Determination of fungal succession during municipal solid waste composting using a cloning-based analysis.

AIMS: The microbiota at industrial full-scale composting plants has earlier been fragmentarily studied with molecular methods. Here, fungal communities from different stages of a full-scale and a pilot-scale composting reactors were studied before and after wood ash amendment. METHODS AND RESULT: The portion of fungal biomass, determined using phospholipid fatty acid analysis, varied between 6.3% and 38.5% in different composting phases. The fungal internal transcribed spacer (ITS) area was cloned and sequenced from 19 samples representing different stages of the composting processes. Altogether 2986 sequenced clones were grouped into 166 phylotypes from which 35% had a close match in the sequence databases. The fungal communities of the samples were related with the measured environmental variables in order to identify phylotypes typical of certain composting conditions. The fungal phylotypes could be grouped into those that dominated the mesophilic low pH initial phases (sequences similar to genera Candida, Pichia and Dipodascaceae) and those found mostly or exclusively in the thermophilic phase (sequences clustering to Thermomyces, Candida and Rhizomucor), but a few were also present throughout the whole process. CONCLUSIONS: The community composition was found to vary between suboptimally and optimally operating processes. In addition, there were differences in fungal communities between processes of industrial and pilot scale. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this study reveal the fungal diversity with molecular methods in industrial composting process. This is also one of the first studies conducted with samples from an industrial biowaste composting process.

Gas chromatographic-mass spectrometric detection of 2- and 3-hydroxy fatty acids as methyl esters from soil, sediment and biofilm.

Hydroxy fatty acids (OH-FAs) can be used in the characterization of microbial communities, especially Gram-negative bacteria. We prepared methyl esters of 2- and 3-OH-FAs from the lipid extraction residue of soil, sediment, and biofilm samples without further purification or derivatization of hydroxyl groups. OH-FA methyl esters were analyzed using a gas chromatograph equipped with a mass selective detector (GC-MS). The ions followed in MS were m/z 103 for 3-OH-FAs and m/z 90 and M-59 for 2-OH-FAs. The rapid determination of 3- and 2-OH-FAs concomitantly with phospholipid fatty acids provided more detailed information on the microbial communities present in soil, sediment, and drinking water biofilm.