Bacterial classification, structure and function columbia university. The major characteristics of bacteria are based on their size, shape and arrangements 1. The morphological study of bacteria requires the use of microscopes. Colony size can vary because a colony is larger if its more spread out. Staphylococcus medical microbiology ncbi bookshelf. Xanthomonas species can cause bacterial spots and blights of leaves, stems, and fruits on a wide variety of plant species. Although genetic divergence highlights the evolutionary relationships of bacteria, morphological and biochemical features of bacteria remain important in the identification and classification of those organisms.
Microscopic bacteria grow together in visible colonies. Assign an isolate number to each pure colony and record all colony characteristics on the data sheet. Use of a dissecting scope can aid in distinguishing between differing colony types. Unlike other strains of bacilli, however, salmonella does not produce spores. Enterobacteriaceae family contains a large number of genera that are biochemically and genetically related to one another. Begin initial testing to determine presumptive identification of pure strain. With their enormous adaptability and metabolic versatility, bacteria are found in every habitat on earth, carrying out many of the vital processes. In the identification of bacteria and fungi much weight is placed on how the organism grows in or on media. Rod shaped bacteria are called bacilli singular bacillus. Characteristics of streptomycetes streptomyces is the largest genus of actinobacteria and the type genus of the family streptomycetaceae hong et al. Phenotypic characteristics used as a means of identification for fungi rely on microscopic morphology for accurate and correct identification2. If colonies are not well isolated, the plate will have to be reinoculated on bhia and thoroughly struck over the entire plate surface to achieve isolation of bacteria. Mutations in bacteria can be detected by a technique called replica plating, which allows the genetic characteristics of the colonies to be investigated without. Color, texture and growth pattern are better colony characteristics to observe.
The result of conducted research using the pour plate method 171 cfu bacterial colonies obtained from the dilution of 105 and 116 cfu bacteria. When assessing inhibitory activity against the indicator strain l. Begin initial testing to determine presumptive identification of pure strain bacterial cultures co, motility, catalase, and gram stain. Improvements on colony morphology identification towards bacterial. This exercise will help you identify the cultural characteristics of a bacterium on an agar plate called colony morphology. Colonies that differ in appearance are typically different bacterial strains, species, or genera.
Jul 11, 2017 morphological characteristics are really important when characterizing bacteria and fungi. Common characteristics of family enterobacteriaceae are. It is motile by peritrichous flagellae, though some strains are nonmotile. These isolates were categorized into two main genus lactobacillus and streptococcus. The coagulasenegative staphylococci cns are now known to comprise over 30 other species. Learn the characteristics and vocabulary used to describe the appearance of those colonies and test your knowledge with practice examples in. All four strains are mannitol positive best seen in fig. Biology 3b laboratory cultural characteristics of bacteria page 1 of 7 biology 3b laboratory cultural characteristics of bacteria objectives.
The group includes thermotolerant coliforms and bacteria of faecal origin, as well as some bacteria that may be isolated from environmental sources. Bacteria definition, shapes, characteristics, types. A colony is defined as a visible mass of microorganisms all originating from a. Apr 28, 2019 in the identification of bacteria and fungi much weight is placed on how the organism grows in or on media. The usual bacteria that you see range in size from 0. Bacterial colony characteristics flashcards quizlet. Bacterial classification, structure and function introduction the purpose of this lecture is to introduce you to terminology used in microbiology. Colony morphology can sometimes be useful in bacterial identification. Microbiology module escherichia coli and klebsiella microbiology 216 notes 21 escherichia coli and klebsiella escherichia coli 21. Growth is best on blood agar and chocolate agar after incubation for 25 days.
Jan 09, 2020 cultural characteristics of bacillus cereus. Pdf in this paper we report quantitative measurements of bacterial colony morphologies that are subsequently used to predict forward scattering. They are aerobic, freeliving soil microbes that play an important role in the nitrogen cycle in nature, binding atmospheric nitrogen, which is inaccessible to plants, and releasing it in the form of ammonium ions into the soil nitrogen fixation. Culture characteristic of bacteria prepared by samira fattah assis. On nutrient agar at 37c, it forms large 25 mm greywhite, granular colonies with a less wavy edge. Escherichia coli colony morphology and microscopic. In macconkey agar medium, the colonies of klebsiella pneumoniae are pink colored due to the lactose fermentation which is of great importance in differentiating k. The colony becomes visible to the naked eye and the number of colonies on a plate can be counted. Bacteroides characteristics, classification, pathogenesis. Escherichia, shigella, salmonella, enterobacter, proteus, yersinia etc. The arrangement how close together or far apart the bacteria are is due to how they were streaked on the plate. Identification and characteristics of lactic acid bacteria isolated from masai fermented milk in northern tanzania.
Bacterial colony morphology and identification of bacteria. Colony morphology is the way scientists identify bacteria. A colony is defined as a visible mass of microorganisms all originating from a single mother cell, therefore a colony constitutes a clone of bacteria all genetically alike. Azotobacter is a genus of usually motile, oval or spherical bacteria that form thickwalled cysts and may produce large quantities of capsular slime. Indeed, bacteria are classified on the basis of many characteristics.
Learn vocabulary, terms, and more with flashcards, games, and other study tools. Bacteria in the genus staphylococcus are pathogens of man and other mammals. Streptomyces species are chemoorganotrophic, filamentous. Quizlet flashcards, activities and games help you improve your grades.
