title: [Isolation, identification and characterization of acid-producing strains from psychrotolerant biogas fermentation].
abstract: OBJECTIVE
  The aim of this study was to screen acid-producing strains from the broth of psychrotolerant biogas fermentation and evaluate the acid-producing character of them.
  
  
  METHODS
  Acid-producing strains were isolated by a medium with methyl red at 4 degrees C in Petri dishes and identified by morphology observation and 16S rRNA sequencing. Moreover, the ability of hydrolysis of starch, fermentation of carbohydrates, liquefaction of gelatin and production of catalase were studied.
  
  
  RESULTS
  Two acid-producing strains (FJ-8 and FJ-15) were isolated. The result of the 16S rRNA phylogenetic tree shows that FJ-8 and FJ-15 belong to Pseudomonas sp. and Shewanella sp., respectively. Both FJ-8 and FJ-15 could hydrolyze starch, liquidize gelatin and produce catalase. The optimum temperature for acid-producing of FJ-8 and FJ-15 is 15 degrees C and 20 degrees C, respectively. After 10 days cultivation at 4 degrees C, the concentration of acetic acid was 792 mg/L and 966 mg/L of FJ-8 and FJ-15, respectively.
  
  
  CONCLUSIONS
  The selected strains, FJ-8 and FJ-15, have the potential to produce acids at low temperature.
authors.forename: Yongqing
authors.initials: Y
authors.lastname: Wan
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.lastname: Mandlaa
authors.forename: Ruihua
authors.initials: R
authors.lastname: Tian
authors.forename: Ruigang
authors.initials: R
authors.lastname: Wang
authors.forename: Kaihong
authors.initials: K
authors.lastname: Duan
mesh_terms: D000143:Acids / Q000737:chemistry / Q000378:metabolism*; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D056804:Biofuels / Q000032:analysis / Q000382:microbiology*; D002681:China; D004269:DNA, Bacterial / Q000235:genetics; D005285:Fermentation; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D000143:Acids; D056804:Biofuels; D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S