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Variation of broth composition by addition of broiler litter composting substrate extracts: influence on faecal bacterial growth
Author(s) -
Sobratee N.,
Mohee R.,
Driver M.F.B.
Publication year - 2009
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/j.1365-2672.2009.04318.x
Subject(s) - compost , bacterial growth , broiler , food science , growth curve (statistics) , bacteria , litter , escherichia coli , biology , substrate (aquarium) , manure , microbiology and biotechnology , composition (language) , growth rate , zoology , chemistry , mathematics , ecology , biochemistry , statistics , genetics , linguistics , philosophy , gene , geometry
Aim: This study investigates differences in bacterial growth response in broth amended with compost‐substrate extracts periodically bypassed during broiler litter composting. Methods and Results: Compost samples, suspended in diluent were mixed with double strength broth into which ampicillin selective (0·3 g l −1 ) Escherichia coli and E. faecalis were separately seeded. Growth was measured by viable cell count. The Levenberg–Marquardt algorithm was applied to obtain a four‐parameter sigmoidal function that best described the diminishing height transitions of the curves for extracts of increasing composting age. The time course of the growth rate followed a unimodal bell‐shaped curve. The Microfit © application was run to generate information of direct microbiological interest: increasing λ and decreasing μ max for both bacteria with time. Conclusion: More than the curve‐fitting process, the Unified model option of the Microfit © application has confirmed the significant differences ( P < 0·05) in the growth curve behaviour with more stabilized substrate extracts. The study demonstrates further scopes for characterization of the sanitization potential and indirectly, the impact of indigenous microbial competitive exclusion effects on enteric bacteria. Significance and Impact of the Study: A different outlook to understanding faecal bacterial growth dynamics in compost has been presented, using predictive microbiology concepts. Further structured studies are needed to fine‐tune the generality of the findings for model development.