pH Effect and pH Changes during Biocellulose Production by Gluconacetobacter xylinus in Moringa oleifera Tea-Sugar Medium

Abstract

The study was carried out to determine the effect of pH and pH changes accompanying Biocellulose (BC) production by Gluconacetobacter xylinus (GX) in a Moringa oleifera tea-sugar medium. The authors adopted experimental and comparative design for the study. Moringa oleifera leaves were harvested at the front of Physics laboratory, Federal College of Education (Technical) Omoku. Nigeria. Banana was purchased from vendors in Omoku market and kept for 5-7 days to allow the development of acetic acid bacteria. Gluconacetobacter xylinus (GX) was isolated from spoiled banana and used to inoculate Moringa oleifera tea-yeast extract medium to which different concentrations of sugars-fructose, glucose and a combination of glucose and fructose were added. The pH of the medium was adjusted to pH ranging from 4-8, sterilized by autoclaving at 121°C for 15min. Media were inoculated in duplicates with 0.1 ml of GX and incubated at 30°C for 15 days to observe for cellulosic pellicle. The pellicles were extracted by alkaline hydrolysis, washed and weighed. Changes in pH were also monitored in the course of the fermentation. The Mean BC yield were 0.175±0.12, 0.182±0.12, 0.085 ±0.05, 0.025 ±0.03 and 0.018 ±0.03 at pH 4,5,6,7 and 8 respectively. pH changes during fermentation tended towards neutral or near-neutral range while it increased from an initial value of 4 and 5 to around 6. pH 7-8 of the fermenting mixture decreased with increasing sugar concentration but in the order, Glucose-fructose medium<Glucose medium<Fructose medium. The result of this study showed that Biocellulose, which is a biopolymer used for various industrial applications can be produced from a readily and sustainable source, Moringa olefera leaves with control of pH and concentration of added sugar.