EMISSION OF CLIMATE-RELEVANT TRACE GASES AND SUCCESSION OF MICROBIAL COMMUNITIES DURING OPEN-WINDOW COMPOSTING

Determination of different indicators of microbial biomass, community structure, and bioactivity by the fumigation extraction method, as wel l as determination of phospholipid fatty acids (PLFAs) and their subfr actions and the measurement of trace gases, respectively, provides val uable information about microbial succession in composting processes, The emission rates of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) increased successively during compost maturation: initial ly in the presence of easily degradable nutrients, during high tempera ture, and after the temperature had cooled down, respectively, The emi ssion rate patterns of these trace gases corresponded to the concentra tions of PLFAs and their particular subfractions, (i) Similar to the C O2 emission rates, microbial biomass estimations by fumigation extract ion and by determination of the amount of total PLFAs showed a discont inuous decrease during the composting process, with a slight increase at the end of the observation period, (ii) An increase in ether lipids , indicating the enhanced presence of archaean methanogens, and an ele vated CH4 emission were observed at the same time, (iii) The period of enhanced N2O emission corresponded to the increase in beta and omega hydroxy fatty acids derived from the outer membrane. Additionally, the continuous increase in branched-chain fatty acids suggested an increa se in gram-positive bacteria and actinomycetes, and the decrease in po lyunsaturated fatty acids indicated a decrease in eukaryotic cells dur ing the composting.