Microbial population dynamics during fed-batch operation of commercially available garbage composters.
Microbial populations in terms of quantity, quality, and activity were monitored during 2 months of start-up operation of commercially available composters for fed-batch treatment of household biowaste. All the reactors, operated at a waste-loading rate of 0.7 kg day(-1) (wet wt), showed a mass reduction efficiency of 88-93%. The core temperature in the reactors fluctuated between 31 degrees C and 58 degrees C due to self-heating. The pH declined during the early stage of operation and steadied at pH 7.4-9.3 during the fully acclimated stage. The moisture content was 48-63% early in the process and 30-40% at the steady state. Both direct total counts and plate counts of bacteria increased via two phases (designated phases I, II) and reached an order of magnitude of 10(11) cells g(-1) (dry wt) at the steady state. Microbial community changes during the start-up period were studied by culture-independent quinone profiling and denatured gradient gel electrophoresis (DGGE) of PCR-amplified 16S rDNA. In all the reactors, ubiquinones predominated during phase I, whereas partially saturated menaquinones became predominant during phase II. This suggested that there was a drastic population shift from ubiquinone-containing Proteobacteria to Actinobacteria during the start-up period. The DGGE analysis of the bacterial community in one of the reactors also demonstrated a drastic population shift during phase I and the predominance of members of the phyla Proteobacteria and Bacteroidetes during the overall period. But this molecular analysis failed to detect actinobacterial clones from the reactor at any stage.
Department of Ecological Engineering, Toyohashi University of Technology, 441-8580, Toyohashi, Japan.
T
T
Narihiro
T
T
Abe
Y
Y
Yamanaka
A
A
Hiraishi
D039903:Actinobacteria / Q000145:classification / Q000302:isolation & purification; D001419:Bacteria / Q000145:classification / Q000254:growth & development* / Q000302:isolation & purification; D041963:Bacteroidetes / Q000145:classification / Q000302:isolation & purification; D019149:Bioreactors; D015169:Colony Count, Microbial; D004269:DNA, Bacterial / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism; D004275:DNA, Ribosomal / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism; D017753:Ecosystem; D004591:Electrophoresis, Polyacrylamide Gel; D005735:Garbage; D006863:Hydrogen-Ion Concentration; D009691:Nucleic Acid Denaturation; D016133:Polymerase Chain Reaction; D020560:Proteobacteria / Q000145:classification / Q000302:isolation & purification; D011809:Quinones / Q000032:analysis / Q000302:isolation & purification; D012037:Refuse Disposal / Q000379:methods*; D012987:Soil; D012988:Soil Microbiology; D013696:Temperature
D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D011809:Quinones; D012987:Soil