In order to improve the use of waste beer yeast (WBY) for bacterial cellulose production by Gluconacetobacter
hansenii CGMCC 3917, a two-step pre-treatment was designed. First WBY was treated by 4 methods: 0.1 M
NaOH treatment, high speed homogenizer, ultrasonication and microwave treatment followed by hydrolysis
(121 C, 20 min) under mild acid condition (pH 2). The optimal pre-treatment conditions were evaluated by
the reducing sugar yield after hydrolysis. 15% WBY treated by ultrasonication for 40 min had the highest
reducing sugar yield (29.19%), followed by NaOH treatment (28.98%), high speed homogenizer (13.33%)
and microwaves (13.01%). Treated WBY hydrolysates were directly supplied as only nutrient source for BC
production. A sugar concentration of 3% WBY hydrolysates treated by ultrasonication gave the highest BC
yield (7.02 g/L), almost 6 times as that from untreated WBY (1.21 g/L). Furthermore, the properties of the
BC were as good as those obtained from the conventional chemical media.