title: Occurrence of psychrotolerant Bacillus cereus group strains in ice creams.
abstract: The occurrences of Bacillus cereus group strains in 40 ice cream samples were investigated. Among 109 isolated B. cereus group strains confirmed by 16S rDNA sequence analysis only 50 were identified as B. cereus and one as B. thuringiensis by using FDA (U.S. Food and Drug Administration) standard, indicating the two identification standards were highly inconsistent. Furthermore, the psychrotolerant growth properties and the occurrence of specific psychrotolerant genes of the isolates were also studied. Both psychrotolerant 16S rDNA fragments and enterotoxic genes could be detected among mesophilic and psychrotolerant strains. No relationship among psychrotolerance, presence of psychrotolerant 16S rDNA fragments and enterotoxic genes were found and the specific cspA fragment was only detected in a small fraction (9.5%) of the psychrotolerant isolates. One psychrotolerant isolate Bw2-1 was identified as B. weihenstephanensis, but no clear distinguishing characteristics between B. weihenstephanensis and psychrotolerant B. cereus were found. These results might be of importance for gaining further understanding of the growth properties of B. weihenstephanensis and psychrotolerant B. cereus as well as their contribution to food poisoning.
authors.affiliation: Center for Applied and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
authors.forename: Guoping
authors.initials: G
authors.lastname: Zhou
authors.forename: Dasheng
authors.initials: D
authors.lastname: Zheng
authors.forename: Lina
authors.initials: L
authors.lastname: Dou
authors.forename: Quanxin
authors.initials: Q
authors.lastname: Cai
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Yuan
mesh_terms: D001409:Bacillus cereus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000528:radiation effects; D001413:Bacillus thuringiensis / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D003080:Cold Temperature; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D005798:Genes, Bacterial; D006801:Humans; D007054:Ice Cream / Q000382:microbiology*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D014481:United States
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S