title: Changes in the rRNA levels of specific microbial groups in activated sludge during sample handling and storage.
abstract: OBJECTIVE
  To quantitatively analyse the changes in group-specific rRNA levels in activated sludge as a function of sample handling and storage procedure.
  
  
  RESULTS
  Quantitative membrane hybridizations with (32)P-labelled oligonucleotide probes were used to analyse the effects of different sample handling and storage conditions on the relative rRNA levels of the alpha, beta, and gamma-Proteobacteria, the Cytophaga-Flavobacteria group, and the mycolic acid-containing actinomycetes in activated sludge. Group-specific rRNA levels, expressed as percentages of total 16S rRNA detected with a universal probe, in samples maintained at room temperature significantly changed after 48 h. Group-specific rRNA levels in samples treated with chloramphenicol showed significant change after 72 h.
  
  
  CONCLUSIONS
  Sample storage at room temperature is a viable option if freezing or analysis can be performed within 24 h, while treatment with chlorampenicol can extend that time to at least 48 h.
  
  
  CONCLUSIONS
  Handling, shipping, and storage of environmental samples under several conditions may result in inaccurate determination of the microbial populations in microbial ecology studies.
authors: Department of Civil, Construction and Environmental Engineering, North Carolina State University, Raleigh, NC 27695-7908, USA.
authors: J E
authors: JE
authors: Keith
authors: J G
authors: JG
authors: Boyer
authors: F L
authors: FL
authors: de los Reyes
mesh_terms: D039903:Actinobacteria / Q000302:isolation & purification; D004783:Environmental Microbiology; D005417:Flavobacterium / Q000302:isolation & purification; D009693:Nucleic Acid Hybridization; D011309:Preservation, Biological; D020560:Proteobacteria / Q000302:isolation & purification; D012329:RNA, Bacterial / Q000032:analysis*; D012331:RNA, Fungal / Q000032:analysis*; D012335:RNA, Ribosomal / Q000032:analysis*; D012722:Sewage / Q000382:microbiology*; D013997:Time Factors
chemical_list: D012329:RNA, Bacterial; D012331:RNA, Fungal; D012335:RNA, Ribosomal; D012722:Sewage