Thin stillage (TS), wastewater from rice wine distillery, was used as a cost-free feedstock to replace the costly traditional Hestrin and Schramm (HS) medium for BC production by Gluconacetobacter xylinus. Due to the rich organic acids and amino acids content in TS, BC production was significantly enhanced as 50 (v/v) % of HS medium was replaced with TS. In the 50/50 TS-HS medium, BC concentration of 6.26 g/l could be obtained after 7 days static cultivation which is approximately 50% higher than that could be produced in HS-only medium. The BC produced by TS containing medium had slightly denser reticulated structures and higher crystallinity index values but with lower water holding capacities than that obtained from HS medium. Based on the 50% cost-free TS, the 50/50 TS-HS medium had a BC production feedstock cost about 67% lower than that of traditional HS medium. The employment of cost-free TS to replace a portion of HS medium to achieve a higher BC production not only can reduce the BC production cost but also solve the wastewater disposal problem of winery industry. (C) 2012, The Society for Biotechnology, Japan. All rights reserved.