American Society of Agricultural and Biological Engineers

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Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Transactions of the ASAE. Vol. 46(3): 919–927 . (doi: 10.13031/2013.13568) @2003
Authors:   P. D. Schloss, A. G. Hay, D. B. Wilson, L. P. Walker
Keywords:   Automated ribosomal intergenic spacer analysis (ARISA), Composting, Inoculum, Reproducibility

Traditional analysis of composting process dynamics has focused on changes in physical variables such as temperature, pH, and effluent gas composition. However, to better understand the effect and value of microbial inoculation for reducing process variability, it is necessary to employ techniques that allow for the measurement of changes in community composition. In this study, automated ribosomal intergenic spacer amplification (ARISA) analysis was performed to characterize the ability of inoculated microorganisms from primary effluent wastewater to persist during the initial stages of composting in micro–scale reactors. We found that while the initial microbial communities differed based on inoculation level, after 24 h the microbial community no longer resembled the initial community. In addition, the effect of inoculation was no longer apparent at this point. There was a clear relationship between the variability observed between physical process variables and the composition of the microbial communities. The largest source of variation was due to seasonal changes, suggesting that despite the addition of an inoculum, a source of inoculation that varies between reactor groups is not being controlled. It is hypothesized that this source of inoculation is either from the air being forced through the reactors or from sparsely populated microbial populations in the initial substrate that become active at different rates in different reactor groups. Furthermore, this analysis demonstrates that it is possible to employ a simple molecular technique to understand the effects of inoculation and process reproducibility in a traditional agricultural waste treatment bioprocess.

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