Cultivable bacterial diversity and amylase production in two typical light-flavor Daqus of Chinese spirits

Abstract

Culture-dependent methods and molecular techniques were used to simultaneously investigate the cultivable bacterial diversity and amylase production in two typical light-flavor Daqus of Chinese spirits. Eight bacteria were identified from Niulanshan Daqu (Bacillus licheniformis, Bacillus subtilis, Bacillus cereus, Bacillus sonorensis, Streptomyces albus, Bacillus atrophaeus, Bacillus tequilensis and Bacillus megaterium) and eight from Hongxing Daqu (B. licheniformis, B. subtilis, B. cereus, Bacillus thuringiensis, Bacillus altitudinis, Bacillus pumilus, Geobacillus stearothermophilus and Bacillus amyloliquefaciens). All of the bacterial isolates from the Hongxing Daqu could produce extracellular α-amylase with a maximum yield of 25.3 U/ml by B. cereus H17, whereas B. licheniformis H55 could produce a maximum glucoamylase yield of 41.6 U/ml. Some of the bacterial isolates from the Niulanshan Daqu could also produce extracellular α-amylase and glucoamylase. The maximum yield of 27.6 U/ml α-amylase was achieved by B. subtilis N3, and the maximum yield of 58.1 U/ml glucoamylase was achieved by B. cereus N25. Bacillus licheniformis, B. subtilis and B. cereus were not only the dominant bacteria, but also possessed high α-amylase and glucoamylase activities, which may play very important roles during fermentation.

Keywords:

• Chinese spirits
• Daqu
• bacterial diversity
• 16S rRNA gene
• α-amylase
• glucoamylase

Acknowledgements

The authors are thankful to those who sent the Daqu samples for this research.

Funding

This research was financially supported by the National Key Technology R&D Program of China [no. 2012BAK17B11] and Beijing Municipal Commission of Education and Subsidy for Outstanding People of Beijing [no. KM201311417007; PXM2013_014209_07_000082; 2011A005022000004].

Disclosure statement

No potential conflict of interest was reported by the authors.