A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. Bacteria are very difficult to study microscopically unless stained. Pdf morphology and classification of bacteria find, read and cite all the. Biology 3b laboratory cultural characteristics of bacteria page 3 of 7 part b. There are various culture media used for the cultivation of pseudomonas aeruginosa p. Describing bacterial colonies pdf document from rutgers. The selected representative isolates were chosen among 191 isolates on the basis of their colony characteristics in selective media plates, various staining properties, catalase reactions, and motility table 1. The plate count method or spread plate relies on bacteria growing a colony on a nutrient medium.
The term colony morphology refers to the visible characteristics of a colony. A colony is a group of bacteria that are growing together. Although bacterial and fungi colonies have many characteristics and some can be rare, there are. Isolation, identification and characterization of lactic acid. Citrobacter freundii bacteria have a long rod shape with a typical length of 15. Microscopic examination of various bacteria the type of cell wall that a bacterium has can be determined by utilizing various staining techniques.
Bacterial colony characteristics study guide by rodriguezk3 includes 45 questions covering vocabulary, terms and more. The coagulasepositive staphylococci constitute the most pathogenic species s aureus. The cetrimide agar medium which is a selective medium for the p. Isolation and identification of lactic acid bacteria from tarag in eastern inner mongolia of china by 16s rrna sequences and dgge analysis. Bacteria colony characteristics flashcards quizlet. Many of the traditional or familiar bacteria are found in this family e. A colony is defined as a visible mass of microorganisms all. To be effective, the dilution of the original sample must be arranged so that on average between 30 and 300 colonies of the target bacterium are grown. Complete the following morphology descriptions for each of the given samples to the best of your abilities you may use the internet to further your search. It would take about 1,000 bacteria, one m in length, placed endtoend to equal one millimeter, which is about the width of a pencil line. Traditionally they were divided into two groups on the basis of their ability to clot blood plasma the coagulase reaction.
Biology 3b laboratory cultural characteristics of bacteria. Cover different classification schemes for grouping bacteria, especially the use of the gram stain 2. Isolation and characteristics of lactic acid bacteria isolated from ripe mulberries in taiwan yisheng chen1, huichung wu1,d, fujitoshi yanagida2 1department of biotechnology, ming chuan university, no. Although one might not necessarily see the importance of colonial morphology at first, it really can be. During that period many of the bacteria that cause human disease were identified and characterized. Identification of bacteria and fungi by diagnostic laboratories is based on phenotypic characteristics, usually by direct comparison of unknown with those of type cultures1. In this article we will discuss about escherichia coli e. However, colony morphology is not a reliable way to identify bacteria, as many different types of bacteria have similar colony morphology. The number of bacterial cells present in the mammalian gut shows a continuum that goes from 10 1 to 10 3 bacteria per gram of contents in the stomach and duodenum, progressing to 10 4 to 10 7 bacteria per gram in the jejunum and ileum and culminating in 10 11 to 10 12 cells per gram in the colon figure 3a. The colony characteristics of individual bacterial and fungal colony are carefully observed and used during these studies. Other shapes will be considered later in the course. Incubate at 2024c for 24 hours to allow bacterial growth. Colony morphology is a way scientists can identify bacteria.
A colony is defined as a visible mass of microorganisms all originating from a single mother cell. Difference between bacterial and fungal colonies compare. In order to help categorize bacteria, they can be separated into groups, such as gramnegative and grampositive. Bacteria are microscopic unicellular organism they are true living organism that belongs to the kingdom prokaryotes.
Bacteria bacteria classification by morphology, biochemistry, and other features. Bacterial isolates may be identified using conventional methods based on. Colony morphology is a good method commonly used by scientists to identify and describe them. Introduction to bacteria morphology and classification most bacteria singular, bacterium are very small, on the order of a few micrometers m 106 meters in length. Pathogenic species show high degrees of specificity and some are split into multiple pathovars, a species designation based on host specificity citrus canker, caused by xanthomonas citri subsp. Four different strains of escherichia coli on endo agar with biochemical slope. Actinomycete, order actinomycetales, any member of a heterogeneous group of grampositive, generally anaerobic bacteria noted for a filamentous and branching growth pattern that results, in most forms, in an extensive colony, or mycelium. The following are important biochemical tests for the identification of bacterial genera that are important in. Bacteria classification by morphology, biochemistry, and. Instead, their dna, a double strand that is continuous and circular, is located in a nucleoid. The identification of microbial characteristics and number of. Colony morphology is a method that scientists use to describe the characteristics of an individual colony of bacteria growing on agar in a petri dish. Total lab count at aerobic and anaerobic condition.
First report of donut colony morphology among diphtheroids isolated in blood. To distinguish how various growth media will affect colony growth. Glucose fermentation with gas production, urea and h 2 s negative, lactose positive with exception of strain d late lactose fermenter. Once you have completed this lesson you should be able to describe a bacteria colony using the correct morphology characteristics. Colony morphology can sometimes be useful in bacterial.
Pdf morphology characterization of bacterial colonies for. Isolation, identification and characterization of lactic. Escherichia coli colony morphology and microscopic appearance. They are microaerophilic, require 510% co 2 and high humidity. Bacterial colony morphology bacteria grow on solid media as colonies. Key features of these bacterial colonies serve as an important criteria for their identification. The mycelium in some species may break apart to form rod or coccoidshaped forms. Complete hemolysis bhemolysis on blood containing agar. On macconkey agar, salmonella colonies appear colorless and transparent, though they sometimes have dark centers.
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