direct and indirect methods of measuring microbial growth ppt

In this exercise, you will compare three methods of bacterial In situations where determining the number of microorganisms is difficult or undesirable for other reasons, the use of indirect methods can be an excellent alternative. Number of cells per mm = number of cells counted * dilution * 50,000. You can measure the cell mass two ways, through dry weight measurements which allows a more accurate estimation of cell masses but is very time consuming. Direct measurements involve methods that count cell numbers directly. A one-milliliter sample of the water is diluted in a 1:10 dilution series. All others are indirect methods and is applicable only in special circumstances. Use a spectrophotometer- a beam of light is transmitted through a bacterial suspension to a light-sensitive detector. Direct microscopic counts quantify all . Rapid Methods for Detection of Microorganisms in Food. Detection of microorganisms in foods. measuring the turbidity of the culture solution can be used in estimating numbers of bacterial cells, if a growth curve for the conditions used has already been established. The ________ method is used to indirectly measure microbial growth of filamentous bacteria and molds. Dr. O is building an entire video library that will allow anyone to learn Microbiology and Anatomy & Physiology for free. Method. Therefore, if I want to measure how long a piece of wood, I just measure it. Application. direct methods- count cells indirect methods- estimate cell numbers turbidity measured spectrophotometer, measure population metabolic activity, dry weight measure filamentous mass Know the different phases of a standard growth curve. Microbial Nutrition, Ecology, and Growth. The number of colonies is proportional to the number of cells. Dr. O is building an entire video library that will allow anyone to learn Microbiology and Anatomy & Physiology for free. In this article we will discuss about the techniques used for measuring cell numbers and cell mass of microorganisms. With direct measurements, measuring instruments such as Vernier calipers, micrometers, and coordinate measuring machines are used to measure the dimensions of the target directly. techniques, bacterial staining and microscopy, bacterial metabolism, and control of microbial growth. These techniques provide numerical information about a sample. B. bacteria whether by counting colonies after growth in nutrient medium, or counting stained cells microscopically. It is one of the simplest methods used to analyze trends in growth because it uses a spectrophotometer to track changes in the optical density (OD) over time. Direct information, such as the aerobic respiration rate or specific methanogenic activity, provides information on the actual activity of the biomass, and can be used for example to record respirograms (time series of respiration rates) in the lab. Two methods can be used to count cells: directly by microscopy, using an electronic particle . Most methods of counting are based on indirect or direct counts of tiny samples. Introduction. a number of direct or indirect methods. Methods of Measuring Microbial Biomass Pool Sizes. The filter used are made of inert material like acetate, cellulose nitrate, polyamide, polycarbonate, polypropylene or polytetrafluoroethylene. Question: On a piece of paper create a Venn diagram comparing and contrasting direct and indirect methods of measuring microbial growth . When a few bacteria are inoculated into a liquid growth medium or any solid culture media and the population is counted at intervals. Explain three indirect methods of measuring cell growth. To detect microbial loads, foodborne pathogens, and their toxins. 'Direct measurement' refers to measuring exactly the thing that you are looking to measure, while 'indirect measurement' means that you're measuring something by measuring something else. Understand and perform indirect measurement of bacterial growth through spectrophotometer readings and optical density measurements. The conventional methods used for the quantitative or qualitative detection of microorganisms and toxins in foods take a relatively long time. Dense populations should be diluted using serial dilution techniques. Other methods, such as viable plate counts, can also be used for determining bacterial growth Some methods measure cell numbers; other methods measure the population's total mass, which is often directly proportional to cell numbers. The indirect methods, the second category, are those based on the measurement of metabolic activity or of products of metabolic activity. For detection of pathogenic bacteria, immunological based methods (ELISA) are . T or F: Direct methods