Application of genotypic and phenotypic analyses to commercial probiotic strain identity and relatedness.
OBJECTIVE
The objective of this study was to generate strain-specific genomic patterns of a bank of 67 commercial and reference probiotic strains, with a focus on probiotic lactobacilli.


RESULTS
Pulsed-field gel electrophoresis (PFGE) was used as the primary method for strain differentiation. This method was compared with carbohydrate fermentation analysis. To supplement visual comparison, PFGE patterns were analysed quantitatively by cluster analysis using unweighted pair group method with arithmetic averages. SmaI, NotI and XbaI were found to effectively generate clear and easy-to-interpret PFGE patterns of a range of probiotic strains. Some probiotic strains from different sources shared highly similar PFGE patterns.


CONCLUSIONS
Results document the value of genotypic strain identification methods, combined with phenotypic methods, for determining probiotic strain identity and relatedness. No correlation was found between relatedness determined by carbohydrate fermentation profiles alone compared with PFGE analysis alone. Some commercial strains are probably derived from similar sources.


CONCLUSIONS
This approach is valuable to the probiotic industry to develop commercial strain identification patterns, to provide quality control of strain manufacturing production runs, to track use of protected strains and to determine the relatedness among different research and commercial probiotic strains.
Dairy Products Technology Center, California Polytechnic State University, San Luis Obispo, USA.
P S M
PS
Yeung
C L
CL
Kitts
R
R
Cano
P S
PS
Tong
M E
ME
Sanders
D015373:Bacterial Typing Techniques / Q000379:methods*; D001644:Bifidobacterium / Q000145:classification / Q000235:genetics / Q000378:metabolism; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000235:genetics; D003611:Dairy Products / Q000382:microbiology; D016521:Electrophoresis, Gel, Pulsed-Field / Q000379:methods; D005838:Genotype; D007218:Industrial Microbiology / Q000379:methods; D007778:Lactobacillus / Q000145:classification* / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D019936:Probiotics / Q000378:metabolism*
D004269:DNA, Bacterial