The Development of Acetobacter Xylinum Growth Measurement Through Total Protein Analysis

Acetobacter xylinum, an aerobic Gram-negative bacterium secretes ribbon-like cellulose polymer through the cell wall during growth. The information available on the growth determination of this organism was largely based on turbidimetric measurements which are inaccurate due to the presence of cellulose fragments in the growth medium. Therefore, this study was aimed at developing a rapid and more accurate method for the determination of A. xylinum growth through total protein analysis. The fermentation process was carried out at room temperature in static cultures using Hestrin-Schramm medium at pH 6.4 for 19 days. The methods used for the bacterial growth determination included the total protein content, cell dry weight, viable plate count, and turbidimetry. The total cellular protein content was determined based on the Lowry method after the cells were hydrolyzed in 3 % (w/v) of potassium hydroxide (KOH) and boiled for 20 minutes. It was found that the growth profile obtained through the total protein analysis has similar pattern with other conventional methods. However, this method was found to be more accurate and less time-consuming compared to viable plate count and cell dry weight. The growth curve obtained showed four microbial growth phases, namely lag phase (day 0 - day 3), log phase (day 4 - day 12), stationary phase (day 13 - day 16), and finally death phase. The average total cellular protein content of A. xylinum was 27.1 ± 6.8 % by weight percent. (author)