Enzymatic biodegradation of a mannan and galactoglucomannan extracted from African rose wood and Agba wood by hemicellulase from Bacillus trypoxylicola

Abstract

Biodegradability varies from polymer to polymer due to the difference in chemical composition. The purpose of this study is to provide a proper understanding on the biodegradability of two previously extracted and characterized hemicellulose biopolymers; ARW (a linear mannan) and AW (a galactoglucomannan). In the current study, previously extracted and characterized hemicellulose from African rose wood (ARW) and Agba wood (AW) were subjected to hydrolysis by hemicellulase from a freshly isolated soil bacterium identified as Bacillus trypoxylicola with 99% sequence similarity. The hemicellulose from ARW and AW were soluble in water. The specific activity of hemicellulase from B. trypoxylicola on hemicellulose extracted from ARW from day 2 to 7 (694.44 ± 1.61 to 734.19 ± 14.12 U/mg) was significantly higher than that of AW (434.09 ± 3.76 to 37.36 ± 25.65 U/mg) with P-values ≤ 0.05. The concentration of reducing sugars released from AW between day 2 and day 6 (3.46 ± 0.04 to 3.00 ± 0.04 mM) exceeded that of ARW (2.53 ± 0.01 to 2.40 ± 0.02 mM), p-values ≤ 0.05, except for day 7 which was 2.51 ± 1.15 and 2.18 ± 0.03 U/mg for AW and ARW, respectively, P-value = 0.185. Hemicellulose from ARW showed some degree of resistance to microbial/enzymatic degradation with maximum reducing sugar release of 2.92 ± 0.08 mM on D4 when compared to that of AW, 3.56 ± 0.07 mM on D3.