers. I learned so much in this class and when I finish I felt very accomplished. Very clear on what he teaches. U must read and study a lot in order to pass. U don't need the book tests are straight off his power-points. He's a very nice man and knows what he's teaching. His tests are based of for his notes do you won't need the book. Pay attention to his lectures because what he says during lecture could end up on a quiz or test. He's such a sweet and funny man. All Rights Reserved. Composition: SNP Best-Set Printer: The Maple-V ail Book Manufacturing Group Cover Printer: Phoenix Color Elsevier Academic Press 30 Corporate Drive, Suite 400, Burlington, MA 01803, USA 525 B Street, Suite 1900, San Diego, California 92101-4495, USA 84 Theobald's Road, London WC1X 8RR, UK This book is printed on acid-free paper. All rights reserved.
http://chateau-malbrouck.com/images/case-exercise-testing-system-manual.pdf
No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher.Her tag read: “Be kind—I’m blind. ” You know—you can learn an awful lot from a blind dog that loves you. Ian Pepper, August 3, 2004 T o Peggy, Peter and Phillip. Chuck Gerba, A ugust 3, 2004 T able of Contents Overall, this Environmental Microbiology Laboratory Manual is optimally designed for use with students that are concurrently taking a lecture class in Environmental Microbiology, using the text “Environmental Microbiology” (R.M. Maier, I.L. Pepper, and C.P. Gerba—Academic Press). Experiment 1 introduces students to the basic concepts of bacterial growth in pure culture. These concepts are illustrated using standard broth culture and dilution and plating techniques. Experiment 2 demonstrates how to measure soil moisture content, and discusses the signi?cance of soil moisture on soil microbial activity. Experiment 3 introduces the student to soil as a habitat for microorganisms, the main types of soil microorganisms, and interactions between organisms and soil. Such activities not only affect nutrient cycling, but also interactions with organic and metal contaminants. Experiment 7 demonstrates the conver- sion of reduced forms of sulfur to sulfate, while Experiment 8 illustrates a method to monitor general metabolic activity via dehydrogenase activity. Experiment 9 documents the important autotrophic activities of nitri?cation, and subsequent denitri?cation which can be autotrophic or heterotrophic. Experiments 10, 11, and 12 illustrate bacterial responses to organic and metal contaminants. In contrast Experiments 13 and 14 evaluate uptake of assimi- lable carbon and oxygen. Experiments 15 and 16 teach basic methods for coliform detection and quanti?cation in water.
Experiment 17 illustrates the detection of bacteriophages. Con- temporary methods for the rapid detection of coliforms are the subject of Experiments 18 and 19. Experiments 20 and 21 outline procedures for the detection of enteric viruses and protozoan parasites. Experiment 22 looks at the topic of dis- infection. MANUAL CONVENTIONS Each experiment generally contains the following sections: Overview A brief synopsis of the experiment designed to give the student the big picture. Theory and Signi?cance This section describes biological, chemical, and physical principles behind the assays performed, how they relate to the environment, and the signi?cance of the topic. Procedure The labs are broken up into multiple periods to facilitate the organization of experiments that can run concomitantly. A detailed description of the ma- terials and equipment needed to carry out the experiment for each student is given at the head of each period. T ricks of the T rade These are practical tips to help the student make the experiment successful. At ?rst glance these seem very simplistic, but experience has shown the authors that these hints will prevent the mistakes that students have fre- quently made in the past, and would likely make again. P otential Hazards Safety aspects associated with the experiment are identi?ed for the student. Calculations Calculations necessary for the analysis of experimentally determined data are assigned along with a discussion of the formulas used. Questions and Problems Assignments are available for the student to demonstrate an understanding of the material in each experiment. References A listing of useful articles and books is also supplied. SUGGESTED SOIL TYPES AND TESTS Soil Selection Soils for the soil microbiology section should be chosen to represent as diverse a range of soil types as possible. All rights reserved. xvii Each colony is then referred to as a colony forming unit ( CFU ).
In addition to providing an estimate of bacterial numbers, this procedure allows the opportunity to obtain pure culture iso- lates. Oftentimes, researchers will measure the turbidity of the liquid culture at different time intervals using a spectrophotometer. The comparison of tur- bidity with plating results allows for a quick estimation of bacteria numbers in future studies. These techniques are used in all aspects of microbiology including clinical and environmental microbiology. Because of its importance this topic is introduced here as the ?rst exercise in this laboratory manual. The growth of a bacterial isolate will be followed as a function of time to illustrate the various phases of growth that occur in liquid culture. Intuitively one can recognize that bacterial growth (via cell division) in liquid media will continue to occur until: a) nutrients become limiting; or b) microbial waste products accumulate and inhibit growth (Maier et al., 2000). T o understand and de?ne the growth of a particular microorganism, cells are placed in a ?ask in which the nutrient supply and environmental conditions are controlled. If the liquid medium supplies all the nutrients required for growth and environmental parameters are conducive to growth, the increase in numbers can be measured as a function of time to obtain a growth curve. Several distinct growth phases can be observed within a growth curve (Figure 1-1). These include the lag phase, the exponential or log phase, the stationary phase, and the death phase. These phases correspond to distinct periods of growth and associated physiological changes (T able 1-1).Experiment 1—Dilution and Plating of Bacteria and Growth Curves Theoretically, the time taken for cell division to occur is the mean generation time or doubling time. The mean generation time can be calculated through the use of a dilution and plating experiment.
