Analysis of Bacterial Abundance and Species Diversity in Various Soils
type: CreativeWork
description: Different soil types display a wide range of nutrient content, microbial abundance and diversity. Many of the microbes viable in soil have practical functions in the agricultural and medical fields while others are pathogenic. Garden topsoil, potting soil, forest soil, compost and manure were the five soil types investigated in this study for bacterial abundance, species diversity, and nutrient content. We hypothesized that manure and compost would have the most nutrients and be highest in number and diversity of bacteria. Likewise, we hypothesized that potting soil would be low in all three areas. Each soil sample was diluted, plated on Plate Count Agar and incubated at 37oC for 2 days in order to maximize the number of colonies able to grow on the media. The bacteria count was determined by plate count assay and the microbial abundance by using 16S rDNA to sequence isolated species and compare the number of genera present in each soil type. A qualitative nutrient analysis was conducted to evaluate the relative nutrient content of each soil type. It was determined that the compost was richest in nitrate, phosphorus and potassium, while the other soils were low in all three. The manure exhibited a significantly higher bacterial count than all the other samples. Potting soil, compost, garden topsoil and forest soil followed with less significant variance. Similarly, the manure represented the greatest number of genera from the 16S rDNA sequencing than the other samples.
abstract: Different soil types display a wide range of nutrient content, microbial abundance and diversity. Many of the microbes viable in soil have practical functions in the agricultural and medical fields while others are pathogenic. Garden topsoil, potting soil, forest soil, compost and manure were the five soil types investigated in this study for bacterial abundance, species diversity, and nutrient content. We hypothesized that manure and compost would have the most nutrients and be highest in number and diversity of bacteria. Likewise, we hypothesized that potting soil would be low in all three areas. Each soil sample was diluted, plated on Plate Count Agar and incubated at 37oC for 2 days in order to maximize the number of colonies able to grow on the media. The bacteria count was determined by plate count assay and the microbial abundance by using 16S rDNA to sequence isolated species and compare the number of genera present in each soil type. A qualitative nutrient analysis was conducted to evaluate the relative nutrient content of each soil type. It was determined that the compost was richest in nitrate, phosphorus and potassium, while the other soils were low in all three. The manure exhibited a significantly higher bacterial count than all the other samples. Potting soil, compost, garden topsoil and forest soil followed with less significant variance. Similarly, the manure represented the greatest number of genera from the 16S rDNA sequencing than the other samples.
author: Roth, McKenzie L.
language: English
keywords: Microbiology, Soil nutrients, soil bacteria, soil microbes, bacterial abundance, microbial abundance, compost, manure, topsoil, potting soil, forest soil, 16S rDNA
date published: 2012
date modified: 2026-07-24T03:35:52Z
provider: OhioLINK
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Ashland University Honors Theses