Indigenous microbial community of barley greatly influences grain germination and malt quality

Abstract

The present study was carried out to investigate the impacts of bacterial and fungal communities on grain germination and on the malting properties of good-quality two-row barley. In order to suppress the growth of bacterial and/or fungal communities, various antibiotics were added to the first steeping water of barley. This study was also designed to explore the dynamics of the bacterial community in the malting process after antimicrobial treatments by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The diverse microbial community played an active role in the malting ecosystem. Even previously undescribed bacterial species were found in the malting ecosystem. Suppression of the bacterial community mainly consisting of Gram-negative bacteria was advantageous with respect to grain germination and wort separation. In addition, more extract was obtained after antibacterial treatments. The fungal community significantly contributed to the production of microbial β-glucanases and xylanases, and was also involved in proteolysis. An improved understanding of the complex microbial community and its role in malting enables a more controlled process management and the production of high quality malt with tailored properties. © 2007 The Institute of Brewing & Distilling.