of measuring microbial growth are more accurate than indirect methods. It has been reported that there are 10 10 -10 12 live microorganisms per gram in the human colon [].The resident microbial groups in the stomach, small, and large intestine are crucial for human health. Besides direct methods of counting cells, other methods, based on an indirect detection of cell density, are commonly used to estimate and compare cell densities in a culture. The purpose of this chapter is to present a summary of techniques for measuring growth and analysing chemical composition of microalgae. MPN is most commonly applied in the water industry for quality testing of water i.e to ensure whether the water is safe or not in terms of bacteria present in it. Those that attempt to count all the microorganisms of a particular type, for example, bacteria, fungi, algae, and protozoa, in a given sample give a total count of all the . Indirect Cell Counts. These methods measure some quantifiable cell property that increases as a direct result of microbial growth. It is important to monitor cell growth and biological and biocatalytic activities in cell metabolism. Indirect methods-measuring live cells only (viable counts) 1. This is the most common method used to rapidly estimate bacterial numbers. Direct microscopic count. 454 Various types of microorganisms, known as gut microbiota, are inhabitants of the human gastrointestinal tract. INDIRECT METHODS OF MEASUREMENT OF MICROBIAL GROWTH Submitted by, Jeeva Raj Joseph 1st sem. Common test formats for microbial food testing are ELISA assays, real-time PCR tests, nutrient plates and agar plates. Qualitative and quantitative analysis in microbiology Various techniques have been devised to permit the analysis of the structure and function of microorganisms . Both of these classes of methods are reviewed belou. cm). In the food industry the potential for simultaneously testing many samples makes electrical methods a useful means for assessing the quality of raw materials and products. Microbial Growth * * * * * * * * * * * * * * * * * * * * * * * * * * * * Growth of Microbes Increase in number of cells, not cell size One cell becomes colony of millions of cells Growth of Microbes Control of growth is important for infection control growth of industrial and biotech organisms Factors Regulating Growth Nutrients Environmental conditions: temperature, pH, osmotic pressure . Growth of Microbial Populations • Measuring Microbial Growth • Indirect methods • Turbidity Direct light Light source Uninoculated tube Light-sensitive detector Light source Inoculated broth culture Scattered light that does not reach reflector Measurement of Bacterial Growth. 2 Food Spoilage Temperatures Requirements for Growth Physical Requirements 2.pH: 4Most bacteria prefer neutral pH (6.5 -7.5). MathBench- Australia Microbiology: Methods for counting bacteria Dec 2015 page 3 For example, if you prepared a sample and got a spectrophotometer reading of 0.5, you would find 0.5 on the x-axis and read the bacterial count off the y-axis -- about 26 million/mL 2. Abstract. : pickling). EC Nutrition 14.1 (2019): 68-74. The foremost approach is to measure the turbidity (cloudiness) of a sample of bacteria in a liquid suspension. Decrease the global dependence on hazardous agricultural chemicals. Microbiology. Bacterial Requirements Temperature and Oxygen Measurement of Microbial Growth CFU Direct Viable Plate Counts Serial Dilutions Pour Plate Spread Plate Membrane Filtration Counting Chamber MPN (fecal, H20, food) Indirect Turbidity Metabolic activity Metabolic Classifications Temperature Oxygen requirements pH Pressure Radiation Growth Curve Labeled Phases Lag phase Adaptive Start metabolism 1-3 . Measurements of microbial growth Introduction. Measuring Bacterial Growth can be achieved by Filtration method. There are perhaps as many methods and modifications to these methods as there are active phycologists today. [The factor of 50,000 is used in order to determine the cell count for 1 ml: 1 ml = 1000 mm3 = (50 times the chamber depth of 0.02 mm) * 1000.] False (Both of these types of methods are merely ways of estimating the actual number of microbial cells present.) For example: False. Title: PowerPoint Presentation Author: karlm Created Date: 1/31/2010 2:52:35 AM The Different Methods of Measuring Feed Digestibility: A Review 70 stance is determined. Direct methods 2.1. 