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Biocontained Carcass Composting for Control of Infectious Disease Outbreak in Livestock
Published on: May 6, 2010
Dead bacterial biomass-assimilating bacterial populations in compost revealed by high-sensitivity stable isotope
Dai Hanajima1, Tomo Aoyagi2, Tomoyuki Hori2
1Dairy Research Division, Hokkaido Agricultural Research Center, National Agriculture and Food Research Organization (NARO), 1 Hitsujigaoka, Toyohira, Sapporo 062-8555, Japan.
Abstract:
Pathogens are known to survive in compost and to regrow under the influence of certain factors, such as moisture content, temperature and nutrient availability. Dead biomass, by providing available nutrients, is a factor that may affect pathogen regrowth. However, the indigenous microorganisms, including pathogens, that grown on the dead biomass of compost have not yet been identified. Here, the regrowth potential of the pathogenic indicator bacterium Escherichia coli in the presence of dead bacterial biomass was determined, and the biomass metabolizers that grew competitively with E. coli were identified by high-sensitivity stable isotope probing of rRNA. Culture-dependent analysis indicated that the addition of dead bacterial biomass did not stimulate E. coli growth. High-throughput analysis of density-resolved 16S rRNA molecules from compost samples amended with carbon-13-labeled dead bacterial biomass revealed dead bacterial-assimilating bacteria, including Sphingobium sp., myxobacterial lineages and Bacillales. These bacteria are potentially competitive with pathogens due to their preferential assimilation of dead biomass in compost.
Insights
Dead bacterial biomass in compost does not promote pathogen regrowth. Instead, indigenous bacteria like Sphingobium sp. consume this biomass, potentially outcompeting pathogens in compost environments.
Area of Science:
- Environmental microbiology
- Compost microbiology
- Bacterial ecology
Background:
- Pathogens can survive and regrow in compost, influenced by factors like moisture, temperature, and nutrients.
- Dead microbial biomass in compost provides nutrients that may affect pathogen regrowth.
- The specific microorganisms, including pathogens, that utilize dead biomass in compost are not well-identified.
Purpose of the Study:
- To determine the regrowth potential of the pathogenic indicator bacterium Escherichia coli in compost with dead bacterial biomass.
- To identify microorganisms that metabolize dead bacterial biomass and grow competitively with E. coli.
Main Methods:
- Culture-dependent analysis to assess E. coli growth.
- High-sensitivity stable isotope probing of rRNA (using 13C-labeled biomass) to identify biomass metabolizers.
- High-throughput sequencing of 16S rRNA molecules.
Main Results:
- Addition of dead bacterial biomass did not stimulate E. coli growth in compost.
- Indigenous bacteria, including Sphingobium sp., myxobacterial lineages, and Bacillales, were identified as consumers of dead bacterial biomass.
- These identified bacteria preferentially assimilated the dead biomass.
Conclusions:
- Dead bacterial biomass in compost does not enhance the regrowth of the pathogen Escherichia coli.
- Certain indigenous compost bacteria possess the capability to metabolize dead bacterial biomass.
- These biomass-metabolizing bacteria may compete with and limit pathogen growth in compost.
