Conclusions
The use of PLFA analysis provides a method for following
general patterns in microbial community composition that
occur during composting. In this study, a full and pilot-scale
facility were compared. In addition, several different types of
material were composted. The patterns of change in community
structure (based on PLFA profiles) in material processed
at the full-scale facility were similar to those observed
at the pilot-scale, although they differed significantly in the
time of their occurrence. The microbial community within
the pilot-scale system progressed more rapidly through the
expected changes than did the full-scale community. Regardless,
the PLFA profile pattern that emerged (from the
complete process) was consistent, predictable, and in agreement
with the microbial communities expected. Given this,
the PLFA profile may be a useful tool for determining—in
any given run—the stage of composting attained. It might
also provide a means of identifying stages where a process
parameter or other problem is retarding progress. In this
fashion, it may allow optimization of a composting situation.
PLFA analysis also indicated that a specific community
structure was present in stabilized composts.
Characterization of microbial community PLFA structure
of stabilized composts may, thus, provide a method of determining
maturity and/or stabilization of varied composts.
The extraction and analysis of PLFAs is probably too complicated
and/or expensive a method to be employed routinely
by commercial compost operations. It may be feasible
for compost laboratories such as the P&G facility evaluated
here to use this type of analysis for process optimization
studies and for the evaluation of material (or waste stream)
compostability. The applicability and validity of using a pilot-
scale facility was verified by this study, where the P&G
system realistically simulated and supported the same general
microbial communities found at the full-scale facility.