title: The effect of pH on growth of Clostridium botulinum type A and expression of bontA and botR during different growth stages.
abstract: In this study, the effects of pH on the growth, relative expressions of bontA and botR genes, and neurotoxin formation of foodborne pathogens Clostridium botulinum type A were systematically studied throughout its growth stage. As in the previous reports, no C. botulinum growth was observed at extremely acidic pH. However, the effect of alkaline pH on the growth and neurotoxin production of C. botulinum was first revealed in this study. The maximum growth rate at pH 9.0 was similar to that at other pH values, although the lag phase at pH 9.0 was 16 h longer than that at pH 8.0. The peak of bontA mRNA expression at pH 9.0 was only 15.5% compared with that at pH 7.0. However, the neurotoxin concentration quantified in the cultures did not differ significantly. BotR is a known regulatory protein of bontA. The quantitative relationship between bontA and botR at different growth stages was first determined in this study. The mRNA levels of bontA were found to be positively correlated with those of botR, and the ratio of the mRNA transcript varied with pH. All these findings provide important physiological information on C. botulinum and thereby contribute to the improvement of food safety.
authors.affiliation: State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Li
authors.forename: Renmao
authors.initials: R
authors.lastname: Tian
authors.forename: Kun
authors.initials: K
authors.lastname: Cai
authors.forename: Qin
authors.initials: Q
authors.lastname: Wang
authors.forename: Fanghong
authors.initials: F
authors.lastname: Chen
authors.forename: Huali
authors.initials: H
authors.lastname: Fang
authors.forename: Sen
authors.initials: S
authors.lastname: Luo
authors.forename: Zhan
authors.initials: Z
authors.lastname: Li
authors.forename: Dehui
authors.initials: D
authors.lastname: Wang
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Hou
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D019274:Botulinum Toxins, Type A / Q000235:genetics / Q000378:metabolism*; D047013:Clostridium botulinum type A / Q000235:genetics* / Q000254:growth & development*; D005506:Food Contamination / Q000032:analysis; D005516:Food Microbiology; D059022:Food Safety; D015964:Gene Expression Regulation, Bacterial; D006863:Hydrogen-Ion Concentration; D009498:Neurotoxins / Q000235:genetics / Q000378:metabolism; D012329:RNA, Bacterial / Q000302:isolation & purification; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C116103:BotR protein, Clostridium botulinum; D009498:Neurotoxins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D015534:Trans-Activators; D019274:Botulinum Toxins, Type A