Compare the difference in the shape of the curves in the death phase (colony-forming units (CFUs) versus optical density). The difference is due to the fact that dead cells still result in turbidity. Table 1-1 The F our Phases of Bacterial Growth Phase Characteristics 1. Lag Phase Slow growth or lack of growth due to physiological adaptation of cells to culture conditions or dilution of exoenzymes due to initial low cell densities. 2. Exponential or Log Phase Optimal growth rates during which cell numbers double at discrete time intervals known as the mean generation time (Fig. 1-2). 3. Stationary Phase Growth (cell division) and death of cells counterbalance each other resulting in no net increase in cell numbers. 4. Death Phase Death rate exceeds growth rate resulting in a net loss of viable cells. 1 Difco Detroit, MI. All rights reserved. 5 2 4 2 n 2 3 2 2 2 1 2 0 Bacterial Growth Cell division Cell division Cell division Cell division Cell division Cell division Cell division Cell division Figure 1-2 Exponential cell division. Each cell division results in a doubling of the cell number. At low cell numbers the increase is not very large, however after a few generations, cell numbers increase explosively.After n divisions we have 2 n cells. Experiment 1—Dilution and Plating of Bacteria and Growth Curves 1. Make a 10-fold dilution series: 2. For one dilution, transfer 0.1 ml of suspension to each plate. After inoculatng all replicate plates in one dilution, go to 3. Repeat for next two dilutions. 3. For each plate, sterilize a glass hockey stick spreader in a flame after dipping it in ethanol. Let the spreader cool briefly. Go to 4. 5. Repeat steps 2, 3, and 4 for each dilution. When done, let the agar dry for a few minutes, tape the plates together, and incubate them upside down for one week. 4. Briefly touch the spreader to the agar of an inoculated plate to cool, away from the inoculum.
Then, spread the inoculum by moving the spreader in an arc on the surface of the agar while rotating the plate. Continue until the inoculum has been absorbed into the agar. Repeat 3 and 4 for the other replicates.It may be desirable to split the 5 ml cultures into smaller volumes so each lab group has their own tube for assay. Keep all cultures on ice until use. Each dilution tube will have 900 m l of dilution ?uid (sterile saline). A dilution series will be needed for each E. coli culture (T 0 thru T 8 ). 2. Begin dilutions by adding 100 m l of E.coli from the tube labeled T 0 which is the initial E. coli culture to tube A. T ube A is the 10 - 1 dilution of T 0. 3. V ortex the 10 - 1 tube for 5 seconds. 4. Follow this by subsequently adding 100 m l of T ube A to the next tube of saline (T ube B). T ube B is a 10 - 2 dilution of T 0. Repeat until completing the dilution series, referring to T able 1-2 to see how far you will need to make dilutions for each E. coli culture. Remember to vortex each tube prior to transfer. It is also important to use a new pipette tip for each transfer. 5. Repeat dilutions for T 1 through T 8 or for whatever samples were assigned to you. Again refer to T able 1-2 to see how far you need to make your dilutions. 6. Plate according to the regiment speci?ed in T able 1-2. 7. Label plates with the dilution and volume to be added to the plate. Make sure the label contains the time point plated (T 1 thru T 8 ) identi- ?cation. Use triplicate plates for each dilution. 8. Pipette 100 m l from each of the three dilutions to be plated. Add 100 m l of each dilution tube to be plated by pipetting the amount to the center of the agar plate (Figure 1-3). 9. Immediately spread the aliquot by utilizing a ?ame sterilized “L ” shaped glass rod. If the aliquot is not spread immediately, it will sorb in situ in the plate resulting in bacterial overgrowth at the spot of initial inoculation. 10.
