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Ubiquity of Microorganisms

I. Introduction

Microorganisms are found in nature either in their substrate or as aerial contaminants. In

conditions where their food and environmental needs are properly met, they actively proliferate.However, when food or environmental factors become limiting, their growth may be arrested.

Under severe conditions they may ultimately die.

II. Materials and Methods

Materials:

Prepoured nutrient agar !"#$ plates !% per group$

& piece paper mold with a %' cm% cut at the center

(.& ) sterile peptone water in test tube

% pieces sterile cotton swabs

*( ) ethanol

+etergent

unsen burner or alcohol lamp

Procedure

&. -roups of most students for each shall do the following:

a$ /0pose open plates to the air inside and outside the laboratory for ' minutes

b$ 1ouch agar surface with finger tips before and after running fingers through hair

c$ 1ouch agar surface with finger tips before and aftr washing hands with detergent

d$ 2pread &% drops of tap watr on the agar surface by swirling the plate, and scatter fine soil

particles on the surface of another agar plate.%. Incubate plates in an inverted position inside a plastic bag for %3 hours at room temperature or

at *45.

III. 6esults

2pecies

7orm /levation Margin 5olor "umber

2pecies &

2pecies %

2pecies

2pecies 3

2pecies '

2pecies 8

&. 5ompare the relative abundance of growth on the plates.

%. 2elect isolated colonies from the growth and characteri9e based on type of margin, elevation,

te0ture and color.. /ach student selects a colony to purify for /0ercise 3.

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I. +iscussion

&. ;hat is the source of microorganisms growing on your plate