Investigation of Effect of Yeast Addition in Bacterial Cellulose Production

Abstract

Commercially, Bacterial Cellulose (BC) is synthesized by a monoculture of bacteria from the Komagataeibacter genus. Yet, the same bacteria is also found to be able to coexist with other bacteria and yeasts in kombucha. The role of yeasts in kombucha is still uncertain with possibilities that the yeast can help break down sucrose for bacteria and synthesize acids to promote the bacteria’s growth. However, there is also a possibility that the yeasts can outcompete the bacteria causing them to starve. This study aims to investigate the effects of yeast isolate, Dekkera bruxellensis, on BC production by K. intermedius; particularly the effects of different concentrations and at different timepoints of the fermentation in a media containing sugarcane molasses, acetate buffer (pH 4.75 and 0.2 M) and synthetic caffeine. CFU count, BC yield, SEM and pH values were taken to investigate the effects of yeast towards bacteria growth. Results show that the bacteria was able to increase the pH during fermentation up to 9. Adding high concentrations of yeast on day 0 was able to slow down the pH increase, increase bacteria survival for a longer period of time and increase BC yield. Low concentrations of yeast had the same effect, but caused a decrease in BC yield. Adding yeasts on day 7 was found to have no effect on BC yield and bacteria survival. The presence of yeast was found to not affect the bacteria’s growth and the morphology of coculture’s BC was found to be more web-like.