This document discusses the importance of soil as a nutrient-rich medium for plants and a habitat for various bacteria. It details an experiment conducted to identify and compare bacterial populations in normal soil versus chicken farm soil, showing that chicken farm soil is more contaminated due to its higher nutrient content. The study employed techniques such as serial dilution, spread plating, and various staining methods to analyze microbial diversity and contamination levels.

1. Introduction
Soil is an important source which is rich of nutrients for plants. Besides that, soil
also act as an excellent medium that suitable for various type of bacteria to survive.
The identities of microbes that survived in soil are unable to determine directly as there
are A huge number of species of bacteria contained in this medium. To study the level
of contaminated of soil by microbes and the types of the bacteria that survive in
different types of condition, the selective condition is provided to carry out the
experiment. Since the identification and comparison, the types of microbes that
survived in soil cannot be determined directly, therefore a series of an experiment is
carried out. Isolation of microbes from two soil sample which is normal soil and chicken
farm soil is done by using the technique of serial dilution and spread plate. The series
of dilution in tubes were 10-2
,10-3
, 10-4
,10-5
, and 10-6
and transfer them into a nutrient
agar plate and nutrient agar plate with 7.5% NaCl after each dilution. After incubation
of the plates, the enumeration of microorganisms is started by technique of standard
Plate Count and identification of colony morphology. The colonies which grew in agar
plate streak into new agar plate which is a pure culture for microbes and incubated it.
Lastly, identification and differentiation of microorganisms with using simple stain, gram
stain and endospore stain methods. In the gram stain, crystal violet dye, gram’s iodine
and counterstain safranin are used to differentiated whether the microbes contain in
both soils are gram-positive or negative bacteria. However, endospore stain is to
determine the present of endospore in the bacteria with using counterstain safranin
and malachite green dye. From this experiment, we can conclude out the level of
contaminated of soil with different condition and also the types of the bacteria that
survive in different types of condition. From these two issues, we can that chicken farm
soil is more contaminated by bacteria than normal soil as chicken farm soil provide
higher nutrients to bacteria that normal soil. As we can have counted the number colony
from in the plates with a higher dilution of bacteria is the lowest number of population
of bacteria. Besides that, chicken farm soil is more contaminated than the normal soil,
thus the amount and types of microbes will be higher in normal soil. Furthermore, the
growth of microbes in plate agar with 7.5 % of NaCl will be more active than the normal
nutrient agar. Thus, microbes are more flavour to survive in salty media they are gram
negative bacteria which have thin cell wall than the gram positive bacteria. There are
not only vegetative endospores bacteria live in soil but also the bacteria without
endospore. In short, soil is a media that rich of different species of microbes that we
can explore.