Bacterial Community Dynamics during Malting Based on T-RFLP and 454 Pyrosequencing Profiles

Abstract:

Characterization of the microflora during malting is an essential step towards process management and optimization. The aim of this study was to characterize the bacterial communities using two culture-independent methods，including Terminal Restriction Fragment Length Polymorphism（T-RFLP） and 454 pyrosequencing，targeting the 16S rRNA gene. In order to analyze bacterial communities and dynamics fully and precisely，the same batch of barley originated from two harvest years using two malting methods was studied in entire bacterial community and lactic acid bacteria（LAB）. The results showed that the bacterial community structure of barley from different years was different and changed during the malting process，but there was no significance difference between the two malting methods. Zooming in the LAB community using 454 pyrosequencing revealed a total of 139 operational taxonomic units（OTUs）. LAB diversity appeared relatively limited since 88% of the sequences were covered by the same five OTUs（representing members of Weissella，Lactobacillus and Leuconostoc） present in all samples investigated. Fluctuations in the relative abundances of the dominant LAB were observed with the process conditions. In addition，both the year of harvest and malting environment influenced the LAB community structure.