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Group-specific PCR-RFLP and real-time PCR methods for detection and tentative discrimination of strictly anaerobic beer-spoilage bacteria of the class Clostridia.

Abstract：

:The strictly anaerobic brewery contaminants of the genera Pectinatus, Megasphaera, Selenomonas and Zymophilus in the class Clostridia constitute an important group of spoilage bacteria of unpasteurised, packaged beers. The aim of this study was to develop and evaluate group-specific PCR methods to detect and differentiate these bacteria in beer. A group-specific primer pair targeting a 342-bp variable region of the 16S rRNA gene was designed and evaluated in end-point PCR with gel electrophoresis and in real-time PCR with SYBR Green I dye. Significant cross-reactions with DNAs from any of the forty-two brewery-related, non-target microbes or from real brewery samples were not detected in either PCR system. The group-specific end-point and real-time PCR products could be differentiated according to species/genus and spoilage potential using restriction fragment length polymorphism (KpnI, XmnI, BssHII, ScaI) and melting point curve analysis, respectively. In combination with a rapid DNA extraction method, the PCR reactions detected ca 10(0)-10(3) CFU per 25 ml of beer depending on the strain and on the PCR system. The end-point and real-time PCR analysis took 6-7 h and 2-3 h, respectively. Pre-PCR enrichment of beer samples for 1-3 days ensured the detection of even a single cultivable cell. The PCR and cultivation results of real brewery samples were mostly congruent but the PCR methods were occasionally more sensitive. The PCR methods developed allow the detection of all the nine beer-spoilage Pectinatus, Megasphaera, Selenomonas and Zymophilus species in a single reaction and their differentiation below group level and reduce the analysis time for testing of their presence in beer samples by 1-2 days. The methods can be applied for brewery routine quality control and for studying occurrence, diversity and numbers of the strictly anaerobic beer spoilers in the brewing process.

journal_name

Int J Food Microbiol

journal_title

International journal of food microbiology

authors

Juvonen R,Koivula T,Haikara A

doi

10.1016/j.ijfoodmicro.2008.03.042

subject

Has Abstract

pub_date

2008-07-15 00:00:00

pages

162-9

issue

eissn

0168-1605

issn

1879-3460

pii

S0168-1605(08)00165-7

journal_volume

125

pub_type

杂志文章

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Group-specific PCR-RFLP and real-time PCR methods for detection and tentative discrimination of strictly anaerobic beer-spoilage bacteria of the class Clostridia.