2. The four general approaches used for estimating the sizes of microbial populations are direct and indirect counts of cells and direct and indirect measurements of microbial biomass. D. Measurement of a specific chemical change produced on a constituent of the medium Answer: C Clarification: To measure the dry weight of cells is the most direct approach for quantitative measurement. Other techniques are quantitative in their intent. On a piece of paper create a Venn diagram comparing and contrasting direct and indirect methods of measuring microbial growth. A variation of the direct microscopic count has been used to observe and measure growth of bacteria in natural environments. Plates should have between 30 and 300 colonies to be statistically significant. TURBIDITY Turbidimetry is a simple, rapid method for following growth. A variety of methods are available to predict cell growth by direct or indirect measurements. Viable cell count is one such method. These are based on different parameters of cells such as dry-weight and wet-weight measurement, absorbance, cell plate, density, turbidity, ATP measurement, viable count, ATPase activity and use of Coulter counter. In this way, turbidity can be used as an indirect measurement of the cell count. A spectrophotometer or calorimeter can be used for turbidimetric measurements of cell mass. The maximum allowable limits for toxic chemicals (mg/l) and trace elements (mg/l) in municipal drinking water and for dialysate water are shown in Table 1.The chemical contaminants that can be found in water or the dialyzing fluid and have produced toxicity in patients are aluminum, chloramine, copper, fluoride, lead, nickel, nitrate, sulfate, and zinc (9,10,24 . 21-5 Methods for Growth and Storage of Microalgal Cultures ... 447 21-6 Methods for Estimating Photosynthesis ... 453 21-7 Methods for Measuring Cyanobacterial Dinitrogen Fixation ... 454 21-8 Methods for Studying Endosymbiotic Cyanobacteria in Cycad Roots . Chapter 7. 2 Discuss four methods of measuring bacterial growth. The second way of measuring cell mass is done with a spectrophotometer. or when measuring the response of an individual to a vaccine. However, to relate a direct cell count to a turbidity value, a standard curve must first be established. [14], who found that Cmic and basal respiration increased by 330% and 58.4% . (The greater the absorbance, the greater the number of bacteria.) Toxic residues of bacteria in food and beverage samples can be analyzed with test kits for bacterial toxins. T or F: Bacterial growth curves are plotted on graphs that have a logarithmic scale on both the x- and y-axes. 1. MPN Method. A sample of ocean water is tested for its bacterial content in a plate count assay. They have the ability to: Reduce the insects and disease damage. 4Acidity inhibits most microbial growth and is used frequently for food preservation (e.g. With direct measurements, measuring instruments such as Vernier calipers, micrometers, and coordinate measuring machines are used to measure the dimensions of the target directly. Filename: CelCount.ppt Hugh B. Fackrell Presentation Outline Direct Counts Microscopic Electronic counter Dilution series Membrane filtration Indirect Counts Optical density Weight of culture Chemical Direct Counts: Microscopic Calibrated stained smear Counting chamber Epifluorescence Calibrated Stained Smear Petroff- Hauser Counting Chamber Epifluorescence Microscopy Nucleic acid specific dye . Plate counts-only viable cells will grow into colonies. 0.1 milliliter of the second dilution tube is plated in a pour plate. Feel free to reach out if there ar. 9. Microbial Nutrition • Nutrition is a process of acquiring chemical substances from the environment • The absorbed nutrients are used - for energy yielding processes - growth • The chemical elements absolutely needed - essential nutrients - Macronutrients: C, H, O… Culture methods for viruses, bacteria, and parasites are preferred because they detect and quantify infectivity, which is the most relevant unit of measure in terms of health risk. There are many different ways to measure the growth of microbial populations. Indirect information refers to The methods include standard plate counts, turbidimetric measurements, visual comparison of turbidity with a known standard, direct microscopic counts, cell mass determination, and measurement of cellular activity. Several methods exist for this purpose. Some techniques are qualitative in their intent. 3. Stimulate plant growth through mobilizing nutrients in the soil. Viable cell count (colony counts) Enumeration of bacteria in milk, foods, soil, water, laboratory cultures, etc. . Using a spectrophotometer to measure the optical density at 600 nm (OD600) of a bacterial culture to different rapid methods have been developed . Plotting a Bacterial Growth Using Turbidimetric Determination. 1) Turbidity- As bacteria multiply in a liquid medium, the medium becomes turbid, or cloudy with cells. Measurement (Count) of Cell Numbers: 1. 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