Repeat the plating for each dilution series for T 1 through T 8 cultures. F ollowing this, store plates in refrigerator until the next class period.All rights reserved. Experiment 1—Dilution and Plating of Bacteria and Growth Curves Figure 1-4 Example of a dilution series of E. coli plated at three dilutions. Dilutions decrease from left to right. Here, plate A is the one which should be counted (Photo courtesy K.L. Josephson). All rights reserved. Experiment 1—Dilution and Plating of Bacteria and Growth Curves In addition, soil moisture content controls the amount of pore space occupied by water and air, thereby deter- mining whether the soil environment is aerobic or anaerobic. The moisture content of a soil can dramatically alter the physical appearance and proper- ties of a soil. F igure 2-1 shows a Pima clay loam soil with varying amounts of soil moisture. Finally, the extent of soil moisture in?uences the transport of soluble constituents through the pro?le, into subsurface environments (Maier et al., 2000). All soil microbes require water or moisture, and are surrounded by water ?lms from which they obtain nutrients and excrete wastes (Maier et al., 2000). Most of the analyses performed in this section of the manual will involve standardization of ?nal results on a dry weight soil basis. This is important as soils vary widely in moisture content both between soils and for any given soil over time, whereas the dry weight of a soil is constant over time. Coarse-textured soils high in sand which contain no colloidal sized particles such as clay, contain water that is easily removed from the soil by drying. Water contained within the minerals (structural water) is very small in quan- tity, and is only removed at high temperature. In contrast to coarse particles, colloidal particles, such as clays, contain both structural water and signi?cant amounts of adsorbed water.
This adsorbed water is intimately associated with the mineral structure of the particle and may be as dif?cult to remove as the structural water. In addition, water held adsorbed to clays is less available to soil microbes. Therefore, drying under elevated temperature is usually employed to remove free and structural water.In microbial analyses, soil moisture content is usually reported as the gravi- metric moisture content, q g, which, as the name implies, is the mass of water per unit mass of oven dry soil. It is de?ned as: (2-1) where: m is the moist soil mass prior to drying, and d is the dry mass of the same soil after drying in an oven. On the other hand, soil moisture content as determined by some ?eld instru- ments, such as a neutron probe, is often expressed as the volumetric water content, q v, which is the volume of water per unit volume of soil. It is related to q g by the following equation: (2-2) where: p b is the soil bulk density (commonly 1.4 to 1.6 g cm - 3, and p w is the density of water (1.0 g cm - 3 ). However, the availability of water to microorganisms and plants alike is very much a function of how tightly the water is bound to the soil particles. Often the term “?eld-capacity” has been used to describe the water content of a wetted soil pro?le in the ?eld, after the soil has been allowed to drain for two days (Jury et al., 1991). Soils at “?eld capacity” are generally optimal for aerobic soil microbes since oxygen and moisture are readily available. T he sample on the far left is completely dry, whereas the one on the far right is saturated with water. (Photo courtesy K.L. J osephson). All rights reserved. 13 You will additionally need the equation to manipulate the moisture content of your soils. 1. One hundred grams of moist soil has 50 moisture on a dry weight basis. How much dry soil is there in this soil sample.
Experiment 2—Soil Moisture Content Determination A technique developed back in the 1930s is still a valu- able learning tool today. This is the contact slide or buried-slide technique of Rossi et al. (1936), which is a simple technique for qualitatively assessing the spatial relationships between soil microorganisms. Although it is not reliable enough to quantify soil microorganisms as the original authors had intended, it is useful to illustrate the orientation of soil organisms to one another and to soil particles. It also allows students to see bacteria, actinomycetes and fungi, perhaps for the ?rst time, through the use of a microscope (Maier et al., 2000). The technique involves burying a glass slide in soil for a de?ned period of time (Figure 3-1). Nutrient amendments, such as the carbon source glucose and the nitrogen source ammonium nitrate, encourage the rapid pro- liferation of heterotrophic microorganisms. After removing the slide from within the soil, the slide is ?xed with acetic acid and stained to provide contrast, as the often colorless organisms would otherwise not be visible under a microscope. V iewed under a microscope, soil bacteria, actinomycetes, and fungi can be seen growing on soil particles, in pure colonies on the slide, and in juxtaposition to each other, often with bacteria lining the fungal hyphae. Spore formation by actinomycetes or fungi can also be observed. Examples of what may be seen are shown in Figures 3-2 and 3-3. EXPERIMENT 3 Experiment 3—Contact Slide Assay Figure 3-1 Examples of soil microcosms with inserted buried glass slides (Photo courtesy K.L. Josephson). Wave of bacteria (smooth edges) Fungal hyphae Bacteria on fungal hyphae Soil particles (irregular edges) Figure 3-2 Contact slide images using the 100.This soil moisture content is often close to ?eld capacity. Measure out this much distilled water with a graduated cylinder and add it to each of two vials. All rights reserved.
