1887

Color-Removal by Microorganisms Isolated from Human Hands

    Author: Tsukasa Ito1
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    Affiliations: 1: Division of Civil & Environmental Engineering Science, Gunma University, Kiryu Gunma, Japan 376-8515
    AUTHOR AND ARTICLE INFORMATION AUTHOR AND ARTICLE INFORMATION
    • Published 02 December 2013
    • Corresponding author. Mailing address: Division of Civil & Environmental Engineering Science, Faculty of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu Gunma, Japan 376-8515. Phone and fax: +81-(0)277-30-1692. E-mail: t.ito@gunma-u.ac.jp.
    • ©2013 Author(s). Published by the American Society for Microbiology.
    Source: J. Microbiol. Biol. Educ. December 2013 vol. 14 no. 2 244-247. doi:10.1128/jmbe.v14i2.545
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    Abstract:

    Microorganisms are essential for human life. Microorganisms decompose the carbon compounds in dead animals and plants and convert them into carbon dioxide. Intestinal bacteria assist in food digestion. Some vitamins are produced by bacteria that live in the intestines. Sewage and industrial wastewater are treated by activated sludge composed of microbial communities. All of these are due to the ability of microbes to produce many enzymes that can degrade chemicals. How do teachers make students understand that microorganisms are always associated with humans, and that microorganisms have the ability to degrade chemicals? The presence of microorganisms on humans can be shown by incubating agar plates after they are touched by the hands of students. The ability of microorganisms to degrade chemicals can be shown by an analytical measurement of the degradation of chemicals. When the chemicals are dyes (colorants) in water, microbial activity on degradation of dyes can be demonstrated by observing a decreasing degree of color as a result of the enzymatic activity (e.g., azoreductase). Dyes are widely used in the textile, food, and cosmetic industries. They are generally resistant to conventional biological wastewater treatment systems such as the activated sludge process (4). The discharge of wastewater containing dye pollutes surface water. The ability of microorganisms to decolorize and degrade dyes has been widely investigated to use for bioremediation purposes (5). The goal of this tip is to understand the presence of bacteria on human skin and the ability of bacteria to degrade colorant chemicals (decolorization). In this tip, students first cultivate and isolate bacteria on their hands, and then examine potential decolorization activity of each bacterium by observing the degree of color of the liquid in tubes in which bacteria isolated from students’ hands were inoculated. Decolorization activity of bacterial isolates from human skin has been reported recently (6). To date this author has frequently obtained colorant-degrading bacterial isolates from human hands as a result of work on a scientific education project. This tip does not require analytical measurements. Students can examine a number of bacterial isolates simultaneously. Therefore, it is appropriate for high school and introductory level college courses.

Key Concept Ranking

Surface Water
0.5848656
Activated Sludge
0.5833333
Analytical Instruments
0.57241976
Sodium Chloride
0.5520833
Carbon Dioxide
0.5416667
Wastewater Treatment
0.52955824
0.5848656

References & Citations

1. American Society for Microbiology 2012 Guidelines for biosafety in teaching laboratories Available from the ASM website: http://www.asm.org/index.php/educators/curriculum-guidelines
2. Becton, Dickinson and Company 2009 Difco & BBL manual of microbiological culture media 2nd ed 282 316
3. Burleson KM, Martinez-Vaz BM 2011 Microbes in mascara: hypothesis-driven research in a nonmajor biology lab J Microbiol Biol Educ 12 166 175 23653761 3577261
4. Seshadri S, Bishop PL, Agha AM 1994 Anaerobic/aerobic treatment of selected azo dyes in wastewater Waste Manage 15 127 137 10.1016/0956-053X(94)90005-1 http://dx.doi.org/10.1016/0956-053X(94)90005-1
5. Srinivasan A, Viraraghavan T 2010 Decolorization of dye wastewaters by biosorbents: a review J Env Man 91 1915 1929 10.1016/j.jenvman.2010.05.003 http://dx.doi.org/10.1016/j.jenvman.2010.05.003
6. Stingley RL, Zou W, Heinze TM, Chen H, Cerniglia CE 2010 Metabolism of azo dyes by human skin microbiota J Med Microbiol 59 108 114 10.1099/jmm.0.012617-0 http://dx.doi.org/10.1099/jmm.0.012617-0
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/content/journal/jmbe/10.1128/jmbe.v14i2.545
2013-12-02
2017-11-18

Abstract:

Microorganisms are essential for human life. Microorganisms decompose the carbon compounds in dead animals and plants and convert them into carbon dioxide. Intestinal bacteria assist in food digestion. Some vitamins are produced by bacteria that live in the intestines. Sewage and industrial wastewater are treated by activated sludge composed of microbial communities. All of these are due to the ability of microbes to produce many enzymes that can degrade chemicals. How do teachers make students understand that microorganisms are always associated with humans, and that microorganisms have the ability to degrade chemicals? The presence of microorganisms on humans can be shown by incubating agar plates after they are touched by the hands of students. The ability of microorganisms to degrade chemicals can be shown by an analytical measurement of the degradation of chemicals. When the chemicals are dyes (colorants) in water, microbial activity on degradation of dyes can be demonstrated by observing a decreasing degree of color as a result of the enzymatic activity (e.g., azoreductase). Dyes are widely used in the textile, food, and cosmetic industries. They are generally resistant to conventional biological wastewater treatment systems such as the activated sludge process (4). The discharge of wastewater containing dye pollutes surface water. The ability of microorganisms to decolorize and degrade dyes has been widely investigated to use for bioremediation purposes (5). The goal of this tip is to understand the presence of bacteria on human skin and the ability of bacteria to degrade colorant chemicals (decolorization). In this tip, students first cultivate and isolate bacteria on their hands, and then examine potential decolorization activity of each bacterium by observing the degree of color of the liquid in tubes in which bacteria isolated from students’ hands were inoculated. Decolorization activity of bacterial isolates from human skin has been reported recently (6). To date this author has frequently obtained colorant-degrading bacterial isolates from human hands as a result of work on a scientific education project. This tip does not require analytical measurements. Students can examine a number of bacterial isolates simultaneously. Therefore, it is appropriate for high school and introductory level college courses.

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Figures

Image of FIGURE 1.

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FIGURE 1.

Experimental flow from incubation of bacteria on hands to functional evaluation of color removal. (a) First, students touch agar plates, which are then incubated for one week at room temperature (25°C). (b) Students transfer bacteria to new LB agar plates one by one, and the agar plates are incubated for one week at room temperature (25°C). (c) Students collect bacteria grown on the agar plate with a homogenization pestle. (d) Collected bacteria are suspended in colored water. (e) Bacterial suspensions are added to tubes containing dye and LB medium. (f) The bacterial turbidity is adjusted to a 1 McFarland standard, and the tubes are incubated statically at room temperature. (g) Within one week, some tubes typically show bacterial removal of colorant. Photo (g) is taken after 2 days of incubation. Left tube in the photo is not yet decolorized because of the slow rate of decolorization. (a) is performed in the 1st week, (b) in the 2nd week, and (c) to (f) in the 3rd week. (g) is observed in the 4th week.

Source: J. Microbiol. Biol. Educ. December 2013 vol. 14 no. 2 244-247. doi:10.1128/jmbe.v14i2.545
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