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Isolation and identification of high pressure‐resistant bacteria naturally contaminating strawberry pulp
Author(s) -
Huang Jingjing,
Wang Siyuan,
Zhang LiYun,
Wu Jihong,
Xu Zenghui,
Liao Xiaojun,
Hao Yanling,
Zhang Yan
Publication year - 2012
Publication title -
international journal of food science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.831
H-Index - 96
eISSN - 1365-2621
pISSN - 0950-5423
DOI - 10.1111/j.1365-2621.2012.03144.x
Subject(s) - 16s ribosomal rna , bacteria , biology , strain (injury) , hydrostatic pressure , microbiology and biotechnology , ribosomal rna , gene , food science , biochemistry , genetics , physics , anatomy , thermodynamics
Summary The inactivation of bacteria naturally present in strawberry pulp was investigated after high hydrostatic pressure ( HHP ) treatment at pressure levels up to 600 MPa at 25 °C for 5 ~ 25 min. Five strains of pressure‐resistant bacteria designated as A, B, C, D and E were isolated and identified. The five strains were gram‐positive, spore‐forming, rods or rod in chains. Growth of the strains was observed at 30 ~ 45 °C, and strain B also grew well at 55 °C. They could produce acid from glucose and were catalase‐positive. Analysis of 16S r RNA gene sequences showed that the five strains belonged to the genus B acillus . Strain A and D exhibited the greatest 16S r RNA gene sequence similarity of 99% with B . licheniformis and B . firmus , respectively. By combination of phenotypic characteristics and 16 S rRNA gene sequences, strain C was B . mycoides and E was B . pumilus . On the basis of physiological and biochemical characteristics, gyr B gene sequences analysis and whole‐cell fatty acids analysis, strain B was B. amyloliquefaciens . Further studies showed that strain B ( B . amyloliquefaciens ) exhibited the highest pressure resistance, and it was reduced by 4.62‐log after treatment at 600 MPa for 25 min at 25 °C as the most effective observed inactivation.