21 Soil particles Fungal hyphae Actinomycete filament Bacterium on actinomycete filament Figure 3-3 Contact slide images using the 100.Stir to dissolve the amendments. Do not amend the control vial. 4. Mix the contents of the treatment and control vials into their respective cups by adding the liquid to the soil in small aliquots, and mixing with a spatula after each moisture addition. F or heavy textured clay soils avoid mixing as this will “puddle” the soil. 5. For each cup, label two clean microscope slides, designating the soil and treatment for that slide. There will be two slides for each cup. Insert each slide vertically into its respective cup, leaving 2 cm of each slide projecting above the soil surface (see Figures 3-4). Do not force the slides as they will break. 6. Cover the cups with plastic wrap, securing with a rubber band. Puncture the wrap or foil several times with a probe to allow air in and yet pre- clude excessive evaporation of moisture. Weigh each cup. Incubate the soil-?lled cups at room temperature in a designated incubator for one week. Mark and identify the side to be stained (see Figures 3-5 and 3-6). 3. Gently tap the slide on the bench top to remove large soil particles from the slide surface. Figure 3-4 Position of the slides in the tumbler containing soil. Side to be stained Figure 3-5 Withdrawing a slide from the soil. Gently tilt the slide to one side before pulling straight up so as not to disturb the organisms on the upper face. Dry and examine the slide microscopically using the oil immersion objective. All rights reserved. 23 Figure 3-6 Example of how the slide plus accompanying soil should look following removal of the slide from the soil (Photo courtesy K.L. J osephson). Speculate as to why there were or were not any differences between soils and treatments. 5. How did you distinguish fungi from actinomycetes? 6. Discuss the usefulness of the method. Experiment 3—Contact Slide Assay Academic Press, San Diego. Rossi, G.
, Riccardo, S., Gesue, G., Stanganelli, M., and Wang, T.K. (1936) Direct microscopic and bacteriological investigations of the soil. All rights reserved. 25 Since soils generally contain millions of fungi per gram, normally a dilution series of the soil is made by suspending a given amount of soil in a dispers- ing solution (often deionized water), and transferring aliquots of the suspen- sions to fresh solution until the suspension is diluted suf?ciently to allow individual discrete fungal colonies to grow on the agar plates. After inoculation on several replicate agar plates, the plates are incubated at an appropriate temperature and counted after they have formed macro- scopic fungal colonies (Figure 4-1). Because the assumption is that one fungal colony is derived from one organism, the term colony forming units ( CFUs ) is used in the ?nal analysis, with the results expressed in terms of CFUs per gram of oven dry soil. V alues for culturable fungal counts from a fertile soil have been reported as around 10 6 fungal “propagules” (spores, hyphae, or hyphal fragments) per gram of dry soil (Pepper et al., 1996). Figure 4-2 describes a dilution and plating protocol procedure. Beginning at step 1, a 10-fold dilution series is performed.A 10-fold series is very common as the calculations for the determinations of the organism count is very simple. Here, 10 g of moist soil is added to 95 ml (solution A) of deionized water and shaken well to disperse the organisms. The reason that 10g of soil EXPERIMENT 4 Experiment 4—Filamentous Fungi are used is that 10 g of soil occupies approximately 5 ml. W orking diligently, the dilution series is continued to the highest desired dilution (tubes C, D, and E). The three most diluted sus- pensions are plated. Three different dilutions (tubes C, D, and E) are plated so as to increase the chance of obtaining a dilution that will result in a count- able number of organisms. (See Figure 4-3 for a plated dilution series.
) Here, pour plates are utilized for the plating procedure. The dilution of inter- est is vortexed and 1.0 ml of suspension is removed from the tube and added to each of two sterile Petri dishes. Before the soil particles in the inoculum can settle, pour plates are made (step 3a). Here, a suitable agar is poured into the plate with the one ml of inoculum. The agar is at a temperature warm enough to keep the agar ?uid, but cool enough not to kill the organisms or destroy any heat-sensitive amendments to the agar (e.g., antibiotics). Then the plate is gently swirled (step 3b) to distribute the agar and inoculum across the bottom of the plate (without splashing agar on the sides or lid of the dish). F inally, the agar is allowed to solidify, and the plates are incubated upside down to prevent condensation from falling on the growing surface of the agar (step 4). Using pour plates is useful for fungi since fungi can rapidly grow through agar but bacteria cannot. Other types of plating are possible. Spread plating Figure 4-1 An example of a fungal pour plate, with macroscopic colonies (Photo courtesy K.L. Josephson). As the described technique involves working and incubating in the open air, aerobic and facultative anaerobic organisms are enumerated. Obligate anaerobes are not enumerated. Culturable heterotrophic plate counts have been in use for enumerating organisms since the nineteenth-century. They continue to be used today as they are inexpensive to perform, require little labor, are quick, and are fairly reproducible. However, they do suffer from a number of errors which must be considered when evaluating the results. All rights reserved. 29 Step 1. Make a 10-fold diltion series. Step 2. For one dilution (C), transfer 1.0 mL of soil dilutions to replicate agar plates. Repeat for next two dilutions (D and E). Step 3a. Add molten agar cooled to 45. C to the dish containing the soil suspension. Step 4. Incubate plates under specified conditions. Step 5.